Battery

Abstract

The present application relates to the technical field of batteries. Disclosed is a battery. The battery comprises: a casing comprising a terminal assembly; and a cylindrical jelly roll comprising a jelly roll body and a plurality of tabs led from the jelly roll body, wherein the tabs are configured to be electrically connected to the terminal assembly or the casing; the plurality of tabs are distributed in a plurality of layers in the radial direction of the jelly roll body; the width of a single tab is E, satisfies: 2mm≤E≤9mm; and the difference between the maximum thickness and the minimum thickness of the jelly roll body is d, and the number of wound layers of the jelly roll body is n and satisfies: 0.08≤d·n≤0.9. By comprehensively controlling the relationship between the difference d between the maximum thickness and the minimum thickness of the jelly roll body and the number n of wound layers of a battery cell, the battery provided in the present application can ensure the alignment of the tabs in the radial direction of the battery cell as much as possible, thereby effectively reducing tab misalignment, such that gaps between front and rear layers after winding are more uniform, an effective welding area is ensured, and the overcurrent capability is guaranteed.

Description

Battery

[0001] This application claims priority to Chinese Patent Application No. 2024114433717, filed on October 16, 2024, entitled "Battery", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery technology, specifically to a battery. Background Technology

[0003] In related technologies, battery cells are often electrically connected to terminals via tabs, or via adapter plates. Taking direct connection between tabs and terminals as an example, during the cell manufacturing stage, multiple tabs are cut from one edge of the electrode sheet, and after the electrode sheet is wound, the tabs at the corresponding positions are flattened to facilitate electrical connection with the terminals.

[0004] However, since the electrode sheet includes a current collector and an active material layer, after the active material is coated onto the current collector, it is formed on the current collector through a rolling process. This results in uneven electrode sheet thickness, which increases the gap between the front and rear layers after winding. Consequently, it leads to poor alignment of the tabs in the radial direction of the cell, which reduces the welding area of ​​the tabs and terminals, resulting in insufficient current carrying capacity. Summary of the Invention

[0005] In view of this, this application provides a battery to solve the problem of insufficient overcurrent capacity caused by poor alignment of the tabs in the radial direction of the cell.

[0006] This application provides a battery, comprising:

[0007] The housing has a pole assembly mounted on it.

[0008] A cylindrical core, comprising a core body and multiple tabs; the tabs are used for electrical connection with a pole assembly or a housing; the multiple tabs are distributed in multiple layers along the radial direction of the core body.

[0009] When the cylindrical core is in the unfolded state, the width of a single tab along the length of the cylindrical core is E, which satisfies: 2mm≤E≤9mm;

[0010] The difference between the maximum and minimum thickness of the core body is d, and the number of winding layers of the core body is n, satisfying: 0.08≤d·n≤0.9. Beneficial effects:

[0011] The battery provided in this application achieves better tab alignment by controlling the relationship between the number of winding layers and the thickness difference of the core body, ensuring sufficient welding area for subsequent bonding and guaranteeing current carrying capacity. Furthermore, by limiting the width E of a single tab to a range of 2mm ≤ E ≤ 9mm, each tab is made a small tab with a relatively small width. Since multiple tabs extend from the cylindrical core body, slits are provided between adjacent tabs to allow multiple tabs to overlap after the cylindrical core is wound, forming a tab area and ensuring sufficient welding area. If a single large tab is used, it is prone to wrinkling or even folding during the cylindrical core winding process, which is detrimental to ensuring sufficient welding area. Therefore, slits are provided to cut the large tab into multiple small tabs to avoid wrinkling during winding. However, due to the difference in electrode thickness, mis-layering of the electrode tabs is prone to occur during winding. At the same time, due to the use of small electrode tabs, there are gaps between adjacent individual electrode tabs in the circumferential direction of the cylindrical core, which will exacerbate the risk of mis-layering. Therefore, it is necessary to strictly control the relationship between the thickness difference d and the number of winding layers n to avoid severe mis-layering and insufficient subsequent electrical connection area. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0013] Figure 1 is a schematic diagram of the battery of this application;

[0014] Figure 2 is an exploded view of the battery of this application;

[0015] Figure 3 is a schematic diagram of the cylindrical core of this application from a top view;

[0016] Figure 4 is a schematic diagram of the electrode unfolded state of this application;

[0017] Figure 5 is a schematic diagram of multi-point measurement when the electrode sheet of this application is in the unfolded state;

[0018] Figure 6 is a schematic diagram of section AA in Figure 5;

[0019] Figure 7 is a schematic diagram of another type of electrode tab in the unfolded state of the electrode sheet of this application.

[0020] Explanation of reference numerals in the attached drawings: 1. Shell; 2. Cylindrical core; 21. Tab area; 22. Electrode; 221. Tab; 222. Core body; 223. Single-layer tab assembly; 224. Thinning area; 3. Cover plate; 31. Pole post assembly; 32. Adapter piece. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] In the description of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0024] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0025] In related technologies, battery cells are often electrically connected to terminals via tabs, or via adapter plates. Taking direct connection between tabs and terminals as an example, during cell fabrication, multiple tabs are cut from one edge of the electrode sheet. After the electrode sheet is wound, the tabs at corresponding positions are flattened so that the tabs overlap to form a tab welding area, facilitating welding connection with the terminal.

[0026] If each tab is in an ideal and uniform distribution after the electrode is wound, the area of ​​the tab welding area can be effectively guaranteed. However, since the electrode includes a current collector and an active material layer, after the active material is coated onto the current collector, it is formed on the current collector through a rolling process. This results in uneven electrode thickness, which increases the gap between the front and rear layers after winding. Consequently, the alignment of the tabs is poor in the radial direction of the cell, resulting in excessive overlap between the tabs. This reduces the effective area of ​​the tab welding area, which means that the welding area of ​​the subsequent tabs and terminals is reduced, which can easily lead to insufficient current carrying capacity.

[0027] The battery provided in the embodiments of this application achieves better electrode alignment by controlling the relationship between the number of winding layers and the thickness difference of the core body 222, ensuring sufficient welding area for the electrode and guaranteeing overcurrent capacity.

[0028] The embodiments of this application are described below with reference to Figures 1 to 7.

[0029] According to an embodiment of this application, a battery is provided, comprising:

[0030] Housing 1, on which a pole assembly 31 is provided;

[0031] The cylindrical core 2 includes a core body 222 and multiple tabs 221; the tabs 221 are used for electrical connection with the pole assembly 31 or the housing 1; the multiple tabs 221 are distributed in multiple layers along the radial direction of the core body 222.

[0032] When the cylindrical core 2 is in the unfolded state, the width of a single tab 221 along the length direction of the cylindrical core 2 is E, which satisfies: 2mm≤E≤9mm;

[0033] The difference between the maximum and minimum thickness of the core body 222 is d, and the number of winding layers of the core body 222 is n, satisfying: 0.08≤d·n≤0.9.

[0034] The cylindrical core 2 has a cylindrical structure, and the shell 1 is fitted over the cylindrical core 2. In this embodiment, the structure of the shell 1 is not limited, and it can be cylindrical or hexagonal prism, etc., as long as it can place the cylindrical core 2 inside the shell 1 and constrain the cylindrical core 2.

[0035] The housing 1 includes a pole assembly 31, which is used for subsequent electrical connection with other structures, such as a busbar, to output current.

[0036] The housing 1 includes a housing body and a cover plate 3. The pole post assembly 31 can be disposed on the housing body or on the cover plate 3.

[0037] The core body 222 is formed by winding the electrode sheet. In this embodiment, the core body 222 specifically refers to the area other than the thinning area 224 removed along the width direction of the electrode sheet when it is in the unfolded state.

[0038] The width of a single tab 221 refers to the width of a single tab 221 along the length of the cylindrical core 2 when the core 2 is in the unfolded state. During measurement, the core body 222 can be flattened, and the dimension of the tab 221 measured along the length of the electrode sheet at this time is the width of the tab 221.

[0039] The structure of a single tab 221 can be in various forms, such as rectangular (as shown in Figure 4), trapezoidal (as shown in Figure 7), or other irregular shapes.

[0040] Since there are various structural forms of a single tab 221, the measurement method for the width E of a single tab 221 also differs: when the single tab is rectangular, it refers to the dimension in the length direction of the cylindrical core 2 when the cylindrical core 2 is in the unfolded state; when the single tab is trapezoidal, it refers to the maximum dimension in the length direction of the cylindrical core 2 when the cylindrical core 2 is in the unfolded state.

[0041] The battery provided in this application achieves good tab alignment by controlling the relationship between the number of winding layers and the thickness difference of the core body 222, ensuring sufficient welding area for the tabs and guaranteeing current carrying capacity. Furthermore, by limiting the width E of a single tab 221 to a range of 2mm ≤ E ≤ 9mm, each tab 221 is made a small tab with a smaller width. Since the cylindrical core 2 has multiple tabs 221 extending from the core body 222, slits are provided between adjacent tabs 221 to allow them to overlap after the cylindrical core 2 is wound, forming a tab area 21 and ensuring sufficient welding area. If a single large tab is used, it is prone to wrinkling or even folding during the winding process of the cylindrical core 2, which is detrimental to ensuring welding area. Therefore, slits are provided to cut the large tab into multiple small tabs to avoid wrinkling during the winding process. However, due to the difference in electrode thickness, misalignment of the tabs is prone to occur during winding. At the same time, due to the use of small tabs, there are gaps between the tabs, which will exacerbate the risk of misalignment. Therefore, it is necessary to strictly control the relationship between the thickness difference d and the number of winding layers n to avoid severe misalignment and insufficient subsequent electrical connection area.

[0042] In this embodiment, the width E of a single tab 221 can be 2mm, 3mm, 4mm, 5mm, 6mm, 8mm, or 9mm, etc.

[0043] In this embodiment, an opening is formed on one side of the housing 1 along the axial direction, and a cover plate 3 is placed over the opening of the housing 1. The cylindrical core 2 is disposed inside the housing 1. As a variation, the housing 1 can also have openings on both sides along the axial direction, and the cover plate 3 is placed over the opening of the housing 1.

[0044] The cylindrical core 2 includes an electrode 22, which can be specifically divided into a positive electrode and a negative electrode. The cylindrical core 2 is formed by stacking the positive electrode, the negative electrode, and the separator, and then winding them together.

[0045] After the cylindrical core 2 is wound, multiple tabs 221 are stacked to form a tab area 21, which is used to electrically connect with the terminal assembly 31 or the housing 1, thereby conducting the current of the cylindrical core 2 to the outside of the battery.

[0046] The pole assembly 31 includes a pole and an adapter plate 32. One side of the adapter plate 32 is fixedly connected to the pole, and the other side of the adapter plate 32 is connected to the tab region 21.

[0047] In this embodiment, the electrode sheet 22 includes multiple tabs 221. The electrode sheet 22 is wound to form a core, and each layer of the core includes multiple tabs 221. Multiple tabs 221 in the tab area 21 of the same core layer form a single-layer tab group 223. When the electrode sheet thickness is relatively uniform, after the cylindrical core 2 is wound, the gap between layers along the radial direction is consistent, and the alignment of adjacent single-layer tab groups 223 is good, which can effectively ensure the effective area of ​​the tab area 21, thereby ensuring the welding area between the tab area 21 and the pole. Conversely, when the electrode sheet thickness is uneven, that is, when the difference between the maximum thickness and the minimum thickness of the core body 222 is large, the alignment of adjacent single-layer tab groups 223 along the radial direction is poor. When the number of winding layers is relatively large, it will further aggravate the misalignment of the tabs, which will easily cause insufficient effective area of ​​the tab area 21, reduce the welding area between the tab area 21 and the pole, and easily cause insufficient current carrying capacity. By comprehensively controlling the relationship between the difference d between the maximum and minimum thickness of the core body 222 and the number of winding layers n of the cylindrical core 2, the alignment of the tabs in the radial direction of the cell can be guaranteed as much as possible, effectively reducing the occurrence of tab misalignment.

[0048] When d·n is too large, that is, the difference between the maximum and minimum thickness of the core body 222 is large, or the number of winding layers is large, or both exist, it is easy to cause poor alignment of the tabs in the radial direction of the cell, which reduces the welding area of ​​the tab area 21 and the pole, and easily causes insufficient current carrying capacity.

[0049] When d·n is too small, if the difference between the maximum and minimum thickness of the core body 222 is small, the requirements for production process control are strict, the process implementation is more difficult, and production costs are greatly increased. If the number of winding layers is small, it is easy to lead to low battery energy density.

[0050] Electrode 22 includes a positive electrode and a negative electrode; the positive electrode includes a positive current collector and a positive active material layer, and the negative electrode includes a negative current collector and a negative active material layer. The positive current collector is not particularly limited, as long as it is conductive and will not cause adverse chemical changes in the battery, and can be made of, for example, stainless steel, aluminum, nickel, titanium, sintered carbon, or aluminum or stainless steel surface-treated with one of carbon, nickel, titanium, silver, etc. The negative current collector can be made of copper, stainless steel, nickel, titanium, etc.; in a specific embodiment, the positive electrode can be made of aluminum, and the negative electrode can be made of copper.

[0051] Positive electrode active materials include positive electrode active materials, such as nickel-cobalt-manganese ternary materials, lithium iron phosphate materials, and lithium manganese iron phosphate materials; negative electrode active materials include negative electrode active materials, such as artificial graphite, natural graphite, and silicon-based materials.

[0052] After the active material is coated onto the current collector and formed on it through a rolling process, uneven thickness of the core body 222 may occur. To obtain the thickness of the core body 222 and thus determine its maximum and minimum thickness, the core body 222 can be flattened during measurement. Certain areas (X1, X2, and X3 as shown in Figure 5) are taken from the middle, first, and last sections of the core body 222. Multiple measurements are taken (as shown in Figure 5, the circles in X1, X2, and X3 represent random measurement points) to determine the maximum and minimum thicknesses within each area (as shown in Figure 6, the maximum thickness in X1 is d1, and the minimum thickness is d2). The minimum thickness is then subtracted from the maximum thickness to obtain the difference d between the maximum and minimum thicknesses of the core body 222. Specifically, in this embodiment, the areas of the middle, first, and last sections can be 2500 mm². 2 In the middle, mid-section, and tail sections, 50 measurement sites were randomly selected in each area.

[0053] In some embodiments, the number of tabs 221 on the same layer is multiple.

[0054] Multiple means two or more.

[0055] Since the cylindrical core 2 has multiple tabs 221 extending from the core body 222, slits are provided between adjacent tabs 221 to allow them to overlap after the cylindrical core 2 is wound, forming a tab area 21 and ensuring sufficient welding area. At the same time, gaps between the tabs can exacerbate the risk of mis-layering; therefore, the relationship between the thickness difference d and the number of winding layers n needs to be strictly controlled to avoid severe mis-layering.

[0056] In some embodiments, the difference d between the maximum thickness and the minimum thickness of the core body 222 satisfies: 0.002mm≤d≤0.012mm.

[0057] In this embodiment, the difference d between the maximum thickness and the minimum thickness of the core body 222 can be 0.002mm, 0.005mm, 0.008mm, 0.010mm, 0.011mm, or 0.012mm, etc.

[0058] By controlling the difference d between the maximum and minimum thickness of the core body 222, the uniformity of the gap between layers along the radial direction is better after the cylindrical core 2 is wound, thereby ensuring good alignment of the tabs, ensuring sufficient welding area for the tabs, and ensuring the current carrying capacity.

[0059] When the difference d between the maximum and minimum thickness of the core body 222 exceeds the upper limit, the thickness consistency of the core body 222 is poor. After winding, it is easy to increase the gap between the front and rear layers, which in turn leads to poor alignment of the tabs in the radial direction of the cell. This results in too much overlap between the tabs 221, reducing the effective area of ​​the tab area 21. In other words, the welding area of ​​the tab area 21 and the pole is reduced, which can easily lead to insufficient current carrying capacity.

[0060] When the difference d between the maximum and minimum thickness of the core body 222 exceeds the lower limit, the requirements for production process control are strict, the process implementation is more difficult, and the production cost is greatly increased.

[0061] In some embodiments, the dimension of the tab 221 in the radial direction is H, which satisfies: 240≤H / d≤5000.

[0062] The smaller the radial dimension H of the tab 221, the more stringent the accuracy requirements between misaligned layers. When the radial dimension H of the tab 221 is smaller, the current cross-sectional area is smaller, and the difference d needs to be smaller to ensure the consistency of the electrode thickness, thereby reducing the risk of subsequent misalignment and avoiding insufficient current.

[0063] In some embodiments, the tab 221 includes a positive tab and a negative tab, which are located on the same side of the core body 222 along the axial direction; one of the positive tab and the negative tab is electrically connected to the pole assembly 31, and the other is electrically connected to the housing 1, and satisfies: 0.12≤d·n≤0.8.

[0064] The positive and negative electrodes are located on the same side of the winding core body 222 along the axial direction. With the positive and negative electrodes exiting from the same side, the pole and housing 1 serve as output electrodes, respectively, and are electrically connected to the positive and negative electrodes. This results in a shorter current path and lower impedance for subsequent electrical connections. Conversely, if the positive and negative electrodes exit from opposite sides, the current path of one electrode must pass through the housing, resulting in a longer current path and higher impedance.

[0065] Since the positive and negative electrodes are located on the same side of the core body 222 along the axial direction, the positive and negative electrodes need to share the area of ​​the same end face of the core body 222, which reduces the area of ​​each electrode that can be set. Therefore, the range of d·n can be further selected as 0.12≤d·n≤0.8 to further ensure the alignment of the electrodes, ensure that the electrodes have sufficient welding area in the future, and ensure the current carrying capacity.

[0066] In some embodiments, the diameter of the cylindrical core 2 is D, which satisfies: 40mm≤D≤56mm.

[0067] When the positive and negative electrodes are located on the same side of the core body 222 along the axial direction, the misalignment of the electrodes will exacerbate the insufficient current carrying capacity of the positive and negative electrodes. Therefore, the diameter of the cylindrical core 2 needs to be set larger to increase the area of ​​the setting area of ​​the positive and negative electrodes, thereby ensuring the current carrying capacity.

[0068] In this embodiment, the diameter D of the cylindrical core 2 can be 40mm, 42mm, 45mm, 47mm, 49mm, 50mm, 52mm, or 56mm, etc.

[0069] In some embodiments, the radial dimension of the tab 221 is H, and the diameter of the cylindrical core 2 is D, satisfying: 0.05≤H / D≤0.25.

[0070] It should be noted that when measuring the radial dimension H of the tab 221, it can be the distance from the end of the tab 221 closest to the core body 222 to the end furthest from the core body 222 along the width direction of the core after the cylindrical core 2 is unfolded.

[0071] When the positive and negative tabs are on the same side, they share the same cell end face, resulting in relatively small current-carrying areas for each. Therefore, the H / D range needs to be controlled. H / D cannot be too small, as this requires more tab layers, increasing the risk of subsequent layer misalignment. Conversely, H / D cannot be too large, as this increases the radial tab size, increasing the risk of tab folding during winding. Furthermore, because the positive and negative tabs are on the same side, excessively long radial tabs can cause the innermost positive and negative tabs closest to the center of the core to overlap, posing a short-circuit risk. Further explanation regarding overlap between the positive and negative tabs: Since the tabs are initially vertical, they are later flattened and folded back onto the end face. Excessively long tabs increase the risk of overlap between the innermost positive and negative tabs.

[0072] In some embodiments, the tab 221 is rectangular in shape, satisfying: 0.002mm≤d≤0.008mm;

[0073] Alternatively, the shape of the tab 221 is trapezoidal, satisfying: 0.002mm≤d≤0.01mm.

[0074] When the shape of the tab 221 is rectangular, the gap between the tabs in the same layer is larger, which increases the probability of subsequent displacement deviation. Therefore, the range of d needs to be smaller.

[0075] When the shape of the tab 221 is trapezoidal, the gap between the tabs in the same layer is smaller, which reduces the probability of subsequent displacement deviation. Therefore, the range of d can be slightly larger.

[0076] In some embodiments, multiple tabs 221 are stacked to form a tab region 21. Along the radial direction, the tab region 21 is constructed in a fan shape, satisfying: 0.003mm≤d≤0.012mm.

[0077] The tab region 21 is fan-shaped, which can be easily matched with the shape of the battery cell. By stacking multiple tabs 221 to form the tab region 21, the risk of tab misalignment can be reduced, and the allowable range of d can be larger.

[0078] Furthermore, in this embodiment, the range of d can be selected as: 0.003mm≤d≤0.0085mm.

[0079] Furthermore, in this embodiment, the range of d can be selected as: 0.0035mm≤d≤0.011mm.

[0080] In some other embodiments, the tab 221 includes a positive tab and a negative tab, which are located on both sides of the core body 222 along the axial direction; the dimension of the tab 221 in the radial direction is H, and the diameter of the cylindrical core 2 is D, satisfying: 0.03≤H / D≤0.2.

[0081] In this embodiment, the positive and negative tabs are located on opposite sides of the core body 222 along the axial direction; that is, the positive and negative tabs are located on opposite sides, so that the positive and negative tabs do not need to share the area of ​​the same end face of the core body 222. This ensures that the area of ​​the positive and negative tabs is increased, and the H / D ratio can be set relatively small to reduce the overlap of tabs between adjacent layers and avoid the tab area becoming too thick after the tabs are folded. During the cell processing, the tabs are first cut out on the electrode sheet. The tabs are initially upright and then folded back. If H is too large, the overlap of the tabs after folding will be large, resulting in an increase in the thickness of the tabs in the battery assembly. In addition, it will also increase the risk of tab folding during the winding process.

[0082] In some embodiments, the tab 221 is rectangular in shape, satisfying: 0.003mm≤d≤0.0085mm;

[0083] Alternatively, the shape of the tab 221 is trapezoidal, satisfying: 0.0035mm≤d≤0.011mm.

[0084] Since positive and negative tabs can be set on different end faces of the cell, the positive and negative electrode areas can be set larger. Therefore, in the scheme where the positive and negative tabs are on opposite sides, compared with the scheme where the positive and negative tabs are on the same side, the difference d between the maximum and minimum thickness of the core body 222 can be appropriately increased to reduce the limitations on the process conditions during electrode processing and improve production efficiency.

[0085] In some embodiments, the difference between the number of outermost tabs 221 and the number of innermost tabs 221 in the radial direction is m, which satisfies: m is greater than or equal to 3; and satisfies: 0.002mm≤d≤0.01mm.

[0086] Due to the thickness difference d, misalignment may occur between the tabs of different winding layers after winding. When m is relatively small, such as when m is 1 or 2, the risk of overall misalignment of the tabs after winding is relatively small. However, when the difference m between the number of tabs 221 in the outermost layer and the number of tabs 221 in the innermost layer is large, such as when m is greater than or equal to 3, the risk of overall misalignment is easily increased after winding, which may lead to a larger circumferential distance between the outermost and innermost tabs. Since the welding of the tabs and the pole assembly mainly relies on the middle area to be welded together, when the risk of misalignment increases, the effective welding area is reduced, affecting the current flow. Therefore, it is necessary to more precisely control the value range of d to reduce the further increase in the risk of misalignment.

[0087] Additionally, the difference between the number of outermost tabs 221 and the number of innermost tabs 221 is m, which also satisfies that m is less than or equal to 8.

[0088] By limiting the upper limit of m, it is possible to avoid having too many layers, which would require overly strict limits on the thickness difference of the electrode sheets, resulting in overly stringent electrode processing conditions.

[0089] In some embodiments, as shown in FIG3, the angle between the lines connecting the outermost tab 221 and the innermost tab 221 to the axis of the cylindrical core 2 in the radial direction is A, which satisfies: 0°<A≤18°.

[0090] It should be noted that, along the radial direction, the outermost tab and the innermost tab refer to the outermost edge of the outermost layer and the innermost edge of the innermost layer, respectively.

[0091] By limiting the angle between the lines connecting the outermost and innermost tabs to the axis of the cylindrical core 2, the tab misalignment distance is controlled within a certain range, thus avoiding subsequent impact on the tab flow area.

[0092] In some embodiments, the thickness of the core body 222 is C, which satisfies: C≥0.080mm; and satisfies: 0.12≤d·n≤0.8.

[0093] When the thickness C of the core body 222 is greater than 0.080 mm, the thickness of the core body 222 is relatively large. After the cylindrical core 2 is wound, the gap between the layers along the radial direction is relatively large, which increases the risk of misalignment of the tabs. The alignment of adjacent single-layer tab groups 223 along the radial direction is poor. Therefore, the value of d·n needs to be smaller.

[0094] In addition, when the thickness is relatively large, it is more difficult to control the thickness consistency of the electrode sheet during the rolling process.

[0095] In some embodiments, the cylindrical core 2 includes a thinning region 224, and the difference between the maximum thickness and the minimum thickness of the cylindrical core 2 in the thinning region 224 is F, which satisfies: 8μm≤F≤60μm.

[0096] As shown in Figure 6, the thinned region 224 refers to certain areas in the coating of the electrode 22, where the coated material is thinner than in other areas, forming a gradient distribution structure. The thickness of the thinned region is one of the important parameters affecting battery performance. First, thinning the electrode can reduce the battery's internal resistance, improving its discharge performance and charging speed. Second, appropriate thinning can increase the specific surface area of ​​the positive electrode, which is beneficial for increasing the contact area between the electrode material and the electrolyte, thereby improving the battery's energy density and cycle life. However, excessively thinned regions can also lead to a decrease in the mechanical strength of the electrode, increasing the battery's safety risks.

[0097] Because the thinning zone is closer to the root of the tab, the tab will undergo a reverse folding process starting from the position near the root. If the thickness difference in the thinning zone is relatively large, it will increase the risk of misalignment of the tabs between different layers. When the difference F between the maximum and minimum thickness of the core body 222 in the thinning zone exceeds the upper limit, the thickness consistency of the core body 222 in the thinning zone is poor, which will cause some tabs and the preceding tabs to not be distributed radially, thereby increasing the degree of tab misalignment and reducing the effective area of ​​the tab area 21. That is, the welding area of ​​the subsequent tab area 21 and the pole is reduced, which can easily lead to insufficient current carrying capacity.

[0098] When the difference F between the maximum and minimum thickness of the core body 222 in the thinning zone exceeds the lower limit, the requirements for production process control conditions are strict, the process implementation is more difficult, and the production cost is greatly increased.

[0099] In some embodiments, the number of winding layers n of the cylindrical core 2 satisfies: n≤200.

[0100] When the number of winding layers n of the cylindrical core 2 exceeds the upper limit, the excessive number of winding layers in the cylindrical core 2 will further exacerbate the misalignment of the tabs due to the accumulation of errors. This can easily lead to insufficient effective area of ​​the tab region 21, reducing the welding area between the tab region 21 and the terminal post, and resulting in insufficient current carrying capacity. When the number of winding layers n of the cylindrical core 2 exceeds the lower limit, it can easily lead to low battery energy density.

[0101] In some embodiments, as shown in FIG3, the cylindrical core 2 includes a positive electrode sheet and a negative electrode sheet. After the cylindrical core 2 is wound, multiple tabs 221 of the positive electrode sheet are stacked to form a positive electrode tab region, and multiple tabs 221 of the negative electrode sheet are stacked to form a negative electrode tab region. The positive electrode tab region and the negative electrode tab region are located on the same side of the cylindrical core 2 along the axial direction, and the positive electrode tab region and the negative electrode tab region are spaced apart from each other.

[0102] Obviously, the above embodiments are merely examples for clear illustration and are not intended to limit the implementation. Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and all such modifications and variations fall within the scope defined by this application.

Claims

1. A battery, characterized in that, include: A housing (1), on which a pole assembly (31) is provided; A cylindrical core (2) includes a core body (222) and a plurality of tabs (221); the tabs (221) are used to electrically connect with the pole assembly (31) or the housing (1); the plurality of tabs (221) are distributed in multiple layers along the radial direction of the core body (222); When the cylindrical core (2) is in the unfolded state, the width of a single tab (221) along the length direction of the cylindrical core (2) is E, which satisfies: 2mm≤E≤9mm; The difference between the maximum and minimum thickness of the core body (222) is d, where d is in mm. The number of winding layers of the core body (222) is n, which satisfies: 0.08≤d·n≤0.

9.

2. The battery according to claim 1, characterized in that, The number of the tabs (221) on the same layer is multiple.

3. The battery according to claim 1 or 2, characterized in that, The difference d between the maximum and minimum thickness of the core body (222) satisfies: 0.002mm≤d≤0.012mm.

4. The battery according to any one of claims 1 to 3, characterized in that, The radial dimension of the electrode tab (221) is H, which satisfies: 240≤H / d≤5000, and the unit of dimension H is mm.

5. The battery according to any one of claims 1 to 4, characterized in that, The tab (221) includes a positive tab and a negative tab, which are located on the same side of the core body (222) along the axial direction; one of the positive tab and the negative tab is electrically connected to the pole assembly (31), and the other is electrically connected to the housing (1), and satisfies: 0.12≤d·n≤0.

8.

6. The battery according to claim 5, characterized in that, The diameter of the cylindrical core (2) is D, which satisfies: 40mm≤D≤56mm, where the unit of diameter D is mm.

7. The battery according to claim 5, characterized in that, The radial dimension of the tab (221) is H, and the diameter of the cylindrical core (2) is D, satisfying: 0.05≤H / D≤0.

25.

8. The battery according to claim 5, characterized in that, The electrode tab (221) is rectangular in shape, satisfying: 0.002mm≤d≤0.008mm; Alternatively, the shape of the tab (221) is trapezoidal, satisfying: 0.002mm≤d≤0.01mm.

9. The battery according to any one of claims 1 to 8, characterized in that, Multiple tabs (221) are stacked to form a tab region (21). Along the radial direction, the tab region (21) is constructed in a fan shape, satisfying: 0.003mm≤d≤0.012mm.

10. The battery according to any one of claims 1 to 9, characterized in that, The electrode tab (221) includes a positive electrode tab and a negative electrode tab, which are located on both sides of the core body (222) along the axial direction. The dimension of the electrode tab (221) in the radial direction is H, and the diameter of the cylindrical core (2) is D, satisfying: 0.03≤H / D≤0.2, where the unit of diameter D is mm.

11. The battery according to claim 10, characterized in that, The electrode tab (221) is rectangular in shape, satisfying: 0.003mm≤d≤0.0085mm, where d is in mm; Alternatively, the shape of the tab (221) is trapezoidal, satisfying: 0.0035mm≤d≤0.011mm.

12. The battery according to any one of claims 1 to 11, characterized in that, Along the radial direction, the difference between the number of the outermost tabs (221) and the number of the innermost tabs (221) is m, which satisfies: m is greater than or equal to 3; and satisfies: 0.002mm≤d≤0.01mm.

13. The battery according to any one of claims 1 to 12, characterized in that, Along the radial direction, the angle between the line connecting the outermost tab (221) and the innermost tab (221) to the axis of the cylindrical core (2) is A, which satisfies: 0°<A≤18°.

14. The battery according to any one of claims 1 to 13, characterized in that, The thickness of the core body (222) is C, which satisfies: C≥0.080mm; and satisfies: 0.12≤d·n≤0.

8.

15. The battery according to any one of claims 1 to 14, characterized in that, The cylindrical core (2) includes a thinning zone, and the difference between the maximum and minimum thickness of the cylindrical core (2) in the thinning zone is F, which satisfies: 8μm≤F≤60μm.

16. The battery according to claim 12, characterized in that, m is less than or equal to 8.

17. The battery according to claim 15, characterized in that, The thinning area refers to the area coated on the electrode (22), and the thickness of the thinning area is less than the thickness of other areas in the coating area.

18. The battery according to claim 15, characterized in that, The thinned area is closer to the root of the tab.

19. The battery according to any one of claims 1 to 18, characterized in that, A slit or gap is provided between adjacent electrodes in the plurality of electrodes (221).

20. The battery according to any one of claims 1 to 19, characterized in that, The number of winding layers n of the cylindrical core (2) satisfies: n≤200.

21. The battery according to any one of claims 1 to 20, characterized in that, The pole assembly (31) includes a pole and an adapter plate (32). One side of the adapter plate (32) is fixedly connected to the pole, and the other side of the adapter plate (32) is connected to the tab region (21).

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