Battery cell and battery

Abstract

The invention relates to the technical field of batteries, in particular to a battery cell and a battery. The battery cell comprises a first pole piece, a second pole piece and a diaphragm, the first pole piece comprises a first current collector, a first active material layer and first gummed paper; a plurality of first concave-convex structures are arranged on the first active material layers at intervals, the first concave-convex structures form first concave parts on one first active material layer, and the first concave-convex structures form first convex parts on the other first active material layer; the first gummed paper covers part of the first concave-convex structures, a plurality of second concave-convex structures are arranged on the first gummed paper at intervals, and the second concave-convex structures form second convex parts and second concave parts on the two opposite sides of the first gummed paper respectively; and the second convex part and the first concave part are correspondingly arranged or the second concave part and the first convex part are correspondingly arranged. The electrolyte is not easy to enter between the first gummed paper and the first active material layer, and side reaction between the electrolyte and the adhesive layer is reduced, so that failure of the adhesive layer is prevented, and lithium precipitation is not easy to occur at the edge of the gummed paper.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery cell and a battery. Background Art

[0002] With the rapid development of lithium-ion battery technology, people have put forward higher requirements on the energy density, cycle life and safety performance of lithium-ion batteries.

[0003] At present, the battery cell includes a positive electrode sheet, a negative electrode sheet and a separator between the positive electrode sheet and the negative electrode sheet. Adhesive tape is respectively attached to the active material layer of the positive electrode sheet and the active material layer of the negative electrode sheet to avoid contact short circuit between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet, the separator and the negative electrode sheet are stacked and wound to form a battery cell. In order to avoid the problem of lithium precipitation caused by the reduction of the inter-electrode distance due to the expansion of the positive electrode sheet and the negative electrode sheet during the charge and discharge process of the battery, a concave-convex structure is provided on the positive electrode sheet and / or the negative electrode sheet.

[0004] However, the adhesive tape cannot adhere well to the active material layer of the electrode, and the electrolyte will enter between the adhesive tape and the active material layer of the electrode, causing lithium deposition at the edge of the negative electrode corresponding to the adhesive tape. Summary of the invention

[0005] Based on this, the present application provides a battery cell and a battery to solve the problem in the prior art that the adhesive tape cannot be well bonded to the active material layer of the electrode, resulting in lithium deposition at the edge of the negative electrode corresponding to the adhesive tape.

[0006] On the one hand, the present application provides a battery cell, comprising a first pole piece, a second pole piece, and a separator located between the first pole piece and the second pole piece, wherein the first pole piece, the second pole piece, and the separator are stacked and wound to form a battery cell;

[0007] The first pole piece includes a first current collector, a first active material layer located on both sides of the first current collector, and a first adhesive tape attached to the first active material layer, wherein the first adhesive tape is located on a side of the first active material layer away from the first current collector;

[0008] The second pole piece includes a second pole lug;

[0009] A plurality of first concavo-convex structures are arranged at intervals on the first active material layer, wherein the first concavo-convex structures form a first concave portion on one of the first active material layers, and the first concavo-convex structures form a first convex portion on another first active material layer;

[0010] The first adhesive tape covers part of the first concave-convex structure, and the first adhesive tape covers the projection of the second electrode tab on the first electrode sheet; a plurality of second concave-convex structures are arranged at intervals on the first adhesive tape, and the second concave-convex structures form a second convex portion and a second concave portion on opposite sides of the first adhesive tape respectively;

[0011] The second convex portion is arranged correspondingly to the first concave portion or the second concave portion is arranged correspondingly to the first convex portion.

[0012] In a possible implementation, the difference between the height of the first convex portion and the depth of the second concave portion is less than or equal to 1 mm; the difference between the depth of the first concave portion and the height of the second convex portion is less than or equal to 1 mm.

[0013] In a possible implementation manner, the first pole piece has a first edge, and the first edge and an adjacent second concave-convex structure have a first interval in the second direction.

[0014] In a possible implementation, the width of the first interval is W1, and W1 satisfies:

[0015] 1mm≤W1≤5mm.

[0016] In a possible implementation, the first adhesive tape has a first side edge and a second side edge that are oppositely arranged in the first direction, and the first adhesive tape has a third side edge that is away from the first edge in the second direction;

[0017] A second interval is formed between the first side edge, the second side edge and the third side edge and the adjacent second concave-convex structures.

[0018] In a possible implementation, the width of the second interval is W2, and W2 satisfies:

[0019] 0.5mm≤W2≤5mm.

[0020] In a possible implementation, in the first concave-convex structure located outside the first adhesive tape, a first side edge, a second side edge, and a third side edge respectively have a third interval with adjacent first concave-convex structures.

[0021] In a possible implementation, the width of the third interval is W3, and W3 satisfies:

[0022] 0.5mm≤W3≤5mm.

[0023] In a possible implementation, the depth of the second concave portion covering the first concave portion is H1, the thickness of the straight region of the first active material layer is H2, and H1 and H2 satisfy:

[0024] 0.6×H2≤H1≤0.9×H2.

[0025] In a possible implementation, first adhesive tape is respectively attached to the two first active material layers;

[0026] The first adhesive tapes on the two first active material layers are arranged at intervals along the first direction, and the first adhesive tapes on the two first active material layers are respectively located on two opposite sides of the second electrode tab.

[0027] In a possible implementation, the first pole piece further includes a first pole ear and a second adhesive tape;

[0028] The first current collector and the first active material layer define a tab groove, the first tab extends into the tab groove and is electrically connected to the first current collector;

[0029] The second adhesive tape is disposed on the side of the first active material layer away from the first current collector and covers the electrode tab groove;

[0030] A plurality of third concave-convex structures are arranged at intervals on the second adhesive tape.

[0031] In a possible implementation, the first concave-convex structure has a first projection in the third direction, and the diameter of the circumscribed circle of the first projection is R1, and R1 satisfies:

[0032] 0.3mm≤R1≤8mm; and / or,

[0033] The first concave-convex structure has a first projection in the third direction, and the distance between the edges of the circumscribed circles of two adjacent first projections is D1, and D1 satisfies:

[0034] 1mm≤D1≤6mm; and / or,

[0035] The depth of the first concave portion is H3, and H3 satisfies:

[0036] 3μm≤H3≤80μm; and / or,

[0037] The first concave-convex structure has a first projection in the third direction, and at least one corner of the first projection is rounded.

[0038] In a possible implementation, the tensile strength of the first adhesive tape is 30 N / m²-170 N / m².

[0039] On the other hand, the present application also provides a battery, comprising the above-mentioned battery cell.

[0040] The cell and battery provided by the present application have a first adhesive tape attached to the first active material layer of the first pole piece of the cell. By arranging a plurality of first concave-convex structures at intervals on the first active material layer of the first pole piece, the liquid retention between the first pole piece and the second pole piece is ensured, and a buffer space can also be reserved for the expansion of the pole piece. The first concave-convex structure is also arranged in the area where the first adhesive tape is attached to the first active material layer, so that there will be no lack of electrolyte between the area where the first adhesive tape is attached to the first active material layer and the second pole piece, thereby avoiding lithium precipitation due to lack of electrolyte.

[0041] In the process of attaching the first adhesive tape, by applying roller pressure to the first adhesive tape, the first convex part on the first active material layer is extended into the second concave part of the first adhesive tape, or the second convex part of the first adhesive tape is extended into the first concave part on the first active material layer, so that the air between the first adhesive tape and the first concave-convex structure corresponding to it is discharged, and the gap between the first active material layer and the first adhesive tape caused by the setting of the first concave-convex structure is reduced. Through the cooperation between the second concave-convex structure of the first adhesive tape and the first concave-convex structure of the first active material layer, the first adhesive tape and the first active material layer can be attached more closely, and the electrolyte is not easy to enter between the first adhesive tape and the first active material layer, thereby reducing the side reaction between the electrolyte and the adhesive layer, preventing the adhesive layer from failing, making it difficult for lithium to be deposited at the edge of the adhesive tape and relieving the lithium deposition of the corresponding negative electrode sheet. In addition, the first protrusion on the first active material layer extends into the second concave portion of the first adhesive tape, or the second protrusion of the first adhesive tape extends into the first concave portion on the first active material layer, thereby increasing the friction between the first adhesive tape and the first active material layer. The first adhesive tape is not easily displaced relative to the first active material layer, and thus the first adhesive tape can reliably avoid a short circuit between the first electrode plate and the second electrode plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0043] Figure 1 It is a schematic diagram of the structure of a battery cell in the prior art;

[0044] Figure 2 is a schematic structural diagram of a first pole piece in the prior art;

[0045] Figure 3 It is a schematic diagram of the first pole piece facing the inside of the battery cell and the outside of the battery cell in the prior art;

[0046] Figure 4 A schematic diagram of the first pole piece provided in an embodiment of the present application facing the inside of the battery cell and the outside of the battery cell;

[0047] Figure 5 A cross-sectional view of a first pole piece provided in an embodiment of the present application at a position of a first adhesive tape covering a first protrusion;

[0048] Figure 6 A cross-sectional view of a first pole piece provided in an embodiment of the present application at a position of a first adhesive tape covering a first recess;

[0049] Figure 7 for Figure 4 A local enlarged schematic diagram of the location of the dotted box in the middle.

[0050] Description of reference numerals:

[0051] 100-first pole piece; 110-first current collector; 120-first active material layer; 121-first concave-convex structure; 1211-first concave portion; 1212-first convex portion; 130-first pole ear; 140-first adhesive tape; 141-second concave-convex structure; 1411-second concave portion; 1412-second convex portion; 142-first side edge; 143-second side edge; 144-third side edge; 150-second adhesive tape; 151-third concave-convex structure; 160-pole ear groove; 170-first edge;

[0052] 200-second pole piece; 210-second pole ear;

[0053] 300-Diaphragm.

[0054] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme in the embodiment of the present application will be described in more detail below in conjunction with the drawings in the preferred embodiments of the present application. In the drawings, the same or similar reference numerals throughout represent the same or similar parts or parts with the same or similar functions. The described embodiments are part of the embodiments of the present application, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limitations on the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application. The embodiments of the present application are described in detail below in conjunction with the drawings.

[0056] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, or it can be an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0057] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are orientations or positional relationships based on the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0058] The terms "first", "second" and "third" (if any) in the specification and claims of this application and the above drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0059] In addition, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, for example, a process, method, system, product, or display comprising a series of steps or elements is not necessarily limited to those steps or elements explicitly listed, but may include other steps or elements not explicitly listed or inherent to such process, method, product, or display.

[0060] In the prior art, such as Figure 1 and Figure 2 As shown, the battery cell includes a first pole piece 100, a second pole piece 200, and a diaphragm 300 located between the first pole piece 100 and the second pole piece 200. The first pole piece 100, the diaphragm 300, and the second pole piece 200 are stacked and wound to form a battery cell. The cross section of the battery cell presents a flat elliptical structure, with arc areas on both sides and a plane area in the middle. During the charging and discharging process of the battery, the first pole piece 100 and the second pole piece 200 will expand, and the arc area of ​​the battery cell has a particularity that the stress is large, which can easily lead to the deformation of the battery cell due to the extrusion of the arc area. The plane area of ​​the battery cell has been extruded in the hot pressing process during the production process, and the plane area will be squeezed very tightly, resulting in poor infiltration of the electrolyte.

[0061] like Figure 3As shown, some battery cells will form a plurality of first concave-convex structures 121 on the first active material layer 120 of the first electrode sheet 100. The plurality of first concave-convex structures 121 allow a micro gap to appear between the first electrode sheet 100 and the second electrode sheet 200 for storing electrolyte, while relieving the squeezing between the electrodes caused by the expansion of the first electrode sheet 100 and the second electrode sheet 200, thereby relieving the deformation and excessive expansion of the battery cell. Adhesive tape needs to be provided on the first electrode sheet 100 to prevent the burrs generated during the welding of the pole tabs from piercing the diaphragm 300 and causing a short circuit. If the tape is attached to the first concave-convex structure 121, the adhesive layer of the tape cannot fit well with the first active material layer 120 of the first electrode 100, and there is a gap between the tape and the first active material layer 120 due to the existence of the first concave-convex structure 121. The electrolyte will enter between the tape and the first active material layer 120. During the charge and discharge process of the battery, the part of the first active material layer 120 covered by the tape will release lithium ions, and the electrolyte between the tape and the first active material layer 120 will move to the edge of the tape, causing lithium deposition at the edge of the tape.

[0062] If the area of ​​the first pole piece 100 where the tape is provided does not have the first concave-convex structure 121, the area of ​​the first pole piece 100 where the tape is provided will lack electrolyte compared to other areas, resulting in lithium deposition during battery cycling.

[0063] After repeated thinking and verification, the inventor found that if multiple first concave-convex structures are formed on the first active material layer of the first pole piece, and some of the first concave-convex structures are located in the area where the adhesive tape is pasted, lithium deposition can be avoided in the area where the adhesive tape is pasted due to lack of electrolyte. Multiple second concave-convex structures are arranged at intervals on the adhesive tape of the first pole piece, and the second concave-convex structures form second convex parts and second concave parts on opposite sides of the adhesive tape, respectively, and the second convex parts are arranged corresponding to the first concave parts, and the second concave parts are arranged corresponding to the first convex parts. After the adhesive tape is pasted on the first active material layer, the first convex part can extend into the second concave part or the second convex part can extend into the first concave part. The gap between the adhesive tape and the first active material layer can be reduced by the cooperation between the second concave-convex structure and the first concave-convex structure, so that lithium deposition is not easy to occur at the edge of the adhesive tape, and the friction between the adhesive tape and the first active material layer is increased, and the battery cell is not prone to problems such as insufficient electrolyte, expansion and extrusion deformation, interface deterioration caused by lithium deposition, and cycle failure.

[0064] In view of this, the inventor has designed a battery cell and a battery, in which a plurality of first concave-convex structures are formed on the first active material layer of the first pole piece, and the adhesive tape of the first pole piece covers part of the first concave-convex structures, so that the battery cell is not prone to expansion, extrusion, deformation, and insufficient liquid retention. A plurality of second concave-convex structures are arranged on the adhesive tape at intervals, and the gap between the adhesive tape and the first active material layer of the first pole piece is reduced by the cooperation between the second concave-convex structures and the first concave-convex structures, so that lithium deposition is not likely to occur at the edge of the adhesive tape, and the friction between the adhesive tape and the first active material layer is increased.

[0065] The technical solutions of the battery cell and the battery provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0066] The battery cell provided in the embodiment of the present application includes a first pole piece 100, a second pole piece 200 and a diaphragm 300. The diaphragm 300 is located between the first pole piece 100 and the second pole piece 200. The first pole piece 100, the second pole piece 200 and the diaphragm 300 are stacked and wound to form a battery cell. The positions of the first pole piece 100, the second pole piece 200 and the diaphragm 300 in the battery cell are similar to Figure 1 The positions in the existing cells shown are the same.

[0067] It can be understood that the battery cell provided in the embodiment of the present application is a winding core, and the cross-section of the battery cell presents a flat elliptical structure, with arc areas on both sides and a plane area in the middle. Among them, one of the first pole piece 100 and the second pole piece 200 is a positive pole piece and the other is a negative pole piece. The diaphragm 300 between the first pole piece 100 and the second pole piece 200 can prevent contact short circuit between the first pole piece 100 and the second pole piece 200. This embodiment is described by taking the first pole piece 100 as a positive pole piece and the second pole piece 200 as a negative pole piece as an example, but it is not a limitation on the scope of protection.

[0068] The first electrode sheet 100 includes a first current collector 110, a first active material layer 120 located on both sides of the first current collector 110, and a first adhesive tape 140 attached to the first active material layer 120. The first adhesive tape 140 is located on the side of the first active material layer 120 away from the first current collector 110. Schematically, the relative positions of the first current collector 110, the first active material layer 120 and the first adhesive tape 140 are as follows: Figure 2 The conventional first pole piece 100 shown is the same.

[0069] When the first electrode sheet 100 is a positive electrode sheet, aluminum foil can be used as the first current collector 110, and the thickness of the first active material layer 120 on both sides of the first current collector 110 is the same. In the length direction of the first electrode sheet 100, that is, the direction indicated by the X-axis in the figure, one end of the first active material layer 120 on one side of the first current collector 110 exceeds one end of the first active material layer 120 on the other side of the first current collector 110, and the ends of the first active material layer 120 on both sides of the first current collector 110 do not extend to the edge of the first current collector 110. The first current collector 110 and the first active material layers 120 on both sides of the first current collector 110 define a double-sided area, a single-sided area and an empty foil area. The first current collector 110 is provided with the first active material layer 120 on both sides of the double-sided area, the first current collector 110 is provided with the first active material layer 120 on only one side of the single-sided area, and the first current collector 110 is not provided with the first active material layer 120 on both sides of the empty foil area. After the first pole piece 100 , the separator 300 and the second pole piece 200 are wound to form a battery cell, the side of the first pole piece 100 with the longer first active material layer 120 faces the inside of the battery cell, and the side with the shorter first active material layer 120 faces the outside of the battery cell.

[0070] The second pole piece 200 includes a second pole tab 210. Schematically, the second pole piece 200 also includes a second current collector and a second active material layer located on both sides of the second current collector. The second pole tab 210 can be electrically connected to the second current collector by welding. The position of the second pole tab 210 in the battery cell can be the same as that of the second pole tab 210. Figure 1 The existing cells shown are the same.

[0071] like Figure 4-Figure 6 As shown, a plurality of first concave-convex structures 121 are arranged at intervals on the first active material layer 120, the first concave-convex structures 121 form a first concave portion 1211 on one of the first active material layers 120, and the first concave-convex structures 121 form a first convex portion 1212 on another first active material layer 120. The positions of the plurality of first concave portions 1211 correspond to the positions of the plurality of first convex portions 1212, the first concave portions 1211 have the same shape as the corresponding first convex portions 1212, and the depth of the first concave portions 1211 is the same as the height of the corresponding first convex portions 1212.

[0072] Exemplarily, a plurality of first concave-convex structures 121 spaced apart can be formed on the first active material layer 120 by embossing. Specifically, a roller or mold with a specific pattern can be used to press the first pole piece 100 along the thickness direction of the first pole piece 100, i.e., the direction indicated by the Z axis in the accompanying drawings, and the first active material forms the first concave-convex structure 121 at the position corresponding to the pattern, and the first current collector 110 and the area corresponding to the first concave-convex structure 121 also form a concave-convex structure. Among them, the first convex portion 1212 can be toward the outside of the battery cell or toward the inside of the battery cell, which is not limited here. The shape of the first concave-convex structure 121 can be circular, elliptical, irregular, rhombus or irregular polygonal, etc., which is not limited here.

[0073] It is worth mentioning that the plurality of first protrusions 1212 can play a supporting role between the first pole piece 100-diaphragm 300-second pole piece 200, so that a micro gap appears between the first pole piece 100 and the second pole piece 200 for storing electrolyte and ensuring the amount of liquid between the first pole piece 100 and the second pole piece 200. The first recess 1211 can play a role in storing electrolyte and also ensure the amount of liquid between the first pole piece 100 and the second pole piece 200.

[0074] The first adhesive tape 140 covers part of the first concave-convex structure 121, and the first adhesive tape 140 covers the projection of the second pole ear 210 on the first pole piece 100. The first adhesive tape 140 includes a substrate and an adhesive layer, and can be attached to the first active material layer 120 through the adhesive layer. The substrate can play an insulating role to prevent the burrs generated by the second pole ear 210 of the second pole piece 200 during welding from piercing the diaphragm 300 and contacting the first pole piece 100 to cause a short circuit in the battery.

[0075] A plurality of second concave-convex structures 141 are arranged at intervals on the first adhesive tape 140, and the second concave-convex structures 141 respectively form second convex portions 1412 and second concave portions 1411 on opposite sides of the first adhesive tape 140. In the same first adhesive tape 140, the shape of the second concave portion 1411 is the same as the shape of the corresponding second convex portion 1412, and the depth of the second concave portion 1411 is the same as the height of the corresponding second convex portion 1412.

[0076] The second convex portion 1412 is arranged correspondingly to the first concave portion 1211 or the second concave portion 1411 is arranged correspondingly to the first convex portion 1212. Schematically, the spacing between the plurality of second concave-convex structures 141 is the same as the spacing between the plurality of first concave-convex structures 121 covered by the first adhesive tape 140 on the first active material layer 120. Figure 5 As shown, when the first adhesive tape 140 covers the first convex portion 1212 of the first concave-convex structure 121, the first convex portion 1212 extends into the interior of the second concave portion 1411. Figure 6As shown, when the first adhesive tape 140 covers the first concave portion 1211 of the first concave-convex structure 121, the second convex portion 1412 extends into the first concave portion 1211. The number of the second concave-convex structures 141 on the first adhesive tape 140 is related to the length and width of the first adhesive tape 140. The larger the area of ​​the first adhesive tape 140, the greater the number of the second concave-convex structures 141.

[0077] In the battery cell provided in this embodiment, a first adhesive tape 140 is attached to the first active material layer 120 of the first pole piece 100. A plurality of first concave-convex structures 121 are arranged at intervals on the first active material layer 120 of the first pole piece 100. The first concave-convex structures 121 form a first concave portion 1211 on one of the first active material layers 120, and the first concave-convex structures 121 form a first convex portion 1212 on another first active material layer 120. The plurality of first convex portions 1212 can play a supporting role between the first pole piece 100 and the second pole piece 200, so that a micro gap appears between the first pole piece 100 and the second pole piece 200 for storing electrolyte; the plurality of first concave portions 1211 can also play a role in storing electrolyte. The above arrangement can ensure the amount of liquid retained between the first pole piece 100 and the second pole piece 200. At the same time, the plurality of first convex portions 1212 can also reserve internal space between the first pole piece 100 and the second pole piece 200 for the expansion of the pole pieces, thereby alleviating the extrusion between the pole pieces caused by the expansion of the first pole piece 100 and the second pole piece 200, and the battery cell is not prone to expansion, extrusion and deformation. The problems of lithium deposition and interface deterioration are not prone to occur between the first pole piece 100 and the second pole piece 200, thereby ensuring the cycle performance of the battery. The first adhesive tape 140 covers part of the first concave-convex structure 121, that is, the area where the first active material layer 120 is attached with the first adhesive tape 140 is also provided with the first concave-convex structure 121, and the area where the first active material layer 120 is attached with the first adhesive tape 140 is also provided with the first concave-convex structure 121, so that there will be no lack of electrolyte between the area where the first active material layer 120 is attached with the first adhesive tape 140 and the second pole piece 200, thereby avoiding lithium deposition due to lack of electrolyte.

[0078] A plurality of second concave-convex structures 141 are arranged at intervals on the first adhesive tape 140, and the second concave-convex structures 141 respectively form second convex portions 1412 and second concave portions 1411 on opposite sides of the first adhesive tape 140. The second convex portions 1412 are arranged correspondingly to the first concave portions 1211, or the second concave portions 1411 are arranged correspondingly to the first convex portions 1212. In the process of attaching the first adhesive tape 140, by applying roller pressure to the first adhesive tape 140, the first convex portions 1212 on the first active material layer 120 are extended into the second concave portions 1411 of the first adhesive tape 140, or the second convex portions 1412 of the first adhesive tape 140 are extended into the first concave portions 1211 on the first active material layer 120, so that the air between the first adhesive tape 140 and the corresponding first concave-convex structures 121 is discharged, and the gap between the first active material layer 120 and the first adhesive tape 140 caused by the arrangement of the first concave-convex structures 121 is reduced. Through the cooperation between the second concave-convex structure 141 of the first adhesive tape 140 and the first concave-convex structure 121 of the first active material layer 120, the first adhesive tape 140 and the first active material layer 120 can be more closely attached, and the electrolyte is not easy to enter between the first adhesive tape 140 and the first active material layer 120, thereby reducing the side reaction between the electrolyte and the adhesive layer, preventing the adhesive layer from failing, making it less likely for lithium to be deposited at the edge of the adhesive tape and alleviating the lithium deposition of the corresponding negative electrode sheet.

[0079] In addition, the first protrusion 1212 on the first active material layer 120 extends into the second concave portion 1411 of the first adhesive tape 140 or the second protrusion 1412 of the first adhesive tape 140 extends into the first concave portion 1211 on the first active material layer 120, thereby increasing the friction between the first adhesive tape 140 and the first active material layer 120. The first adhesive tape 140 is not easily displaced relative to the first active material layer 120, and thus the first adhesive tape 140 can reliably avoid a short circuit between the first electrode 100 and the second electrode 200.

[0080] Indicatively, Figure 7 As shown, the first concave-convex structure 121 has a first projection in the third direction, and the diameter of the circumscribed circle of the first projection is R1, and R1 satisfies: 0.3 mm≤R1≤8 mm.

[0081] It should be noted that the third direction is the thickness direction of the first pole piece 100, that is, the direction indicated by the Z axis of the accompanying drawing. Among them, when the shape of the first concave-convex structure 121 is circular, R1 is the diameter of the circle. Exemplarily, the size of R1 can be 0.3mm, 2mm, 4mm, 6mm or 8mm, etc., which is not limited here. When R1 is less than 0.3mm, the area of ​​the first concave-convex structure 121 is too small, and it is easy to cause a tip effect when the first concave-convex structure 121 is set on the first active material layer 120, resulting in damage to the first pole piece 100; when R1 is greater than 8mm, the convex surface span of the first convex portion 1212 formed by the first concave-convex structure 121 on one side of the first pole piece 100 is too large, which is not conducive to the multiple first convex portions 1212 playing a supporting role between the first pole piece 100 and the second pole piece 200.

[0082] This structure ensures that the first pole piece 100 is not easily damaged when the first concave-convex structure 121 is set, and at the same time, it can ensure that the multiple first convex parts 1212 play a good supporting role, ensure the liquid retention between the first pole piece 100 and the second pole piece 200, and at the same time reliably alleviate the extrusion between the pole pieces caused by the expansion of the first pole piece 100 and the second pole piece 200, so that the battery cell is not prone to expansion, extrusion and deformation.

[0083] Preferably, 1mm≤R1≤3mm. For example, 1mm, 1.5mm, 2mm or 3mm. The above arrangement further ensures that the first pole piece 100 is not easily damaged when the first concave-convex structure 121 is arranged, and further ensures the liquid retention between the first pole piece 100 and the second pole piece 200. The plurality of first convex portions 1212 can further alleviate the squeezing between the pole pieces caused by the expansion of the first pole piece 100 and the second pole piece 200.

[0084] In one possible implementation, Figure 7 As shown, the first concave-convex structure 121 has a first projection in the third direction, and the distance between the edges of the circumscribed circles of two adjacent first projections is D1, and D1 satisfies: 1mm≤D1≤6mm.

[0085] For example, the distance between the edges of two adjacent circumscribed circles may be 1 mm, 2 mm, 4 mm or 6 mm, etc., and no unique limitation is made here. When D1 is less than 1 mm, in the process of setting the first concave-convex structure 121 on the first active material layer 120, two adjacent first concave-convex structures 121 are prone to overlap, resulting in damage to the first pole piece 100; when D1 is greater than 6 mm, the distance between the two adjacent first concave-convex structures 121 is too large, and the multiple first convex portions 1212 are difficult to play an effective supporting role between the first pole piece 100 and the second pole piece 200, and the electrolyte is easily lacking between the first pole piece 100 and the second pole piece 200, and the battery cell is prone to expansion, extrusion and deformation. In other words, by limiting the size of D1, it is possible to avoid overlapping between two adjacent first concave-convex structures 121, while ensuring that the multiple first convex portions 1212 can play a good supporting role between the first pole piece 100 and the second pole piece 200.

[0086] Preferably, 1.5 mm ≤ D1 ≤ 4 mm. For example, D1 may be 1.5 mm, 2 mm, 3 mm or 4 mm. The above arrangement further avoids overlap between two adjacent first concave-convex structures 121, and further ensures that the plurality of first convex portions 1212 can play a good supporting role between the first pole piece 100 and the second pole piece 200.

[0087] like Figure 5 As shown, the depth of the first concave portion 1211 is H3, and H3 satisfies: 3 μm≤H3≤80 μm.

[0088] Among them, the depth H3 of the first concave portion 1211 is the same as the height of the corresponding first convex portion 1212. The size of H3 can be tested by a 3D profilometer. Exemplarily, H3 can be 3μm, 20μm, 40μm or 80μm, etc., and is not limited here. The specific size of H3 can be controlled by setting the height of the protrusion of the pattern on the roller or mold and the size of the force applied to the first pole piece 100 during pressing. The above setting means are conventional operations in this field. When H3 is less than 3μm, the multiple first convex portions 1212 do not play an effective supporting role between the first pole piece 100 and the second pole piece 200, and are invalid protrusions, which cannot allow the electrolyte to have sufficient infiltration of the battery cell; when H3 is greater than 80μm, the protrusion of the first concave portion 1211 corresponding to the first convex portion 1212 is too large, which will cause serious stratification between the first pole piece 100 and the second pole piece 200 and cause new interface problems. That is to say, the above arrangement can ensure the liquid retention between the first pole piece 100 and the second pole piece 200, ensure that the electrolyte can sufficiently penetrate the battery cell, and at the same time avoid new interface problems caused by excessive gap between the first pole piece 100 and the second pole piece 200.

[0089] In a possible implementation, the first concave-convex structure 121 has a first projection in the third direction, and at least one corner of the first projection is a rounded corner. The radius of the rounded corner can be set as needed and is not limited here. The above setting reduces the number of sharp corners in the shape of the first concave-convex structure 121.

[0090] In a specific implementation, all corners of the first projection may be rounded.

[0091] When a roller or a mold with a specific pattern is used to press along the first pole piece 100 to form the first concave-convex structure 121, the shape of the first concave-convex structure 121 is the same as the shape of the pattern on the roller or the mold. The sharp edge of the pattern on the roller or the mold can easily pierce the first active material layer 120, causing cracks and causing powder loss.

[0092] In this embodiment, the first electrode sheet 100 is not prone to powder loss when the first concave-convex structure 121 is provided on the first active material layer 120 , and the battery is not prone to short circuit and fire due to particles falling off the first active material layer 120 .

[0093] In other embodiments, the shape of the first concavo-convex structure 121 is circular, elliptical or quasi-circular. The above arrangement also makes it difficult for powder to fall off when the first concavo-convex structure 121 is arranged on the first active material layer 120 of the first electrode plate 100 .

[0094] Illustratively, the tensile strength of the first adhesive tape 140 is 30 N / m²-170 N / m².

[0095] It is understood by those skilled in the art that the tensile strength of the first adhesive tape 140 can be controlled by setting the base material of the first adhesive tape 140 and the thickness of the first adhesive tape 140. When the tensile strength of the first adhesive tape 140 is less than 30N / m², the second concave-convex structure 141 is set on the first adhesive tape 140, which easily causes the first adhesive tape 140 to crack, and the portion of the first active material layer 120 covered by the first adhesive tape 140 will participate in the charge and discharge reaction, resulting in lithium deposition in the battery. When the tensile strength of the first adhesive tape 140 is greater than 170N / m², the cost of the first adhesive tape 140 is high, which increases the production cost of the battery. In other words, the above-mentioned setting can both prevent the first adhesive tape 140 from cracking and control the cost of the first adhesive tape 140.

[0096] In one embodiment, Figure 5 and Figure 6 As shown, the difference between the height of the first convex portion 1212 and the depth of the second concave portion 1411 is less than or equal to 1 mm. The difference between the depth of the first concave portion 1211 and the height of the second convex portion 1412 is less than or equal to 1 mm.

[0097] When the first adhesive tape 140 covers the first concave portion 1211 of the first active material layer 120, the second convex portion 1412 of the second concave-convex structure 141 fits with the first concave portion 1211; when the first adhesive tape 140 covers the first convex portion 1212 of the first active material layer 120, the second concave portion 1411 of the second concave-convex structure 141 fits with the first convex portion 1212. During the production of the first pole piece 100, the first adhesive tape 140 can be firstly attached to the first active material layer 120, and the first pole piece 100 is pressed by a roller or a mold, and the roller or the mold simultaneously presses the first concave-convex structure 121 and the second concave-convex structure 141 in the area of ​​the first adhesive tape 140, and the second concave-convex structure 141 fits with the corresponding first concave-convex structure 121.

[0098] Through the above arrangement, on the one hand, the production efficiency of the first pole piece 100 is improved, and on the other hand, a gap between the first adhesive tape 140 and the first active material layer 120 can be avoided, and the electrolyte will not enter between the first adhesive tape 140 and the first active material layer 120, thereby avoiding lithium deposition at the edge of the first adhesive tape 140. The adhesive layer of the first adhesive tape 140 will not have a side reaction with the electrolyte to cause the adhesive layer to fail, and the first adhesive tape 140 can be reliably attached to the first active material layer 120. In addition, the second concave-convex structure 141 is attached to the corresponding first concave-convex structure 121, further increasing the friction between the first adhesive tape 140 and the first active material layer 120, and the first adhesive tape 140 will not be displaced relative to the first active material layer 120, which is more conducive to the first adhesive tape 140 absorbing burrs from one side of the second pole piece 200, further avoiding the risk of short circuit.

[0099] In a specific embodiment, Figure 4 and Figure 7 As shown, the first pole piece 100 has a first edge 170 , and the first edge 170 and the adjacent second concave-convex structure 141 have a first interval in the second direction.

[0100] It should be noted that the second direction is the width direction of the first pole piece 100, that is, the direction indicated by the Y axis in the figure. The first edge 170 is the edge in the width direction of the first pole piece 100. The first interval defines a first avoidance area.

[0101] It is worth mentioning that during the winding process of the battery cell, it is necessary to ensure that the edge of the negative electrode sheet covers the edge of the positive electrode sheet. During winding, the edge of the electrode sheet is positioned by a positioning device such as a laser device to correct the deviation. The above-mentioned first interval can prevent the first concave-convex structure 121 from causing wavy edges on the edge of the first electrode sheet 100, ensure the positioning effect during the winding of the battery cell, and avoid poor coverage of the battery cell. In addition, the first air avoidance area can also prevent the first concave-convex structure 121 from being set at the edge of the first electrode sheet 100, causing the first electrode sheet 100 to "fall off".

[0102] Indicatively, Figure 7 As shown, the width of the first interval is W1, and W1 satisfies: 1mm≤W1≤5mm.

[0103] It should be noted that the width W1 of the first interval is the interval between the first edge 170 and the nearest second concave-convex structure 141 in the second direction. For example, the size of W1 can be 1mm, 2mm, 3mm or 5mm, etc., which is not limited here. When W1 is less than 1mm, when the first concave-convex structure 121 is set, part of the first concave-convex structure 121 may be located at the edge of the first pole piece 100 due to processing tolerance, which affects the deviation correction during the winding of the battery cell, resulting in poor coverage of the battery cell and causing the first pole piece 100 to "fall powder"; when W1 is greater than 5mm, the multiple first convex portions 1212 are difficult to play a supporting role between the first pole piece 100 and the second pole piece 200, and it is difficult to effectively ensure the liquid retention between the first pole piece 100 and the second pole piece 200 at the position of the first adhesive tape 140. At the same time, the multiple first convex portions of the first pole piece 100 at the position of the first adhesive tape 140 are difficult to effectively alleviate the extrusion between the pole pieces caused by the expansion of the first pole piece 100 and the second pole piece 200, resulting in expansion, extrusion and deformation of the battery cell.

[0104] The above arrangement ensures the deviation correction during winding of the battery cell, and at the same time ensures the liquid retention between the first pole piece 100 and the second pole piece 200 at the position of the first adhesive tape 140, and the battery cell is not prone to expansion, extrusion and deformation.

[0105] In a more specific embodiment, Figure 4 and Figure 7 As shown, the first adhesive tape 140 has a first side edge 142 and a second side edge 143 oppositely disposed in the first direction, and the first adhesive tape 140 has a third side edge 144 away from the first edge 170 in the second direction.

[0106] It should be noted that the first direction is the length direction of the first electrode 100, that is, the direction indicated by the X axis in the figure. Figure 7 The third side edge 144 of the first adhesive tape 140 is the first adhesive tape 140 at the left and right sides of Figure 7 The lower side of the .

[0107] A second interval is formed between the first side edge 142 , the second side edge 143 and the third side edge 144 and the adjacent second concavo-convex structures 141 .

[0108] Schematically, the first side edge 142, the second side edge 143 and the third side edge 144 respectively define a second avoidance zone with the adjacent second concave-convex structure 141, that is, the second concave-convex structure 141 is not arranged at the edge of the first adhesive tape 140 and there is a distance between the second concave-convex structure 141 and the edge of the first adhesive tape 140. It can be understood that the first concave-convex structure 121 corresponding to the second concave-convex structure 141 is also not located at the edge of the first adhesive tape 140 and there is a distance between the first adhesive tape 140 and the edge of the first adhesive tape 140.

[0109] Through the above configuration, the first concave-convex structure 121 covered by the first adhesive tape 140 will not cause the first adhesive tape 140 to warp, thereby preventing the edge of the first adhesive tape 140 from warping and introducing electrolyte, ensuring the bonding reliability between the first adhesive tape 140 and the first active material layer 120 while preventing lithium deposition at the edge of the first adhesive tape 140.

[0110] Indicatively, Figure 7 As shown, the width W2 of the second interval is 0.5 mm-5 mm.

[0111] Wherein, W2 is the minimum width of the second air avoidance area, for example, the size of W2 can be 0.5mm, 1.5mm, 4mm or 5mm, etc. When W2 is less than 0.5mm, the second concave-convex structure 141 and the corresponding first concave-convex structure 121 may be located at the edge of the adhesive tape due to processing tolerance, causing the edge of the first adhesive tape 140 to be lifted and introduce electrolyte; when W2 is greater than 5mm, the number of the first concave-convex structures 121 in the area where the first active material layer 120 is attached to the first adhesive tape 140 is small, and the support of the multiple first concave-convex structures 121 in the area where the first adhesive tape 140 is attached is weak, making it difficult to effectively ensure the amount of liquid retained between the first pole piece 100 and the second pole piece 200 at the position of the first adhesive tape 140, and the battery cell is prone to expansion, extrusion and deformation at the position of the first adhesive tape 140.

[0112] The above arrangement can reliably prevent the edge of the first adhesive tape 140 from warping and introducing electrolyte, while ensuring the amount of liquid retained between the first pole piece 100 and the second pole piece 200 at the position of the first adhesive tape 140, so that the battery cell is not prone to expansion, extrusion and deformation.

[0113] like Figure 4 and Figure 7 As shown, in the first concave-convex structure 121 located outside the first adhesive tape 140 , the first side edge 142 , the second side edge 143 , and the third side edge 144 have a third interval with adjacent first concave-convex structures 121 .

[0114] Schematically, the first side edge 142, the second side edge 143 and the third side edge 144 respectively define a third avoidance zone between the first concave-convex structure 121 adjacent to the outer side of the first adhesive tape 140. Through the above arrangement, the first concave-convex structure 121 can be prevented from being located at the edge of the first adhesive tape 140, and the first concave-convex structure 121 will not cause the edge of the first adhesive tape 140 to be lifted and introduce electrolyte, thereby ensuring the reliability of the bonding between the first adhesive tape 140 and the first active material layer 120 while avoiding lithium deposition at the edge of the first adhesive tape 140.

[0115] In a specific embodiment, Figure 7 As shown, the width W3 of the third interval is 0.5 mm-5 mm.

[0116] Wherein, W3 is the minimum width of the third air avoidance zone, for example, the size of W3 can be 0.5mm, 1.5mm, 4mm or 5mm, etc. When W3 is less than 0.5mm, the first concave-convex structure 121 on the outer side of the first adhesive tape 140 may be located at the edge of the adhesive tape due to processing tolerance, causing the edge of the first adhesive tape 140 to be lifted and introduce electrolyte; when W3 is greater than 5mm, the first concave-convex structure 121 on the outer side of the first adhesive tape 140 is too far away from the first adhesive tape 140, and it is difficult to effectively ensure the amount of liquid retained between the first pole piece 100 and the second pole piece 200 at the outer edge of the first adhesive tape 140, and the battery cell is prone to expansion, extrusion and deformation at the outer edge of the first adhesive tape 140.

[0117] The above arrangement can reliably prevent the edge of the first adhesive tape 140 from curling up and introducing electrolyte, while ensuring the liquid retention between the first electrode piece 100 and the second electrode piece 200 at the outer edge of the first adhesive tape 140, so that the battery cell is not prone to expansion, extrusion and deformation at the outer edge of the first adhesive tape 140.

[0118] In one embodiment, Figure 6 As shown, the depth of the second concave portion 1411 covering the first concave portion 1211 is H1, the thickness of the straight region of the first active material layer 120 is H2, and H1 and H2 satisfy: 0.6×H2≤H1≤0.9×H2.

[0119] Illustratively, H1 = (0.6-0.9) × H2. The ratio between H1 and H2 can be 0.6, 0.7, 0.8 or 0.9, etc., and is not limited here. When H1 < 0.6 × H2, the depth of the first concave-convex structure 121 and the second concave-convex structure 141 is too small, and the first concave-convex structure 121 and the second concave-convex structure 141 play a small role in storing electrolyte and increasing friction to prevent the first adhesive tape 140 from shifting. When H1 > 0.9 × H2, when the first electrode 100 is in the process of setting the first concave-convex structure 121 and the second concave-convex structure 141, the first active material layer 120 will be fractured, which increases the cross-section of the first active material layer 120, increases the side reactions, and causes the electrolyte to be consumed too quickly.

[0120] It should be noted that when the first pole piece 100 is pressed with a roller or a mold with a specific pattern, the first adhesive tape 140 covering the first concave portion 1211 contacts the roller or the mold with the specific pattern. When the first active material layer 120 with the first concave portion 1211 is broken, the first active material layer 120 with the first convex portion 1212 may not be broken; when the first active material layer 120 with the first convex portion 1212 is broken, the first active material layer 120 with the first concave portion 1211 will definitely be broken. By limiting the size of H1, it can be ensured that both first active material layers 120 will not be broken.

[0121] This structure, by limiting the ratio between H1 and H2, prevents the first active material layer 120 from being fractured, while ensuring the amount of liquid retained between the first electrode 100 and the second electrode 200, and effectively increases the friction between the first adhesive tape 140 and the first active material layer 120.

[0122] like Figure 4 As shown, first adhesive tapes 140 are respectively attached to the two first active material layers 120. The first adhesive tapes 140 on the two first active material layers 120 are arranged at intervals along the first direction, and the first adhesive tapes 140 on the two first active material layers 120 are respectively located on opposite sides of the second electrode tab 210. It can be understood that the first adhesive tape 140 on one of the first active material layers 120 covers a plurality of first protrusions 1212, and the second concave portions 1411 of the first adhesive tape 140 are arranged corresponding to the first protrusions 1212, that is, the first protrusions 1212 extend into the corresponding second concave portions 1411. The first adhesive tape 140 on the other first active material layer 120 covers a plurality of first concave portions 1211, and the second protrusions 1412 of the first adhesive tape 140 are arranged corresponding to the first concave portions 1211, that is, the second protrusions 1412 extend into the corresponding first concave portions 1211. The first adhesive tapes 140 on the two first active material layers 120 are respectively opposite to the two sides of the second electrode tab 210.

[0123] Through the above arrangement, the burrs of the welding of the second pole tab 210 will not cause short circuits on both sides of the second pole tab 210. At the same time, the liquid retention between the first pole piece 100 and the second pole piece 200 at the two first adhesive tapes 140 positions can be guaranteed, and the battery cell is not prone to expansion, extrusion and deformation at the two first adhesive tapes 140 positions.

[0124] In one embodiment, Figure 4 As shown, the first electrode sheet 100 further includes a first electrode tab 130 and a second adhesive tape 150. The positions of the first electrode tab 130 and the second adhesive tape 150 in the first electrode sheet 100 may be Figure 2 The first electrode sheet 100 shown is the same as the conventional one, the first current collector 110 and the first active material layer 120 define a tab groove 160, the first tab 130 extends into the tab groove 160 and is electrically connected to the first current collector 110. The second adhesive tape 150 is disposed on the side of the first active material layer 120 away from the first current collector 110 and covers the tab groove 160. Figure 4 As shown, a plurality of third concave-convex structures 151 are arranged at intervals on the second adhesive tape 150 .

[0125] Among them, the first pole ear 130 can be electrically connected to the first current collector 110 by welding. The first pole piece 100 and the second pole piece 200 are both pole ear center structures to reduce the internal resistance of the battery cell. Schematically, the second adhesive tape 150 can also include a substrate and an adhesive layer, which can be attached to the first active material layer 120 through the adhesive layer. It can be understood that by covering the pole ear groove 160 with the second adhesive tape 150, the burrs generated during the welding of the first pole ear 130 can be prevented from piercing the diaphragm 300 and causing a short circuit. Schematically, the third concave-convex structure 151 forms a third convex portion on one side of the second adhesive tape 150, and the third concave-convex structure 151 forms a third concave portion on the other side of the second adhesive tape 150.

[0126] In a possible implementation, after the second adhesive tape 150 is attached to the first active material layer 120, the first electrode sheet 100 is pressed using a roller or a mold with a specific pattern to form a plurality of third recesses on the second adhesive tape 150. In another possible implementation, the second adhesive tape 150 may be pressed using a roller or a mold with a specific pattern to form a plurality of third concave-convex structures 151 on the second adhesive tape 150, and then the second adhesive tape 150 with the third concave-convex structures 151 is attached to the first active material layer 120.

[0127] By forming the third concave-convex structure 151 on the second adhesive tape 150 , the plurality of third concave-convex structures 151 can also play the role of storing electrolyte between the first pole piece 100 and the second pole piece 200 , thereby ensuring the amount of electrolyte retained between the first pole piece 100 and the second pole piece 200 .

[0128] The present application also provides a battery, comprising the above-mentioned battery cell.

[0129] The battery provided in the present application uses the above-mentioned battery cell, so the liquid retention between the first pole piece 100 and the second pole piece 200 can be effectively guaranteed, the battery cell is not prone to expansion, extrusion and deformation, and the battery has high cycle performance and safety.

[0130] The following is a detailed introduction to the battery of the present application through specific embodiments. The specific differences between the following batteries are shown in Table 1.

[0131] Example 1

[0132] The battery preparation of this embodiment includes the following steps:

[0133] 1. Preparation of positive electrode:

[0134] Lithium cobalt oxide, SP, and PVDF are mixed in a mass ratio of 97.6:1.4:1, and NMP is added and stirred evenly to prepare a positive electrode slurry; the positive electrode slurry is coated on both surfaces of an aluminum foil with a thickness of 10 μm. After baking and rolling, the positive electrode slurry forms a positive electrode active material layer, and the thickness H2 of the positive electrode active material layer is 90 μm.

[0135] The first adhesive tape 140 is attached to the side of the positive electrode active material layer away from the aluminum foil. The positive electrode sheet has a first edge 170 in the width direction, the first adhesive tape 140 has a first side edge 142 and a second side edge 143 oppositely arranged in the length direction of the positive electrode sheet, and the first adhesive tape 140 has a third side edge 144 away from the edge of the positive electrode sheet in the width direction of the positive electrode sheet.

[0136] The positive electrode sheet is rolled using an embossing roller, so that a plurality of first concave-convex structures 121 are formed on the positive electrode active material layer, and part of the first concave-convex structures 121 are covered by the first adhesive tape 140. The first concave-convex structure 121 forms a first concave portion 1211 on one of the first active material layers 120, and the first concave-convex structure 121 forms a first convex portion 1212 on another first active material layer 120. The depth H3 of the first concave portion 1211 is 65 μm.

[0137] The first concave-convex structure 121 has a first projection in the thickness direction of the first pole piece 100 , the diameter R1 of the circumscribed circle of the first projection is 2 mm, and the distance D1 between the circumscribed circles of two adjacent first projections is 3 mm.

[0138] The embossing roller forms a plurality of second concave-convex structures 141 on the first adhesive tape 140, and the second concave-convex structures 141 are attached to the corresponding first concave-convex structures 121. The second concave-convex structures 141 form second convex portions 1412 on one side of the first adhesive tape 140, and the second concave-convex structures 141 form second concave portions 1411 on the other side of the first adhesive tape 140. The depth of the second concave portion 1411 of the second concave-convex structure 141 covering the first concave portion 1211 is H1, and the size of H1 is the same as H3.

[0139] In the width direction of the first electrode sheet 100, the first edge 170 and the adjacent second concave-convex structure 141 have a first interval in the width direction of the positive electrode sheet, and the width W1 of the first interval is 3mm. The first side 142, the second side 143 and the third side 144 have a second interval with the adjacent second concave-convex structure 141, and the width W2 of the second interval is 2mm. In the first concave-convex structure 121 located outside the first adhesive tape 140, the first side 142, the second side 143 and the third side 144 have a third interval with the adjacent first concave-convex structure 121, and the width W3 of the third interval is 2mm.

[0140] 2. Preparation of negative electrode sheet:

[0141] The negative electrode active material doped with 10% silicon carbon was mixed with SP, CMC-Li, and PAA in a mass ratio of 97:0.4:0.1:2.5, and deionized water was added to prepare the negative electrode slurry; the negative electrode slurry was coated on both surfaces of the copper foil, and after baking and rolling, a negative electrode sheet with a thickness of 230μm was obtained. The negative electrode ear was welded on the copper foil.

[0142] 3. Preparation of diaphragm 300:

[0143] The polyethylene diaphragm 300 is made by conventional technology and has a thickness of 10 μm.

[0144] 4. Assembly:

[0145] The positive electrode sheet, the separator 300 and the negative electrode sheet are wound together to obtain a battery cell, wherein the projection of the first adhesive tape 140 on the negative electrode sheet covers the tab on the negative electrode sheet.

[0146] The battery is then packaged, baked, injected, formed, sealed again, sorted and OCV to obtain a battery. The electrolyte is a commercially available conventional electrolyte, and the lithium salt is LiFP6.

[0147] Example 2

[0148] Example 2 is carried out with reference to Example 1, except that the depth H1 of the second concave portion 1411 of the second concave-convex structure 141 covering the first concave portion 1211 and the depth H3 of the first concave portion 1211 are both 50 μm.

[0149] Example 3

[0150] Example 3 is carried out with reference to Example 1, except that the depth H1 of the second concave portion 1411 of the second concave-convex structure 141 covering the first concave portion 1211 and the depth H3 of the first concave portion 1211 are both 54 μm.

[0151] Example 4

[0152] Example 4 is carried out with reference to Example 1, except that the depth H1 of the second concave portion 1411 of the second concave-convex structure 141 covering the first concave portion 1211 and the depth H3 of the first concave portion 1211 are both 72 μm.

[0153] Example 5

[0154] Example 5 is carried out with reference to Example 1, except that the depth H1 of the second concave portion 1411 of the second concave-convex structure 141 covering the first concave portion 1211 and the depth H3 of the first concave portion 1211 are both 81 μm.

[0155] Example 6

[0156] Example 6 is carried out with reference to Example 1, except that the depth H1 of the second concave portion 1411 of the second concave-convex structure 141 covering the first concave portion 1211 and the depth H3 of the first concave portion 1211 are both 85 μm.

[0157] Example 7

[0158] Example 7 is carried out with reference to Example 1, except that the width W1 of the first interval is 0.5 mm.

[0159] Example 8

[0160] Example 8 is carried out with reference to Example 1, except that the width W1 of the first interval is 1 mm.

[0161] Example 9

[0162] Example 9 is carried out with reference to Example 1, except that the width W1 of the first interval is 5 mm.

[0163] Example 10

[0164] Example 10 is carried out with reference to Example 1, except that the width W1 of the first interval is 6 mm.

[0165] Embodiment 11

[0166] Example 11 is carried out with reference to Example 1, except that the width W2 of the second interval is 0.5 mm.

[0167] Example 12

[0168] Example 12 is carried out with reference to Example 1, except that the width W2 of the second interval is 1 mm.

[0169] Embodiment 13

[0170] Example 13 is carried out with reference to Example 1, except that the width W2 of the second interval is 3 mm.

[0171] Embodiment 14

[0172] Example 14 is carried out with reference to Example 1, except that the width W2 of the second interval is 5 mm.

[0173] Embodiment 15

[0174] Example 15 is carried out with reference to Example 1, except that the width W2 of the second interval is 6 mm.

[0175] Example 16

[0176] Example 16 is carried out with reference to Example 1, except that the width W3 of the third interval is 0.5 mm.

[0177] Embodiment 17

[0178] Example 17 is carried out with reference to Example 1, except that the width W3 of the third interval is 1 mm.

[0179] Embodiment 18

[0180] Example 18 is carried out with reference to Example 1, except that the width W3 of the third interval is 3 mm.

[0181] Embodiment 19

[0182] Example 19 is carried out with reference to Example 1, except that the width W3 of the third interval is 5 mm.

[0183] Embodiment 20

[0184] Example 20 is carried out with reference to Example 1, except that the width W3 of the third interval is 6 mm.

[0185] Embodiment 21

[0186] Example 21 is carried out with reference to Example 1, and the diameter R1 of the circumscribed circle of the first projection is 0.2 mm.

[0187] Embodiment 22

[0188] Example 22 is carried out with reference to Example 1, and the diameter R1 of the circumscribed circle of the first projection is 0.3 mm.

[0189] Embodiment 23

[0190] Example 23 is carried out with reference to Example 1, and the diameter R1 of the circumscribed circle of the first projection is 1 mm.

[0191] Embodiment 24

[0192] Example 24 is carried out with reference to Example 1, and the diameter R1 of the circumscribed circle of the first projection is 3 mm.

[0193] Embodiment 25

[0194] Example 25 is carried out with reference to Example 1, and the diameter R1 of the circumscribed circle of the first projection is 8 mm.

[0195] Embodiment 26

[0196] Example 26 is carried out with reference to Example 1, and the diameter R1 of the circumscribed circle of the first projection is 9 mm.

[0197] Embodiment 27

[0198] Example 27 is carried out with reference to Example 1, and the distance D1 between the circumscribed circles of two adjacent first projections is 0.5 mm.

[0199] Embodiment 28

[0200] Example 28 is carried out with reference to Example 1, and the distance D1 between the circumscribed circles of two adjacent first projections is 1 mm.

[0201] Embodiment 29

[0202] Example 29 is carried out with reference to Example 1, and the distance D1 between the circumscribed circles of two adjacent first projections is 1.5 mm.

[0203] Embodiment 30

[0204] Example 30 is carried out with reference to Example 1, and the distance D1 between the circumscribed circles of two adjacent first projections is 4 mm.

[0205] Embodiment 31

[0206] Example 31 is carried out with reference to Example 1, and the distance D1 between the circumscribed circles of two adjacent first projections is 6 mm.

[0207] Embodiment 32

[0208] Example 32 is carried out with reference to Example 1, and the distance D1 between the circumscribed circles of two adjacent first projections is 7 mm.

[0209] Comparative Example 1

[0210] Comparative Example 1 is carried out with reference to Example 1, except that the first concavo-convex structure 121 is not provided at the position where the first adhesive tape 140 is attached to the positive electrode active material layer, and the second concavo-convex structure 141 is not provided on the first adhesive tape 140 .

[0211] Comparative Example 2

[0212] Comparative Example 2 is carried out with reference to Example 1, except that, during the preparation of the positive electrode sheet, the positive electrode sheet is first rolled with an embossing roller, so that a plurality of first concave-convex structures 121 are formed on the positive electrode sheet, and part of the first concave-convex structures 121 are located in the area of ​​the positive electrode active material layer for attaching the first adhesive tape 140. After the positive electrode sheet is rolled by the embossing roller, the first adhesive tape 140 is attached to the positive electrode active material layer, and the first adhesive tape 140 covers part of the first concave-convex structures 121, and the second concave-convex structure 141 is not provided on the first adhesive tape 140.

[0213] Table 1:

[0214]

[0215]

[0216] The relevant performances of the batteries in the above embodiments and comparative examples were tested, and the test results are recorded in Table 2. The test method is as follows:

[0217] 1. Liquid retention test

[0218] The liquid retention volume is the amount of electrolyte that is ultimately retained in the lithium-ion battery. In order to ensure the consumption of electrolyte during the formation of the lithium-ion battery, a certain amount of electrolyte is usually injected, and then the excess electrolyte is extracted after formation; it is measured by weighing, the injection volume is m1, and the electrolyte extraction volume is m2.

[0219] Liquid retention volume = m1-m2.

[0220] 2. Battery expansion rate test

[0221] Charge to 4.5V at 1C at room temperature 25℃, discharge to 3.0V at cut-off current 0.025C / 0.5C, cycle 800T, use 600g PPG to measure the cell thickness every 100T, expansion rate = (Tcycle-Tfresh cell) / Tfresh cell.

[0222] 3. Positive electrode tensile strength test

[0223] A vertical tensile testing machine was used for testing. The positive electrode sheets obtained in the above embodiments and comparative examples were fixed on the clamps at both ends of the tensile testing machine. The two ends of the clamps were aligned. The tensile equipment button was started. The equipment moved at a speed of 10 mm / s until the positive electrode sheet broke, and the tensile data was read out.

[0224] 4. Lithium deposition on negative electrode

[0225] After the battery cell expansion rate test was performed on the batteries obtained in the above embodiment and the comparative example, the batteries obtained in the above embodiment and the comparative example were fully charged, and the batteries were disassembled in a dry room environment to observe the lithium deposition of the negative electrode sheet.

[0226] Table 2:

[0227]

[0228]

[0229] As shown in Table 2, the liquid retention amount of Comparative Example 1 is lower than that of Comparative Example 2, the battery cell expansion rate of Comparative Example 1 is higher than that of Comparative Example 2, and the lithium deposition of the negative electrode sheets in Comparative Example 1 and Comparative Example 2 is different. It can be seen that the arrangement of the first concave-convex structure 121 in the area where the first adhesive tape 140 is attached to the positive electrode sheet is beneficial to increasing the liquid retention amount of the battery, reducing the expansion rate of the battery, and alleviating the lithium deposition on the negative electrode sheet. Comparing Example 1 and Comparative Example 2, there will be no serious lithium deposition at the edge of the adhesive tape corresponding to the negative electrode sheet in Example 1. This is because through the cooperation between the first concave-convex structure 121 and the second concave-convex structure 141, the electrolyte is not easy to enter between the first adhesive tape 140 and the first active material layer 120, so that lithium deposition is not easy to occur at the edge of the adhesive tape.

[0230] It can be seen from Examples 2 and 6 that the battery's liquid retention capacity is less than 7.5, and lithium is slightly deposited on the surface of the negative electrode. The reason is that the depths of the first concave portion 1211 and the second concave portion 1411 in Example 2 are relatively small, resulting in the first concave-convex structure 121 and the second concave-convex structure 141 having a relatively small role in storing electrolyte; the depths of the first concave portion 1211 and the second concave-convex structure 141 in Example 6 are too large, and when the first concave-convex structure 121 and the second concave-convex structure 141 are provided on the positive electrode, the first active material layer 120 is fractured, which increases the side reactions of the first active material layer 120 and causes the electrolyte to be consumed too quickly. It can be seen from Example 1 and Example 3 to Example 5 that the liquid retention amount is greater than 7.6, and there is no lithium deposition on the surface of the negative electrode sheet. This indicates that controlling the depth of the first recess 1211 and the second recess 1411 within an appropriate range so that 0.6×H2≤H1≤0.9×H2 is beneficial to ensuring the liquid retention amount between the positive electrode sheet and the negative electrode sheet, and avoiding lithium deposition due to insufficient electrolyte.

[0231] As can be seen from Example 7, the edge of the negative electrode sheet is slightly degraded, indicating that due to processing tolerances, part of the first concave-convex structure 121 may be located at the edge of the first electrode sheet 100, resulting in poor core coverage; as can be seen from Example 10, the liquid retention amount is less than 7.5, the expansion rate is greater than 10, and there is slight lithium deposition at the edge of the negative electrode sheet. This is because the multiple first convex portions 1212 are difficult to provide effective support between the positive electrode sheet and the negative electrode sheet, and the liquid retention amount between the two electrode sheets at the position of the first adhesive tape 140 cannot be effectively guaranteed. As can be seen from Examples 1, 8, and 9, the liquid retention amount is greater than 7.6, the expansion rate is less than 10, and there is no lithium deposition on the negative electrode sheet, indicating that controlling the width W1 of the first interval to 1mm≤W1≤5mm can ensure the deviation correction during winding of the battery cell, and at the same time ensure the liquid retention amount between the positive electrode sheet and the negative electrode sheet at the position of the first adhesive tape 140, and the battery cell is not prone to expansion, extrusion, and deformation.

[0232] It can be seen from Example 15 that the liquid retention amount is lower than 7.55, and the expansion rate is greater than 11, indicating that the second concave-convex structure 141 on the first adhesive tape and the first concave-convex structure 121 corresponding to the second concave-convex structure 141 are far away from the edge of the first adhesive tape 140, and the support of the multiple first concave-convex structures 121 in the area where the first adhesive tape 140 is attached is weak, and it is difficult to effectively ensure the liquid retention amount between the first electrode 100 and the second electrode 200 at the position of the first adhesive tape 140, and lithium deposition is caused at the edge of the adhesive tape corresponding to the negative electrode. It can be seen from Example 1, Example 11 to Example 14 that the liquid retention amount is greater than 7.6, the expansion rate is less than 10.5, and there is no lithium deposition on the surface of the negative electrode, indicating that when the width W2 of the second interval is controlled at 0.5mm-5mm, the edge of the first adhesive tape 140 will not be lifted and the electrolyte will not be introduced, the liquid retention amount between the positive electrode and the negative electrode at the position of the first adhesive tape 140 is guaranteed, and the battery cell is not prone to expansion, extrusion and deformation. It can be seen from Examples 1, 12 and 13 that when the width W2 of the second interval is between 1mm and 3mm, the liquid retention amount is not less than 7.7 and the expansion rate is less than 10, indicating that the support of the multiple first concave-convex structures 121 in the area where the first tape 140 is affixed is relatively strong, further ensuring the liquid retention amount between the positive electrode sheet and the negative electrode sheet at the position of the first tape 140, and the battery cell is less prone to expansion, extrusion and deformation. The width W2 of the second interval is not set to be smaller, which is beneficial to controlling the production cost of the battery.

[0233] It can be seen from Example 20 that the liquid retention amount is less than 7.6, the expansion rate is greater than 11, and the edge of the negative electrode sheet corresponding to the adhesive tape has slight lithium deposition. It can be seen from Example 1, Example 16 to Example 19 that the liquid retention amount is greater than 7.6, the expansion rate is less than 10.5, and there is no lithium deposition on the negative electrode sheet. It shows that when the width W3 of the third interval is controlled in the range of 0.5mm-5mm, it can ensure that the edge of the first adhesive tape 140 will not be lifted, and the liquid retention amount between the positive electrode sheet and the negative electrode sheet at the position of the first adhesive tape 140 can be guaranteed, and the battery cell is not prone to expansion, extrusion and deformation. It can be seen from Example 1, Example 17 and Example 18 that when the width W3 of the third interval is 1mm-3mm, the liquid retention amount is greater than 7.65 and the expansion rate is less than 10, which further ensures the liquid retention amount between the positive electrode sheet and the negative electrode sheet at the position of the first adhesive tape 140, and the battery cell is less likely to expand, squeeze and deform. The width W3 of the third interval is not set small, which is conducive to controlling the production cost of the battery.

[0234] It can be seen from Example 21 that the tensile strength of the positive electrode sheet is less than 250; it can be seen from Example 26 that the liquid retention amount is less than 7.5, and the expansion rate is greater than 10. It can be seen from Example 1, Example 22 to Example 25 that the tensile strength of the positive electrode sheet is greater than 270, the liquid retention amount is greater than 7.6, and the expansion rate is less than 10, indicating that when the diameter R1 of the projected circumscribed circle of the first concave-convex structure in the third direction is controlled to be 0.3mm-8mm, it will not cause damage to the positive electrode sheet, ensure the liquid retention amount between the positive electrode sheet and the negative electrode sheet, and reliably alleviate the extrusion between the electrodes caused by the expansion of the positive electrode sheet and the negative electrode sheet, so that the battery cell is not prone to expansion, extrusion and deformation. It can be seen from Example 1, Example 23, and Example 24 that the liquid retention amount is greater than 7.7 and the expansion rate is less than 9.8, indicating that when R1 is controlled to be 1mm-3mm, the liquid retention amount between the positive electrode sheet and the negative electrode sheet can be further guaranteed, and the multiple first concave-convex structures 121 can further alleviate the extrusion between the electrodes caused by the expansion of the positive electrode sheet and the negative electrode sheet.

[0235] It can be seen from Example 27 that the tensile strength of the positive electrode sheet is less than 250; it can be seen from Example 32 that the liquid retention amount is less than 7.5, and the expansion rate is greater than 10. It can be seen from Example 1, Example 28 to Example 31 that the tensile strength of the positive electrode sheet is greater than 270, the liquid retention amount is greater than 7.6, and the expansion rate is less than 10, indicating that when the spacing between two adjacent first concave-convex structures is controlled to be 1mm-6mm, the positive electrode sheet will not be damaged while ensuring the liquid retention amount between the positive electrode sheet and the negative electrode sheet, and at the same time, the extrusion between the electrodes caused by the expansion of the positive electrode sheet and the negative electrode sheet can be reliably alleviated, so that the battery cell is not prone to expansion, extrusion and deformation. It can be seen from Example 1, Example 29, and Example 30 that the liquid retention amount is greater than 7.7 and the expansion rate is less than 9.8, indicating that when the spacing between two adjacent first concave-convex structures is controlled to be 1.5mm-4mm, the liquid retention amount between the positive electrode sheet and the negative electrode sheet can be further guaranteed, and multiple first concave-convex structures 121 can further alleviate the extrusion between the electrodes caused by the expansion of the positive electrode sheet and the negative electrode sheet.

[0236] Finally, it should be noted that those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses or adaptations of the present invention, which follow the general principles of the present invention and include common knowledge or customary technical means in the art not disclosed by the present invention, are not limited to the precise structure described above and shown in the drawings, and may be modified and changed in various ways without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A battery cell, characterized in that: The battery cell comprises a first pole piece, a second pole piece and a diaphragm located between the first pole piece and the second pole piece, wherein the first pole piece, the second pole piece and the diaphragm are stacked and wound to form the battery cell; The first pole piece includes a first current collector, a first active material layer located on both sides of the first current collector, and a first adhesive tape attached to the first active material layer, wherein the first adhesive tape is located on a side of the first active material layer away from the first current collector; The second pole piece includes a second pole lug; A plurality of first concavo-convex structures are arranged at intervals on the first active material layer, wherein the first concavo-convex structures form a first concave portion on one of the first active material layers, and the first concavo-convex structures form a first convex portion on another of the first active material layers; The first adhesive tape covers part of the first concave-convex structure, and the first adhesive tape covers the projection of the second electrode tab on the first electrode sheet; a plurality of second concave-convex structures are arranged at intervals on the first adhesive tape, and the second concave-convex structures form second convex portions and second concave portions on opposite sides of the first adhesive tape respectively; The second convex portion is arranged corresponding to the first concave portion or the second concave portion is arranged corresponding to the first convex portion.

2. The battery cell according to claim 1, characterized in that: The difference between the height of the first convex portion and the depth of the second concave portion is less than or equal to 1 mm; the difference between the depth of the first concave portion and the height of the second convex portion is less than or equal to 1 mm.

3. The battery cell according to claim 2, characterized in that: The first pole piece has a first edge, and a first interval is formed between the first edge and the adjacent second concave-convex structure in a second direction.

4. The battery cell according to claim 3, characterized in that: The width of the first interval is W1, and W1 satisfies: 1mm≤W1≤5mm.

5. The battery cell according to claim 3, characterized in that: The first adhesive tape has a first side edge and a second side edge that are oppositely arranged in a first direction, and the first adhesive tape has a third side edge that is away from the first edge in a second direction; A second interval is formed between the first side edge, the second side edge and the third side edge and the adjacent second concave-convex structures.

6. The battery cell according to claim 5, characterized in that: The width of the second interval is W2, and W2 satisfies: 0.5mm≤W2≤5mm.

7. The battery cell according to claim 5, characterized in that: In the first concave-convex structure located outside the first adhesive tape, a third interval is formed between the first side edge, the second side edge and the third side edge and adjacent first concave-convex structures.

8. The battery cell according to claim 7, characterized in that: The width of the third interval is W3, and W3 satisfies: 0.5mm≤W3≤5mm.

9. The battery cell according to claim 2, characterized in that: The depth of the second concave portion covering the first concave portion is H1, the thickness of the straight region of the first active material layer is H2, and H1 and H2 satisfy: 0.6×H2≤H1≤0.9×H2.

10. The battery cell according to any one of claims 1 to 9, characterized in that: The first adhesive tape is respectively attached to the two first active material layers; The first adhesive tapes on the two first active material layers are arranged at intervals along the first direction, and the first adhesive tapes on the two first active material layers are respectively located on two opposite sides of the second electrode tab.

11. The battery cell according to any one of claims 1 to 9, characterized in that: The first pole piece also includes a first pole ear and a second adhesive tape; The first current collector and the first active material layer define a tab groove, the first tab extends into the tab groove and is electrically connected to the first current collector; The second adhesive tape is disposed on a side of the first active material layer away from the first current collector and covers the tab groove; A plurality of third concave-convex structures are arranged at intervals on the second adhesive tape.

12. The battery cell according to any one of claims 1 to 9, characterized in that: The first concave-convex structure has a first projection in the third direction, and the diameter of the circumscribed circle of the first projection is R1, and R1 satisfies: 0.3mm≤R1≤8mm; and / or, The first concave-convex structure has a first projection in the third direction, and the distance between the edges of the circumscribed circles of two adjacent first projections is D1, and D1 satisfies: 1mm≤D1≤6mm; and / or, The depth of the first recess is H3, and H3 satisfies: 3μm≤H3≤80μm; and / or, The first concave-convex structure has a first projection in the third direction, and at least one corner of the first projection is rounded.

13. The battery cell according to any one of claims 1 to 9, characterized in that: The tensile strength of the first adhesive tape is 30N / m²-170N / m².

14. A battery, characterized in that: A battery cell comprising the battery cell described in any one of claims 1 to 13.

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