CN117637989A

CN117637989A - Pole piece, electrode assembly and battery

Info

Publication number: CN117637989A
Application number: CN202410111468.1A
Authority: CN
Inventors: 李肖龙; 刘伟
Original assignee: Ningde Amperex Technology Ltd
Current assignee: Ningde Amperex Technology Ltd
Priority date: 2024-01-26
Filing date: 2024-01-26
Publication date: 2024-03-01
Anticipated expiration: 2044-01-26
Also published as: CN117637989B; CN118553849A

Abstract

The application discloses a pole piece, electrode assembly and battery. The surface of the active material layer of the pole piece, which faces away from the current collector, is provided with a salient point area, a pole lug area and an end part void area; the pole piece comprises a plurality of first convex parts distributed in the salient point areas, and the plurality of first convex parts are protruded towards the same side of the pole piece in the thickness direction of the pole piece; the end part void area is arranged at the end part of the salient point area in the length direction of the pole piece and extends to the edge of the pole piece; the tab area extends to the edge of the pole piece in the width direction of the pole piece; the lug assembly is arranged in the lug area and is arranged at intervals with the salient points. Through setting up bump area, utmost point ear district and the tip of pole piece and keeping away the dead zone and combine together, can effectively improve the interface problem that the extrusion caused between the electrode layer, improve the cycle performance of battery.

Description

Pole piece, electrode assembly and battery

Technical Field

The application relates to the technical field of electrochemical devices, in particular to a pole piece, an electrode assembly and a battery.

Background

The cycle life is a key performance of the lithium ion battery, the improvement of the cycle life is a long-term continuous research and development direction, besides the improvement and innovation of the battery material end, the cycle life is effectively assisted by structural design and improvement, and more design requirements are also provided for the winding mode of the electrode assembly of the battery cell.

Disclosure of Invention

The inventors have found that there may be a squeeze between layers of the electrode assembly, including a squeeze where corner portions and straight portions exist. Particularly, in the charge and discharge process of the battery, the expansion and extrusion of the electrode assembly are further aggravated, so that electrolyte between layers is insufficient, the electrolyte is poorly infiltrated, interface deterioration is easy to occur, and even abnormal conditions such as poor infiltration, circulation failure and the like occur.

The embodiment of the application provides a pole piece, an electrode assembly and a battery, which can improve the problem of extrusion between electrode assembly layers.

In a first aspect, embodiments of the present application provide a pole piece, where the pole piece includes a current collector and an active material layer disposed on a surface of the current collector, and a surface of the active material layer facing away from the current collector has a bump area and an end void area; the pole piece comprises a plurality of first convex parts distributed in the salient point areas, and the first convex parts protrude towards the same side of the pole piece in the thickness direction of the pole piece; the end part clearance area is arranged at the end part of the salient point area in the length direction of the pole piece and extends to the edge of the pole piece; in the width direction of the pole piece, the shortest distance between the salient point area and the edge of the active material layer is T1, and T1 meets the following conditions: t1 is more than or equal to 0.5mm and less than or equal to 30mm.

In some exemplary embodiments, a surface of the active material layer facing away from the current collector includes a tab region extending in the pole piece width direction to an edge of the pole piece; the tab area is used for arranging tab assemblies, and the tab assemblies are arranged at intervals with the salient point areas.

In some exemplary embodiments, the current collector includes a coating portion and a hollow foil portion, the active material layer is provided on a surface of the coating portion, and the hollow foil portion is provided outside the hollow foil portion in a length direction of the pole piece.

In some exemplary embodiments, the end void areas include a head void area and a tail void area, and in the length direction of the pole piece, the head void area is arranged at one end of the bump area, and the tail void area is arranged at the other end of the bump area; the pole piece is used for winding from the head clearance area and the isolating film along the length direction of the pole piece to form a flat electrode main body.

In some exemplary embodiments, in the length direction of the pole piece, the size of the head clearance area is a, and the size of the ending clearance area is D, where a satisfies: a is more than or equal to 30mm and less than or equal to 1000mm, and D meets the following conditions: d is more than or equal to 30mm and less than or equal to 1000mm.

In some exemplary embodiments, in the length direction of the pole piece, the size of the head clearance area is a, and the size of the ending clearance area is D, where a satisfies: a is more than or equal to 60mm and less than or equal to 500mm, and D meets the following conditions: d is more than or equal to 100mm and less than or equal to 500mm.

In some exemplary embodiments, T1 satisfies: t1 is more than or equal to 1mm and less than or equal to 30mm.

In some exemplary embodiments, T1 satisfies: t1 is more than or equal to 3mm and less than or equal to 30mm.

In some exemplary embodiments, T1 satisfies: t1 is more than or equal to 3mm and less than or equal to 20mm.

In some exemplary embodiments, a surface of the active material layer facing away from the current collector in a width direction of the electrode sheet has a first region connected to one side of the bump region, a second region connected to the other side of the bump region, the first region extending to an edge of the active material layer in a direction away from the second region, the second region extending to an edge of the active material layer in a direction away from the first region; setting T11 as the width of the first region in the pole piece width direction, and T12 as the width of the second region in the pole piece width direction, wherein the difference between the width T11 of the first region in the pole piece width direction and the width T12 of the second region in the pole piece width direction is Δt1, Δt1= |t11-t12|, and Δt1 satisfies: delta T1 is more than or equal to 0mm and less than or equal to 29.5mm.

In some exemplary embodiments, the tab assembly is spaced from the bump area by a distance T2, and T2 satisfies: t2 is more than or equal to 0.5mm and less than or equal to 30mm; the tab assembly comprises a tab; and/or, the tab assembly comprises a protective adhesive.

In some exemplary embodiments, the number of tab regions is one, and the tab regions extend along the length of the pole piece to meet the end void region.

In some exemplary embodiments, a surface of the active material layer facing away from the current collector in a width direction of the tab has a first region connected to a side of the bump region, the first region being located on a side of the bump region facing away from the tab region and extending to an edge of the tab; the width of the tab area in the width direction of the pole piece is W1, and W1 satisfies the following conditions: w1 is more than or equal to 2mm and less than or equal to 40mm.

In some exemplary embodiments, the tab region and the bump region are each a plurality of in number; and one lug area is arranged between two adjacent salient point areas in the length direction of the pole piece, and each lug area penetrates through the pole piece along the width direction of the pole piece.

In some exemplary embodiments, the bump region has at least one keep-out opening region, each of the keep-out opening regions extends to the pole piece edge in the pole piece width direction to form the tab region, and a plurality of the keep-out opening regions extend toward the same edge of the pole piece in the pole piece width direction.

In some exemplary embodiments, the tab area has a dimension W3 in the length direction of the pole piece, where W3 satisfies: w3 is more than or equal to 10mm and less than or equal to 50mm.

In some exemplary embodiments, the pole piece is configured to be wound with a separator film along a length direction of the pole piece for a plurality of turns to form an electrode body; each circle of pole piece comprises a straight part and corner parts arranged at two ends of the straight part, and the lug areas are arranged on the straight part; in the length direction of the pole piece, the dimension of the corner part is W5, and the dimension of the salient point area is W6;

the bump area is provided at the corner portion, wherein w6=w5; or the salient point areas are arranged at the corner parts and extend to the straight parts, and the two salient point areas of the same circle of pole pieces are arranged at intervals, wherein W6 is more than W5.

In some exemplary embodiments, W5 satisfies: w5 is more than or equal to 0.5mm and less than or equal to 20mm; and/or, W6 satisfies: w6 is more than or equal to 0.5mm and less than or equal to 100mm.

In some exemplary embodiments, the dimensions W6 of all the bump areas in the length direction of the pole piece are equal; or from the inner ring to the outer ring of the electrode main body, the dimension W6 of the salient point area in the length direction of the pole piece is gradually increased.

In some exemplary embodiments, the pole piece is configured to be wound with a separator film along a length direction of the pole piece for a plurality of turns to form an electrode body; each circle of pole piece comprises a straight part and corner parts arranged at two ends of the straight part, and the lug areas are arranged on the straight part; the height of the first convex portion provided at the corner portion is h1, h1 satisfying: h1 is more than or equal to 55 mu m and less than or equal to 70 mu m; the height of the first convex part arranged on the straight part is h2, and h2 meets the following conditions: h2 is more than or equal to 10 mu m and less than or equal to 18 mu m.

In some exemplary embodiments, the pole piece is configured to be wound with a separator film along a length direction of the pole piece for a plurality of turns to form an electrode body; the plurality of first protrusions of each turn of the pole piece are protruded toward the winding center of the electrode body in the thickness direction of the pole piece.

In some exemplary embodiments, the outer contour of the first protrusion is circular, elliptical, or regular polygon; or, the outer contour sizes of the first convex parts are equal; or, in the width direction of the pole piece, the outer contour dimension of the first convex part gradually decreases from the central area to the edge area of the salient point area; or; in the length direction of the pole piece, the outer contour dimension of the first convex part gradually decreases from the central area to the edge area of the salient point area.

In a second aspect, the present application provides an electrode assembly, the electrode assembly includes a plurality of tab assemblies, the above-mentioned pole pieces, and a separator disposed between the two pole pieces, and the separator and the two pole pieces are wound along a length direction of the pole pieces to form a flat electrode body.

In some exemplary embodiments, the tab assembly includes a tab disposed in a tab region of the pole piece; the tab includes with the linkage segment that the pole piece is connected and stretches out the butt joint section at pole piece edge, the linkage segment deviates from the protruding a plurality of second convex parts that are equipped with in surface of pole piece.

In a third aspect, the present application provides a battery comprising a housing and an electrode assembly as described above, the electrode assembly being disposed in an interior space of the housing.

Based on pole piece, electrode assembly and battery of this application embodiment, keep away the district through setting up the tip and can provide the coiling buffer for electrode body is convoluteed, and then improve electrode body's coiling stability, reduce the unstable condition of coiling that directly brings for coiling start point or end point by the region that has first convex part, and combine the utmost point ear district under this circumstances, prevent that electrode body installs the intermediate level of utmost point ear assembly and take place to expand and drive utmost point ear assembly and cause the extrusion to electrode body, reduce the damage of utmost point ear assembly to electrode body, utmost point ear district extends to the pole piece edge, because there is the existence of first convex part, the supporting role of first convex part performance can continue to utmost point ear district, make the difficult emergence extrusion of utmost point ear district department of pole piece, and can also reserve a part regional holding electrolyte, improve electrolytic infiltration effect. Therefore, the electrode assembly provided by the embodiment of the application can not only improve the interface problem caused by extrusion between electrode layers by combining the salient point area, the lug area and the end part clearance area of the pole piece, but also effectively improve the cycle performance of the battery when the electrode assembly is applied to the battery.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic partial side view of an electrode body according to one embodiment of the present application;

FIG. 2 is a schematic view of an expanded structure of a pole piece according to an embodiment of the present application having a tab region;

FIG. 3 is a schematic view of an expanded structure of a pole piece according to another embodiment of the present application with a tab region;

FIG. 4 is a schematic view of an expanded structure of a pole piece in an embodiment of the present application, in which a tab region does not extend through a bump region;

FIG. 5 is a schematic view of an expanded structure of a pole piece having a second protrusion according to one embodiment of the present application;

FIG. 6 is a schematic view of an expanded structure of a pole piece with a tab region penetrating a bump region according to an embodiment of the present application;

FIG. 7 is a schematic view of an expanded structure of a pole piece when a plurality of bump areas have equal widths in a length direction of the pole piece according to an embodiment of the present application;

FIG. 8 is a schematic view of an expanded structure of a pole piece when the width of a plurality of bump areas in the length direction of the pole piece is gradually increased according to an embodiment of the present application;

fig. 9 is a schematic view of an expanded structure of a pole piece when a first protrusion of a central region of a bump area is larger in size according to an embodiment of the present application.

Reference numerals:

20. an electrode main body; 21. a straight portion; 22. corner portions; 100. a tab; 110. a second convex portion; 200. a protective adhesive; 40. a tab assembly; 50. a separation film;

300. a pole piece; 310. bump areas; 311. a first convex portion; 320. a tab region; 330. end void areas; 331. head keep-away area; 332. ending and avoiding empty areas; 341. a first region; 342. a second region; 3411. a first edge; 3421. a second edge; 3101. a first boundary; 3102. a second boundary; 301. a positive electrode sheet; 302. a negative electrode plate;

x, length direction; y, width direction; z, thickness direction.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the present application.

The inventors found that the electrode assembly swells during the charge and discharge of the battery, the extrusion of the corner portions of the electrode assembly is further increased, resulting in insufficient electrolyte at the corner portions, poor impregnation, and easy occurrence of interface deterioration, even cycle failure.

The inventor also found that, in the process of processing the electrode assembly, the positive electrode sheet, the separator and the negative electrode sheet are sequentially laminated and wound for a plurality of turns to form an electrode main body with a plurality of turns of winding units, and by increasing the interval between two adjacent turns of winding units and arranging supporting structures such as salient points, gummed paper and the like to support the two adjacent turns of winding units, the extrusion problem caused by expansion of the electrode assembly can be improved, but the improvement effect is still poor, for example, the salient point structures are arranged on the whole surface of the electrode sheet, the adjacent turns of winding units can be supported, the interface problem of the electrode sheet at the corner part can be improved, and meanwhile, the novel interface problem, the electrolyte shortage and other negative effects can be brought to the straight part.

Based on this, the embodiment of the application provides an electrode assembly and a battery, aiming at the problems of infiltration and pole piece interfaces of different positions and different degrees, the bump distribution design is carried out in the targeted positioning, so that the negative influence on the normal interface part is reduced while the infiltration and interface problems are effectively improved.

As shown in fig. 1, the electrode assembly of the embodiment of the present application includes two electrode sheets 300 having opposite polarities, and a separator 50 provided between the two electrode sheets 300. As shown in fig. 2, which is a schematic front view structure of one of the pole pieces 300 in an unfolded state, the pole pieces 300 have a longitudinal direction X, a width direction Y and a thickness direction Z perpendicular to each other, and the longitudinal direction X, the width direction Y and the thickness direction Z of the two pole pieces 300 with opposite polarities are identical, and the separator 50 is disposed between the two pole pieces 300 with opposite polarities in the thickness direction Z of the pole pieces 300. One of the two pole pieces 300 with opposite polarities is a positive pole piece 301, the other is a negative pole piece 302, and the isolating film 50 has insulation property for separating the positive pole piece 301 and the negative pole piece 302, so as to prevent the positive pole piece 301 and the negative pole piece 302 from being shorted.

In this embodiment, the separator 50 and the two pole pieces 300 are wound for a plurality of turns along the length direction X of the pole pieces 300 to form the electrode body 20, the length direction X of the pole pieces is the winding direction of the pole pieces, and the width direction Y is perpendicular to the length direction X. The electrode body 20 is flat, and each turn of the electrode sheet 300 includes two straight portions 21 and two corner portions 22, the two straight portions 21 being connected between the two corner portions 22. The corner portions 22 of two adjacent turns of pole pieces 300 are easy to squeeze each other, and the straight portion 21 and the corner portions 22 of each turn of pole pieces 300 are also squeezed, so that the corner portions 22 are high-incidence areas where the electrode main body 20 is squeezed, and the problems of insufficient electrolyte and poor infiltration are easy to occur when the corner portions 22 are squeezed, so that the interfaces of the pole pieces 300 of the corner portions 22 are deteriorated, and even the situation of circulation failure occurs.

In this embodiment, at least one pole piece 300 of the two pole pieces 300 has a bump area 310, the pole piece 300 includes a plurality of first protruding portions 311 distributed in the bump area 310, and the plurality of first protruding portions 311 protrude toward the same side of the pole piece 300 in the thickness direction Z of the pole piece 300. Thus, after the two pole pieces 300 and the isolating film 50 are wound for a plurality of circles to form the electrode main body 20, the first protruding portions 311 provide support for the isolating film 50 to contact, when the electrode main body 20 expands, the isolating film 50 can still be supported by the first protruding portions 311, and the contact area between the first protruding portions 311 and the isolating film 50 is small, so that a space is reserved between the part of the pole piece 300 corresponding to the salient point area 310 and the isolating film 50 for accommodating electrolyte, and abnormal conditions such as insufficient electrolyte and poor infiltration between the pole piece 300 and the isolating film 50 caused by expansion extrusion are prevented.

When the two pole pieces 300 and the separator 50 are flattened and laminated in the thickness direction Z of the pole pieces 300, the plurality of first protrusions 311 of one pole piece 300 may protrude toward the side where the other pole piece 300 is located, so that after the two pole pieces 300 and the separator 50 are wound in the length direction X of the pole pieces 300, the first protrusions 311 of the pole pieces 300 protrude toward the side where the winding center of the electrode body 20 is located. Alternatively, when the two pole pieces 300 and the separator 50 are flattened and laminated in the thickness direction Z of the pole pieces 300, the plurality of first protrusions 311 of one pole piece 300 may face the first protrusions 311 of the side facing away from the other pole piece 300, so that after the two pole pieces 300 and the separator 50 are wound in the length direction X of the pole pieces 300, the first protrusions 311 of the pole pieces 300 protrude toward the side facing away from the winding center of the electrode body 20. When both pole pieces 300 have the bump areas 310, the first convex portion 311 of either pole piece 300 of both pole pieces 300 is convex toward the side where the other pole piece 300 is located, or the first convex portion 311 of either pole piece 300 of both pole pieces 300 is convex toward the side where the other pole piece 300 is located. The above description is merely exemplary, and the direction of the first protrusion 311 of each pole piece 300 is not limited in this application, and may be specifically selected according to actual needs.

The pole piece 300 comprises a current collector and an active material layer, the active material layer is arranged on the surface of the current collector, a salient point area 310 is arranged on the surface, facing away from the current collector, of the active material layer, a pole lug area 320 and an end part clearance area 330 are arranged on the surface, facing away from the current collector, of the active material layer with the salient point area 310, no first protruding portion 311 is arranged on the pole lug area 320 and the end part clearance area 330, after the two pole pieces 300 and the isolating membrane 50 are wound, the pole piece 300 can be arranged at intervals with the isolating membrane 50 on the surface, corresponding to the pole lug area 320 and the end part clearance area 330.

As shown in fig. 2, the end keep-out area 330 is disposed at the end of the bump area 310 in the length direction X of the pole piece 300 and extends to the edge of the pole piece 300, correspondingly, after the two pole pieces 300 and the isolating film 50 are wound, the end keep-out area 330 may be disposed at the innermost turns of the electrode body 20, so as to facilitate the winding formation of the electrode body 20, and facilitate the improvement of the structural stability of the central area of the electrode body 20, or the end keep-out area 330 may be disposed at the outermost turns of the electrode body 20, and the end keep-out area 330 may be used as a buffer area between the first protrusion 311 and the ending end of the electrode body 20, so that the part of the pole piece 300 corresponding to the end keep-out area 330 may more stably bind the inner layer structure of the electrode body 20, thereby facilitating the improvement of the packaging stability of the outer layer area of the electrode body 20, and particularly, when the electrode body 20 has a tendency of expanding, the end keep-out area 330 without the first protrusion 311 is adopted, and the occurrence of the situation that the ending slip of the electrode body 20 due to the expansion stress is prevented, and the stability of the structure of the electrode body 20 is improved.

As shown in fig. 2, the tab area 320 extends to the edge of the pole piece 300 in the width direction Y of the pole piece 300, the tab assembly 40 is disposed in the tab area 320, and the tab assembly 40 is disposed at a distance from the bump area 310. When the tab assembly 40 is mounted in the tab area 320, the processing manner thereof affects the mounting stability of the tab assembly 40, and affects the stability of the structure around the tab assembly 40, and further affects the stability of the interface of the pole piece 300, for example, when the tab assembly 40 is press-mounted on the pole piece 300 by adopting a rolling manner, the tab assembly 40 and the area provided with the first protrusion 311 are press-bonded together, or the distance between the tab assembly 40 and the first protrusion 311 is too short, the deformation of the first protrusion 311, the occurrence of the indentation, and the like may occur, and further the interface of the pole piece 300 in the area near the tab assembly 40 may be deteriorated. According to the embodiment of the application, the tab area 320 is used for installing the tab assembly 40, so that the tab assembly 40 is convenient to install, the process difficulty is reduced, the installation stability of the tab assembly 40 is improved, the interface stability near the tab assembly 40 is improved, the tab assembly 40 and the first convex part 311 can be dislocated in the thickness direction Z of the pole piece 300, and the improvement of the energy density of a battery is facilitated when the electrode assembly is applied to the battery.

It can be understood that the wider the distribution range of the plurality of first protrusions 311 provided to the electrode sheet 300, the larger the effective supporting area of the plurality of first protrusions 311 to the whole electrode body 20, and thus the fewer the problems due to the extrusion. However, the inventors of the present application found that the first protrusions 311 are provided indiscriminately in the respective regions of the pole piece 300, and that the problem of pressing of the corner portions 22 can be improved, but the flat portions 21 are adversely affected, for example, poor local infiltration of the electrolyte, insufficient holding amount of the electrolyte, and the like. According to the embodiment of the application, the tab area 320 and the end portion clearance area 330 are combined, wherein the end portion clearance area 330 is arranged to provide a winding buffer area for winding the electrode main body 20, so that the winding stability of the electrode main body 20 is improved, the occurrence of unstable winding caused by the fact that an area with the first convex portion 311 is a winding starting point or a winding end point is reduced, the flat portion 21 is protected, the tab area 320 is combined, the portion of the electrode main body 20, which is provided with the tab assembly 40, is prevented from expanding to drive the tab assembly 40 to extrude the electrode main body 20, the mutual damage of the tab assembly 40 and the electrode main body 20 is reduced, the tab area 320 extends to the edge of the pole piece 300, the supporting effect exerted by the first convex portion 311 can be continued to the tab area 320, the electrode tab area 320 of the pole piece 300 is not easy to extrude, a part of the area can be reserved for containing electrolyte, the electrolyte can be conveniently put in and put in the electrode main body 20, and the electrolytic infiltration effect is improved. Therefore, in the electrode assembly of the embodiment of the application, not only the interface problem caused by extrusion of the corner portion 22 can be improved, but also the negative problem of the straight portion 21 caused by extrusion can be reduced, and when the electrode assembly is applied to a battery, the performance of the corner position of the battery core can be improved, and the overall cycle performance of the battery is improved.

The end keep-out area 330 in the embodiment of the present application includes at least one of a head keep-out area 331 and a tail keep-out area 332, and the head keep-out area 331 and the tail keep-out area 332 respectively penetrate through the pole piece 300 in the width direction Y of the pole piece 300. In the length direction X of the pole piece 300, a head clearance area 331 is arranged at one end of the bump area 310, and a tail clearance area 332 is arranged at the other end of the bump area 310; the electrode sheet 300 is wound from the head space 331 and the separator 50 along the longitudinal direction X of the electrode sheet 300 to form the flat electrode body 20. When the head clearance area 331 and the ending clearance area 332 need to be selected, the embodiment of the present application prefers that the end clearance area 330 includes the ending clearance area 332, which is more helpful for improving the winding stability of the electrode body 20. More preferably, the end keep-out area 330 includes both the head keep-out area 331 and the ending keep-out area 332, which can more effectively improve the winding stability of the electrode body 20. Alternatively, in the unfolded state of the pole piece 300, the outer contour shape of the head keep-out area 331 is rectangular, and the outer contour shape of the tail keep-out area 332 is rectangular.

As shown in fig. 2, in the length direction X of the pole piece 300, the size of the ending clearance area 332 is D, and D satisfies: d is more than or equal to 30mm and less than or equal to 1000mm. For example, D may be in the range of 30mm, 50mm, 100mm, 150mm, 300mm, 500mm, 1000mm, or any two of these. When the dimension D of the ending clearance area 332 is within the range of 30 mm-1000 mm, the ending clearance area 332 is made to have a suitable length for ending, so that the connection stability of the ending position of the electrode main body 20 is improved, the whole electrode assembly is further made to have good winding stability, the distribution range of the salient points adjacent to the outer ring is made to be suitable, and therefore support is provided for the winding unit positioned on the outer ring, and the extrusion problem of the outer ring of the electrode main body 20 is improved. When D is less than the lower limit of 30mm, the size of the finishing void region 332 is too small, and the distance from the bump in the length direction X of the electrode sheet 300 to the edge of the electrode sheet 300 is too small, so that it is difficult to improve the packaging stability at the finishing of the electrode body 20. When D is greater than the upper limit 1000mm, the size of the ending clearance area 332 is oversized, the occupied area is oversized, the bump distribution area is insufficient, the supporting effect of the first convex part 311 is poor, and the electrolyte infiltration effect of the pole piece 300 of the outer ring is difficult to improve. Preferably, D satisfies: d is more than or equal to 100mm and less than or equal to 500mm.

In the length direction X of the pole piece 300, the size of the head keep-out area 331 is a, and a satisfies: 30 mm.ltoreq.A.ltoreq.1000 mm, for example, A may be in the range of 30mm, 50mm, 100mm, 200mm, 1000mm or any two thereof. When the size A of the head keep-out area 331 is in the range of 30 mm-1000 mm, the distribution range of the salient point area 310 is suitable, the first convex part 311 positioned at the inner ring can better play a supporting role, the electrolyte infiltration effect of the inner ring of the electrode main body 20 is improved, meanwhile, the head keep-out area 331 and the ending keep-out area 332 are matched conveniently, and the head keep-out area 331 and the ending keep-out area 332 have a proper interval for setting the salient point area 310, so that the distribution range of the salient point area 310 is suitable, and the extrusion problem is better improved. When A is less than the lower limit of 30mm, the head keep-out area 331 is too short in size, which is inconvenient for aligning the ends of the two pole pieces 300 and the isolation film 50. When a is greater than the upper limit 1000mm, the head keep-out area 331 is excessively long, occupies a large area, and causes insufficient supporting force of the inner ring of the electrode main body 20, so that abnormal conditions such as insufficient electrolyte infiltration of the inner ring of the electrode main body 20 are easily caused. Preferably, a satisfies: a is more than or equal to 60mm and less than or equal to 500mm.

The bump area 310 is disposed at a distance from the edge of the pole piece 300 in the width direction Y of the pole piece 300, as shown in fig. 3 and 4, in the width direction Y of the pole piece 300, the pole piece 300 has a first area 341 connected to one side of the bump area 310, a second area 342 connected to the other side of the bump area 310, and the first area 341 extends to the edge of the pole piece 300 in a direction away from the second area 342, and the second area 342 extends to the edge of the pole piece 300 in a direction away from the first area 341, that is, two opposite boundaries of the bump area 310 in the width direction Y of the pole piece 300 are respectively spaced from the corresponding edges of the pole piece 300.

The shortest distance between the bump area 310 and the edge of the electrode sheet 300 coated with the active material layer in the width direction Y is T1, and T1 satisfies: t1 is 0.5 mm.ltoreq.T1.ltoreq.30mm, for example T1 may be in the range of 0.5mm, 1mm, 2mm, 10mm, 15mm, 20mm, 30mm or any two of these. When T1 is less than the lower limit of 0.5mm, the bump area 310 is too close to the edge of the pole piece 300 coated with the active material layer, which will easily cause deformation of the first protruding portion 311 due to extrusion, in addition, due to the stress existing after the first protruding portion 311 is processed, the width of the area reserved at the edge of the bump area 310, where the first protruding portion 311 is not provided, is too narrow, and the pole piece 300 in the edge area is easy to have abnormal structures such as bending, rugged, and wavy edges due to the stress, which affects the accuracy of monitoring and positioning of the pole piece 300 in the winding process. When T1 is greater than the upper limit of 30mm, the bump area 310 is too far from the edge of the electrode sheet 300 coated with the active material layer, the distribution area of the first protrusions 311 is too small, and the supporting force is insufficient. Preferably, T1 satisfies: t1 is more than or equal to 1mm and less than or equal to 30mm. More preferably, T1 satisfies: t1 is more than or equal to 3mm and less than or equal to 30mm. The tab area 320 is attached with the protective adhesive 200, and in the tab area 320, positions other than the tab 100 are coated with active material layers, and other areas of the pole piece 300 are coated with active material layers. The active material layer of the pole piece 300 is arranged on the surface of the current collector, and covers the whole surface of the current collector in the thickness direction of the pole piece 300; in other embodiments, the current collector comprises a coating part and an empty foil part, the empty foil part is connected to the outer side of the coating part in the width direction Y of the pole piece 300, the active material layer covers the surface of the whole coating part and avoids the surface of the empty foil part, and the design can better reduce lithium precipitation, reduce the influence of cold pressing on the deformation of the battery core and improve the safety performance of the battery.

Specifically, pole piece 300 has a first edge 3411 and a second edge 3421 disposed opposite each other in the width direction Y of pole piece 300, bump area 310 has a first boundary 3101 and a second boundary 3102 disposed opposite each other in the width direction Y of pole piece 300, first region 341 is formed between first edge 3411 and first boundary 3101, and second region 342 is formed between second edge 3421 and second boundary 3102. In the width direction Y of the pole piece 300, the distance between the first edge 3411 and the first boundary 3101 is the width T11 of the first region 341 in the width direction Y of the pole piece 300, and the distance between the second edge 3421 and the second boundary 3102 is the width T12 of the second region 342 in the width direction Y of the pole piece 300. When the tab 300 has the first region 341 and the second region 342, the distance T1 of the bump region 310 from the edge of the active material layer in the width direction Y of the tab 300 includes T11 and T12, T11 satisfies: t11 is more than or equal to 0.5mm and less than or equal to 30mm, and T12 meets the following conditions: 0.5mm is less than or equal to T12 is less than or equal to 30mm, wherein the difference between the width T11 of the first region 341 in the width direction Y of the pole piece 300 and the width T12 of the second region 342 in the width direction Y of the pole piece 300 is DeltaT 1, deltaT 1= |T11-T12|, and DeltaT 1 satisfies: when the range is satisfied, the migration rate of lithium ions can be enabled to satisfy a proper range in the high-rate charge and discharge test process, and the high-low temperature cycle performance of the battery is improved.

In addition, the tab assembly 40 and the bump area 310 are also disposed at intervals, so that the first protrusion 311 is conveniently processed on the pole piece 300, and the tab assembly 40 is conveniently mounted on the tab area 320 of the pole piece 300, and the mounting stability of the tab assembly 40 and the structural stability of the first protrusion 311 are provided.

As shown in fig. 2 and 4, the spacing between the tab assembly 40 and the bump area 310 is T2, wherein the spacing between the tab assembly 40 and the bump area 310 includes a pitch in the length direction X and a pitch in the width direction Y of the pole piece 300, and the pitch in both directions is T2. T2 satisfies: t2 is 0.5 mm.ltoreq.T2.ltoreq.30mm, for example T2 may be in the range 0.5mm, 1mm, 2mm, 8mm, 10mm, 15mm, 20mm, 30mm or any two thereof. When T2 is in the range of 0.5 mm-30 mm, the distance between the tab assembly 40 and the bump area 310 is proper, so that the support requirement of the first protruding portion 311 on the tab assembly 40 can be met, and the processing can be facilitated. When T2 is smaller than the lower limit 0.5mm, the spacing is too small, and when the tab assembly 40 is mounted on the tab area 320 of the pole piece 300, the structural stability of the first protruding portion 311 is easily affected, and the process difficulty is high. When T2 is greater than the upper limit of 30mm, the pitch is excessively large, the tab region 320 occupies a large space, and the region where the first protruding portions 311 are distributed is correspondingly reduced, which easily results in insufficient supporting force of the first protruding portions 311 distributed in the bump region 310.

The tab assembly 40 includes a plurality of tabs 100, wherein a portion of the tabs 100 are mounted on one of the pole pieces 300, and another portion of the tabs 100 are mounted on the other pole piece 300, wherein the tab 100 mounted on the positive pole piece 301 is a positive tab, and the tab 100 mounted on the negative pole piece 302 is a negative tab. When the tabs 100 are provided to the pole piece 300 having the bump regions 310, the tab regions 320, and the end void regions 330, each tab 100 is provided to one of the tab regions 320. Alternatively, when only one of the two pole pieces 300 having opposite polarities has the bump area 310, the tab area 320 and the end void area 330, one of the tabs 100 is disposed corresponding to the tab area 320 of one of the pole pieces 300, and the other tab 100 is directly mounted on the edge area of the other pole piece 300. Alternatively, when two pole pieces 300 with opposite polarities have the bump area 310, the tab area 320 and the end void area 330, one part of the tabs 100 is disposed corresponding to the tab area 320 of one of the pole pieces 300, and the other part of the tabs 100 is disposed corresponding to the tab area 320 of one of the pole pieces 300. It should be noted that, after the separator 50 and the two pole pieces 300 are wound to form the flat electrode body 20, the tab 100 mounted on one of the pole pieces 300 is required to be spaced from the tab 100 mounted on the other pole piece 300 to prevent shorting of the two pole pieces 300 with opposite polarities.

Optionally, as shown in fig. 5, the tab 100 includes a connection section connected to the pole piece 300 and a butt section extending out of the edge of the pole piece 300, where a surface of the connection section facing away from the pole piece is convexly provided with a plurality of second protrusions 110, and the second protrusions 110 provide support for the structure at the tab 100, for example, the second protrusions 110 contact with the isolation film 50 to provide support for the isolation film 50, so as to improve the electrolyte wetting effect at the tab 100. Further, the boundary of the region where the tab 100 is provided with the plurality of second protrusions 110 is flush with the second boundary 3102 of the bump region 310. Wherein, the shape, size and arrangement of both the second convex portion 110 and the first convex portion 311 may be set to be the same.

When lithium ions migrate to the position of the negative electrode lug, the position of the negative electrode lug is free of a graphite and other lithium intercalation structure, so that lithium is easy to be separated from the position of the negative electrode lug. Optionally, the tab assembly 40 further includes a plurality of protective adhesives 200, and after the separator 50 and the two electrode plates 300 are wound to form the flat electrode body 20, each protective adhesive 200 is attached to the surface of the negative electrode tab, so as to separate the positive electrode plate from the negative electrode tab and prevent lithium from being separated around the negative electrode tab.

Alternatively, all the protective adhesives 200 are mounted to the same pole piece 300, for example, all the protective adhesives 200 are mounted to the same pole piece 300 having the bump area 310, the tab area 320, and the end void area 330, or all the protective adhesives 200 are mounted to one of the pole pieces 300 where the bump area 310, the tab area 320, and the end void area 330 are not provided. Or, a part of the protective adhesive 200 is mounted on one of the pole pieces 300, and another part of the protective adhesive 200 is mounted on the other pole piece 300. When the protective adhesive 200 is mounted on the pole piece 300 having the bump area 310, the tab area 320 and the end clearance area 330, each protective adhesive 200 is mounted on one of the tab areas 320.

In the embodiment of the present application, the number of tab regions 320 may be one or more. As shown in fig. 2 and 3, the number of tab regions 320 is one, and the tab regions 320 extend along the length direction X of the pole piece 300 to meet the end keep-out region 330, specifically, in the length direction X of the pole piece 300, one end of the tab regions 320 is connected to the head keep-out region 331, and the other end is connected to the tail keep-out region 332. Thus, the salient point area 310 has a regular peripheral outline, the first convex part 311 is conveniently machined in the salient point area 310 of the pole piece 300, the machining efficiency is high, the position of the lug assembly 40 mounted in the lug area 320 is flexible, and the lug assembly is convenient to adapt to various mounting requirements.

Alternatively, as shown in fig. 2, in the width direction Y of the pole piece 300, the pole piece 300 has a first region 341 connected to one side of the bump region 310, and a tab region 320 connected to the other side of the bump region 310, that is, in this case, the pole piece 300 is not provided with a second region 342, and at this time, the width T11 of the first region 341 in the width direction Y of the pole piece 300 is the distance T1 between the bump region 310 and the edge of the width direction Y of the pole piece 300. In the width direction Y of the pole piece 300, the width of the tab area 320 is W1, T1< W1, in this case, the width of the tab area 320 is wider, so that the contact area of the tab assembly 40 mounted on the pole piece 300 is conveniently increased, and the mounting stability of the tab assembly 40 is improved. Further, W1 satisfies: w1 is 2 mm.ltoreq.W1 is 40mm, for example, W1 may be 2mm, 6mm, 10mm, 15mm, 28mm, 30mm, 40mm or a range of any two of these.

Alternatively, as shown in fig. 3, in the width direction Y of the pole piece 300, the pole piece 300 has a first region 341 connected to one side of the bump region 310, a second region 342 connected to the other side of the bump region 310, and a part of the second region 342 away from the bump forms a tab region 320, where the width of the tab region 320 is W1, W1< T1, specifically W1< T12. In this way, the areas on both sides of the bump area 310 are fully utilized for mounting the tab assembly 40, so that more areas are designed for arranging the first protruding portion 311, the supporting area of the first protruding portion 311 is increased, and the supporting stability of the first protruding portion 311 is further improved.

As shown in fig. 6, the number of tab regions 320 and bump regions 310 is plural, and one tab region 320 is disposed between two adjacent bump regions 310 in the length direction X of the pole piece 300, and each tab region 320 penetrates the pole piece 300 along the width direction Y of the pole piece 300, so that the first protruding portion 311 is conveniently processed in the plural bump regions 310 of the pole piece 300. Correspondingly, the tab assembly disposed in the tab region 320 may extend from one edge of the pole piece 300 to the other edge in the width direction Y of the pole piece 300, and both ends of the pole piece may protrude from the edges of the pole piece 300. Alternatively, the edge profile of the tab area 320 may be rectangular, square, or the like, and the edge profile of the bump area 310 may be rectangular, square, or the like. In the length direction X of the pole piece 300, the width of any tab area 320 is W3, where W3 satisfies: w3 is 4 mm.ltoreq.W3 is.ltoreq.100 mm, for example W3 may be in the range of 4mm, 6mm, 10mm, 15mm, 20mm, 25mm, 50mm, 80mm, 100mm or any two thereof. Setting W3 in the range of 4 mm-100 mm is convenient for distribute the width of tab area 320 and bump area 310, improves the supporting stability of first convex portion 311 of bump area 310, and then improves the stability of electrode main body 20 structure.

Referring to fig. 4 again, the bump area 310 has at least one avoidance opening area, each avoidance opening area extends to an edge of the pole piece 300 along the width direction Y of the pole piece 300 to form a tab area 320, and a plurality of avoidance opening areas extend toward the same edge of the pole piece 300 along the width direction Y of the pole piece 300, for example, each of the avoidance opening areas extends toward the second edge 3421 of the pole piece. At this time, the pole piece 300 has a first region 341 and a plurality of second regions 342, and each of the gap opening regions extends along the width direction Y of the pole piece 300 and passes between two adjacent second regions 342, and further extends to the edge of the pole piece 300 to form the tab region 320. In this embodiment, the areas of the protruding point region 310 and the tab region 320 designed by the design can be larger by fully utilizing each partial region of the pole piece 300, so that the pole piece is suitable for mounting the tab assembly 40 with a larger connection area, and the effective supporting area of the first protruding portion 311 of the protruding point region 310 is larger. Alternatively, in the present embodiment, the edge profile of the tab area 320 may have a rectangular shape, a square shape, or a polygonal shape. In the width direction Y of the pole piece 300, the width of the tab area 320 is W1, T1< W1, in this case, the width of the tab area 320 is wider, so as to improve the contact area of the tab assembly 40 mounted on the pole piece 300.

As shown in fig. 7, alternatively, the tab area 320 is disposed on the straight portion 21, the bump area 310 is disposed on the corner portion 22, the dimension of the corner portion 22 is W5, the dimension of the bump area 310 is W6, w6=w5 in the length direction X of the pole piece 300, so that the first protrusion 311 only contacts the corner portion 22 with the corresponding pole piece 300 to provide support, in this case, the first protrusion 311 can provide good support, and has the effect of balancing the wetting of the straight portion 21 and the corner portion 22, thereby improving the cell short plate and the cell cycle performance as a whole.

As shown in fig. 8, alternatively, the tab region 320 is disposed on the straight portion 21, the bump region 310 is disposed on the corner portion 22 and extends to the straight portion 21, and two bump regions 310 of the same ring of pole pieces 300 are disposed at intervals, in the length direction X of the pole pieces 300, the size of the corner portion 22 is W5, the size of the bump region 310 is W6, W6 > W5, so that the first protruding portion 311 of the bump region 310 can support more area, the infiltration channel of the pole pieces 300 can be improved, the problems of insufficient electrolyte and premature failure in partial areas caused by unbalanced infiltration can be solved, the cycle performance can be improved, and further, when the electrode assembly is applied to a battery, the charge-discharge cycle life of the battery 3C/5C can be improved, and the cycle number of the original 300CL of the battery can be improved to be more than 800 CL.

Alternatively, W5 satisfies: w5 is 0.5 mm.ltoreq.W5 is 20mm, for example, W5 may be in the range of 0.5mm, 2mm, 5mm, 8mm, 10mm, 12mm, 15mm, 20mm or any two thereof. W6 satisfies: w6 is 0.5 mm.ltoreq.W6 is 100mm, for example, W6 may be in the range of 0.5mm, 2mm, 8mm, 15mm, 30mm, 50mm, 100mm or any two thereof.

As shown in the pole piece 300 of fig. 7, alternatively, the dimension W6 of all the bump areas 310 in the length direction X of the pole piece 300 is equal, it will be understood that the circumference of each ring of the pole piece 300 gradually increases from the inner ring to the outer ring of the electrode body 20, wherein the dimension W of the corner portion 22 of the outermost pole piece 300 in the length direction X of the pole piece 300 is _max ，W6≥W _max In this way, each bump region 310 can cover a corresponding corner portion 22 with all bump regions 310 having the same dimension W6 in the length direction X of the pole piece 300, and wherein a portion of the bump regions 310 can also extend to partially cover the straight portion 21 with covering the corner portion 22.

Alternatively, the dimension W6 of the bump area 310 in the length direction X of the electrode body 20 gradually increases from the inner ring to the outer ring of the electrode body 20, and at this time, the dimension W6 of the bump area 310 in the length direction X of the electrode body 20 gradually increases from the inner ring to the outer ring of the electrode body 20, that is, as the dimension of the corner portion 22 in the length direction X of the electrode body 300 increases, in which case the dimension W6 of the bump area 310 in the length direction X of the electrode body 300 may be equal to the dimension of the corresponding corner portion 22 in the length direction X of the electrode body 300, that is, the bump area 310 covers only the corresponding corner portion 22; alternatively, the dimension W6 of the bump area 310 in the length direction X of the pole piece 300 may be larger than the dimension of the corresponding corner portion 22 in the length direction X of the pole piece 300, that is, the bump area 310 covers the corresponding corner portion 22 and extends to the flat portion 21.

In this embodiment, the first protruding portion 311 has a top and a bottom, the bottom of the first protruding portion 311 is connected to a surface (the surface may be a plane or a convex arc surface) of other structures of the pole piece 300, the first protruding portion 311 extends from the bottom thereof to be protruding on the surface in contact with the surface, the top of the first protruding portion 311 is a point where the first protruding portion 311 is farthest from the bottom in the thickness direction of the pole piece 300, and the thickness of the first protruding portion 311 is a dimension from the top of the first protruding portion 311 to the bottom of the first protruding portion 311 in the thickness direction of the pole piece 300. When the corner portion 22 has the first convex portion 311, the first convex portion 311 provided to the corner portion 22 has a height h1. When the flat portion 21 has the first convex portion 311, the height of the first convex portion 311 provided in the flat portion 21 is h2, wherein h2 is equal to or less than h1, to improve the electrolyte wetting effect. Further, h1 satisfies: h1 is more than or equal to 55 mu m and less than or equal to 70 mu m; the height of the first convex portion 311 provided in the straight portion 21 is h2, h2 satisfies: h2 is more than or equal to 10 mu m and less than or equal to 18 mu m.

In addition to the solutions in fig. 7 and 8, in the embodiment of the present application, when the straight portion 21 and the corner portion 22 are provided with the first convex portions 311, respectively, h 2. Ltoreq.h1, 55 μm. Ltoreq.h1. Ltoreq.70 μm,10 μm. Ltoreq.h2. Ltoreq.18 μm are satisfied.

In addition, it is preferable that the electrode sheet 300 is wound with the separator 50 along the length direction of the electrode sheet 300 for a plurality of turns to form the electrode body 20, and the plurality of first protrusions 311 of each turn of the electrode sheet 300 are protruded toward the winding center of the electrode body 20 in the thickness direction of the electrode sheet 300, so that the infiltration of the electrolyte is improved more effectively.

Alternatively, the outer contour of the first convex portion 311 is circular, elliptical, or regular polygon. The top surface of the first protruding portion 311, which is in contact with the isolation film 50, is an arc surface, so as to prevent the top end of the first protruding portion 311 from being too sharp to scratch the isolation film 50.

Alternatively, the outer contour dimensions of the first protruding portions 311 are equal. For example, when the outer contour of the first convex portion 311 is circular, the outer contour radius of each circular first convex portion 311 is equal; when the outer contour of the first convex portion 311 is a regular polygon, the radii of the circles circumscribed by the regular polygon are equal.

The two pole pieces 300 with opposite polarities and the isolating film 50 are wound to form the flat electrode main body 20, the probability of insufficient electrolyte caused by extrusion in the central area of the salient point area 310 is higher, in the embodiment of the application, the outer outline size of the first convex part 311 positioned in the central area of the salient point area 310 is larger, the distance between the pole piece 300 in the central area of the salient point area 310 and the isolating film 50 is increased, so that insufficient electrolyte in the central area of the salient point area 310 is improved, and the electrolyte infiltration effect is improved. The pole pieces 300 in fig. 2 to 8 can be designed in such a way that the outer dimension of the first protruding portion 311 in the central region of the protruding point region 310 is relatively large and the outer dimension of the first protruding portion 311 in the edge region of the protruding point region 310 is relatively small, so as to improve the electrolyte shortage. Alternatively, as shown in fig. 9, in the width direction Y of the pole piece 300, the outer contour dimension of the first convex portion 311 gradually decreases from the center region to the edge region of the bump region 310; and/or, in the length direction X of the pole piece 300, the outer contour dimension of the first protruding portion 311 gradually decreases from the center region toward the edge region of the bump region 310.

The pole piece 300 of the embodiment of the present application includes a current collector and an active material layer provided on a surface of the current collector, and the first protrusion 311 may be formed by a portion of the current collector and a portion of the active material layer. For example, the first protruding portion 311 according to the embodiment of the present application may be manufactured by a rolling method, specifically, one side of the pole piece 300 acts on a partial region of the pole piece 300, and the current collector and the active material layer in the region are deformed and bent together, that is, the first protruding portion 311 is formed.

The positive electrode tab 301, the negative electrode tab 302, the separator 50, the positive electrode tab 100, and the negative electrode tab 100 are not particularly limited in the embodiment of the present application, and various elements known in the art to be usable as an electrode assembly are applicable to the present application.

In some exemplary embodiments, the negative electrode tab 302 may include a negative electrode current collector and a negative electrode active material layer disposed on a surface of the negative electrode current collector. Illustratively, the negative electrode current collector may employ at least one of copper foil, aluminum foil, nickel foil, or carbon-based current collector; the thickness of the negative electrode current collector may be 1 μm to 200 μm. The anode active material layer may be disposed on one surface or both opposite surfaces of the anode current collector, and further, in the thickness direction ZZ of the anode tab, the anode active material layer may be coated only on a partial region of the anode current collector. Illustratively, the thickness of the anode active material layer may be 10 μm to 500 μm.

The anode active material layer includes an anode active material, and illustratively, the anode active material includes at least one of lithium metal, natural graphite, artificial graphite, or a silicon-based material including at least one of silicon, a silicon oxygen compound, a silicon carbon compound, or a silicon alloy. The anode active material layer may further include a conductive agent and/or a binder. Illustratively, the conductive agent in the anode active material layer may include at least one of carbon black, acetylene black, ketjen black, sheet graphite, graphene, carbon nanotubes, carbon fibers, or carbon nanowires; the binder in the anode active material layer may include at least one of carboxymethyl cellulose CMC, polyacrylic acid, polyacrylate, polyvinyl pyrrolidone, polyaniline, polyimide, polyamideimide, polysiloxane, styrene-butadiene rubber, epoxy resin, polyester resin, polyurethane resin, or polyfluorene.

In some exemplary embodiments, the positive electrode tab 301 includes a positive electrode current collector and a positive electrode active material layer disposed on a surface of the positive electrode current collector. The positive electrode current collector may be exemplified by aluminum foil, and of course, other positive electrode current collectors commonly used in the art may be used, and the thickness of the positive electrode current collector may be 1 to 200 μm. The positive electrode active material layer may be disposed on one surface or both opposite surfaces of the positive electrode collector, and further, in the thickness direction Z of the positive electrode tab 301, the positive electrode active material layer may be coated only on a partial region of the positive electrode collector, and the thickness of the positive electrode active material layer may be 10 to 500 μm.

The positive electrode active material layer includes a positive electrode active material including LiCoO ₂ 、LiNiO ₂ 、LiMn ₂ O ₄ 、LiCo _1-y MyO ₂ 、LiNi _1-y MyO ₂ 、LiMn _2-y MyO ₄ 、LiNi _x Co _y Mn _z M _1-x-y-z O ₂ Wherein M is at least one selected from Fe, co, ni, mn, mg, cu, zn, al, sn, B, ga, cr, sr, V or Ti, and 0.ltoreq.y.ltoreq.1, 0.ltoreq.x.ltoreq.1, 0.ltoreq.z.ltoreq.1, and x+y+z.ltoreq.1. For example, the positive electrode active material may include at least one of lithium cobaltate, lithium manganate, lithium iron phosphate, lithium iron manganese phosphate, lithium nickel cobalt manganate, lithium nickel cobalt aluminate, or lithium nickel manganate, and the positive electrode active material may be subjected to doping and/or coating treatment. The positive electrode active material layer further includes a binder and a conductive agent. Illustratively, positive electrode activityThe binder in the material layer may include at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride-hexafluoropropylene, a styrene-acrylate copolymer, a styrene-butadiene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinyl acetate, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, or polyhexafluoropropylene; the conductive agent in the positive electrode active material layer may include at least one of conductive carbon black, acetylene black, ketjen black, sheet graphite, graphene, carbon nanotubes, or carbon fibers.

In some exemplary embodiments, the barrier film 50 includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyethylene terephthalate, polyimide, or aramid. For example, the polyethylene includes at least one selected from high density polyethylene, low density polyethylene, or ultra high molecular weight polyethylene. In particular, polyethylene and polypropylene, which have good effects in preventing short circuits and can improve the stability of the electrode assembly through a shutdown effect. The thickness of the separation film 50 is in the range of about 3 μm to 500 μm.

The embodiment of the application also provides a battery, which comprises a shell and the electrode assembly, wherein the electrode assembly is arranged in the inner space of the shell. The battery further includes an electrolyte filled in the inner space of the case and impregnating the electrode assembly. The electrolyte is not particularly limited in the embodiment, and various materials known in the art to be usable as an electrolyte are suitable for the present application.

The present application is further illustrated below by taking an electrode assembly of a lithium ion battery as an example in conjunction with specific embodiments. It should be understood that these examples are illustrative only of the present application and are not intended to limit the scope of the present application.

In the examples and comparative examples of the present application, lithium ion batteries were prepared and tested for performance using the following methods:

1. preparation method of lithium ion battery

(1) Preparation of positive electrode sheet 301

Will be positive electrode activeMaterial lithium cobalt oxide LiCoO ₂ Conductive carbon black of conductive agent and polyvinylidene fluoride PVDF as binder in weight ratio of 97.9:0.9:1.2 in N-methylpyrrolidone NMP solution to form a positive electrode slurry. And (3) adopting an aluminum foil with the diameter of 9 mu m as a positive current collector, coating positive electrode slurry on the positive current collector, and drying, cold pressing and cutting to obtain the positive electrode plate. The positive electrode active material layer of the positive electrode sheet 301 had a compacted density of 4.2g/cm ³ 。

In the following embodiments, the positive electrode tab 301 has a bump region 310, a tab region 320, and an end void region 330.

(2) Preparation of negative electrode tab 302

Artificial graphite as a cathode active material, SBR as a binder and CMC as a thickener are mixed according to the weight ratio of 97.4:1.4:1.2 in deionized water to form a negative electrode slurry. And (3) adopting copper foil with the thickness of 10 mu m as a negative current collector, coating negative electrode slurry on the negative current collector, drying, cold pressing and cutting to obtain a negative electrode plate. The compacted density of the anode active material layer of the anode sheet was 1.8g/cm ³ 。

(3) Preparation of the release film 50

The membrane substrate is polyethylene PE with the thickness of 5 mu m, one surface of the membrane substrate is coated with an alumina ceramic layer with the thickness of 2 mu m, and finally, two surfaces of the membrane substrate coated with a single-layer ceramic layer are respectively coated with a binder polyvinylidene fluoride PVDF with the thickness of 2.5mg/1540.25mm, and the membrane substrate is dried to form a porous layer. The porosity of the porous layer of the separator 50 was 39%.

(4) Preparation of electrolyte

Under the environment with the water content less than 10 ppm, ethylene carbonate abbreviated as EC, propylene carbonate abbreviated as PC, diethyl carbonate abbreviated as DEC, ethyl propionate abbreviated as EP and propyl propionate abbreviated as PP are uniformly mixed according to the mass ratio of 1:1:1:1:1:1, and then electrolyte salt LiPF is used for preparing the electrolyte ₆ Dissolving in the non-aqueous solvent, and mixing to obtain electrolyte, wherein based on electrolyte mass, liPF ₆ The mass percentage of (2) is 12.5%.

(5) Assembly of lithium ion electrons

The positive electrode lug 100 is mounted in one lug area 320 of the positive electrode plate 301 in a rolling manner, the protective adhesive 200 is adhered to the other lug area 320 of the positive electrode plate 301, and the negative electrode lug 100 is mounted in the edge area of the negative electrode plate 302 in a rolling manner.

The positive electrode sheet 301 with the positive electrode tab 100, the separator 50, and the negative electrode sheet 302 with the negative electrode tab 100 are sequentially stacked, so that the separator 50 is positioned between the positive electrode sheet 301 and the negative electrode sheet 302 to perform the function of separation, and the electrode body 20 is obtained by winding. And placing the electrode assembly in an outer packaging aluminum plastic film, dehydrating at 80 ℃, injecting the electrolyte, packaging, and performing technological processes such as formation, degassing, trimming and the like to obtain the lithium ion battery. The following describes a method of testing various parameters of various embodiments of the present application.

2. Performance test of lithium ion battery

(1) 25 ℃ cycle test

The electrode assembly was charged constant current to full charge voltage (maximum cell design voltage 4.5V) at a charge current of 2C/5C in an environment of 25C, then charged constant voltage at maximum voltage until current was 0.02C, then discharged constant current at discharge current of 0.5C until final voltage was 3.0V, and the discharge capacity of the first cycle was recorded. And repeating the steps to carry out charge and discharge cycles, and recording the cycle times N when the cycle capacity retention rate is less than or equal to 80 percent.

Cycle capacity retention= (discharge capacity of nth cycle/discharge capacity of first cycle) ×100%.

(2) 45 ℃ cycle test

The electrode assembly was charged constant current to full charge voltage (maximum cell design voltage 4.5V) at a charge current of 2C/5C in an environment of 45C, then charged constant voltage at maximum voltage until current was 0.02C, then discharged constant current at discharge current of 0.5C until final voltage was 3.0V, and the discharge capacity of the first cycle was recorded. Then repeating the steps to carry out charge and discharge circulation, and recording the circulation times N when the circulation capacity retention rate is less than 80 percent.

(3) Winding rate testing

Winding an isolating film between two pole pieces 300 (a positive pole piece 301 and a negative pole piece 302) with opposite polarities in an integral winding machine to form an electrode main body, measuring the distance M (M is more than 0.1mm and is qualified) between the edges of the negative pole piece 302 of the electrode main body and the edges of the positive pole piece 301 in the width direction of the positive pole piece 301 by using X-Ray equipment, continuously preparing samples, counting the total number T (the total number is 100) of the samples, and counting the number N of qualified products;

winding rate=n/t×100%

(4) Test of infiltration improvement effect

After the step of filling the aluminum plastic film into the outer package is finished, standing for 24 hours at normal temperature (25 ℃), disassembling and observing the wetting condition of the isolating film, and estimating and comparing the area of the wetted part, wherein the electrode assembly is divided into 3 grades of remarkable (60% -100% of wetting area), medium (30% -60% of wetting area) and no difference (0% -30% of wetting area); the unwetted areas are typically irregular water grain boundaries and the difference in area size can be directly visually observed.

(5) Liquid retention test

The liquid retention amount is the amount of electrolyte finally retained in the lithium ion battery, and in order to ensure the consumption of the electrolyte in the formation of the lithium ion battery, a certain amount of electrolyte is generally injected more, and the redundant electrolyte is extracted after the formation; measuring by weighing, injecting the liquid amount m1, and extracting the electrolyte liquid amount m2;

Liquid retention = m1-m2.

In table 1, examples 1-1 to 1-21 employ the electrode sheet 300 shown in fig. 4 as the positive electrode sheet 300. The relevant parameters in examples 1-1 to 1-21 are shown in Table I.

TABLE I

Comparative examples 1-1 to 1-3, examples 1-2 to 1-21 are different from example 1-1 in that the spacing T1 between the tab region 310 and the edge of the pole piece, the spacing T21 between the tab and the tab region 310, and the spacing T22 between the protective paste and the tab region 310 of the lithium ion battery are different (here, the spacing T2 between the tab and the tab region 310 of the lithium ion battery is denoted as T21, and the spacing T2 between the protective paste and the tab region 310 is denoted as T22 for convenience of description), and the parameters and performance test results of the lithium ion batteries in comparative examples 1-1 to 1-3, examples 1-1 to 1-21 are shown in table 1.

TABLE 1

As can be seen from comparative examples 1-1 to 1-3, examples 1-1 to 1-9 in table 1, the spacing T1 of the bump area 310 from the edge of the pole piece 300 satisfies: t1 is more than or equal to 0.5mm and less than or equal to 30mm, the flatness of the edge of the pole piece 300 is good, the normal temperature and high temperature cycle performance of the lithium ion battery is improved, and the high-rate charge and discharge performance is improved very high. In addition, the winding rate in the actual production process is improved. When T1 is less than the lower limit of 0.5mm, since the first protrusion 311 is too close to the edge of the electrode sheet 300, when the first protrusion 311 is rolled on the electrode sheet 300, the edge of the electrode sheet 300 is liable to be wavy curled due to rolling stress, flatness is poor, and cycle performance of the lithium ion battery is lowered. When T1 is greater than the upper limit 30mm, the area of the bump region 310 is too small, and the effective supporting area of the first protrusion 311 provided in the bump region 310 is insufficient, resulting in insufficient electrolyte channels of the lithium ion battery, poor high-temperature and normal-temperature cycle performance improvement effects, inability to improve high-current charge and discharge performance, and adverse effects on the winding rate.

As can be seen from examples 1-10 to 1-15 in table 1, the spacing T21 between the tab 100 and the bump area 310 is 1mm to 30mm, the normal temperature and high temperature cycle performance of the lithium ion battery is improved, and the high-rate charge and discharge performance is improved. In addition, the winding rate in the actual production process is improved.

According to examples 1-16 to 1-21 in table 1, it can be seen that the distance T22 between the protective paste and the bump area 310 is 0.5 mm-30 mm, the normal temperature and high temperature cycle performance of the lithium ion battery is improved, and the high-rate charge and discharge performance is improved. In addition, the winding rate in the actual production process is improved.

In table 2, comparative examples 2-1 to 2-2, examples 1-4, examples 2-1 to 2-12 employ the electrode sheet 300 shown in fig. 4 as the positive electrode sheet 300. Examples 2-1 to 2-12 are different from examples 1-4 in that the dimension W1 of the tab region in the pole piece width direction Y and the dimension of the tab region in the pole piece length direction X are different, the spacing T21 between the tab and the bump region and the spacing T22 between the protective paste and the bump region are equal and each 4mm, and the parameters and performance test results of the lithium ion batteries in comparative examples 2-1 to 2, examples 1-4, and examples 2-1 to 2-12 are shown in table 2.

TABLE 2

As can be seen from comparative examples 2-1 to 2, examples 1-4, and examples 2-1 to 2-7 in table 2, in the present example, the pole piece 300 is provided with the bump region 310 and the end void region 330, which can effectively improve the normal temperature cycle and the high temperature cycle performance of the lithium ion battery.

Among them, according to examples 2-12, comparative examples 1-1 and comparative examples 1-2, when the pole piece 300 has the head keep-out area 331 and the ending keep-out area 332, there is substantially no influence on the winding rate, and when the opposite head keep-out area 331 and ending keep-out area 332 are eliminated, the winding rate is greatly reduced.

According to comparative examples 2-1 to 2, examples 1-4, and examples 2-1 to 2-12, it can be seen that the provision of the electrode tab 300 having the bump region 310, the tab region 320, and the end void region 330 can also improve the cycle performance of the lithium ion battery at normal and high temperatures. This is effected by the proper arrangement of tab region 320 and end keep-out region 330. The tab area 320 is properly arranged in the dimension W1 of the width direction Y of the pole piece 300, so that the bump area 310 can avoid the positions of the tab and the impregnated gummed paper, and the damage interface of the tab and the gummed paper is prevented from being deteriorated; the size W3 of the tab area 320 in the length direction X of the pole piece 300 is reasonable, the area occupation ratio of the bump area 310 can be large enough, the improvement on the cycle performance of the lithium ion battery is more remarkable, both W1 and W3 are reasonably arranged at the same time, the area occupation ratio of the bump area 310 is large enough while avoiding the positions of the tab and the impregnated gummed paper, and the improvement effect on the cycle performance at high temperature and normal temperature is optimal.

From examples 1-4, examples 2-1 to 2-3, examples 2-9 to 2-12, comparative examples 2-1 to 2-2, it can be seen that the dimension W1 of the tab region 320 in the length direction X of the pole piece 300 satisfies: w1 is less than or equal to 2mm and less than or equal to 40mm, the cycle performance of the lithium ion battery can be improved, and the improvement of the 2C high-rate charge-discharge cycle is more remarkable, and the main reason is that the reasonable arrangement of W1 can improve the interface, and meanwhile, the electrode lugs can be avoided, and the damage to the electrode lugs is reduced. When W1 is larger than the upper limit of 40mm, the electrode lugs are avoided, but the avoiding interval is too large, the area of the salient point area is reduced, so that poor improvement effect on the interface is weakened, and the final cycle performance falls back;

as can be seen from examples 2-4 to 2-7, examples 2-10 to 2-12, comparative examples 2-1 to 2-2, the dimension W3 of the tab region 320 in the length direction X of the pole piece 300 satisfies: w3 is more than or equal to 10mm and less than or equal to 50mm, the normal temperature cycle performance and the high temperature of the lithium ion battery can be improved, and the improvement effect is more obvious under the 2C high-rate charge-discharge cycle condition. When W3 is larger than the upper limit of 50mm, the improvement effect of the areas on the two sides of the lug is weakened due to the fact that the distance between the salient point area and the lug area is too large, and therefore the circulation performance is influenced.

In table 3, examples 3-1 to 3-12 employ the electrode sheet 300 shown in fig. 4 as the positive electrode sheet 300. Examples 3-1 to 3-12 are different from examples 1-2 in that the size a of the head clearance area and the size D of the tail clearance area of the lithium ion battery are different, and the parameters and performance test results of the lithium ion batteries in examples 3-1 to 3-12 are shown in table 3.

TABLE 3 Table 3

As can be seen from examples 3-1 to 3-4 and examples 3-9 to 3-10 in table 3, the size a of the head space area 331 satisfies: a is more than or equal to 30mm and less than or equal to 1000mm, has less influence on winding rate and improves the normal temperature cycle performance and the high temperature cycle performance of the battery under high-rate current density. When A is smaller than the lower limit by 30mm, the winding feeding precision can be affected, when A is larger than the upper limit by 1000mm, the avoiding area is overlarge, the area occupied ratio of the salient point area is reduced, and the circulation improvement effect is reduced. Preferably, a satisfies: a is more than or equal to 60mm and less than or equal to 500mm.

From examples 3-5 to 3-8, and examples 3-11 to 3-12 in Table 3, it can be seen that the dimension D of the finish void region 332 satisfies: d is more than or equal to 30mm and less than or equal to 1000mm, the influence on the winding rate of the lithium ion battery is relatively small, and the normal temperature cycle performance and the high temperature cycle performance under the current density of 5C are improved. When D is lower than the lower limit of 30mm, the winding ending precision is affected, and the winding quality is insufficient. When D is higher than the upper limit of 1000mm, the cycle performance of the lithium ion battery can be reduced and fall back, because when D is too large, the salient points are added to the interface area of the original straight part of the tail part, so that the interlayer spacing of the original straight part is too large, the lithium ion transmission path is increased, the efficiency is reduced, the lithium intercalation is insufficient, and finally the cycle performance is influenced.

In table 4, the electrode sheet 300 shown in fig. 7 was used as the positive electrode sheet 300 in examples 4-1 to 4-8, W6 was the size of the bump area at each turn of the electrode sheet, and the size of the bump area at each turn of the electrode sheet was equal, and the parameters and performance test results of the lithium ion batteries in examples 4-1 to 4-8 and examples 1-4 are shown in table 4. The dimensions A of the head void region, the dimension D of the tail void region, and the spacing T1 between the bump region and the edge of the pole piece in examples 4-1 to 4-8 are the same as those in examples 1-4.

TABLE 4 Table 4

In Table 5, the pole piece 300 shown in FIG. 8 was used as the positive pole piece 300 in examples 5-1 to 5-9, and the size A of the head clearance area, the size D of the tail clearance area, and the spacing T1 between the bump area and the edge of the pole piece in examples 5-1 to 5-9 were the same as those in examples 1-4. The parameters and performance test results of the lithium ion batteries in comparative example 5-1, example 5-1 to example 5-9 are shown in table 5. In fig. 8, the size W6 of the bump area gradually increases from the inner ring to the outer ring, W6 in table 5 is the size of the bump area of the pole piece of the outermost ring, wherein the size W6 (i) of the bump area of the ith ring is sequentially calculated from the outside to the inside according to the following formula:

W6（i）=W6-(i*t*π)

wherein i is the number of layers of the electrode assembly from outside to inside;

t is the thickness of the pole piece of 0.12mm;

w6 (i) less than 0 indicates that the layer is not bumped.

TABLE 5

As can be seen from the embodiments in tables 4 and 5, when the bump areas 310 are disposed corresponding to the corner portions 22, and the sizes of the respective bump areas 310 of the pole piece 300 in the length direction X of the pole piece 300 are equal or approximately equal, the size W6 of the bump areas 310 in the length direction X of the pole piece 300 satisfies: w6 is more than or equal to 0.5mm and less than or equal to 100m, and the electrolyte holding quantity and the electrolyte infiltration effect of the lithium ion battery are improved.

When W6 is too small, the size of the bump area 310 in the length direction X of the pole piece 300 is too small, the area occupation ratio of the bump area 310 is greatly reduced, the extrusion of the battery core cannot be effectively supported, the electrolyte channel is blocked, and the circulation performance is reduced.

When W6 is greater than the upper limit of 100mm, the size of the bump area 310 in the length direction X of the pole piece 300 is too large to cover almost all areas of the pole piece, so that on one hand, the pole ear and the impregnated gummed paper cannot be avoided, the interface between the pole ear and the impregnated gummed paper is deteriorated, and finally the pole piece is spread to the whole pole piece, so that the improvement effect of the cycle performance is greatly weakened, and the weakening of the improvement effect is more remarkable in the test of the high-rate battery cell.

The same or similar reference numerals in the drawings of the present embodiment correspond to the same or similar components; in the description of the present application, it should be understood that, if there is an azimuth or positional relationship indicated by terms such as "upper", "lower", "left", "right", etc., based on the azimuth or positional relationship shown in the drawings, this is for convenience of description and simplification of the description, but does not indicate or imply that the apparatus or element to be referred must have a specific azimuth, be constructed and operated in a specific azimuth, and thus terms describing the positional relationship in the drawings are merely used for illustration and are not to be construed as limitations of the present patent, and that the specific meaning of the terms described above may be understood by those of ordinary skill in the art according to the specific circumstances.

The foregoing description of the preferred embodiments of the present application is not intended to be limiting, but is intended to cover any and all modifications, equivalents, and alternatives falling within the spirit and principles of the present application.

Claims

1. The pole piece is characterized by comprising a current collector and an active material layer arranged on the surface of the current collector, wherein the surface of the active material layer, which faces away from the current collector, is provided with a lug area, a salient point area and an end part clearance area; the pole piece comprises a plurality of first convex parts distributed in the salient point areas, and the first convex parts protrude towards the same side of the pole piece in the thickness direction of the pole piece; the end part clearance area is arranged at the end part of the salient point area in the length direction of the pole piece and extends to the edge of the pole piece; the tab area extends to the edge of the pole piece in the width direction of the pole piece, and is used for arranging a tab assembly;

in the width direction of the pole piece, the shortest distance between the salient point area and the edge of the active material layer is T1, and T1 meets the following conditions: t1 is more than or equal to 0.5mm and less than or equal to 30mm; the interval of the lug component and the salient point area is T2, and T2 meets the following conditions: t2 is more than or equal to 0.5mm and less than or equal to 30mm.

2. The pole piece of claim 1, wherein the end void comprises a head void and a tail void, the head void being disposed at one end of the bump region and the tail void being disposed at the other end of the bump region in the length direction of the pole piece; the pole piece is used for winding from the head clearance area and the isolating film along the length direction of the pole piece to form a flat electrode main body.

3. The pole piece of claim 2, wherein in the length direction of the pole piece, the head void area has a size a and the tail void area has a size D, a satisfying: a is more than or equal to 30mm and less than or equal to 1000mm, and D meets the following conditions: d is more than or equal to 30mm and less than or equal to 1000mm.

4. A pole piece according to claim 3, characterized in that in the length direction of the pole piece, a satisfies: a is more than or equal to 60mm and less than or equal to 500mm, and D meets the following conditions: d is more than or equal to 100mm and less than or equal to 500mm.

5. The pole piece of claim 1, wherein T1 satisfies: t1 is more than or equal to 1mm and less than or equal to 30mm.

6. The pole piece of claim 1, wherein T1 satisfies: t1 is more than or equal to 3mm and less than or equal to 30mm.

7. The pole piece of claim 1, wherein T1 satisfies: t1 is more than or equal to 3mm and less than or equal to 20mm.

8. The pole piece of claim 1, wherein in the pole piece width direction, the surface of the active material layer facing away from the current collector has a first region connected to one side of the bump region, a second region connected to the other side of the bump region, the first region extending to an edge of the active material layer in a direction away from the second region, the second region extending to an edge of the active material layer in a direction away from the first region;

Setting T11 as the width of the first region in the width direction of the pole piece, and T12 as the width of the second region in the width direction of the pole piece, wherein the difference between T11 and T12 is Δt1, Δt1= |t11-t12|, and Δt1 satisfies: delta T1 is more than or equal to 0mm and less than or equal to 29.5mm.

9. The pole piece of claim 1, wherein the tab assembly comprises a tab; and/or, the tab assembly comprises a protective adhesive.

10. The pole piece of claim 1, wherein the number of tab regions is one and the tab regions extend along the length of the pole piece to meet the end void region.

11. The pole piece of claim 1, wherein in the pole piece width direction, the surface of the active material layer facing away from the current collector has a first region connected to a side of the bump region, the first region being located on a side of the bump region facing away from the tab region and extending to an edge of the pole piece;

the width of the tab area in the width direction of the pole piece is W1, and W1 satisfies the following conditions: w1 is more than or equal to 2mm and less than or equal to 40mm.

12. The pole piece of claim 1, wherein the number of tab regions and bump regions are each a plurality; and one lug area is arranged between two adjacent salient point areas in the length direction of the pole piece, and each lug area penetrates through the pole piece along the width direction of the pole piece.

13. The pole piece of claim 1, wherein the bump region has at least one keep-out opening region, each of the keep-out opening regions extends in the pole piece width direction to the pole piece edge to form the tab region, and a plurality of the keep-out opening regions extend in the pole piece width direction toward the same edge of the pole piece.

14. The pole piece of claim 12 or 13, wherein the tab region has a dimension W3 in the length direction of the pole piece, W3 satisfying: w3 is more than or equal to 10mm and less than or equal to 50mm.

15. The pole piece of claim 1, wherein the pole piece is configured to be wound with a separator film a plurality of times along a length direction of the pole piece to form an electrode body; each circle of pole piece comprises a straight part and corner parts arranged at two ends of the straight part, and the lug areas are arranged on the straight part; in the length direction of the pole piece, the dimension of the corner part is W5, and the dimension of the salient point area is W6;

the bump area is provided at the corner portion, wherein w6=w5; or alternatively, the first and second heat exchangers may be,

the salient point areas are arranged at the corner parts and extend to the straight parts, and the salient point areas of the same circle of pole pieces are arranged at intervals, wherein W6 is larger than W5.

16. The pole piece of claim 15, wherein the pole piece is formed from a material selected from the group consisting of,

w5 satisfies: w5 is more than or equal to 0.5mm and less than or equal to 20mm; and/or the number of the groups of groups,

w6 satisfies: w6 is more than or equal to 0.5mm and less than or equal to 100mm.

17. The pole piece of claim 15, wherein the pole piece is formed from a material selected from the group consisting of,

the sizes W6 of all the salient point areas in the length direction of the pole piece are equal; or alternatively, the first and second heat exchangers may be,

from the inner ring to the outer ring of the electrode main body, the dimension W6 of the salient point area in the length direction of the pole piece is gradually increased.

18. The pole piece of claim 1, wherein the pole piece is configured to be wound with a separator film a plurality of times along a length direction of the pole piece to form an electrode body; each circle of pole piece comprises a straight part and corner parts arranged at two ends of the straight part, and the lug areas are arranged on the straight part;

the height of the first convex portion provided at the corner portion is h1, h1 satisfying: h1 is more than or equal to 55 mu m and less than or equal to 70 mu m;

the height of the first convex part arranged on the straight part is h2, and h2 meets the following conditions: h2 is more than or equal to 10 mu m and less than or equal to 18 mu m.

19. The pole piece of claim 1, wherein the pole piece is configured to be wound with a separator film a plurality of times along a length direction of the pole piece to form an electrode body; the plurality of first protrusions of each turn of the pole piece are protruded toward the winding center of the electrode body in the thickness direction of the pole piece.

20. A pole piece as claimed in claim 1, wherein,

the outer contour of the first convex part is round, elliptic or regular polygon; or alternatively, the first and second heat exchangers may be,

the outer contour sizes of the first convex parts are equal; or alternatively, the first and second heat exchangers may be,

in the width direction of the pole piece, the outer contour dimension of the first convex part gradually decreases from the central area to the edge area of the salient point area; or;

in the length direction of the pole piece, the outer contour dimension of the first convex part gradually decreases from the central area to the edge area of the salient point area.

21. An electrode assembly comprising a plurality of tab assemblies, a pole piece according to any one of claims 1 to 20, and a separator disposed between the two pole pieces, wherein the separator and the two pole pieces are wound in a longitudinal direction of the pole pieces to form a flat electrode body.

22. The electrode assembly of claim 21, wherein the tab assembly comprises a tab disposed in a tab region of the pole piece; the tab includes with the linkage segment that the pole piece is connected and stretches out the butt joint section at pole piece edge, the linkage segment deviates from the protruding a plurality of second convex parts that are equipped with in surface of pole piece.

23. A battery, comprising:

a housing; the method comprises the steps of,

the electrode assembly of claim 22, wherein the electrode assembly is disposed in an interior space of the housing.