Full-tab pole piece, roll core pole group and cylindrical lithium ion battery

Abstract

The utility model provides a full-tab pole piece, a roll core pole group and a cylindrical lithium ion battery. The full-tab pole piece comprises a pole piece body, the pole piece body comprises a material area used for coating a polar material and a tab area, the material area and the tab area extend in the length direction of the pole piece body, the tab area comprises a plurality of tabs arranged at intervals in the length direction of the pole piece body, the width of the edge, facing the material area, of each tab is w1, and the width of the edge, facing the material area, of each tab is w2. The distance between the edges, facing the material area, of the two adjacent tabs is w2, and the range of w2 / w1 is 20-30%. By selecting the range of w2 / w1, the size of the tab after leveling can be controlled, and chippings generated by breakage of the tab when the tab enters a shell are reduced, so that the safety performance of the battery is improved; meanwhile, the uniform density of all tabs after leveling is ensured to a certain extent, and effective gaps are reserved between the tabs, so that electrolyte infiltration is facilitated, and the cycle performance of the battery is improved; in addition, the tabs are relatively uniform in density after being flattened, so that the welding performance can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of lithium-ion batteries, and in particular to a full-tab electrode, a wound core electrode group, and a cylindrical lithium-ion battery. Background Art

[0002] The birth of lithium-ion batteries has entered modern life. After years of development, it has now become a popular research field. In related technologies, lithium-ion batteries can be divided into three forms according to the packaging form: square, cylindrical, and soft-pack. Among them, cylindrical lithium-ion batteries have gradually become the focus of lithium-ion battery research due to their good consistency, high production efficiency, and strong heat dissipation ability at the system level, and are widely used in fields such as power tools, electric vehicles, and energy storage. The tab in the electrode is the path for connecting electrons and is an important part of the battery. In recent years, in cylindrical batteries, due to the advantages of full tabs in reducing battery internal resistance, improving battery capacity, and rate discharge ability, full tabs have gradually become the favorite in the new energy field and are the focus of current research on cylindrical lithium-ion batteries.

[0003] As an important electronic connection channel in cylindrical lithium-ion batteries, the corresponding shape, size, etc. of the full tab will have an important impact on the internal resistance of the battery. The tab in the full-tab battery is formed by die-cutting the electrode sheet, and in subsequent processes, the die-cut tab needs to be flattened. In the existing related technologies, due to the unreasonable design of the tab, when the tab is flattened, the size of the tab will increase after being subjected to the flattening force. During the process of placing it into the battery case, the battery case may collide with the tab and the tab is easily broken. The broken tab is likely to fall into the wound core electrode group inside, and falling into the battery may connect the positive electrode sheet and the negative electrode sheet, resulting in battery short circuit and affecting the safety performance of the battery. In addition, due to the unreasonable design of the tab, the flattened full tab will show a phenomenon of uneven density, lacking effective gaps between each other, which is not conducive to the infiltration of the electrolyte, thus affecting the cycle performance of the battery, and at the same time, the uneven density also affects the welding stability. Summary of the Utility Model

[0004] The first object of the present application is to provide a full-tab electrode, which aims to solve the problems existing in the prior art due to the unreasonable design of the full-tab structure, such as easy breakage of the tab foil, generation of chips and falling, poor welding stability, and poor electrolyte infiltration effect, so as to improve the cycle performance and safety performance of the full-tab cylindrical lithium-ion battery.

[0005] To achieve the above object, the solution provided by this application is: a full-tab pole piece, including a pole piece body, the pole piece body includes a material area for coating polar materials and a tab area, both the material area and the tab area extend along the length direction of the pole piece body, the tab area includes a plurality of tabs arranged at intervals along the length direction of the pole piece body, the width of the side of the tab facing the material area is w1, the distance w2 between the sides of two adjacent tabs facing the material area, and the range of w2 / w1 is 20-30%.

[0006] By optimizing the selection of the die-cut tab width w1 and the tab spacing w2, and controlling w2 / w1 within the range of 20-30%, it is beneficial to control the size of the tab after flattening, reduce the generation of debris when the tab enters the shell, reduce the possibility of debris falling into the battery interior, and reduce the probability of battery short circuit. In addition, the appropriate structural design of the tab width w1 and the tab spacing w2 can, to a certain extent, ensure the uniform density of the full tabs after flattening, with a certain effective gap between them, which is beneficial to the infiltration of the electrolyte, thereby improving the cycle performance of the battery. At the same time, due to the relatively uniform full-tab density, the welding stability can be improved.

[0007] As an implementation manner, w1 is 1.5-2.2 mm; from the perspective of process effects, if the tab w1 is too narrow, the tab tension is insufficient, it is easy to scatter and shed chips, and if the tab is too wide, it is easy to wrinkle during winding, and the tab is uneven after flattening, affecting the welding performance.

[0008] As an implementation manner, the tab area further includes a connection area, the connection area is located between the plurality of tabs and the material area, the distance between the side of the tab connected to the connection area and the material area is h2, the shape of the tab is a parallelogram, and the length of the side of the tab away from the material area from the material area is h1, and the range of h2 / h1 is 10-20%.

[0009] The h2 area is the pre-bending area before battery winding. If it is bent at the connection between the tab and the material area, it will damage the material area and affect the coating. Therefore, a certain spacing is given to facilitate bending; if the ratio of h2 / h1 is too small, for example, if the h2 spacing is too small, the pole piece material area will be bent, affecting the battery coating effect and easily causing a short circuit. For example, if the h1 spacing is too large and the tab is too high, it will cause the tab to be inserted during the process of cutting and stacking the height, affecting the performance of the battery. If the ratio of h2 / h1 is too large, for example, if the h2 spacing is too high, the effective height of the tab is short, affecting the welding and current-carrying effects; for another example, if the h1 spacing is too small and the h1 height is too low, the corresponding number of cutting and stacking layers is low, affecting the welding performance.

[0010] As an implementation manner, the length of h2 is 0.4-0.6 mm, which balances the problem of the material area protruding outward and the welding effect and the current-carrying effect.

[0011] As an implementation manner, the shape of the tab is a parallelogram, and the included angle e between the side connected to the side of the tab facing the material area and the width direction of the tab body is 14 - 18 degrees. The purpose of the bevel cutting is to make the tab tend to one side after being flattened. Although there is a spacing after the tab is cut, the tabs can still fit as closely as possible after being flattened, increasing the density of the tabs after being flattened; if the included angle is too small, such as presenting a rectangular structure, it will cause too large a gap between the tabs, resulting in too small an overall density of the tabs, and it is easy to weld through subsequently, thus affecting the welding performance; in addition, if the included angle is too small, due to excessive stress on the tabs, it is still easy to generate particulate debris during the subsequent flattening process, posing a short - circuit risk and affecting the battery safety performance. If the included angle is too large, it will also cause too large an area of the gap between the tabs, resulting in a smaller overall density of the tabs, thus affecting the subsequent welding performance. In addition, too large an included angle leads to too small stress between the tabs, easily causing the wound tab to wrinkle and rupture, ultimately affecting the overall safety performance and cycle performance of the battery. Therefore, in this application, the range of the included angle e is set at 14 - 18 degrees, which can maintain an appropriate density after the tabs are flattened, ensure sufficient electrolyte infiltration effect of the tabs, while taking into account the welding performance of the tabs and reducing the generation of debris particles due to tab breakage, thus having sufficient safety performance and cycle performance.

[0012] As an implementation manner, the length of the multiple tabs in the tab area along the length direction of the tab body is less than the length L of the material area. One end of the two ends of the tab area has a first cut - off area or a second cut - off area. The length of the first cut - off area along the length direction of the tab body is L1, and the range of L1 / L is 5 - 15%. The length of the second cut - off area along the length direction of the tab body is L2, and the range of L2 / L is 10 - 20%. If L1 / L is too small, it is easy to cause blockage of the central hole of the wound core electrode group; if L1 / L is too large, it will cause the diaphragm to be easily exposed, and metal debris to enter the electrolyte, easily causing a short - circuit. If L2 / L is too small, it is easy to cause the wound core electrode group to turn over, resulting in the wound core electrode group protruding from the diaphragm and affecting the insertion into the shell; if L2 / L is too large, it will cause the diaphragm to be easily exposed, and metal debris to enter the electrolyte, easily causing a short - circuit.

[0013] As an implementation manner, the length of the multiple tabs in the tab area along the length direction of the tab body is less than the length L of the material area. One end of the two ends of the tab area has a first cut - off area, and the other end has a second cut - off area. The length of the first cut - off area along the length direction of the tab body is L1, and the range of L1 / L is 5 - 15%. The length of the second cut - off area along the length direction of the tab body is L2, and the range of L2 / L is 10 - 20%.

[0014] As an implementation manner, the length of L1 is 105 - 130 mm, and the length of L2 is 175 - 205 mm, which is beneficial to reducing the blockage of the central hole of the core electrode group and the flanging of the core electrode group during subsequent winding and flattening.

[0015] The second object of the present application is to provide a core electrode group, which includes the full-tab electrode sheet of the first object embodiment. By controlling the size of the full tab, it is beneficial to control the size of the tab after flattening, reduce the generation of debris when the tab enters the shell, reduce the possibility of debris falling into the battery interior, and reduce the probability of battery short circuit. In addition, the structural design of the appropriate tab width w1 and tab spacing w2 can, to a certain extent, ensure that the density of the full tabs after flattening is uniform, and there is a certain effective gap between them, which is beneficial to the infiltration of the electrolyte, thereby improving the cycle performance of the battery. At the same time, due to the relatively uniform density of the full tabs, the welding stability can be improved.

[0016] The third object of the present application is to provide a cylindrical lithium-ion battery, which includes the full-tab electrode sheet of the first object embodiment or the core electrode group of the second object embodiment. Since the debris inside the cylindrical lithium-ion battery is reduced, the possible short circuit inside the cylindrical lithium-ion battery is avoided. In addition, through the reasonable design of the structure of the die-cut tab, the full tab after flattening has an appropriate density, and there is an effective gap between them, which is beneficial to the infiltration of the electrolyte, thereby effectively improving the cycle performance of the battery. At the same time, due to the relatively uniform density of the full tabs, the welding stability can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1 is a schematic diagram of a full-tab electrode sheet provided by an embodiment of the present application;

[0019] Figure 2 is Figure 1 an enlarged view of the partial A in;

[0020] Figure 3 is a schematic diagram of the tab of the core electrode group after flattening provided by an embodiment of the present application;

[0021] Figure 4 is Figure 3 an enlarged view of the partial B in;

[0022] Figure 5 is a schematic diagram of the core electrode group before winding.

[0023] Reference numerals:

[0024] 100 - full tab electrode, 110 - electrode body, 111 - material area, 112 - tab area, 1121 - tab, 1121a - side where the tab is connected to the connection area, 1121b - side where the tab is connected to the side facing the material area, 1121c - side of the tab away from the material area, 1122 - connection area, 1123 - first cut-off area, 1124 - second cut-off area;

[0025] 200 - wound core electrode group, 210 - first separator, 220 - positive electrode, 221 - tab of the positive electrode, 230 - second separator, 240 - negative electrode, 241 - tab of the negative electrode;

[0026] L - length of the material area, L1 - length of the first cut-off area, L2 - length of the second cut-off area, h1 - distance from the side of the tab away from the material area to the material area, h2 - distance from the side where the tab is connected to the connection area to the material area, w1 - width of the side of the tab facing the material area, w2 - distance between the sides of two adjacent tabs facing the material area, c - head end of the wound core electrode group, d - tail end of the wound core electrode group, e - angle between the side where the tab is connected to the side facing the material area and the vertical direction, f - overlapping area of two adjacent tabs after flattening, g - gap area between two adjacent tabs after flattening. Detailed implementation manners

[0027] The embodiments of the present implementation manner will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals indicate the same or similar elements or elements with the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present implementation manner and should not be construed as a limitation of the present implementation manner.

[0028] In the description of the present implementation manner, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present implementation manner and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present implementation manner.

[0029] In the description of the present implementation manner, the meaning of several is one or more, the meaning of multiple is more than two, greater than, less than, exceeding, etc. are understood as not including the number itself, and above, below, within, etc. are understood as including the number itself. If there is a description of first and second, it is only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or the sequence relationship of the indicated technical features.

[0030] In the description of this embodiment, unless otherwise clearly defined, terms such as "setting", "installation", "connection", etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in this embodiment in combination with the specific content of the technical solution.

[0031] Lithium-ion batteries are mainly divided into three forms according to the packaging form: square, cylindrical, and soft-pack. The cylindrical lithium-ion battery mainly includes a housing, a wound core electrode group, positive and negative current collectors, and a cap. The wound core electrode group is formed by winding a separator, a positive electrode sheet, a separator, and a negative electrode sheet in sequence. After winding, a central hole will be formed along the axial direction of the wound core electrode group for injecting electrolyte. Connect the wound core electrode group to the current collector, and the current collector plays the role of collecting current. Then assemble it into the housing, and then connect the cap, current collector, and housing to form a cylindrical lithium-ion battery. Before forming the wound core electrode group, it is necessary to manufacture the positive electrode sheet and the negative electrode sheet. The positive electrode sheet includes a whole electrode sheet body. Generally, the electrode sheet is rectangular, with a length much greater than the width. The electrode sheet body is divided into two regions along the width direction. One region is used for subsequent coating of electrode materials, and the other region is used for subsequent die-cutting of tabs. First, coat the electrode material on the region of the electrode sheet for coating the electrode material, and then die-cut a plurality of tabs arranged at intervals in the tab region. The die-cutting method can be mechanical die-cutting or laser die-cutting, etc. In the process of forming the wound core electrode group, it is necessary to first wind the separator, positive electrode sheet, separator, and negative electrode sheet. The electrode sheet body of the positive electrode sheet includes a material region and a tab region adjacent to the material region. The material region is the region coated with the positive electrode material. The negative electrode sheet is similar to the positive electrode sheet, and the difference is that the material region of the negative electrode sheet is coated with the negative electrode material. The tab region includes a plurality of tabs arranged at intervals along the length direction of the tab body. After winding, it is necessary to flatten the tab region, that is, the tab region bends after receiving the flattening force. After the flattened wound core electrode group is placed in the housing, during the process of inserting it into the housing, the size of the tab becomes larger after receiving the flattening force, and the tab is easily broken and chipped after colliding with the housing. Also, since the tab itself is made of a conductive material, the debris falling into the battery may connect the positive electrode sheet and the negative electrode sheet, causing an internal short circuit of the battery. In addition, due to the unreasonable design of the die-cut tabs, after flattening, the full tabs have uneven density and lack effective gaps between each other, which is not conducive to the infiltration of the electrolyte, thus affecting the cycle performance of the battery. The tabs with uneven density also affect the subsequent welding performance with the current collector.

[0032] In order to avoid the breakage of tabs and the generation of debris caused by the tab flattening process during the manufacturing process of cylindrical lithium-ion batteries, improve the infiltration effect of the electrolyte, enhance the cycle performance of the battery, and enhance the welding performance, as Figure 1 and Figure 2 shown, Figure 2 For Figure 1The enlarged view shown in [A], the present application discloses a full-tab pole piece, including a tab body 110, the pole piece body 110 includes a material area 111 for coating polar materials and a tab area 112. Both the material area 111 and the tab area 112 extend along the length direction of the pole piece body 110. The tab area 112 includes a plurality of tabs 1121 arranged at intervals along the length direction of the tab body 110. The width of the side (1121a) of the tab 1121 facing the material area is w1, and the distance between the sides 1121a of two adjacent tabs 1121 facing the material area 111 is w2.

[0033] Through experimental tests, setting the ratio of w2 / w1 of the tab within the range of 20 - 30% is beneficial to controlling the size of the rolled core pole group after flattening, and avoiding the breakage of the tab 1121 and the generation of debris during the subsequent shell insertion process. At the same time, if the width w1 of the side of the tab facing the material area is too wide, it will cause wrinkles during the winding process. The wrinkles on the tab 1121 will cause the tab 1121 to be uneven after the subsequent flattening process, which is not conducive to the subsequent welding process. That is, after the tab 1121 is flattened, the tab 1121 and the current collector plate need to be welded together. If the flattened tab 1121 is uneven, the thickness in the concave area is thin, which is likely to cause penetration welding; the unevenness also results in poor flatness of the flattened tab 1121, and it is easy to occur disconnection welding in the concave area. Through experimental tests, setting the ratio of w2 / w1 within the range of 20 - 30% can reduce the wrinkles generated on the tab during the pole piece winding process, reduce the breakage of the tab 1121 and the generation of debris during the shell insertion process, and also achieve the effect of facilitating the infiltration of the electrolyte. At the same time, through experimental tests, controlling the ratio of w2 / w1 within the range of 20 - 30% can also improve its self-discharge rate K. The smaller the value of K, the better the battery performance to a certain extent. The applicant tested the K value under different ratios of w2 / w1, as shown in the following table.

[0034]

[0035]

[0036] It can be seen from the table that controlling the ratio of w2 / w1 within the range of 20 - 30% can well improve its self-discharge rate K, and can effectively control the average value of its self-discharge rate K within 0.040, having relatively better battery performance.

[0037] In some embodiments, the width w1 of the edge of the pole ear toward the material area is 0.5-3.0 mm, preferably w1 is 1.0-2.5 mm, and further preferably w1 is 1.5-2.2 mm. The applicant has found through testing that the width w1 of the edge of the pole ear toward the material area is 1.5-2.2 mm, which can balance the size of the pole ear after flattening, improve welding performance and self-discharge rate. Specifically, the width w1 of the edge of the pole ear toward the material area can be 1.7 mm, 1.8 mm, 1.9 mm, and is not specifically limited.

[0038] In some embodiments, the distance w2 between the edges 1121a of two adjacent tabs 1121 facing the material area is 0.2-0.6 mm. When flattening, the tabs 1121 are bent in sequence from the beginning c of the winding to the end d, so that the latter bent tab overlaps the previous tab. Figure 4 As shown, an overlapping area f and a gap area g will be formed between two adjacent pole ears 1121. If the gap area g is too large, the internal resistance of the pole ear will be increased and the current overcurrent effect will be reduced. If the gap area g is reduced as much as possible, the distance w2 between the edges of the two adjacent pole ears facing the material area must be as small as possible, but this will increase the difficulty of die cutting and cause the yield rate to decrease. After testing, the distance w2 between the edges of the two adjacent pole ears facing the material area is controlled to 0.2-0.6mm, which can balance the difficulty of die cutting and the overcurrent effect. In some embodiments, w2 is preferably 0.3-0.5mm. In some embodiments, the distance w2 between the edges of the two adjacent pole ears facing the material area is further preferably 0.3mm, 0.4mm, 0.5mm, etc.

[0039] In some embodiments, the tab area 112 further includes a connection area 1122, which is located between the multiple tabs 1121 and the material area 111, that is, on the tab body 110, there are multiple tabs 1121, connection areas 1122 and material areas 111 arranged in sequence along the width direction of the tab body 110. Figure 2 In the figure, the area between the dotted lines ab is the connection area 1122, the area above the dotted line a is a plurality of pole ears 1121, and the area below the dotted line is the material area 111. In the flattening process, if the pole ear 1121 is directly connected to the material area 111, when the pole ear 1121 is subjected to the flattening force, the material area 111 connected to the pole ear 1121 is easily subjected to force, so that the wound material area 111 may protrude outward, which will affect the subsequent assembly of the core electrode group 200 into the battery housing. Therefore, the purpose of setting the connection area 1122 is to achieve a certain buffer, and the connection area 1122 bends inward when flattening, thereby avoiding the problem of the material area 111 protruding outward.

[0040] In some embodiments, the distance h2 between the side 1121a where the tab 1121 is connected to the connection area 1122 and the material area 111, the shape of the tab 1121 is a parallelogram, the length of the side 1121c of the tab 1121 far from the material area 111 from the material area 111 is h1, and the range of h2 / h1 is 10-20%. The h2 area is the pre-bending area before battery winding. If it is bent at the connection between the tab and the material area, it will damage the material area and affect the coating, so a certain spacing is given to facilitate bending. If the ratio of h2 / h1 is too small, for example, if the h2 spacing is too small, the pole piece material area will be bent, affecting the battery coating effect and easily causing a short circuit. For example, if the h1 spacing is too large and the tab is too high, the tab will be inserted during the process of cutting and stacking height. The tab insertion refers to the overlapping phenomenon after flattening adjacent tabs, which affects the performance of the battery. If the ratio of h2 / h1 is too large, for example, if the H2 spacing is too high, the effective height of the tab is short, affecting the welding and current-carrying effect; for another example, if the h1 spacing is too small and the h1 height is too low, the corresponding number of cutting and stacking layers is low, affecting the welding performance. In some embodiments, h2 / h1 is 13%, 15%, 17%, 19%, etc., and no specific limitation is made.

[0041] As Figure 1 shown, 1121c and 1121a are respectively two parallel sides of the parallelogram, 1121b is the side connecting 1121c and 1121a. As is well known to those skilled in the art, the dotted line 1121a is for illustration, and there is no such dotted line in the actual product. As described above, the tab 1121 is die-cut on the tab body 110. The tab 1121 includes a side 1121a connected to the tab body, two sides 1121b respectively connected to the head and tail ends of this side, which are generated by die-cutting part of the tab material of the tab body, and a side 1121c opposite to the side 1121a connected to the tab body 110. The four sides are connected to form a parallelogram.

[0042] In some embodiments, the distance h2 between the edge 1121a where the tab 1121 is connected to the connection area 1122 and the material area 111 is 0.4 - 0.6 mm. If the distance h2 between the edge where the tab is connected to the connection area and the material area is too high, it will reduce the height of the tab 1121, thus affecting the subsequent welding effect and current-carrying effect. During the battery manufacturing process, the height and diameter of the battery are generally fixed according to industry standards, so it determines that the length, width, and thickness of the electrode sheet body 110 are basically also fixed. A connection area 1121 is reserved in the tab area 112 of the electrode sheet body 110 for bending. At this time, in order to increase the battery capacity as much as possible, the width of the material area 111 remains unchanged, and only the width of the tab 1121 can be reduced. If the width of the connection area 1122 is too wide, it will cause the width of the tab 1121 to be too narrow. If the tab 1121 is too narrow, first, it will affect the welding effect. After being flattened, the outer tab 1121 will overlap above the inner tab 1121. If the tab 1121 is too narrow, some areas will appear very thin due to the small number of overlapping tabs 1121, which is likely to cause penetration welding during subsequent welding; second, it will affect the current-carrying effect. If the tab 1121 is too short, the entire tab area becomes thinner, the internal resistance increases, and the current-carrying current decreases. After testing, when the distance h2 between the edge where the tab is connected to the connection area and the material area is 0.4 - 0.6 mm, it is easy to balance the problem of the material area protruding outward and the welding effect and the current-carrying effect.

[0043] In some embodiments, the angle e between the edge 1121b where the tab faces the material area and the width direction of the electrode sheet body 110 is 14 - 18 degrees.

[0044] The purpose of chamfering is to make the tab tend to one side after being flattened. Although there is a gap after the tab is cut, the tabs can still fit as closely as possible after being flattened, increasing the density of the tabs after being flattened. After being flattened, two adjacent tabs 1121 will form an overlapping area f and a gap area g. If the angle is too small, such as presenting a rectangular structure, there will be an excessive gap area g between the tabs, resulting in too small an overall density of the tabs, which is likely to cause welding through in the subsequent process, thus affecting the welding performance. In addition, if the angle is too small, due to excessive stress on the tabs, it is still easy to generate particulate debris during the subsequent flattening process, posing a short-circuit risk and affecting the battery safety performance. If the angle is too large, it will also cause the area of the gap area g between the tabs to be too large, resulting in a smaller overall density of the tabs, thus affecting the subsequent welding performance. In addition, if the angle is too large, the stress between the tabs is too small, easily causing the wound electrode sheet to wrinkle and rupture, ultimately affecting the overall safety performance and cycle performance of the battery. Therefore, in the present invention, the range of the angle e is set to 14 - 18 degrees, which can maintain an appropriate density after the tabs are flattened, ensure that the tabs have sufficient electrolyte infiltration effect, and can take into account the welding performance of the tabs, thus having sufficient safety performance and cycle performance. The applicant tested the area values of the gap area g with different angles e, as shown in the following table. In some embodiments, the angle e is set to 14 degrees, 16 degrees, 18 degrees, etc.

[0045]

[0046] In some embodiments, such as Figure 5 shown, the wound core electrode group 200 is wound in sequence by a first separator 210, a positive electrode sheet 220, a second separator 230, and a negative electrode sheet 240. One end where the winding starts is called the head end c, and the outermost end after winding is the tail end d. After winding is completed, the first separator 210 is located on the innermost side of the wound core electrode group 200.

[0047] In some embodiments, the length of the plurality of tabs 1121 in the tab area 112 along the length direction of the tab body 110 is less than the length L of the material area 111. One end of the material area 111 along the length direction of the tab body 110 facing the tab area 112 is not connected to the connection area 1122. The end not connected to the connection area 1122 is called the first cutting area 1123. Among them, the end not connected to the connection area 1122 can be located at the head end c or the tail end d.

[0048] In some embodiments, the first cutting area 1123 of the electrode sheet body 110 is located at the head end c, that is, when die-cutting, the head end c of the electrode sheet body 110 is die-cut so that the head end c does not have a tab. If the head end c has a tab, after winding and flattening, the tab located at the head end c is likely to cause the central hole of the wound core electrode group to be blocked, which is not conducive to subsequent electrolyte injection.

[0049] In some embodiments, the length of the first cut area 1123 is L1, and L1 / L is 5-15%. If L1 / L is too small, it is easy to cause blockage of the central hole of the wound core electrode group; if L1 / L is too large, the separator is likely to be exposed, metal debris enters the electrolyte, and it is easy to cause a short circuit. Controlling the value of L1 / L between 5-15% can both reduce the blockage of the central hole of the wound core electrode group and reduce the probability of short circuit. In some embodiments, L1 / L is 7%, 9%, 11%, 13%, etc., and specific values are not limited.

[0050] In some embodiments, the length L1 of the first cut area 1123 is 105-130 mm. Further, L1 is preferably 110 mm, 115 mm, 120 mm, 125 mm, etc., and specific values are not limited.

[0051] In some embodiments, one end of the material area 111 facing the tab area 112 along the length direction of the tab body 110 is not connected to the connection area 1122. The end not connected to the connection area 1122 is called the second cut area 1124. Among them, the second cut area 1124 can be located at the head end c or the tail end d. In some embodiments, the second cut area 1124 is located at the tail end d. If there is a tab at the tail end d, it will cause the tab to protrude outward during the flattening process, affecting the subsequent assembly of the wound core electrode group 200 into the shell.

[0052] In some embodiments, the length of the second cut area 1124 is L2, and L2 / L is 10-20%. If L2 / L is too small, it is easy to cause the wound core electrode group to turn over, resulting in the wound core electrode group protruding from the separator and affecting the shell insertion; if L2 / L is too long, the separator is likely to be exposed, metal debris enters the electrolyte, and it is easy to cause a short circuit. Controlling L2 / L to 10-20% is both convenient for the wound core electrode group to be inserted into the shell and reduces the probability of short circuit. In some embodiments, L2 / L is 13%, 15%, 18%, etc., and specific values are not limited.

[0053] In some embodiments, the length L2 of the second cut area 1124 is 175-205 mm. Further, L2 is preferably 185 mm, 195 mm, etc., and specific values are not limited.

[0054] In some embodiments, one end of the two ends of the tab area 112 has the first cut area 1123, and the other end has the second cut area 1124. The length of the first cut area 1123 along the length direction of the electrode tab body 110 is L1, and the range of L1 / L is 5-15%. The length of the second cut area 1124 along the length direction of the electrode tab body 110 is L2, and the range of L2 / L is 10-20%. In some embodiments, the heights of the first cut area 1123 and the second cut area 1124 are flush along the width direction.

[0055] The embodiment of the present application further provides a wound-core electrode assembly 200, as Figure 3 and Figure 5 shown. The wound-core electrode assembly 200 is formed by winding a first separator 210, a positive electrode sheet 220, a second separator 230, and a negative electrode sheet 240 that are sequentially stacked, and then flattening the tabs of the positive electrode sheet 220 and the negative electrode sheet 240. At least one of the positive electrode sheet 220 and the negative electrode sheet 240 is configured as the full-tab electrode sheet 100 in any of the foregoing embodiments. The tab 221 of the positive electrode sheet is located at one end of the wound-core electrode assembly 200, and the tab 241 of the negative electrode sheet is located at the opposite end of the wound-core electrode assembly 200 along the width direction of the electrode sheet body 110. By controlling the size of the full tab, it is beneficial to control the size of the tab after flattening, reduce the generation of debris when the tab enters the case, reduce the possibility of the debris falling into the battery interior, and reduce the probability of battery short circuit. In addition, with an appropriate structural design of the tab width w1 and the tab spacing w2, it can ensure to a certain extent that the density of the full tabs after flattening is uniform, there are certain effective gaps between them, which is beneficial to the infiltration of the electrolyte, thereby improving the cycle performance of the battery. At the same time, due to the relatively uniform density of the full tabs, the welding stability can be improved.

[0056] The embodiment of the present application further provides a cylindrical lithium-ion battery, including the full-tab electrode sheet 100 in any of the foregoing embodiments or the wound-core electrode assembly 200 in the foregoing embodiments. By controlling the size of the full tab, it is beneficial to control the size of the tab after flattening, reduce the generation of debris when the tab enters the case, reduce the possibility of the debris falling into the battery interior, and reduce the probability of battery short circuit. In addition, with an appropriate structural design of the tab width w1 and the tab spacing w2, it can ensure to a certain extent that the density of the full tabs after flattening is uniform, there are certain effective gaps between them, which is beneficial to the infiltration of the electrolyte, thereby improving the cycle performance of the battery. At the same time, due to the relatively uniform density of the full tabs, the welding stability can be improved.

[0057] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this implementation manner. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0058] Although the embodiments of this implementation manner have been shown and described, those of ordinary skill in the art can understand that: Without departing from the principles and purposes of this implementation manner, various changes, modifications, substitutions, and variations can be made to these embodiments, and the scope of this implementation manner is defined by the claims and their equivalents.

Claims

1. A full-tab pole piece (100), characterized in that, It includes a pole piece body (110), the pole piece body (110) includes a material area (111) for coating polar materials and a tab area (112), both the material area (111) and the tab area (112) extend along the length direction of the pole piece body (110), the tab area (112) includes a plurality of tabs (1121) spaced along the length direction of the pole piece body (110), the width of the side (1121a) of the tab (1121) facing the material area (111) is w1, the distance between the sides (1121a) of two adjacent tabs (1121) facing the material area (111) is w2, and the range of w2 / w1 is 20 - 30%.

2. The all-tab pole piece (100) according to claim 1, characterized in that, The length of the w1 is 1.5 - 2.2 mm.

3. The all-tab pole piece (100) according to claim 1, characterized in that, The tab area (112) further includes a connection area (1122), the connection area (1122) is located between the plurality of tabs (1121) and the material area (111), the distance between the side (1121a) where the tab (1121) is connected to the connection area (1122) and the material area (111) is h2, the shape of the tab (1121) is a parallelogram, the length of the side (1121c) of the tab (1121) away from the material area (111) from the material area (111) is h1, and the range of h2 / h1 is 10 - 20%.

4. The all-tab pole piece (100) according to claim 3, wherein, The length of the h2 is 0.4 - 0.6 mm.

5. The all-tab pole piece (100) according to any one of claims 1-4, characterized in that, The shape of the tab (1121) is a parallelogram, the included angle e between the side (1121b) connected to the side (1121a) of the tab (1121) facing the material area (111) and the width direction of the pole piece body (110) is 14 - 18 degrees.

6. The all-tab pole piece (100) according to any one of claims 1-4, characterized in that, The length of the plurality of tabs (1121) in the tab area (112) along the length direction of the pole piece body (110) is less than the length L of the material area (111), one end of the two ends of the tab area (112) has a first cut-off area (1123) or a second cut-off area (1124), the length of the first cut-off area (1123) along the length direction of the pole piece body (110) is L1, and the range of L1 / L is 5 - 15%, the length of the second cut-off area (1124) along the length direction of the pole piece body (110) is L2, and the range of L2 / L is 10 - 20%.

7. The all-tab pole piece (100) according to any one of claims 1-4, characterized in that, The length of the plurality of tabs (1121) in the tab area (112) along the length direction of the pole piece body (110) is less than the length L of the material area (111), one end of the tab area (112) has a first cut-off area (1123), and the other end has a second cut-off area (1124), the length of the first cut-off area (1123) along the length direction of the pole piece body (110) is L1, and the range of L1 / L is 5 - 15%, the length of the second cut-off area (1124) along the length direction of the pole piece body (110) is L2, and the range of L2 / L is 10 - 20%.

8. The all-tab pole piece (100) according to claim 7, wherein The length of the L1 is 105 - 130 mm, and the length of the L2 is 175 - 205 mm.

9. A winding core electrode group (200), characterized in that, The core electrode assembly (200) is formed by winding a first separator (210), a positive electrode sheet (220), a second separator (230), and a negative electrode sheet (240) which are sequentially stacked, and then flattening the tabs of the positive electrode sheet (220) and the negative electrode sheet (240). At least one of the positive electrode sheet (220) and the negative electrode sheet (240) is configured as the full-tab electrode sheet (100) according to any one of claims 1-8. The tab (221) of the positive electrode sheet is located at one end of the core electrode assembly (200), and the tab (241) of the negative electrode sheet is located at the opposite end of the core electrode assembly (200) along the width direction of the electrode sheet body.

10. A cylindrical lithium-ion battery, characterized in that, It includes the full-tab electrode sheet (100) according to any one of claims 1-8 or the core electrode assembly (200) according to claim 9.

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