An electrode sheet of a battery, a jelly-roll, and a battery

Abstract

The present specification provides an electrode sheet of a battery, a roll core and a battery, by setting a plurality of tab structures in the foil area of the electrode sheet, and the tab structures are distributed in a stepped manner, so that the roll core is formed after the electrode sheet is wound, and the roll core electrode formed by winding is composed of tab structures, because the tab structures are distributed in a stepped manner with high ends and low middle, the tab of the roll core after winding forms a V-shaped full tab structure with high inner and outer layers and low middle layer, at this time, a corresponding shaped current collecting plate can be used to connect with the tab structure, or the inner and outer layer tab structures are gathered to the middle layer tab structure and then connected with the current collecting plate; the effect that all the tab structures of the electrode sheet are connected with the current collecting plate is realized, on the one hand, the connection area of the electrode sheet and the current collecting plate is increased, and the charging and discharging efficiency is improved; on the other hand, the electron flow distance of the electrode sheet is shortened to the width of the electrode sheet, so as to reduce the current resistance of the electrode sheet.

Description

Technical Field

[0001] This specification relates to the field of battery technology, and in particular to a battery electrode sheet, a winding core, and a battery. Background Art

[0002] Wound batteries have an increasingly wide range of applications due to their high degree of production automation, high production efficiency, and good battery consistency. As the demand for battery energy in new energy vehicles and energy storage fields increases, wound batteries in traditional technologies are usually formed by winding a positive electrode sheet, a negative electrode sheet, and a separator. A conductive sheet is led out from the positive electrode sheet and the negative electrode sheet as a positive electrode ear and a negative electrode ear to form the positive and negative electrodes of the wound battery. There are two problems with wound batteries in traditional methods: on the one hand, the positive and negative electrode sheets only use one positive and negative electrode ear as the medium for the flow of electrons, resulting in a low charging and discharging efficiency; on the other hand, since the positive and negative electrode sheets are only provided with an electrode ear at one position, the distance from the edge of the electrode sheet to the electrode ear is relatively long, resulting in a problem of high resistance when electrons flow. Summary of the Invention

[0003] To overcome the problems existing in the related art, this specification provides a battery electrode sheet, a winding core, and a battery.

[0004] According to a first aspect of an embodiment of the present specification, a battery electrode sheet is provided. The electrode sheet has a starting end, a middle point, and a tail end along a winding direction. The electrode sheet includes a coating area for applying a polar coating and a foil area for serving as a tab.

[0005] The foil area includes several tab structures, which are continuously distributed along the edge of the coating area from the starting end to the ending end; among them, the height of the tab structures distributed in a stepped manner from the starting end to the middle point decreases successively; the height of the tab structures distributed from the middle point to the ending end increases successively.

[0006] According to a second aspect of an embodiment of the present specification, a battery core is provided, the core comprising a positive electrode sheet, a negative electrode sheet, and a separator; the positive electrode sheet or the negative electrode sheet is the electrode sheet of the first aspect, the coating area of ​​the positive electrode sheet is coated with a positive electrode coating, and the coating area of ​​the negative electrode sheet is coated with a negative electrode coating;

[0007] The coating area of ​​the positive electrode sheet and the coating area of ​​the negative electrode sheet are stacked, and the diaphragm is stacked between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet, the negative electrode sheet and the diaphragm are wound to form a roll core; wherein, the foil areas of the positive electrode sheet and the negative electrode sheet are oriented in opposite directions, the foil area of ​​the positive electrode sheet is the positive electrode ear, and the foil area of ​​the negative electrode sheet is the negative electrode ear.

[0008] According to a third aspect of the embodiments of this specification, a battery is provided, comprising a housing and a winding core according to the second aspect; the winding core is placed in the housing.

[0009] The technical scheme provided by the embodiment of the specification can include the following beneficial effects:

[0010] In the embodiment of the specification, a plurality of tab structures are arranged in the foil area of the electrode sheet, and the tab structures are distributed in a stepped manner, so that a roll core is formed after the electrode sheet is wound. The roll core electrode formed by winding is composed of tab structures. Because the tab structures are distributed in a stepped manner with high ends and low middle, the tabs of the roll core after winding form a V-shaped full tab structure with high inner and outer layers and low middle layer. At this time, a corresponding shaped current collecting plate can be used to connect with the tab structure, or the inner and outer tab structures are gathered to the middle tab structure and then connected with the current collecting plate. The effect that all tab structures of the electrode sheet are connected with the current collecting plate is achieved. On the one hand, the connection area of the electrode sheet and the current collecting plate is increased, and the charging and discharging efficiency is improved. On the other hand, the electron flow distance of the electrode sheet is shortened to the width of the electrode sheet, so as to reduce the current resistance of the electrode sheet.

[0011] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the specification. BRIEF DESCRIPTION OF DRAWINGS

[0012] The drawings incorporated into the specification and forming part of the specification, show embodiments consistent with the specification, and together with the specification, serve to explain the principles of the specification.

[0013] Figure 1 is a structural schematic diagram of an electrode sheet of a battery according to an exemplary embodiment of the specification.

[0014] Figure 2 is a structural schematic diagram of an electrode sheet of a battery according to another exemplary embodiment of the specification.

[0015] Figure 3 is a structural schematic diagram of a roll core of a battery according to an exemplary embodiment of the specification.

[0016] Figure 4 is Figure 3 a longitudinal sectional schematic diagram.

[0017] Figure 5 is a structural schematic diagram of a roll core of a battery according to another exemplary embodiment of the specification.

[0018] Figure 6 is a structural schematic diagram of a roll core of a battery according to another exemplary embodiment of the specification.

[0019] Figure 7 is Figure 6 a longitudinal sectional schematic diagram.

[0020] Figure 8 is Figure 7 is a partial enlarged view of the B region in the middle.

[0021] Figure 9 is Figure 3 is a longitudinal sectional view of the top.

[0022] Figure 10 is a structural schematic diagram of a battery according to another exemplary embodiment.

[0023] The drawing label: 1, electrode sheet; 11, winding start end; 12, center point; 13, winding end; 14, foil area; 141, tab structure; 15, coating area; 2, winding core; 21, positive electrode sheet; 211, positive electrode tab; 212, cut of the positive electrode tab; 22, negative electrode sheet; 221, negative electrode tab; 222, cut of the negative electrode tab; 23, separator; 24, center hole; 3, shell; 31, current collector. DETAILED DESCRIPTION

[0024] The exemplary embodiments will be described in detail herein with reference to the attached drawings. The description of the exemplary embodiments is intended to apply to various alternative embodiments as well. The following description is not limited to the exemplary embodiments, but rather, is applicable to any apparatus and method consistent with the present description. Various embodiments are provided with reference to the drawings, wherein like reference numerals refer to like elements throughout. The embodiments described herein are intended to encompass all embodiments consistent with the present description, including those that are presently unforeseeable or unappreciated. It will be apparent to those skilled in the art that various modifications and variations can be made to the present disclosure without departing from the spirit or scope of the disclosure. Thus, it is intended that the present disclosure cover modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.

[0025] The terminology used in the present description is for the purpose of describing particular embodiments only and is not intended to be limiting of the present description. As used in the description of the embodiments and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0026] It will be understood that, although the terms first, second, third, etc. can be used herein to describe various information, these terms are not intended to denote a temporal or chronological order. Rather, these terms are used only to distinguish different sets of information from one another. For example, a first information can also be termed a second information, and similarly, a second information can also be termed a first information, without departing from the scope of the present description. As used herein, the word "if' can be interpreted to mean "when" or "upon" or "in response to determining" taking into account the context in which the term is used.

[0027] The existing power battery can be classified into cylindrical battery, knife-type battery, square battery and the like according to shape, and can be classified into dry battery, winding battery and the like according to the type of internal composition of the battery, so the shape of the winding battery is not fixed and can form cylindrical battery, knife-type battery, square battery and the like; the winding battery is usually formed by winding the positive plate, the negative plate and the separator to form a winding core, two ends of the winding core are respectively led out a conductive sheet as the positive and negative poles by the positive plate and the negative plate to form the positive and negative poles of the battery, the winding core is placed in the battery shell, and then the electrolyte is filled into the battery shell to make the positive plate and the negative plate soaked in the electrolyte, the positive and negative poles are connected with the positive and negative current collecting plates of the battery shell, and the current collecting plates are electrically connected with the external electronic equipment, at this time, the ions on the positive plate and the negative plate can flow through the electrolyte to make the electrons flow through the positive and negative poles and the external electronic equipment to form current, so as to realize charging and discharging; the separator separates the positive plate and the negative plate to prevent the positive plate and the negative plate from directly contacting or the ions from flowing quickly to cause short circuit, so the setting of the separator makes the ions of the positive plate and the negative plate only interact through the electrolyte to achieve the effect of protecting the internal environment of the battery; because the electron flow of the battery charging and discharging can only pass through one positive and negative pole as a flow channel, there are two problems: on the one hand, the low electron flow efficiency caused by the small number of channels, that is, the problem of low charging and discharging efficiency; on the other hand, because the positive and negative poles are usually arranged at the two ends of the positive and negative plates, the distance of the electron flow from the other end of the electrode plate to the pole is the length of the electrode plate, that is, the problem of large battery internal resistance.

[0028] For the problems of the winding battery, the traditional technology proposes a full-pole solution, the implementation process of which is as follows: a plurality of poles are arranged continuously or discontinuously on the electrode plate, after the electrode plate is wound, the plurality of poles are rubbed and gathered on the same plane and connected with the current collecting plate, so as to increase the number of poles by arranging a plurality of poles, and to reduce the distance of electron flow and the battery internal resistance by arranging a plurality of poles at different positions of the electrode plate; however, because there is a center hole in the winding battery, the center hole is a structural hole left in the winding process of the winding core and is a channel for introducing electrolyte, which is an indispensable structure for the winding battery; therefore, the center hole needs to be kept open when it is in the battery, so in order to prevent the plurality of poles arranged on the inside of the winding core from blocking the center hole after rubbing, the poles close to the center hole on the inside of the winding core are usually cut off in the traditional technology, so that the poles will not block the center hole in the rubbing process.

[0029] However, the solution in traditional technology still has two problems: on the one hand, the tabs on the inside of the core need to be cut off, so that the number of tabs is reduced, that is, the problems of low charging efficiency and high internal resistance still exist; on the other hand, the flattening process in traditional technology is to use a flattening wheel to rotate and shrink toward the center to squeeze the foils of the positive and negative tabs, so that the positive and negative tab foils are all pressed toward the center and gathered in one area. This flattening method requires the flattening wheel to quickly rotate, rub and squeeze the tabs. Since the positive and negative tab foils are made of metal, the positive and negative tab foils will inevitably drop dust into the inside of the core during the rapid rotation, friction and extrusion process. The dust will pollute the internal environment of the battery, and there is a problem of causing internal short circuits and destroying the internal electrolyte balance.

[0030] The present disclosure is described using a cylindrical wound battery as an example, and the implementation methods of other types of wound batteries are similar.

[0031] Next, the embodiments of this specification are described in detail.

[0032] Figure 1 Schematic diagram of the structure of an electrode sheet of a battery according to an exemplary embodiment of the present specification.

[0033] In the first aspect of the embodiments of this specification, Figure 1 As shown, a battery electrode sheet, the electrode sheet has a starting end, a middle point, and a tail end along the winding direction, and includes a coating area for applying polar coating and a foil area for serving as a tab;

[0034] The foil area includes several tab structures, which are continuously distributed along the edge of the coating area from the starting end to the ending end; among them, the height of the tab structures distributed in a stepped manner from the starting end to the middle point decreases successively; the height of the tab structures distributed from the middle point to the ending end increases successively.

[0035] The electrode sheet in this embodiment can be applied to a variety of scenarios where electrode sheets are needed, and can be but is not limited to being applied to cylindrical wound batteries; the electrode sheet disclosed in this disclosure is illustrated by taking the application to cylindrical batteries as an example. The electrode sheet of the cylindrical battery needs to be wound to form a circular core, and then placed in a circular battery shell to assemble into a battery, so the electrode sheet needs to be wound into a circle. Based on the starting and ending points of the winding, the electrode sheet is sequentially divided into a starting end, a middle point and a tail end along the winding direction. The starting end is the starting point of the electrode sheet winding and is located in the innermost layer of the core after winding. The tail end is the end point of the electrode sheet winding and is located in the outermost layer of the core after winding. The middle point is the middle position between the starting end and the tail end.

[0036] The electrode sheet comprises a coating area and a foil area, the coating area can be but is not limited to a rectangular shape, and the foil area is a stepped structure extending from the edge of the coating area. The coating area and the foil area are an integral metal sheet, and are distinguished only based on the different functions of the two areas. The coating area is mainly used for applying polar materials, which can include positive or negative polar materials. The electrode sheet can be divided into a positive electrode sheet or a negative electrode sheet based on whether the coating area applies positive or negative materials.

[0037] The foil area comprises a plurality of tab structures, which are continuously distributed along the edge of the coating area from the starting end to the ending end. The height of the tab structures distributed in a stepped manner from the starting end to the middle point decreases in turn, and the height of the tab structures distributed from the middle point to the ending end increases in turn, so that the height of the tab structure near the middle point is low, and the height of the tab structure far from the middle point is high.

[0038] In an embodiment, the height difference between adjacent two tab structures is a fixed value, or the height difference between adjacent two tab structures increases at a preset ratio.

[0039] The tab structure in the embodiment is divided into two parts. One part is the tab structure distributed in a stepped manner from the starting end to the middle point, and the height of the tab structure in this part decreases in turn along the distribution direction, and the height difference between adjacent two tab structures can be set as a fixed value or decrease at a preset ratio according to requirements. The other part is the tab structure distributed from the middle point to the ending end, and the height of the tab structure in this part increases in turn along the distribution direction, and the height difference between adjacent two tab structures can be set as a fixed value or increase at a preset ratio according to requirements.

[0040] After the electrode sheet is wound, the tab structures at both ends of the electrode sheet need to be gathered to the tab area. The gathering rule is to gather the tab structure with a higher height towards the direction of the tab structure with a lower height, so as to ensure that all the tab structures can be in a plane, so as to be connected with the current collecting disc subsequently. In the disclosure, because the height of the tab structure at the starting end and the ending end is higher than the height of the tab structure near the middle point, the tab structures of the inner layer and the outer layer need to be gathered to the middle layer after winding.

[0041] In an embodiment, the height of the two tab structures intersecting at the middle point is the same.

[0042] In this embodiment, the tab structures need to be finally folded into the same plane, and the tab structure at the center point is the one with the smallest height. After the electrode sheet is wound, the tab structures need to be folded into the same plane for welding with the current collector plate. The folding process of the tab structure is to fold the tab structure with a higher height towards the tab structure with a lower height. Therefore, the heights of the two tab structures intersecting at the center point are set to be the same, so that the tab structures from the winding start end to the center point and the tab structures from the center point to the end end can be kept in the same plane after folding, which is beneficial for the welding of the tab structures and the current collector plate.

[0043] As an example, as shown in Figure 2 When n tab structures are arranged between the center point and the winding start end and the winding end end, the heights of the tab structures from the center point to the winding start end are H1, H2, H3…Hn, respectively, and the heights of the tab structures from the center point to the winding end end are H1', H2', H3'…Hn', respectively. When the increments and decrements of the heights are fixed values, the height difference Ah=(Hn-H1) / (n-1), H2=H2'=H1+(2-1)Ah, H3=H3'=H1+(3-1)Ah, ……, Hn=Hn'=H1+(n-1)Ah, where Ah is a preset positive number. When the increments or decrements of the heights are in a preset ratio, the height difference Ah=〖((Hn-H1) / (n-1))〗^s, 1

[0044] In an embodiment, the height difference between every two adjacent tab structures from the winding start end to the center point is not less than the height difference between every two adjacent tab structures from the center point to the winding end end.

[0045] In this embodiment, the heights of the two tab structures intersecting at the center point are the same. Therefore, the overall height of the tab structures from the winding start end to the center point is greater than the height of the tab structures from the center point to the winding end end. In this way, when the electrode sheet is wound and the tab structures are folded, the angle of the tab structures from the inner layer to the middle layer after folding is smaller than that in the case where the tab structures at both ends change in the same way, and the folding area of the tab structures from the winding start end to the center point is farther away from the winding center. This achieves the effect of reducing the influence of the welding process on the electrode sheet and other structures.

[0046] Figure 3 is a structural schematic diagram of a jelly-roll of a battery according to an exemplary embodiment of the present specification.

[0047] Figure 4 is a longitudinal sectional schematic diagram of Figure 3

[0048] A second aspect of the embodiment of the present specification is shown in Figure 3 and Figure 4

[0049] A jelly-roll of a battery, the jelly-roll comprising a positive electrode sheet, a negative electrode sheet, and a separator; the positive electrode sheet or the negative electrode sheet is the electrode sheet of the first aspect, the coating area of the positive electrode sheet is coated with a positive electrode coating, and the coating area of the negative electrode sheet is coated with a negative electrode coating;

[0050] The coating area of the positive electrode sheet and the coating area of the negative electrode sheet are laminated, the separator is laminated between the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet, the negative electrode sheet, and the separator are formed into the jelly-roll by winding; wherein the orientation direction of the foil area of the positive electrode sheet and the foil area of the negative electrode sheet are opposite, the foil area of the positive electrode sheet is a positive electrode tab, and the foil area of the negative electrode sheet is a negative electrode tab.

[0051] The jelly-roll in the embodiment is mainly applied to a cylindrical battery, and the jelly-roll is formed by sequentially laminating a positive electrode sheet, at least two separators, and a negative electrode sheet through winding. The lamination manner can be, but is not limited to, a positive electrode sheet, a separator, a negative electrode sheet, and a separator, or a separator, a positive electrode sheet, a separator, and a negative electrode sheet, as long as the positive electrode sheet and the negative electrode sheet cannot directly contact after winding. The positive electrode sheet and the negative electrode sheet operate as a positive electrode and a negative electrode of the battery, and therefore the orientation direction of the foil area of the positive electrode sheet and the foil area of the negative electrode sheet are opposite, so that the tab structure of the foil area of the positive electrode sheet forms a positive electrode tab, and the tab structure of the foil area of the negative electrode sheet forms a negative electrode tab. In order to increase the ion exchange rate of the positive electrode sheet and the negative electrode sheet and increase the space utilization rate of the battery, the coating area of the positive electrode sheet and the coating area of the negative electrode sheet are laminated in coincidence, and the separator is arranged between the positive electrode sheet and the negative electrode sheet to prevent the positive electrode sheet and the negative electrode sheet from directly contacting and causing short circuit. When the position relationship of the coating area of the positive electrode sheet and the coating area of the negative electrode sheet corresponds, the ion exchange rate is the highest, and when the coating area of the positive electrode sheet and the coating area of the negative electrode sheet are misaligned, the positive electrode sheet and the negative electrode sheet are prone to contact each other to cause the problem of open circuit due to the isolation of the separator.

[0052] Since the positive electrode tab and the negative electrode tab of the jelly-roll need to be gathered and welded with the current collector disc to enable the positive electrode tab and the negative electrode tab of the jelly-roll to be electrically connected with external equipment through the current collector disc for charging or discharging, the connection area of the positive electrode tab and the negative electrode tab of the jelly-roll with the current collector disc determines the charging and discharging efficiency of the jelly-roll.

[0053] As shown in Figures 5-8 ​​As shown, in an embodiment, the tab structures of the inner layer and the outer layer of the positive electrode sheet are all bent towards the tab structure of the middle layer, so that the top of the positive tab and the negative tab are located in the same plane.

[0054] The tab structures of the inner layer and the outer layer of the negative electrode sheet are all bent towards the tab structure of the middle layer, so that the top of the negative tab is located in the same plane.

[0055] In this embodiment, after the positive electrode sheet, the negative electrode sheet and the separator are wound to form a roll core, a central hole will exist in the center of the roll core due to the winding process. The positive electrode sheet, the negative electrode sheet and the separator extend outward in a spiral shape from the edge of the central hole, and when the electrolyte is injected into the battery to soak the roll core after the roll core is assembled with the battery shell.

[0056] All the tab structures of the positive electrode sheet constitute a positive tab, and all the tab structures of the negative electrode sheet constitute a negative tab. After the electrode sheet is wound, the inner layer of the roll core is formed at the edge of the central hole of the roll core at the winding start end, and the outer layer of the roll core is formed at the outermost side of the roll core at the winding end. The two tab structures intersecting at the middle point form the middle layer of the roll core. Due to the fact that the heights of the tab structures distributed in a stepped manner from the winding start end of the electrode sheet to the middle point decrease in turn, and the heights of the tab structures distributed from the middle point of the electrode sheet to the winding end increase in turn, the inner layer tab structure and the outer layer tab structure of the positive tab and the negative tab are relatively high, and the middle layer tab structure is the lowest. That is, the height of the tab structure in the positive tab or the negative tab decreases from the inner layer to the middle layer and increases from the middle layer to the outer layer. Therefore, when the tab structure is folded, the tab structure of the middle layer does not need to be folded, and only the tab structures of the inner layer and the outer layer need to be folded to the same plane as the tab structure of the middle layer. In this way, all the tab structures of the positive tab and the negative tab are located in the same plane, which not only enables all the tab structures to be connected with the current collector plate when the positive tab and the negative tab are connected with the current collector plate, but also maximizes the connection area between the positive tab, the negative tab and the current collector plate, thereby improving the charging and discharging efficiency of the roll core.

[0057] On the other hand, since the inner layer tab structure and the outer layer tab structure of the positive tab and the negative tab are all folded towards the middle layer in the present disclosure, the top of the folded tab structure is away from the central hole of the roll core, which prevents the central hole from being blocked and reduces the welding failure rate caused by the heat effect and vibration of the welding between the tab of the roll core and the current collector plate.

[0058] The tab structure of the present disclosure only needs to be bent to concentrate the top of all tab structures on the same plane. The tab folding process is to bend the innermost tab structure of the positive or negative tab except the innermost circle of the tab structure by using a mold. That is, all the tab structures on the outer side are folded inward to the tab structure on the inner side, so that the top of all the tab structures is located on the same plane. The processing step sequence only needs to simply bend the tab structure to achieve the folding effect. The bending folding process can be completed by related molds and other devices, so it does not need to use the traditional rubbing process, that is, there is no problem of dust falling into the core inside, which realizes the effect of reducing the process difficulty and improving the yield.

[0059] The traditional technology adopts rubbing process for the tab, which often sets the height of the tab to the same height to increase the stability in the rubbing process. The scheme of the present disclosure does not need to rub all the tab structures, but through the bending way, the top of all the tab structures is located on the same plane. Therefore, the height of the tab structure of the present disclosure is smaller than the height of the tab that needs to be rubbed by the rubbing process, that is, the effect of reducing the cost is realized. In addition, since the tab structure of the present disclosure gradually increases from the middle layer to the inner layer and the outer layer of the core, in addition to the effect of cost saving, the overall height of the tab structure is low, which also realizes the effect of easier complete folding.

[0060] When the height difference of every two adjacent tab structures from the starting winding end to the middle point is equal to the height difference of every two adjacent tab structures from the middle point to the end winding end, that is, the tab structure height from the middle point to the starting winding end and the tab structure height from the middle point to the end winding end are mutually symmetrical, at this time, the angle of bending the tab structure from the starting winding end to the middle point is the same as the angle of bending the tab structure from the middle point to the end winding end.

[0061] When the height difference of every two adjacent tab structures from the starting winding end to the middle point is greater than the height difference of every two adjacent tab structures from the middle point to the end winding end, that is, except for the two tab structures intersecting at the middle point, the tab structure height from the middle point to the starting winding end is greater than the corresponding tab structure height from the middle point to the end winding end. At this time, the total number of tab structures on both ends of the center point can be the same or different. Taking the tab structure close to the center point as the starting point, the subsequent tab structures of the same order are the tab structure height from the middle point to the starting winding end greater than the corresponding tab structure height from the middle point to the end winding end.

[0062] Since the positive tab is welded with the current collector plate, the current collector plate needs to be welded with the positive post, and the positive post is usually welded close to the center hole. Therefore, if the welding position of the positive tab and the current collector plate is too close to the center hole, the heat affected zone and vibration generated during the welding of the positive post will impact the positive tab or the diaphragm structure of the core to varying degrees, and there is a risk of product failure. When the height difference between each two adjacent tab structures from the starting winding end to the middle point is greater than the height difference between each two adjacent tab structures from the middle point to the end, the tab structure of the positive tab will be more distant from the center, which can avoid the impact of the positive post welding on the positive tab and reduce the failure rate of the finished product.

[0063] The tab structure of the positive and negative tabs is gathered to improve the connection area with the current collector plate, thereby improving the charge and discharge efficiency of the core. However, if the tab structure is too dense after gathering, electrical interference problems may occur. If the tab structure is too sparse after gathering, it will increase the difficulty of sufficient connection with the current collector plate.

[0064] As shown in Figures 7-9 In another embodiment, the tab gathering area width S1 is 1mm≤S1≤10mm.

[0065] In this embodiment, the center hole diameter is φb, 3mm≤φb≤15mm, the core diameter is φa, 20mm≤φa≤80mm, and as shown in Figures 7-8 It can be seen that the height H1 and H1' of the two tab structures intersecting at the middle point are 2mm≤H1=H1'≤5mm, the height of the inner ring tab structure is Hn, and the height of the outer ring tab structure is Hn'. The relationship between the above parameters can be determined by the Pythagorean theorem as 〖((φa-φb) / 4-S1 / 2)〗^x+〖H1〗^y=〖Hn〗^z=〖Hn’〗^z, 1≤x≤3, 1≤y≤3, 1≤z≤3; here, the height difference between each two adjacent tab structures from the starting winding end to the middle point is equal to the height difference between each two adjacent tab structures from the middle point to the end, and other cases are similar, which will not be described here.

[0066] Since the tab structure is continuous and forms a continuous spiral distribution after winding, directly gathering will obviously cause too many wrinkles, which will interfere with the performance of the electrode.

[0067] As shown in Figures 5-8 In an embodiment, the positive tab and the negative tab are each provided with a plurality of slits;

[0068] The slits of the positive tab are radially through from the innermost layer to the outermost layer;

[0069] The slits of the negative tab are radially through from the innermost layer to the outermost layer.

[0070] The positive tab and the negative tab of the core in the embodiment are respectively provided with a plurality of positive tab slits and negative tab slits; the positive tab slits are distributed on the positive tab, the positive tab slits are radially penetrated from the innermost layer to the outermost layer, that is, radially extended from the lowest tab structure to the highest tab structure of the positive tab slits, the positive tab slits penetrate all the tab structures of the positive tab, and the number of the positive tab slits can be set based on requirements, which can be but is not limited to 4-8, and the positive tab slits are circumferentially distributed to divide the positive tab into a plurality of tab areas, at this time, because the positive tab slits exist between the tab areas, the folding of the positive tab can greatly reduce the wrinkles, thereby realizing the effect of reducing the interference of the wrinkles on the positive tab; the negative tab slits are similar to the positive tab slits, and details are not repeated here.

[0071] In another embodiment, in order to effectively avoid excessive wrinkles caused by the positive tab slits and the negative tab slits when the tab structure is bent, the width W1 of the positive tab slits and the negative tab slits can be but is not limited to 0.03mm≤W1≤0.1mm or 1mm≤W1≤3mm.

[0072] In the embodiment, the width and the number of the positive tab slits and the negative tab slits are negatively correlated, the smaller the width is, the more the number needs to be set to prevent the interference between the tab areas when they are folded, and vice versa, the larger the width is, the less the number of the positive tab slits and the negative tab slits can be set.

[0073] Because the foil area and the coating area of the electrode sheet are two adjacent areas, in order to prevent the positive tab slits and the negative tab slits from interfering with the coating area, the depth of the positive tab slits and the negative tab slits needs to be determined.

[0074] In another embodiment, the positive tab slits are penetrated from the top of the tab structure to a preset height away from the coating area.

[0075] The negative tab slits are penetrated from the top of the tab structure to a preset height away from the coating area.

[0076] In the embodiment, the positive tab slits and the negative tab slits are set to be outside a preset distance from the top of the positive coating area and the top of the negative coating area to prevent the slitting process or the tab structure folding process from affecting the coating area, that is, the roots of the positive tab slits and the negative tab slits are away from the top of the positive coating area and the top of the negative coating area by a preset distance of a safety area, which plays a role in protecting the stability of the coating area, and the length of the preset distance can be but is not limited to 1-2mm, which realizes the effect of preventing the coating area from being cut in the slitting process or being bent in the tab folding process.

[0077] Because the center hole exists in the cylindrical battery, and the positive electrode sheet and the negative electrode sheet need to be wound from the edge of the center hole as the starting point, the width of the tab structure is necessarily related to the existence of the center hole.

[0078] In an embodiment, the width of the innermost tab structure is the circumference of the center hole, and the width of the outermost tab structure is the circumference of the outermost layer of the winding core.

[0079] In this embodiment, the width of the tab structure is gradually increased from the starting end to the ending end of the electrode sheet, and the width of the tab structure at the starting end is the length of the first winding, and the width of the tab structure at the ending end is the length of the last winding. Figures 8-9 Because the center hole is circular and is sequentially stacked with the positive electrode sheet, the separator, the negative electrode sheet, and the separator, and is wound to make each layer from the inside to the outside of the positive and negative tabs of the winding core after winding consist of one tab structure, the width of each tab structure needs to be the length of one winding at the current position, that is, the width of the tab structure for the electrode sheet is gradually increased from the starting end to the ending end, so that the width of the innermost tab structure after winding into a winding core is the circumference of the center hole, and the width of the outermost tab structure is the circumference of the outermost layer of the winding core, where the circumference of the outermost layer of the winding core is more specifically the circumference of the outermost layer of the specific electrode sheet, for example, the width of the outermost tab structure of the positive electrode sheet is equal to the circumference of the outermost layer of the positive electrode sheet; the width of the first tab structure is determined based on the circumference of the center hole, the width of the second tab structure is determined based on the thickness of the positive electrode sheet, the thickness of the negative electrode sheet, and the thickness of the separator, and the width of the nth structure is obtained in the same way; as an example, the positive electrode sheet includes n tab structures, the width of the first tab structure is L1=π*φb, the length from the innermost tab structure to the middle layer tab structure is Ln-1=π*[φb+(n-(n-1))*2*(2m+s+t)], …, L2=π*[φb+(n-2)*2*(2m+s+t)], L1=π*[φb+(n-1)*2*(2m+s+t)], the length from the middle layer tab structure to the outermost tab structure is L1’=π*[φb+(n-1+1)*2*(2m+s+t)], L2’=π*[φb+(n-1+2)*2*(2m+s+t)], …, L(n-1)’=π*[φb+(n-1+n-1)*2*(2m+s+t)], Ln’=π*φa; where s is the thickness of the positive electrode sheet, t is the thickness of the negative electrode sheet, m is the thickness of the separator, φb is the diameter of the center hole, and φa is the diameter of the winding core; the width of the tab structure can be adjusted adaptively for other stacking modes, which will not be described here.

[0080] Figure 10 is a structural diagram of a battery according to another exemplary embodiment of the present specification

[0081] The third aspect of the embodiment of the present specification is shown as Figure 10 ; a battery is provided, including a shell and a winding core of the second aspect; the winding core is placed in the shell.

[0082] In this embodiment, the shell comprises an outer shell and two current collecting plates 31, the positive and negative tabs of the winding core are connected with the current collecting plates 31 respectively, and the winding core is placed in the outer shell after being connected with the current collecting plates 31.

[0083] The above described a particular embodiment of the specification. Other embodiments are within the scope of the appended claims. In some cases, the acts or steps recited in the claims can be performed in an order other than that in the embodiments and still achieve desirable results. Additionally, the process depicted in the figures does not necessarily require the particular order shown, or sequential order, to achieve the desired results. In certain implementations, multitasking and parallel processing can be advantageous or necessary.

[0084] Other embodiments of the present specification will be apparent to those skilled in the art upon consideration of the specification and practice of the application disclosed herein. The present specification is intended to cover any variations, uses or adaptations of the present specification following, in general, the principles of the present specification and including such departures from the present specification as come within known or customary practice in the art to which the present specification pertains or relates. The specification is to be regarded as illustrative rather than restrictive, and the true scope of the present specification is to be indicated by the following claims.

[0085] It should be understood that the present specification is not limited to the precise structures as herein described and illustrated in the drawings, and that various modifications and changes can be made without departing from the scope thereof. The scope of the present specification is limited only by the claims that follow.

[0086] The above only describes the preferred embodiments of the present specification, and does not limit the present specification, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present specification shall be included in the protection scope of the present specification.

Claims

1. An electrode sheet of a battery, the electrode sheet being sequentially provided with a winding start end, an intermediate point, and a winding end along a winding direction, characterized by, The electrode sheet comprises a coating area for applying a polar coating and a foil area for serving as a tab; The foil area comprises a plurality of tab structures, which are continuously distributed along the edge of the coating area from the starting winding end to the ending winding end; wherein the heights of the tab structures distributed in a stepped manner from the starting winding end to the intermediate point decrease in turn; the heights of the tab structures distributed from the intermediate point to the ending winding end increase in turn; the heights of the two tab structures intersecting at the intermediate point are the same; the height difference of each two adjacent tab structures from the starting winding end to the intermediate point is not less than the height difference of each two adjacent tab structures from the intermediate point to the ending winding end; the overall height of the tab structures from the starting winding end to the intermediate point is greater than the tab height of the tab structures from the intermediate point to the ending winding end.

2. The electrode sheet of a battery according to claim 1, characterized by The height difference of the two adjacent tab structures is a fixed value.

3. The electrode sheet of a battery according to claim 1, wherein The height difference of the two adjacent tab structures increases or decreases by a preset ratio.

4. A jelly-roll of a battery, characterized by The winding core comprises a positive electrode sheet, a negative electrode sheet and a separator; the positive electrode sheet or the negative electrode sheet is the electrode sheet of any one of claims 1-3, the coating area of the positive electrode sheet is coated with a positive electrode coating, and the coating area of the negative electrode sheet is coated with a negative electrode coating; The coating area of the positive electrode sheet and the coating area of the negative electrode sheet are laminated, the separator is laminated between the positive electrode sheet and the negative electrode sheet, and the positive electrode sheet, the negative electrode sheet and the separator form the winding core by winding; wherein the orientation direction of the foil area of the positive electrode sheet and the foil area of the negative electrode sheet is opposite, the foil area of the positive electrode sheet is a positive tab, and the foil area of the negative electrode sheet is a negative tab.

5. The jelly-roll of a battery according to claim 4, wherein The height of the positive tab or the negative tab decreases from the inner layer to the intermediate layer and increases from the intermediate layer to the outer layer.

6. The jelly-roll battery core according to claim 4, wherein The winding core is provided with a center hole, and the positive electrode sheet, the negative electrode sheet and the separator extend outward in a spiral shape from the edge of the center hole.

7. The jelly-roll battery core according to claim 4, wherein The positive tab and the negative tab are each provided with a plurality of slits; The slit of the positive tab penetrates radially from the innermost layer to the outermost layer; The slit of the negative tab penetrates radially from the innermost layer to the outermost layer.

8. The jelly-roll battery core according to claim 7, wherein The slit of the positive tab penetrates from the top of the tab structure to a preset height from the coating area; The slit of the negative tab penetrates from the top of the tab structure to a preset height from the coating area.

9. The jelly-roll battery core according to claim 4, wherein The tab structures of the inner layer and the outer layer of the positive electrode sheet are bent towards the tab structure of the intermediate layer, so that the top of the positive tab and the top of the negative tab are located on the same plane; The tab structures of the inner layer and the outer layer of the negative electrode sheet are bent towards the tab structure of the intermediate layer, so that the top of the negative tab is located on the same plane.

10. The winding core of the battery according to claim 6, wherein The width of the tab structure of the innermost layer is the circumference of the center hole, and the width of the tab structure of the outermost layer is the circumference of the outermost layer of the winding core.

11. A battery, characterized by The winding core of any one of claims 4-10 is arranged in the shell.

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