Wound cell and battery

Abstract

Winding cell, characterized in that it comprises: a negative electrode plate and a positive electrode plate arranged in a stacked manner; wherein the negative electrode plate comprises a negative electrode current collector having a first surface and a second surface arranged opposite one another in a first direction, the first surface being provided with a first paste layer and the second surface being provided with a second paste layer; wherein the first paste layer is provided with a plurality of grooves, and wherein the centers of two adjacent grooves are spaced apart from each other by a first distance; wherein the positive electrode plate is provided with a plurality of projections and recesses corresponding to the projections, and wherein a surface on which the projections of the positive electrode plate are located and a surface on which the grooves of the negative electrode plate are located are arranged opposite each other; and wherein the dimension of a vertical projection of the protrusion in a thickness direction onto the negative electrode plate, measured in a width direction of the groove, is greater than the first distance.

Description

Technical FieldThe present application relates to the technical field of lithium electronic batteries, in particular to a wound cell and a battery.Prior ArtWith the rapid development of lithium ion battery technology, higher demands are placed on the performances such as energy density, cycle life and safety of a lithium ion battery.When the lithium ion battery is charged and discharged, the negative electrode plate expands, causing the layers of the electrode plate to be pressed together. Specifically, a wound lithium ion battery formed by the winding has a strong stress accumulation in a circular arc region of its wound structure, and in the circular arc region itself, the electrode plates are already compressed. In connection with the expansion of the negative electrode plate in charging and discharging, the electrode plates are compressed even more strongly. This compression is also transmitted from the circular arc region to the planar region. Finally, this compression of the layers leads to an insufficient electrolyte solution between the layers and thus to poor wetting, to a deteriorated interface and even to a lithium deposition from the negative electrode plate, which has a negative effect on the safety of the cell.Disclosure of the InventionIn view of the above problems, in the embodiments of the present application, a wound cell and a battery are provided to solve the problems of the insufficient electrolyte solution and the poor wetting of the electrolyte solution by the compression of the layers of the electrode plates of the wound cell in the related art.In order to achieve the above object, an embodiment of the present application provides the following technical solution:In an embodiment of the present application, there is provided a wound cell including: a negative electrode plate and a positive electrode plate stacked; wherein the positive electrode plate is provided with a plurality of protrusions and recesses disposed opposite to the protrusions.By providing the positive electrode plate with the protrusions and the recesses corresponding to the protrusions, contact with a separator is promoted by the protrusions, and micro spaces between the electrode plates and the separator are increased. The micro-spacings provide a space in which an electrolyte solution can be accommodated so that a sufficient amount of electrolyte solution is present for wetting the electrode plate, thereby avoiding abnormal circumstances such as insufficient electrolyte solution between the electrode plates and the separator, poor wetting or even lithium deposition from the negative electrode plate due to the compression of the layers of the electrode plates.The negative electrode plate includes a negative electrode current collector having, in a first direction, a first surface and a second surface arranged oppositely, the first surface being provided with a first paste layer and the second surface being provided with a second paste layer; the first paste layer being provided with a plurality of grooves, and a surface on which the protrusions of the positive electrode plate are located and a surface on which the grooves of the negative electrode plate are located are arranged oppositely.By providing the negative electrode plate with the groove directly opposite to the protrusion, wetting of the electrolyte solution for the electrode plate can be effectively improved by the groove provided on the negative electrode plate. In addition, a surface on which the protrusions of the positive electrode plate are located and a surface on which the grooves of the negative electrode plate are located are arranged opposite to each other. Thereby, an expansion space for the expansion of the negative electrode plate is provided, so that the compression or deformation of the projection of the positive electrode or the deformation of the groove of the negative electrode caused with the expansion of the negative electrode plate in hot pressing and formation or in charging and discharging of the battery is slowed. This ensures the structural strength of the protrusions and the grooves as well as the bonding strength of the interfaces between the electrode plate and the separator, thereby stably effecting the support of the separator. In addition, the sufficient expansion space can also prevent the negative electrode plate from compressing the separator during expansion and leading to deformation of the separator.The centers of two adjacent ones of the grooves are spaced apart from each other by a first distance, and the dimension of a vertical projection of the projection onto the negative electrode plate measured in the width direction of the groove is larger than the first distance.By disposing the positive electrode protrusion and the negative electrode groove to be opposed to each other and also by making the dimension of a projection of the positive electrode protrusion onto the negative electrode plate larger than the distance between the centers of the negative electrode grooves, the positive electrode protrusion is prevented from being embedded in the negative electrode groove. This promotes an SEI film to be formed by the positive electrode raised portions, so that effective protection is provided for the positive electrode raised portions. And, the active particles of the positive electrode raised portions are prevented from being crushed or even cobalt is deposited therefrom, resulting in a decrease in the structural stability of the positive electrode active material and an accelerated decrease in the battery capacity.In an embodiment of the present application, it is provided that the first surface and the second surface of the negative electrode plate are each provided with a plurality of grooves; wherein the protrusion and the groove are arranged opposite to each other; and wherein the recess and the groove are arranged opposite to each other.Grooves are provided on both sides of the negative electrode plate so that the positive electrode recess and the negative electrode groove are opposed, while the positive electrode projection and the negative electrode groove are opposed. By disposing the positive electrode recess and the negative electrode groove to be opposed to each other, the space between the positive electrode plate and the negative electrode plate can be increased, so that a larger wetting space for the electrolyte solution is provided, and thereby the amount of the stored electrolyte solution is increased.In an embodiment of the present application, it is arranged that the dimension of the projection of the protrusion onto the negative electrode plate in the thickness direction measured in the width direction of the groove is referred to as R1, and the first distance is referred to as S, where R1 / S=1.02 to 8.In the range of the above ratios, it is possible to slow the compression or deformation of the positive electrode protrusion or the deformation of the negative electrode groove caused with the expansion of the negative electrode plate in hot pressing and formation or in charging and discharging of the battery. If the ratio is below this range of the above ratios, it means that the groove width of the first pitch is large. When the negative electrode plate expands and thereby the layers of the electrode plate are compressed, it easily causes the positive electrode protrusion to be embedded in the negative electrode groove, and the SEI film of the positive electrode protrusion to be damaged, thereby leaving the positive electrode protrusion unprotected. If the ratio is above this range of the above ratios, it means that the groove width of the first pitch is small. Thus, the provision of the first distance is meaningless. The groove cannot provide an expansion space for the expansion of the negative electrode plate. In addition, it easily leads to compression or deformation of the positive electrode protrusion or deformation of the negative electrode groove caused by the expansion of the negative electrode plate in hot pressing and formation or in charging and discharging of the battery.In an embodiment of the present application, it is arranged that the dimension of the projection of the protrusion onto the negative electrode plate in the thickness direction measured in the width direction of the groove is referred to as R1, and the groove width of the groove is referred to as M, where R1 / M=8 to 50.In the range of the above ratios, it is possible to slow the compression or deformation of the positive electrode protrusion or the deformation of the negative electrode groove caused with the expansion of the negative electrode plate in hot pressing and formation or in charging and discharging of the battery. If the ratio is below this range of the above ratios, it means that the groove width of the groove is large. When the negative electrode plate expands and thereby the layers of the electrode plate are compressed, it easily causes the positive electrode protrusion to be embedded in the negative electrode groove, and the SEI film of the positive electrode protrusion to be damaged, thereby leaving the positive electrode protrusion unprotected. If the ratio is above this range of the above ratios, it means that the groove width of the groove is small. Thus, the provision of the groove is meaningless. It is difficult for the groove to store sufficient electrolyte solution. The groove can neither provide an expansion space for the expansion of the negative electrode plate nor slow the compression or deformation of the positive electrode protrusion or the deformation of the negative electrode groove caused with the expansion of the negative electrode plate in hot pressing and formation or in charging and discharging the battery.In an exemplary embodiment of the present application, it is provided that the first paste layer and / or the second paste layer comprises a silicon-carbon composite material and / or a silicon-oxygen composite material, wherein the silicon-carbon composite material and / or the silicon-oxygen composite material make up less than or equal to 50% by weight of the mass of the first paste layer and / or of the second paste layer.In an exemplary embodiment of the present application, it is provided that the positive electrode plate includes a positive electrode current collector having, in the first direction, a third surface and a fourth surface arranged oppositely, and the third surface is provided with a third paste layer and the fourth surface is provided with a fourth paste layer; the negative electrode plate and the positive electrode plate are wound around a first central surface, a surface of the positive electrode current collector facing the first central surface is referred to as the third surface, and a surface of the positive electrode current collector facing away from the first central surface is referred to as the fourth surface; the third surface and the first surface are arranged oppositely, and the fourth surface and the second surface are arranged oppositely; wherein the wound cell includes a flat portion and corner portions provided at opposite ends of the flat portion, respectively; and wherein the protrusion protrudes from the third paste layer into the fourth paste layer.Due to the curvature of the corner region, the first surface of the silicon-doped negative electrode plate is subjected to a greater compression than the second surface of the silicon-doped negative electrode plate. When the silicon-doped negative electrode plate expands as a whole, the expansion of the second surface is stronger than the expansion of the first surface, which easily leads to cracking on the second surface of the negative electrode plate. By the first surface and the groove of the negative electrode and the third surface being arranged opposite to the positive electrode, i.e., the depression of the second surface of the negative electrode and the third surface being arranged opposite to the positive electrode, a part of the coating of the second surface can penetrate into the recess of the positive electrode upon a large expansion of the second surface of the negative electrode, and thereby the voltage of the expansion of the negative electrode can be relieved. As a result, the depth of the positive electrode protrusion does not deteriorate, thereby ensuring normal support of the positive electrode protrusion.When the circular arc formed by the outer side of the positive electrode plate wraps around the negative electrode plate, the circumference of the circular arc of the third paste layer on the third surface on the inner side of the positive electrode plate is larger than the circumference of the first surface of the negative electrode plate in the corner portion due to the curvature of the corner portion. This results in that in this range the ratio between the negative area capacitance and the positive area capacitance is reduced, which leads to a risk of lithium deposition. In this embodiment of the present application, by the protrusion protruding from the third paste layer into the fourth paste layer and the depression of the first negative electrode surface and the recess being opposed to the third positive electrode surface, the migration path of the positive electrode active material in the recess is longer and the migration path of the positive electrode active material in the other regions is shorter. This in turn reduces the positive electrode active material in the recess that participates in the charge and discharge reaction, and the negative electrode paste layer on the third surface has enough sites for the aging of lithium ions, thereby increasing the CB value (negative area capacity / positive area capacity) in this range and decreasing the likelihood of lithium deposition in this range.In an embodiment of the present application, it is provided that the sum of the projected areas of the plurality of protrusions onto the negative electrode plate is 60% to 90% of the area of the fourth paste layer; and the wound cell further comprises an electrolyte solution doped with an additive of 1,4-dicyano-2-butene, wherein the content of the additive of 1,4-dicyano-2-butene is 0.05% to 3% of the electrolyte solution.By limiting the portion of the region where the positive electrode protrusions are located on the paste layer, the support effect of the positive electrode protrusion can be ensured. In addition, the electrolyte solution wetted between the positive electrode plate and the negative electrode plate is also doped with a certain content of additive of 1,4-dicyano-2-butene, and 1,4-dicyano-2-butene can provide protection for the edges of the protrusion of the positive electrode and reinforce the edges of the protrusion. The positive electrode protrusion active particles are prevented from being crushed or even cobalt is deposited therefrom, resulting in a decrease in the structural stability of the positive electrode active material and an accelerated decrease in battery capacity.In an embodiment of the present application, it is provided that the projected shape of the protrusion onto the negative electrode plate comprises a circular, semicircular, oval, plumen-shaped, polygonal, diamond-shaped, capsule- or island-shaped shape, etc.In an embodiment of the present application, it is provided that the positive electrode plate includes an upper surface and a lower surface that are arranged opposite to each other, the protrusion protruding outward from the upper surface of the positive electrode plate; the protrusion including a protrusion portion and a base portion that connects the protrusion portion and the upper surface; the protrusion portion is formed as an arc-shaped surface, and / or an edge of the protrusion portion that is connected to the polygonal, diamond-shaped, or island-shaped protrusion by an arc-shaped edge surface and the upper surface is formed as a circular arc-shaped edge.It is to be avoided that the projection has sharp edges in order to prevent powder from falling off its edges during the processing of the projection. In addition, the edges or the top of the protrusion are prevented from piercing the positive electrode paste, thereby preventing the paste from cracking and falling off powder therefrom. Fallen powder particles tend to fall on the negative electrode plate, resulting in risks such as short circuit and fire. Moreover, it can thereby be prevented that the top surface of the protrusion pierces the separator and comes into contact with the negative electrode plate, resulting in a short circuit.In an embodiment of the present application, it is arranged that a connecting line connecting the base portion and an apex of the protrusion portion is referred to as a first connecting line, and an angle between the first connecting line and the upper surface is referred to as a first angle that is 3° to 45°.By limiting the angle between the first connecting line and the upper surface, it is ensured that the positive electrode protrusion has an appropriate slope, so that the positive electrode protrusion serves to support between the positive electrode plate and the negative electrode plate, and can also prevent the positive electrode protrusion from being too sharp to pierce the separator. If the first angle is less than 3°, the protrusion is too small so that it cannot serve to support between the positive electrode plate and the negative electrode plate. If the first angle is greater than 45°, the protrusion has too great a slope, resulting in a tip of the protrusion. This easily leads to a puncture of the separator and thus to a safety problem.In one exemplary embodiment of the present application, it is provided that the corner region has a first thickness H 1 and the flat region has a second thickness H 2, wherein the following applies to the first thickness H 1 and the second thickness H 2: H 1 / (H 2 / 2)=1.05 TO 1.5.Due to the structural properties of the corner region and the accumulation of stresses, the outward expansion of the corner region is limited, ultimately leading to the problem of lithium deposition by the compression of the layers of the electrode plate. In this embodiment of the present application, by providing the positive electrode plate with the protrusions and the recesses disposed opposite to the protrusions and the negative electrode plate with the grooves directly opposite to the protrusions, the above-mentioned thickness ratios are achieved. By setting the thickness ratios as mentioned above, the problem of the lithium deposition in the corner region can be effectively improved. In addition, it is thereby ensured that the protrusions, grooves, and thicknesses of the corner portion and the flat portion are matched to each other to appropriately make the interaction force of the layers of the cell and to ensure that the protrusions of the positive electrode plate and the recesses of the negative electrode plate do not deform during charging and discharging.In an embodiment of the present application, it is provided that for the dimension of a projection of the protrusion onto the negative electrode plate measured in the width direction of the groove, R1=0.3 mm to 8 mm; and / or that a distance between the centers of the projections of two adjacent protrusions onto the negative electrode plate is denoted as D1, wherein D1=1 mm to 6 mm; and / or that for a vertical distance between the base portion and the apex of the protrusion portion measured in the first direction, H3=3 μm to 80 μm.It is to be ensured that the dimension of the projection of the protrusion onto the negative electrode plate is within the above range, thereby avoiding the spike effect by too small a dimension of the protrusion and thus preventing the puncture of the separator. In addition, a greater span of the raised surface of the protrusion due to too large a dimension of the protrusion is also avoided, which impairs the supporting effect of the protrusion. It is to be ensured that the distance between the centers of the protrusions is within the above range, thereby avoiding overlapping of the protrusions or too high a density of the protrusions due to too small a distance between the centers of the protrusions. Otherwise, when the protrusions are formed, the roller pressure is too large, and hence the density of the protrusions is too high, so that it is difficult to relieve the stress between the layers of the cell during charging and discharging, which easily leads to falling of the powder from the electrode plate. In addition, it is also avoided that there is a large span of the raised surface of two adjacent ones of the projections due to too large a distance between the centers of the projections, which impairs the supporting effect of the projection. It is to be ensured that the height of the protrusion is within the above range, thereby preventing a poor supporting effect from being produced and failing to provide a rich wetting space for the electrolyte solution due to a excessively small protrusion. In addition, a strong delamination between the positive electrode plate and the negative electrode plate and thereby a new interfacial problem due to a too large protrusion is also avoided.In an exemplary embodiment of the present application, it is provided that, in the corner region, a vertical distance between an apex of the protrusion of the innermost winding of the winding cell and the base portion of the protrusion is referred to as a first vertical distance, and that a vertical distance between an apex of the protrusion of the outermost winding of the winding cell and the base portion of the protrusion is referred to as a second vertical distance, wherein the first vertical distance is greater than the second vertical distance.The compression in the corner region occurs mainly in some layers of the wound cell in the vicinity of the inner turns. The closer the outer turns approach, the lower the compression pressure, the lower the lack of electrolyte solution and the lower the risk of lithium deposition. By making the vertical distance of the protrusion of the innermost turn of the wound cell larger than the vertical distance of the protrusion of the outermost turn of the wound cell, the retention of the electrolyte solution in the innermost turn of the wound cell can be improved, thereby ensuring that the lithium precipitation and the like do not occur in the inner turns of the cell. Moreover, the width of the corner portion can be reduced by reducing the protrusion of the inner turns in the corner portion, thereby avoiding the cell's spread and increasing the cell's energy density.In an embodiment of the present application, it is provided that the groove width is M=30 μm to 170 μm; and / or the depth of the groove in the first direction is T=10 μm to 60 μm; and / or the first distance is S=0.5 mm to 3 mm.It is to be ensured that the groove width of the grooves is within the above-mentioned range. This prevents the groove from being unable to provide an expansion space for the expansion of the negative electrode plate due to too small a groove width, nor from being able to slow the compression or deformation of the projection of the positive electrode or the deformation of the groove of the negative electrode caused with the expansion of the negative electrode plate in hot pressing and formation or in charging and discharging the battery. In addition, the projection of the positive electrode is prevented from being embedded into the groove of the negative electrode in a vulnerable manner when the negative electrode plate expands due to too large a groove width, and the layers of the electrode plate are thereby pressed together. It is to be ensured that the groove depth of the groove is within the above-mentioned range. This prevents the deformation of the protrusion caused with the expansion of the electrode plate in charging and discharging from being decelerated due to too small a groove depth. Too small a groove depth also results in the amount of stored electrolyte solution being reduced. This also prevents the negative electrode plate from being at risk of breakage in the region of the grooves on account of too great a groove depth. It is to be ensured that the distance between the centers of the grooves is within the above range so that the grooves in the negative electrode plate have an appropriate density.In an exemplary embodiment of the present application, it is provided that the projection of each of the projections onto the negative electrode plate has a center point, wherein a part of the center points distributes on a second connecting line; wherein the projection of the groove onto the negative electrode current collector represents a rectangular area, and wherein the second connecting line and the rectangular area are parallel to each other or intersect each other; and wherein an angle between the second connecting line and the rectangular area is 0° to 45° when the second connecting line and the rectangular area intersect each other.When the second connecting line and the rectangular face are parallel, a plurality of protrusions located on the second connecting line may be disposed opposite to a single groove, which facilitates processing of the protrusions and the grooves. When the second connecting line and the rectangular face intersect, a plurality of protrusions located on the second connecting line are respectively opposed to different grooves, while the angle between the second connecting line and the rectangular face is limited to be within the above range, thereby ensuring that each protrusion on the second connecting line is opposed to the groove.In an embodiment of the present application, a battery including the above-described wound cell is further provided.Brief Description of the FiguresIn order to more clearly explain the technical solutions in the exemplary embodiments of the present application or in the prior art, the drawings required for describing the exemplary embodiments or the prior art are briefly presented below. Obviously, the drawings in the following description represent some embodiments of the present application. The skilled person can also obtain further drawings based on these drawings without inventive activity. FIG. 1 shows a structural schematic illustration of a winding cell in the prior art; FIG. 2 is a structural schematic diagram of a negative electrode plate and a positive electrode plate of the wound cell according to an embodiment of the present application; FIG. 3 is a first structural schematic diagram of the negative electrode plate of the wound cell according to an embodiment of the present application; FIG. 4 is a second structural schematic diagram of the negative electrode plate of the wound cell according to an embodiment of the present application; FIG. 5 is a structural schematic plan view of the negative electrode plate of the wound cell according to an embodiment of the present application; FIG. 6 is a structural schematic diagram of the positive electrode plate of the wound cell according to an embodiment of the present application; FIG. 7 is a structural schematic diagram of the wound cell according to an exemplary embodiment of the present application in a corner region, wherein the positive electrode plate and the negative electrode plate are arranged in a stacked manner; FIG. 8 is a first structural schematic plan view of the positive electrode plate of the wound cell according to an embodiment of the present application; FIG. 9 is a second structural schematic plan view of the positive electrode plate of the wound cell according to an embodiment of the present application; FIG. 10 is a structural schematic diagram of a protrusion of the positive electrode plate of the wound cell according to an embodiment of the present application; FIG. 11 is a schematic diagram showing the slope of the protrusion according to an embodiment of the present application; FIG. 12 shows a first schematic illustration of an intersection between the protrusion and a groove according to an exemplary embodiment of the present application; FIG. 13 shows a second schematic illustration of the intersection between the protrusion and the groove according to an exemplary embodiment of the present application; FIG. 14 shows the thickness specifications for a flat region and a corner region of 10 winding cell types according to an exemplary embodiment of the present application; FIG. 15 shows the specific details for a first diameter and a first spacing of 10 winding cell types according to an exemplary embodiment of the present application; FIG. 16 shows the vertical distances of individual winding layers of the winding cell according to an exemplary embodiment of the present application; and FIG. 17 shows the specific specifications for the first diameter and the groove width of 10 winding cell types according to an exemplary embodiment of the present application.List of reference numbers:100: Negative electrode plate; 101: negative electrode current collector; 102: first paste layer; 103: second paste layer; 110: groove; 1011: first surface; 1012: second surface; 200: positive electrode plate; 201: positive electrode current collector; 202: third paste layer; 203: fourth paste layer; 210: protrusion; 2011: third surface; 2012: fourth surface; 301: first connection line; 302: first horizontal plane; 401: rectangular area; 402: second connection line.DETAILED EMBODIMENTSFIG. 1 illustrates a structure of a winding cell of a wound lithium ion battery in the prior art. The electrode assemblies are stacked and wound to form the wound structure of the cell. The cross section of the wound structure shows a flat elliptical structure, wherein the two sides of the elliptical structure each represent a circular arc region and the center of the elliptical structure represents a planar region. In the figure, the portion of the circular arc portion surrounded by the dotted frame represents a stress concentration portion, and the direction indicated by the arrow is the extension direction in which the positive electrode plate and the negative electrode plate extend. The positive electrode plate and the negative electrode plate expand upon charging and discharging of a lithium ion battery. The planar portion is free to expand upward and downward, while the outward expansion of the circular arc portion is limited due to its structural characteristics and the accumulation of stresses.In addition, the compression is transferred from the circular arc region to the planar region. Since the flat portion was pressed during the production process during the hot pressing, very strong pressing occurs in the flat portion, which in turn leads to poor wetting of the electrolyte solution in the flat portion.Finally, the compression of the layers of the electrode plate leads to poor wetting of the electrolyte solution, so that the amount of the electrolyte solution retained between the layers of the electrode plate is too small, which means that a transmission channel for lithium ions is lost in this region, so that the lithium ions cannot be taken out of the positive electrode plate and thus the lithium ions which are to be taken into the corresponding positions of the negative electrode plate are numerically insufficient. This results in the formation of a violet spot. Finally, the lithium ions from the negative electrode plate cannot be returned to the positive electrode plate, and are finally deposited on the surface of the negative electrode plate, i.e., lithium deposition. Moreover, due to a large expansion of the negative electrode plate during one cycle, it easily leads to compression of the separators in contact with the both sides of the negative electrode plate, resulting in compression of the separators, thereby plugging the micropores of the separators, further increasing the risk of lithium deposition in this region.In the wound cell according to an embodiment of the present application, by providing the positive electrode plate with the protrusions and the recesses corresponding to the protrusions, contact with a separator is promoted by the protrusions, and micro pitches between the electrode plates and the separator are increased. The micro-spacings provide a space in which an electrolyte solution can be accommodated so that a sufficient amount of electrolyte solution is present for wetting the electrode plate, thereby avoiding abnormal circumstances such as insufficient electrolyte solution between the electrode plates and the separator, poor wetting or even lithium deposition from the negative electrode plate due to the compression of the layers of the electrode plates.In addition, by providing the negative electrode plate with the groove directly facing the protrusion, wetting of the electrolyte solution for the negative electrode plate can be effectively improved by the groove provided on the negative electrode plate. In addition, a surface on which the protrusions of the positive electrode plate are located and a surface on which the grooves of the negative electrode plate are located are arranged opposite to each other. Thereby, an expansion space for the expansion of the negative electrode plate is provided, so that the compression or deformation of the projection of the positive electrode or the deformation of the groove of the negative electrode caused with the expansion of the negative electrode plate in hot pressing and formation or in charging and discharging of the battery is slowed. This ensures the structural strength of the protrusions and the grooves as well as the bonding strength of the interfaces between the electrode plate and the separator, thereby stably effecting the support of the separator. In addition, the sufficient expansion space can also prevent the negative electrode plate from compressing the separator during expansion and leading to deformation of the separator.Further, it is arranged that by limiting the dimension of a vertical projection of the projection on the negative electrode plate in the thickness direction to be larger than the distance between the centers of two adjacent grooves, the projection of the positive electrode is prevented from being embedded in the groove of the negative electrode. This promotes an SEI film to be formed by the positive electrode raised portions, so that effective protection is provided for the positive electrode raised portions. And, the active particles of the positive electrode raised portions are prevented from being crushed or even cobalt is deposited therefrom, resulting in a decrease in the structural stability of the positive electrode active material and an accelerated decrease in the battery capacity.In order to clarify the above objects, features, and advantages of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and clearly and fully described below in conjunction with the accompanying drawings in the embodiments of the present application. It is to be understood that the described embodiments are a part of the embodiments of the present application instead of all the embodiments. All other exemplary embodiments which are obtained by the person skilled in the art on the basis of the exemplary embodiments of the present application without inventive activities also belong to the scope of protection of the application.Referring to FIG. 2, a wound cell according to an embodiment of the present application includes: a negative electrode plate 100 and a positive electrode plate 200, wherein the negative electrode plate 100 and the positive electrode plate 200 are arranged in a stacked manner, and wherein the negative electrode plate 100 and the positive electrode plate 200 have opposite polarities.Referring to FIGS. 3 and 5, the negative electrode plate 100 includes a negative electrode current collector 101, wherein the negative electrode current collector 101 has, in a first direction (z-axis shown in the figures), a first surface 1011 and a second surface 1012 that are oppositely disposed, and wherein the first surface 1011 is provided with a first paste layer 102 and the second surface 1012 is provided with a second paste layer 103. Also, the positive electrode plate 200 includes a second current collector 201, the second current collector 201 having, in the first direction (z-axis illustrated in the figures), a third surface 2011 and a fourth surface 2012 arranged opposite to each other, and the third surface 2011 is provided with a third paste layer 202 and the fourth surface 2012 is provided with a fourth paste layer 203.The first paste layer 102 is provided with a plurality of grooves 110 extending in a second direction (y-axis shown in the figures), the plurality of grooves 110 being equidistantly spaced apart from each other in a third direction (x-axis shown in the figures). That is, the grooves 110 extend in a width direction of the negative electrode plate 100, and the plurality of grooves 110 are spaced apart from each other in a length direction of the negative electrode plate 100.Referring to FIGS. 8 to 10, the positive electrode plate 200 has a plurality of arrayed protrusions 210 and a plurality of arrayed recesses, the protrusions 210 and the recesses being arranged opposite to each other. The protrusion 210 may be a protrusion on an upper surface of the positive electrode plate 200, and the recess may be a depression on a lower surface of the positive electrode plate 200.Here, when the negative electrode plate 100 and the positive electrode plate 200 are stacked, the first paste layer 102 and the fourth paste layer 203 are opposed in the first direction (z-axis shown in the figures). In addition, the groove 110 of the first paste layer 102 and the protrusion 210 of the fourth paste layer 203 are disposed opposite to each other in the first direction (z-axis shown in the figures).A surface on which the protrusions of the positive electrode plate are located and a surface on which the grooves of the negative electrode plate are located are arranged opposite to each other. This means that the projection of the protrusion 210 in the first direction and the projection of the groove 110 in the first direction (z-axis, shown in the figures) at least partially overlap, or that the projection of the protrusion 210 in the first direction and the projection of the groove 110 in the first direction completely overlap.In the wound cell according to the embodiment of the present application, by providing the positive electrode plate 200 with the protrusions 210 and the recesses disposed opposite to the protrusions 210, micro spacings between the negative electrode plate 100, the separator, and the positive electrode plate 200 are respectively increased. The protrusions support the contact with the separator, so that there is some support between the negative electrode plate 100 and the positive electrode plate 200. The micro-spacings provide a space in which an electrolyte solution can be accommodated so that a sufficient amount of electrolyte solution is present for wetting the electrode plates, thereby avoiding abnormal circumstances such as insufficient electrolyte solution between the electrode plates and the separator, poor wetting or even lithium deposition from the negative electrode plate due to the compression of the layers of the electrode plates. This ensures that a sufficient amount of electrolyte solution is present for the wetting.In the wound cell according to the embodiment of the present application, by providing the negative electrode plate 100 with the grooves 110 disposed directly opposite to the protrusions 210, an expansion space for the expansion of the negative electrode plate is provided so that the compression or deformation of the protrusion of the positive electrode or the deformation of the groove of the negative electrode caused with the expansion of the negative electrode plate in hot pressing and formation or in charging and discharging of the battery is decelerated. This ensures the structural strength of the protrusions and the grooves as well as the bonding strength of the interfaces between the electrode plate and the separator, thereby stably effecting the support of the separator. In addition, the sufficient expansion space can also prevent the negative electrode plate from compressing the separator during expansion and leading to deformation of the separator.Still referring to FIG. 3, in an embodiment of the present application, the centers of two adjacent grooves 110 are spaced a first distance S apart. The dimension of a vertical projection of the protrusion 210 onto the electrode plate in a thickness direction is referred to as a first width R 1, the first width R 1 being greater than the first distance S.At this time, in the protrusion 210 directly opposite to the groove 110, the protrusion 210 is prevented from being embedded in the negative electrode groove 110. This promotes an SEI film to be formed by the positive electrode raised portions, thereby providing effective protection for the positive electrode protrusion 210. And, the active particles of the positive electrode protrusion 210 are prevented from being crushed or even cobalt is deposited therefrom, resulting in a decrease in the structural stability of the positive electrode active material and an accelerated decrease in battery capacity.In this embodiment of the present application, the relationship between the first width R 1 and the first distance S: R 1 / S=1.02 to 8 holds true.In the range of the above ratios, it is possible to slow the compression or deformation of the positive electrode protrusion 210 or the deformation of the negative electrode groove 110 caused with the expansion of the negative electrode plate 100 in hot pressing and formation or in charging and discharging the battery.If the ratio between the first width R 1 and the first distance S is less than 1.02, it means that the groove width of the first distance S is large. When the negative electrode plate 100 expands and thereby the layers of the electrode plate are compressed, it easily causes the positive electrode protrusion 210 to be embedded in the negative electrode groove 110, and the SEI film of the positive electrode protrusion is damaged, thereby leaving the positive electrode protrusion unprotected. If the ratio between the first width R 1 and the first distance S is greater than 8, this means that the groove width of the first distance S is small. Thus, the provision of the first distance S is meaningless. The first distance S cannot provide an expansion space for the expansion of the negative electrode plate, nor can the compression or deformation of the positive electrode protrusion or the deformation of the negative electrode groove caused with the expansion of the negative electrode plate in hot pressing and formation or in charging and discharging the battery slow.Referring to FIG. 15, 10 types of wound cells (wound cells 1 to 10) are provided, respectively, and the above-mentioned relationships are illustrated by 10 embodiments. In this case, the 10 winding cell types each have different first widths R 1 and different first spacings S, wherein the first width R 1 and the first spacing S of each winding cell type have the ratio mentioned above.By the 10 types of wound cells having the above relationship, the protrusion 210 can be prevented from being embedded in the groove 110 and the protrusion 210 or the groove 110 from deforming as the positive electrode plate and the negative electrode plate of the wound cell expand and thereby the layers of the electrode plates are pressed together, particularly when the layers in the corner portion are pressed together more strongly.Preferably, the ratio between the first width R 1 and the first distance S: R 1 / S=1.05 to 4.In this embodiment of the present application, the first width R1=0.3 mm to 8 mm.If the first width R1 is smaller than 0.3 mm, it tends to give a peak effect, i.e., the highest point of the protrusion 210 forms a sharp protrusion, which leads to the breakage of the separator. When the first width R 1 is larger than 8 mm, the raised surface of the protrusion 210 has a larger span width, which is not favorable for the support between the positive electrode plate and the negative electrode plate.R1=1 mm to 3 mm preferably applies to the first width.It should be noted that, when the projection of the protrusion 210 onto the electrode plate is adapted to a circle, the first width R 1 of the projection of the protrusion 210 onto the electrode plate may correspond to the diameter of this circle.In this embodiment of the present application, a distance between the centers of the projections of two adjacent projections 210 onto the negative electrode plate 100 is referred to as D1, where D1=1 mm to 6 mm.If the distance between the centers D1 is smaller than 1 mm, it easily causes overlapping of the protrusions 210 or too high a density of the protrusions. As a result, when the protrusions are formed, the roller pressure is too large, and hence the density of the protrusions is too high, so that it is difficult to relieve the stresses between the layers of the cell during charging and discharging, which easily leads to falling of the powder from the electrode plate. If the distance between the centers D1 is larger than 6 mm, the raised surfaces of two projections 210 have a larger span width, which cannot serve as support.Preferably, the distance between the centers is D1=1.5 mm to 4 mm.In this embodiment of the present application, the groove 110 has a groove width M in the third direction (x-axis shown in the figures), wherein the first width R 1 is larger than the groove width M, and wherein the relationship between the first width R 1 and the groove width M MAY BE R1 / M=8 TO 50.In the range of the above ratios, it is possible to slow the compression or deformation of the positive electrode protrusion 210 or the deformation of the negative electrode groove 110 caused with the expansion of the negative electrode plate in hot pressing and formation or in charging and discharging the battery.If the ratio between the first width R 1 and the groove width M is less than 8, it means that the groove width of the groove 110 is large. When the negative electrode plate expands and thereby the layers of the electrode plate are compressed, particularly when the layers in the corner portion are more compressed, it easily causes the protrusion 210 to be embedded in the groove 110, and the SEI film of the positive electrode protrusion is damaged, thereby leaving the positive electrode protrusion unprotected. When the ratio between the first width R 1 and the groove width M is greater than 50, it means that the groove width of the groove 110 is small. Thus, the provision of the groove 110 is meaningless. It is difficult for the groove to store sufficient electrolyte solution. The groove 110 may not provide an expansion space for the expansion of the negative electrode plate, nor slow the deformation of the protrusion 210 or the deformation of the groove 110 caused with the expansion of the negative electrode plate in hot pressing and formation or in charging and discharging.Referring to FIG. 17, 10 types of wound cells (wound cells 1 to 10) are provided, respectively, and the above-mentioned relationships are illustrated by 10 embodiments. In this case, the 10 winding cell types each have different first widths R 1 and different slot widths M, wherein the first width R 1 and the slot width M of each winding cell type have the ratio mentioned above.By the 10 types of wound cells having the above relationship, the protrusion 210 can be prevented from being embedded in the groove 110 and the protrusion 210 or the groove 110 from deforming as the positive electrode plate and the negative electrode plate of the wound cell expand and thereby the layers of the electrode plates are pressed together, particularly when the layers in the corner portion are pressed together more strongly.Preferably, the relationship between the first width R 1 and the groove width M CAN BE: R 1 / M=16 to 40.In this embodiment of the present application, the groove 110 has a groove width M in the third direction (x-axis shown in the figures), and the groove width is M=30 μm to 170 μm. It is to be ensured that the groove width M of the grooves 110 is within the above range. If the groove width M is smaller than 30 μm, the groove width M is too small. Thus, the provision of the groove 110 is meaningless. As a result, the groove 110 cannot provide an expansion space for the expansion of the negative electrode plate, nor can the compression or deformation of the positive electrode protrusion 210 or the deformation of the negative electrode groove 110 caused with the expansion of the negative electrode plate in hot pressing and formation or in charging and discharging the battery slow. If the groove width M is larger than 170 μm, the negative electrode plate 100 will expand and thereby compress the layers of the electrode plate. As a result, the positive electrode protrusion 210 is easily embedded in the negative electrode groove 110.Preferably, the groove width M = 60 μm to 120 μm.The groove 110 has a groove depth T in the first direction (z-axis shown in the figures), and the groove depth is T=10 μm~60 μm. If the groove depth T is less than 10 μm, the deformation of the protrusion 210 caused with the expansion of the electrode plate in charging and discharging cannot be slowed down. In addition, this also acts to increase the amount of stored electrolyte solution. If the groove depth T is greater than 60 μm, the thickness of the negative electrode plate is deteriorated, and the portion where the groove 110 is provided is at risk of breakage.Preferably, the groove depth is T=12 μm to 30 μm.The plurality of grooves 110 are equally spaced apart from each other in the second direction (y-axis shown in the figures), and the centers of two adjacent grooves 110 are spaced apart from each other at the first distance S, where the first distance is S=0.5 mm to 3 mm. If the first distance S is less than 0.5 mm, the provision of the groove 110 is meaningless. With the expansion of the electrode plate during charging and discharging, this may easily result in deformation of the protrusion 210 or deformation of the grooves 110. If the first distance S is greater than 3 mm, this means that the first diameter R 1 of the protrusion 210 is also to be increased accordingly. If the first diameter R 1 is too large, the raised surface of the protrusion 210 has a large span width, which is not favorable for the support between the positive electrode plate and the negative electrode plate.Still referring to FIG. 3, the groove 110 has a V-shaped cross-sectional shape in a cross-section in which the first direction (z-axis shown in the figures) is located.Still referring to FIG. 4, the first surface 1011 and the second surface 1012 of the negative electrode current collector 101 are each provided with a plurality of grooves 110, the protrusion 210 and the groove 110 are arranged opposite to each other; and the recess and the groove 110 are arranged opposite to each other.That is, grooves are provided on both sides of the negative electrode plate 100, so that the positive electrode recess and the negative electrode groove 110 are opposed to each other, while the positive electrode protrusion 210 and the negative electrode groove 110 are opposed to each other. By disposing the positive electrode recess and the negative electrode groove 110 opposite to each other, the space between the positive electrode plate 200 and the negative electrode plate 100 can be increased, so that a larger wetting space for the electrolyte solution is provided, and thereby the amount of stored electrolyte solution is increased.In an embodiment of the present application, the wound cell includes a flat portion and corner portions provided at opposite ends of the flat portion, respectively, the corner portion having a first thickness H 1 and the flat portion having a second thickness H 2, and the first thickness H 1 and the second thickness H 2 ARE: H 1 / (H 2 / 2)=1.05 TO 1.5.Note that the second thickness H 2 of the flat portion is referred to as a thickness in the vertical direction shown in FIG. 1, the corner portion is shaped as a circular arc, and the first thickness H 1 of the corner portion is referred to as the radius of the circular arc. In an embodiment, the thickness of the flat portion may also refer to the thickness of all the flat portions of the cell, i.e., the thickness of the cell, and accordingly, the thickness of the corner portion refers to the thickness of all the corner portions in the width direction by the center of gravity of the connection of both ends of the corner portion in the innermost layer.Referring to FIG. 14, 10 types of wound cells (wound cells 1 to 10) are provided, respectively, and the above-mentioned thickness ratios are illustrated by 10 embodiments. Here, the 10 types of wound cells each have different thicknesses in the flat region and different thicknesses in the corner region, wherein the thickness in the flat region and the thickness in the corner region of each type of wound cell have the above-mentioned thickness ratio.Due to the structural properties of the corner region and the accumulation of stresses, the outward expansion of the corner region is limited, ultimately leading to the problem of lithium deposition by the compression of the layers of the electrode plate. By providing the positive electrode plate 200 of a single wound cell with the protrusions 210 and the recesses disposed opposite to the protrusions 210 and the negative electrode plate 100 with the grooves 110 directly opposite to the protrusions 210 in the 10 types of wound cells in this embodiment of the present application, the above-mentioned thickness ratios are achieved. By setting the thickness ratios as mentioned above, the problem of the lithium deposition in the corner region can be effectively improved. In addition, it is thereby ensured that the protrusions, grooves, and thicknesses of the corner portion and the flat portion are matched to each other to appropriately make the interaction force of the layers of the cell and to ensure that the protrusions of the positive electrode plate and the recesses of the negative electrode plate do not deform during charging and discharging.Preferably, the first thickness H1 and the second thickness H2 are H1 / (H2 / 2)=1.08 to 1.3.Referring to FIG. 9, in an embodiment of the present application, the positive electrode plate 200 includes an upper surface and a lower surface that are oppositely disposed, the protrusion protruding outward from the upper surface of the positive electrode plate 200; the protrusion 210 includes a protrusion portion and a base portion that connects the protrusion portion and the upper surface.In the first direction (z-axis shown in the figures), the base portion of the protrusion 210 intersects the surface of the positive electrode plate 200. The base portion of the protrusion 210 is vertically spaced from an apex of the protrusion 210, and the vertical spacing is H3=3 μm to 80 μm.If the vertical distance H3 is smaller than 3 μm, it means that the protrusion 210 is too small so that it cannot serve to support between the positive electrode plate and the negative electrode plate. Thus, the protrusion 210 is a meaningless protrusion and may not achieve sufficient wetting of the electrolyte solution. If the vertical distance H3 is larger than 80 μm, this means that the protrusion 210 is too large, resulting in a strong delamination between the positive electrode plate and the negative electrode plate, thereby leading to a new interfacial problem.The compression in the corner region occurs mainly in some layers of the winding cell in the vicinity of the inner windings. The closer the outer turns approach, the lower the compression pressure, the lower the lack of electrolyte solution and the lower the risk of lithium deposition. Thus, by making the vertical distance of the protrusion of the innermost turn of the wound cell larger than the vertical distance of the protrusion of the outermost turn of the wound cell, the retention of the electrolyte solution in the innermost turn of the wound cell can be improved, thereby ensuring that the lithium precipitation and the like do not occur in the inner turns of the cell. Moreover, the width of the corner portion can be reduced by reducing the protrusion of the inner turns in the corner portion, thereby avoiding the cell's spread and increasing the cell's energy density.Referring to FIG. 16, the vertical distances H 3 of all winding layers of the wound cell are respectively provided to explain the above-mentioned relationships.The innermost turn of the wound cell represents a winding layer in which a winding start portion of the electrode plate is located, while the outermost turn of the wound cell represents a winding layer in which a winding end portion of the electrode plate is located. Between the innermost turn of the winding cell and the outermost turn of the winding cell there are also a plurality of middle turn layers.A first middle turn is adjacent to the innermost turn of the wound cell and the first middle turn surrounds the innermost turn of the wound cell; a second middle turn is adjacent to the first middle turn and the second middle turn surrounds the first middle turn, and so on up to the outermost turn of the wound cell.When the vertical distance H3 of the protrusion 210 of the innermost turn of the wound cell is 80 μm, the vertical distance H3 of the protrusion 210 of the first middle turn may be 75 μm; the vertical distance H3 of the protrusion 210 of the second middle turn may be 70 μm; the vertical distance H3 of the protrusion 210 of the third middle turn may be 65 μm; and the vertical distance H3 of the protrusion 210 of the outermost turn of the wound cell may be 35 μm.Still referring to FIG. 11, in an embodiment of the present application, the protrusion 210 protrudes outward from the upper surface of the positive electrode plate 200; the protrusion 210 including a protrusion portion and a base portion connecting the protrusion portion and the upper surface. The base portion of the protrusion 210 intersects the upper surface of the positive electrode plate 200, and a connecting line connecting the base portion of the protrusion 210 and the apex of the protrusion 210 is referred to as a first connecting line 301, and an angle between the first connecting line 301 and a first horizontal plane 302 is referred to as a first angle that is 3° to 45°.When the first angle is less than 3°, the protrusion 210 is too small so that it cannot serve to support between the positive electrode plate and the negative electrode plate. If the first angle is greater than 45°, the protrusion 210 has too great a slope, resulting in a tip of the protrusion. This easily leads to a puncture of the separator and thus to a safety problem.Preferably, the first angle may be 5° to 25°.In this embodiment of the present application, the shape of the protrusion 210 may include a circular, semicircular, oval, plumen-shaped, polygonal, diamond-shaped, capsule- or island-shaped shape, etc.In an embodiment of the present application, the positive electrode plate 200 includes an upper surface and a lower surface that are oppositely disposed, the protrusion protruding outward from the upper surface of the positive electrode plate 200; the protrusion 210 including a protrusion portion and a base portion that connects the protrusion portion and the upper surface.The protrusion portion is formed as an arc-shaped surface, and / or an edge of the protrusion portion connected to the polygonal, diamond-shaped, or island-shaped protrusion via an arc-shaped edge surface and the upper surface is formed as a circular arc-shaped edge.That is, the corner of the protrusion 210 is formed as a circular arc corner when the protrusion 210 has a shape having corners such as a polygonal or diamond shape and the like. Alternatively, the edges of the protrusion 210 are formed as circular arc edges when the protrusion 210 has a shape having considerably sharp edges such as polygonal or diamond shape.It is to be avoided that the projection has sharp edges in order to prevent powder from falling off its edges during the processing of the projection. In addition, the edges or the top of the protrusion are prevented from piercing the positive electrode paste, thereby preventing the paste from cracking and falling off powder therefrom. Fallen powder particles tend to fall on the negative electrode plate, resulting in risks such as short circuit and fire. Moreover, it can thereby be prevented that the top surface of the protrusion pierces the separator and comes into contact with the negative electrode plate, resulting in a short circuit.Preferably, the protrusion 210 may have a circular shape without a sharp corner.It should be noted that when the state of the positive electrode plate 200 is checked with a 3D profiler, it is clearly seen that the edges of the protrusion 210 are a circular shape.With continued reference to FIGS. 2 and 7, in an embodiment of the present application, the negative electrode plate 100 and the positive electrode plate 200 are wound around a first central surface. A surface of the positive electrode current collector 201 facing the first central surface is referred to as the third surface 2011, and a surface of the positive electrode current collector 201 facing away from the first central surface is referred to as the fourth surface 2012, wherein the third surface 2011 is provided with a third paste layer 202 and the fourth surface 2012 is provided with a fourth paste layer 203, and wherein the protrusion 210 protrudes from the third paste layer 202 into the fourth paste layer 203.The first central surface is a horizontal plane which is perpendicular to the plane of representation in the innermost turn of the wound cell in FIG. 1.Due to the curvature of the corner region, the first surface of the silicon-doped negative electrode plate is subjected to a greater compression than the second surface of the silicon-doped negative electrode plate. When the silicon-doped negative electrode plate expands as a whole, the expansion of the second surface is stronger than the expansion of the first surface, which easily leads to cracking on the second surface of the negative electrode plate. By the first surface and the groove of the negative electrode and the third surface being arranged opposite to the positive electrode, i.e., the depression of the second surface of the negative electrode and the third surface being arranged opposite to the positive electrode, a part of the coating of the second surface can penetrate into the recess of the positive electrode upon a large expansion of the second surface of the negative electrode, and thereby the voltage of the expansion of the negative electrode can be relieved. As a result, the depth of the positive electrode protrusion does not deteriorate, thereby ensuring normal support of the positive electrode protrusion.When the circular arc formed by the third paste layer 202 wraps around the negative electrode plate 100, the circumference of the circular arc of the third paste layer 202 is larger than the circumference of the negative electrode plate 100 in the corner region due to the curvature of the corner region, resulting in that the amount of the positive electrode active substance in this region is larger than the design-defined amount of the positive electrode active substance in this region. That is, the ratio between the negative area capacity and the positive area capacity in this range is decreased, resulting in a risk of lithium deposition.In this embodiment of the present application, by having the protrusion protrude from the third paste layer into the fourth paste layer and the depression of the first negative electrode surface and the recess of the third positive electrode surface opposed to each other, provided that the above facts cannot be changed, the migration path of the positive electrode active material in the recess is longer and the migration path of the positive electrode active material in the other regions is shorter. This in turn reduces the positive electrode active material in the recess that participates in the charge and discharge reaction, and the negative electrode paste layer on the third surface has enough sites for the aging of lithium ions, thereby increasing the CB value (negative area capacity / positive area capacity) in this range and decreasing the likelihood of lithium deposition in this range.Still referring to FIGS. 6 and 7, in an embodiment of the present application, the sum of the projected areas of the plurality of protrusions 210 onto the negative electrode plate 100 is 60% to 90% of the area of the fourth paste layer 203, thereby ensuring the supporting effect of the protrusions 210. If it is less than 60%, the supporting action of the protrusions 210 is impaired. If it is higher than 90%, the normal operation of the pastes is impaired.In addition, the wound cell further comprises an electrolyte solution doped with an additive of 1,4-dicyano-2-butene, wherein the content of the additive of 1,4-dicyano-2-butene is 0.05% to 3% of the electrolyte solution.The electrolyte solution wetted between the positive electrode plate and the negative electrode plate is also doped with a certain content of additive of 1,4-dicyano-2-butene, whereby the electrolyte solution can provide film forming protection for the positive electrode protrusion 210. The active particles of the positive electrode protrusion 210 are prevented from being crushed or even cobalt is deposited therefrom, resulting in a decrease in the structural stability of the positive electrode active material and an accelerated decrease in battery capacity.If the additive content of 1,4-dicyano-2-butene is below this range, the edge of the protrusion 210 remains unprotected. If the additive content of 1,4-dicyano-2-butene is above this range, it will have an effect on the normal use of the electrolytic solution.Referring to FIG. 10, in an embodiment of the present application, the projection of each protrusion 210 onto the first horizontal plane (the horizontal plane on which the y-axis is located) has a center point. A portion of the centers are distributed on the second connecting line 402, the second connecting line 402 being parallel to the second direction (y-axis shown in the figures). The projection of the groove 110 onto the first horizontal plane is a rectangular face 401, and the second connecting line 402 is parallel to the rectangular face 401.When the second connecting line and the rectangular face are parallel, a plurality of protrusions located on the second connecting line may be disposed opposite to a single groove, which facilitates processing of the protrusions and the grooves.Referring to FIG. 11, in another embodiment of the present application, the projection of each protrusion 210 onto the first horizontal plane (the horizontal plane on which the y-axis is located) has a center point. A portion of the centers are distributed on the second connecting line 402, the second connecting line 402 being parallel to the second direction (y-axis shown in the figures). The projection of the groove 110 on the first horizontal plane is a rectangular surface 401, and the second connecting line 402 and the rectangular surface 401 intersect. When the second connecting line 402 and the rectangular face 401 intersect, an angle between the second connecting line 402 and the rectangular face 401 is 0° to 45°.When the second connecting line and the rectangular face intersect, a plurality of protrusions located on the second connecting line are respectively opposed to different grooves, while the angle between the second connecting line and the rectangular face is limited to be within the above range, thereby ensuring that each protrusion on the second connecting line is opposed to the groove.Referring to FIG. 7, in an embodiment of the present application, the first paste layer 102 and / or the second paste layer 103 comprises a silicon-carbon composite material and / or a silicon-oxygen composite material, wherein the silicon-carbon composite material and / or the silicon-oxygen composite material make up less than or equal to 50% by weight of the mass of the first paste layer 102 and / or the second paste layer 103.The silicon-carbon composite material includes a porous carbon matrix, silicon grains in the pores of the porous carbon matrix, and a carbon layer on the surface of the porous carbon matrix. The present invention can be used to deposit the silicon grains in the pores of the porous carbon matrix. By placing the silicon grains in the pores and forming a carbon layer on the surface of the porous carbon matrix, the carbon layer may be crystalline carbon or amorphous carbon. When the silicon grains expand, the inside of the porous carbon matrix can provide a sufficient expansion space, thereby preventing deformation of the overall structure of the silicon-carbon composite material. In addition, the carbon layer may restrict the outward expanding force of the porous carbon matrix during expansion of the silicon to secure the structural strength of the silicon-carbon material, so that problems such as cracking, pulverization, dropping, and the like of the negative electrode active layer are avoided, and thereby cycle performance and multiplication performance of the battery are increased.In a detailed embodiment, the carbon layer includes openings corresponding to the pores of the porous carbon matrix. When the openings are provided in the carbon layer, wettability of the negative electrode plate with electrolyte solution can be improved and expansion performance of the silicon-based material can be reduced, so that impedance of the battery is lowered and cycle performance and multiplication performance of the battery are increased.In a detailed embodiment, the specific surface area of the silicon-carbon composite material and / or of the silicon-oxygen composite material is 0.5 to 10 m 2 / g, for example 0.5 m 2 / g, 1 m 2 / g, 2 m 2 / g, 3 m 2 / g, 4 m 2 / g, 5 m 2 / g, 6 m 2 / g, 7 m 2 / g, 8 m 2 / g, 9 m2 / g or 10 m2 / g, If the specific surface area of the silicon-carbon composite material and / or the silicon-oxygen composite material is within the above range, an appropriate SEI film may be formed on the surface of the negative electrode active layer in charging and discharging. Thereby, the impedance of the battery can be decreased and the cycle power and the multiplication power of the battery can be increased.In a detailed embodiment, the particle size of the silicon-carbon composite and / or the silicon-oxygen composite Dv 50 is 6 to 15 μm, for example 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm or 15 μm. When the particle size Dv50 of the silicon-carbon composite material and / or the silicon-oxygen composite material is within the above range, the particle size Dv50 of the silicon-carbon composite material is suitable for preventing, when the particle size is too small, it easily from increasing the specific surface area of the silicon particles, which in turn leads to an increased side reaction. At the same time, it can be avoided that if the particle size is too large, it easily leads to too large an expansion of the silicon particles, thereby plugging the pores of the porous carbon matrix and impairing the wetting of the electrolyte solution. Thereby, it is able to increase the cycle power and the multiplication power of the battery.In a detailed embodiment, the powder resistance of the silicon-carbon composite material and / or the silicon-oxygen composite material is 0.1 to 1000 Ω·cm, for example, 0.1 Ω·cm, 0.5 Ω·cm, 1 Ω·cm, 5 Ω·cm, 10 Ω·cm, 50 Ω·cm, 100 Ω·cm, 200 Ω·cm, 300 Ω·cm, 400 Ω·cm, 500 Ω·cm, 600 Ω·cm, 700 Ω·cm, 800 Ω·cm, 900 Ω·cm or 1000 Ω·cm. When the powder resistance of the silicon-carbon composite material and / or the silicon-oxygen composite material is within the above range, the silicon-carbon composite material and / or the silicon-oxygen composite material has high electrical conductivity, so that the electrical conductivity of the negative electrode active layer can be increased, and thus the cycle power and the multiplication power of the battery are increased.In a detailed embodiment, the silicon content in the silicon-carbon composite and / or the silicon-oxygen composite is 30% to 75%, for example 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% or 75%, etc. If the silicon content in the silicon-carbon composite is within the above range, the silicon content in the silicon-carbon composite can be prevented from being too high, resulting in excessive expansion of the silicon-carbon composite and deformation of the overall structure of the silicon-carbon composite. Thereby, cracking and pulverization of the negative electrode active layer are avoided, and it is ensured that the energy of the silicon-carbon composite material is utilized appropriately, so that the cycle power and the multiplication power of the battery are increased.The third surface 2011 of the positive electrode current collector 201 is the positive electrode inner surface, and the first surface 1011 of the negative electrode current collector 101 is the negative electrode outer surface, respectively. The outer surface of the negative electrode in the circular arc region expands more, and the silicon-carbon composite material of the negative electrode itself expands more. On this basis, a space for sufficiently expanding the silicon-doped negative electrode active layer on the negative electrode outer surface can be provided by the groove 110 on the negative electrode outer surface corresponding to the recess of the positive electrode inner surface. In addition, the recess on the positive electrode inner surface escapes from the extension of the negative electrode outer surface so as not to affect the depth of the positive electrode protrusion 210 and ensure the normal supporting action of the positive electrode protrusion 210.In an embodiment of the present application, a battery including the above-described wound cell is further provided.In summary, in the embodiments of the present application, a wound cell and a battery are provided, wherein the wound cell includes a negative electrode plate 100 and a positive electrode plate 200 arranged in a stacked manner, and wherein the negative electrode plate 100 and the positive electrode plate 200 have opposite polarities. The negative electrode plate 100 includes a negative electrode current collector 101, the negative electrode current collector 101 having, in a first direction (z-axis shown in the figures), a first surface 1011 and a second surface 1012 arranged opposite to each other, and the first surface 1011 is provided with a first paste layer 102 and the second surface 1012 is provided with a second paste layer 103. The first paste layer 102 is provided with a plurality of grooves 110 extending in a second direction (y-axis shown in the figures), wherein the centers of two adjacent grooves 110 are spaced apart from each other in a third direction by a first distance S. The positive electrode plate 200 has a plurality of protrusions 210 and recesses disposed opposite to the protrusions 210, and the groove 110 and the protrusion 210 are disposed opposite to each other. The dimension of a projection of the protrusion 210 onto the electrode plate is referred to as a first width R 1, wherein the first width R 1 is greater than the first distance S.In the wound cell according to the embodiment of the present application, by providing the positive electrode plate 200 with the protrusions 210 and the recesses disposed opposite to the protrusions 210, micro spacings between the negative electrode plate 100, the separator, and the positive electrode plate 200 are respectively increased. The protrusions support the contact with the separator, so that there is some support between the negative electrode plate 100 and the positive electrode plate 200. The micro-spacings provide a space in which an electrolyte solution can be accommodated so that a sufficient amount of electrolyte solution is present for wetting the electrode plates, thereby avoiding abnormal circumstances such as insufficient electrolyte solution between the electrode plates and the separator, poor wetting or even lithium deposition from the negative electrode plate due to the compression of the layers of the electrode plates. This ensures that a sufficient amount of electrolyte solution is present for the wetting.In addition, in the wound cell according to the embodiment of the present application, by providing the negative electrode plate 100 with the grooves 110 disposed directly opposite to the protrusions 210, an expansion space for the expansion of the negative electrode plate is provided so that the compression or deformation of the protrusion of the positive electrode or the deformation of the groove of the negative electrode caused with the expansion of the negative electrode plate in hot pressing and formation or in charging and discharging of the battery is decelerated. This ensures the structural strength of the protrusions and the grooves as well as the bonding strength of the interfaces between the electrode plate and the separator, thereby stably effecting the support of the separator. In addition, the sufficient expansion space can also prevent the negative electrode plate from compressing the separator during expansion and leading to deformation of the separator.Further, it is provided that the protrusion 210 directly facing the groove 110 is prevented from being embedded in the negative electrode groove 110. This promotes an SEI film to be formed by the positive electrode raised portions, thereby providing effective protection for the positive electrode protrusion 210. And, the active particles of the positive electrode protrusion 210 are prevented from being crushed or even cobalt is deposited therefrom, resulting in a decrease in the structural stability of the positive electrode active material and an accelerated decrease in battery capacity.Each embodiment in this specification will be described stepwise, and each embodiment focuses on the differences from other embodiments, and the same or similar parts of the individual embodiments may be referred to each other.It should be understood that references throughout the specification to "one embodiment," "one embodiment," "one embodiment," "some embodiments," etc., mean that the described embodiment may include specific features, structures, or characteristics. However, this does not mean that each embodiment must include these specific features, structures, or characteristics. Moreover, such terms do not necessarily refer to the same embodiment. When a particular feature, structure, or characteristic is described in connection with an embodiment, it is within the knowledge of those skilled in the art that such feature, structure, or characteristic is implemented in connection with other embodiments that are expressly or not expressly described.In general, terms should be understood at least in part in connection with application in the context. For example, the term "one or more" as used herein, at least in part, in connection with the context, may be used to describe any feature, structure, or property in the singular, or may be used to describe a combination of features, structures, or properties in the plural. Similarly, in conjunction at least in part with the context, terms having "a(s)" or "the" may be used in the singular or the plural above.It should be clearly understood that the terms "over...", "on..." and "over..." in the present disclosure should be construed as broadly as possible so that "over..." means not only "directly on something" but also "over something" and with an intervening feature or layer therebetween. "on..." or "over..." includes not only the meaning of "on something" or "over something" but also the meaning of "on something" or "over something" and without an intervening feature or layer (i.e., directly on something).Moreover, in this context, for ease of illustration, terms indicating relative spatial relationships may be used, e.g., "below," "below," "below," "above," "above," etc., to describe the relationship of one element or feature to another element or feature as illustrated. Terms indicating relative spatial relationships are intended to encompass other orientations in use or operation in addition to the orientation depicted in the figure. A device may also have a different orientation (rotated 90 degrees or offset to a different orientation), in which case the term used herein is to be interpreted accordingly to describe relative spatial relationship.Finally, it should be noted that the above-mentioned individual embodiments are used only to illustrate the technical solutions of the present application instead of limiting them. Although the present application will be described in detail with reference to the above individual embodiments, it should be understood by those skilled in the art that they may modify the technical solutions described in the above embodiments or equivalently replace some or all of the technical features included therein; and that these modifications or substitutions do not, however, lead to the spirit of the respective technical solutions deviating from the scope of the technical solutions of the individual embodiments of the present application.SummaryIn the present application, a wound cell and a battery related to the technical field of the batteries are provided to solve the technical problem of the insufficient electrolytic solution between the layers by compressing the layers of the electrode plates of the wound cell in the related art. The wound cell includes: a negative electrode plate and a positive electrode plate having opposite polarities, the negative electrode plate including a negative electrode current collector having a first surface and a second surface in a first direction, the first surface being provided with a first paste layer and the second surface being provided with a second paste layer; the first paste layer being provided with a plurality of grooves, and the centers of two adjacent grooves being spaced apart from each other at a first distance; the positive electrode plate being provided with a plurality of recesses corresponding to the projections, and a surface on which the projections of the positive electrode plate are located and a surface on which the grooves of the negative electrode plate are located being opposed to each other; and wherein the dimension of a projection of the protrusion onto the negative electrode plate measured in a width direction of the groove is larger than the first distance. By providing the positive electrode plate with the protrusions and the recesses facing the protrusions and providing the negative electrode plate with the grooves facing the protrusions, support is provided between the electrode plates, which increases the micro-distance between the electrode plates and ensures sufficient wetting of the electrolyte solution.

Claims

A wound cell, characterized by comprising: a negative electrode plate and a positive electrode plate arranged in a stacked manner; wherein the negative electrode plate comprises a negative electrode current collector having, in a first direction, a first surface and a second surface arranged in an opposing manner, wherein the first surface is provided with a first paste layer and the second surface is provided with a second paste layer; wherein the first paste layer is provided with a plurality of grooves, and wherein the centers of two adjacent grooves are arranged spaced apart from each other at a first distance; wherein the positive electrode plate is provided with a plurality of protrusions and recesses corresponding to the protrusions, and wherein a surface on which the protrusions of the positive electrode plate are located and a surface on which the grooves of the negative electrode plate are located are arranged in an opposing manner; and wherein the dimension of a vertical projection of the protrusion in a thickness direction onto the negative electrode plate measured in a width direction of the groove is greater than the first distance.The wound cell according to claim 1, characterized in that the first surface and the second surface of the negative electrode plate are respectively provided with the plurality of grooves; wherein the protrusion and the groove are arranged opposite to each other; and wherein the recess and the groove are arranged opposite to each other.The wound cell according to claim 1, characterized in that the dimension of the projection of the protrusion onto the negative electrode plate in the thickness direction measured in the width direction of the groove is referred to as R1, and the first distance is referred to as S, where R1 / S = 1.02 to 8.The wound cell according to claim 1, characterized in that the dimension of the projection of the protrusion onto the negative electrode plate in the thickness direction measured in the width direction of the groove is referred to as R1, and the groove width of the groove is referred to as M, where R1 / M = 8 to 50.The wound cell according to claim 1, characterized in that the first paste layer and / or the second paste layer comprises a silicon-carbon composite material and / or a silicon-oxygen composite material, wherein the silicon-carbon composite material and / or the silicon-oxygen composite material make up less than or equal to 50% by weight of the mass of the first paste layer and / or the second paste layer.The wound cell according to claim 1, characterized in that the positive electrode plate comprises a positive electrode current collector having, in the first direction, a third surface and a fourth surface arranged opposite to each other, and wherein the third surface is provided with a third paste layer and the fourth surface is provided with a fourth paste layer; wherein the negative electrode plate and the positive electrode plate are wound around a first central surface, wherein a surface of the positive electrode current collector facing the first central surface is referred to as the third surface, and a surface of the positive electrode current collector facing away from the first central surface is referred to as the fourth surface; wherein the third surface and the first surface are arranged opposite to each other, and the fourth surface and the second surface are arranged opposite to each other; wherein the wound cell includes a flat portion and corner portions provided at opposite ends of the flat portion, respectively; and wherein the protrusion protrudes from the third paste layer into the fourth paste layer.The wound cell according to claim 6, characterized in that the sum of the projected areas of the plurality of protrusions onto the negative electrode plate is 60% to 90% of the area of the fourth paste layer; and the wound cell further comprises an electrolyte solution doped with 1,4-dicyano-2-butene, wherein the content of the additive of 1,4-dicyano-2-butene is 0.05% to 3% of the electrolyte solution.The wound cell according to claim 6, characterized in that the projected shape of the protrusion on the negative electrode plate comprises a circular, semicircular, oval, plumen-shaped, polygonal, diamond-shaped, capsule- or island-shaped shape, etc.The wound cell according to claim 8, characterized in that the positive electrode plate comprises an upper surface and a lower surface that are oppositely disposed, the protrusion protruding outward from the upper surface of the positive electrode plate; wherein the protrusion comprises a protrusion portion and a base portion connecting the protrusion portion and the upper surface; wherein the protrusion portion is formed in an arc-shaped surface, and / or wherein the protrusion portion is connected to the upper surface by an arc-shaped edge surface.The wound cell according to claim 9, characterized in that a connecting line connecting the base portion and an apex of the protrusion portion is referred to as a first connecting line, and an angle between the first connecting line and the top surface is referred to as a first angle that is 3° to 45°.Winding cell according to Claim 6, characterized in that the winding cell has a first thickness H1 in the corner region and a second thickness H2 in the flat region, wherein the following applies to the first thickness H1 and the second thickness H2: H1 / (H2 / 2)=1.05 to 1.5.The wound cell according to claim 9, characterized in that, for the dimension of the vertical projection of the protrusion onto the negative electrode plate in the thickness direction measured in the width direction of the groove, R1 = 0.3 mm to 8 mm; and / or that, for a distance between the centers of the vertical projections of two adjacent ones of the protrusions onto the negative electrode plate in the thickness direction, D1 = 1 mm to 6 mm; and / or that, for a vertical distance between the base portion and the apex of the protrusion portion measured in the first direction, H3 = 3 μm to 80 μm.The winding cell according to claim 12, characterized in that, in the corner portion, a vertical distance between an apex of the protrusion of the innermost turn of the winding cell and the base portion of the protrusion is referred to as a first vertical distance, and that a vertical distance between an apex of the protrusion of the outermost turn of the winding cell and the base portion of the protrusion is referred to as a second vertical distance, the first vertical distance being larger than the second vertical distance.The winding cell according to claim 4, characterized in that for the groove width: M = 30 μm to 170 μm; and / or that for the depth of the groove in the first direction: T = 10 μm to 60 μm; and / or that for the first distance: S = 0.5 mm to 3 mm.The wound cell according to claim 4, characterized in that the projection of each of the projections onto the negative electrode plate has a center, a part of the centers distributes on a second connection line; wherein the projection of the groove onto the negative electrode current collector represents a rectangular area, and wherein the first connection line and the rectangular area are parallel to each other or intersect each other; and wherein an angle between the first connection line and the rectangular area is 0° to 45° when the first connection line and the rectangular area intersect each other.Battery, characterized in that it comprises a wound cell according to one of Claims 1 to 15.

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