Battery

Abstract

The present invention relates to the technical field of batteries, and discloses a battery, which comprises: a shell, which comprises a pole assembly; the cylindrical roll core comprises a roll core body and a plurality of tabs led out from the roll core body; the tab is used for being electrically connected with a pole assembly or a shell; the plurality of tabs are distributed in multiple layers in the radial direction of the roll core body; the width E of a single tab is greater than or equal to 2mm and less than or equal to 9mm; the difference value between the maximum thickness and the minimum thickness of the roll core body is d, the number of winding layers of the roll core body is n, and d * n is larger than or equal to 0.08 and smaller than or equal to 0.9. According to the battery provided by the invention, by comprehensively controlling the relationship between the difference value d of the maximum thickness and the minimum thickness of the roll core body and the number n of winding layers of the battery core, the tab alignment degree in the radial direction of the battery core can be ensured as much as possible, the tab dislocation condition is effectively reduced, the gap between the front layer and the rear layer after winding is relatively uniform, and the effective welding area is ensured; and the overcurrent capability is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a battery. Background Art

[0002] In the related art, the battery cell is often electrically connected to the pole via the pole tab or via an adapter. Taking the direct electrical connection between the pole tab and the pole as an example, during the preparation of the battery cell, multiple pole tabs are cut from the edge of one end of the pole sheet, and after the pole sheet is wound, the pole tabs at the corresponding positions are flattened to facilitate electrical connection with the pole.

[0003] However, since the pole piece includes a current collector and an active material layer, after the active material is coated on the current collector, it is formed on the current collector through a rolling process, there will be a phenomenon of uneven thickness of the pole piece, which will cause the gap between the front and rear layers to increase after winding, and then cause poor alignment of the pole ears in the radial direction of the battery cell, which will cause the subsequent welding area of ​​the pole ears and the poles to be reduced, resulting in insufficient current capacity. Summary of the invention

[0004] In view of this, the present invention provides a battery to solve the problem of insufficient current capacity caused by poor alignment of the tabs in the radial direction of the battery cell.

[0005] The present invention provides a battery, comprising:

[0006] A shell body, on which a pole assembly is arranged;

[0007] A cylindrical winding core, the cylindrical winding core comprises a winding core body and a plurality of pole ears; the pole ears are used to be electrically connected to the pole assembly or the housing; the plurality of pole ears are distributed in multiple layers along the radial direction of the winding core body;

[0008] When the cylindrical winding core is in the unfolded state, the width of a single pole ear along the length direction of the cylindrical winding core is E, which satisfies: 2mm≤E≤9mm;

[0009] The difference between the maximum thickness and the minimum thickness of the core body is d, and the number of winding layers of the core body is n, which satisfies: 0.08≤d·n≤0.9.

[0010] Beneficial effects:

[0011] The battery provided by the embodiment of the present invention achieves good alignment of the pole ears by controlling the relationship between the number of winding layers and the thickness difference of the winding core body, ensuring that the pole ears have sufficient welding area in the future and ensuring the current capacity. In addition, by limiting the value range of the width E of a single pole ear to 2mm≤E≤9mm; each pole ear is a small pole ear with a smaller width. Since the cylindrical winding core has multiple pole ears extending from the winding core body, slits are set between adjacent pole ears so that after the cylindrical winding core is wound, multiple pole ears can overlap each other to form a pole ear area to ensure sufficient welding area. If a single large pole ear is used, the pole ear is prone to wrinkles or even folds during the winding process of the cylindrical core, which is not conducive to ensuring the welding area. Therefore, the large pole ear is cut into multiple small pole ears by setting a slit to avoid wrinkles during the winding process. However, due to the difference in electrode thickness, the pole ears are prone to misalignment during winding. At the same time, due to the use of small pole ears, there are gaps between adjacent single pole ears in the circumferential direction of the cylindrical winding core, which will increase 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 serious misalignment and cause insufficient subsequent electrical connection area. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0013] Figure 1 is a schematic diagram of a battery of the present invention;

[0014] Figure 2 is an exploded schematic diagram of the battery of the present invention;

[0015] Figure 3 It is a schematic diagram of a top view of a cylindrical winding core of the present invention;

[0016] Figure 4 It is a schematic diagram of the pole piece of the present invention in an unfolded state;

[0017] Figure 5 It is a schematic diagram of multi-point measurement when the pole piece of the present invention is in an unfolded state;

[0018] Figure 6 for Figure 5 Schematic diagram of the AA section;

[0019] Figure 7 It is a schematic diagram of another type of pole ear in the unfolded state of the pole piece of the present invention.

[0020] Description of reference numerals:

[0021] 1. Shell; 2. Cylindrical winding core; 21. Pole ear area; 22. Pole piece; 221. Pole ear; 222. Winding core body; 223. Single-layer pole ear group; 224. Thinning area; 3. Cover plate; 31. Pole column assembly; 32. Adapter. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0023] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention 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 cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0024] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0026] In the related art, the battery cell is often electrically connected to the pole via the pole tab or via an adapter. Taking the direct electrical connection between the pole tab and the pole as an example, during the preparation of the battery cell, multiple pole tabs are cut from the edge of one end of the pole sheet, and after the pole sheet is wound, the pole tabs at the corresponding positions are flattened so that the pole tabs overlap with each other to form a pole tab welding area, which is convenient for welding connection with the pole column.

[0027] If each pole lug is in an ideal uniform distribution state after the pole sheet is wound, the area of ​​the pole lug welding zone can be effectively guaranteed. However, since the pole sheet includes a current collector and an active material layer, after the active material is coated on the current collector, it is formed on the current collector through a rolling process. There will be a phenomenon of uneven pole sheet thickness, which will cause the gap between the front and rear layers to increase after winding, and then lead to poor alignment of the pole lugs in the radial direction of the battery cell, resulting in excessive overlap between the pole lugs, and a reduction in the effective area of ​​the pole lug welding zone, that is, a reduction in the subsequent welding area of ​​the pole lug and the pole column, which can easily lead to insufficient current capacity.

[0028] The battery provided by the embodiment of the present invention achieves better alignment of the tabs by controlling the relationship between the number of winding layers and the thickness difference of the winding core body 222, thereby ensuring that the tabs have sufficient welding area in the future and ensuring the current carrying capacity.

[0029] Combine the following Figures 1 to 7 , describing an embodiment of the present invention.

[0030] According to an embodiment of the present invention, there is provided a battery, comprising:

[0031] A housing 1, on which a pole assembly 31 is arranged;

[0032] The cylindrical winding core 2 includes a winding core body 222 and a plurality of pole ears 221; the pole ears 221 are used to be electrically connected to the pole assembly 31 or the housing 1; the plurality of pole ears 221 are distributed in multiple layers along the radial direction of the winding core body 222;

[0033] When the cylindrical winding core 2 is in the unfolded state, along the length direction of the cylindrical winding core 2, the width of a single pole ear 221 is E, which satisfies: 2mm≤E≤9mm;

[0034] The difference between the maximum thickness and the minimum thickness of the core body 222 is d, and the number of winding layers of the core body 222 is n, which satisfies: 0.08≤d·n≤0.9.

[0035] The cylindrical core 2 has a cylindrical structure, and the shell 1 is sleeved on the outside of the cylindrical core 2. In this embodiment, the structure of the shell 1 is not limited, and it can be a cylindrical or hexagonal shape, as long as the cylindrical core 2 can be placed in the shell 1 and the cylindrical core 2 can be restrained.

[0036] The housing 1 includes a pole assembly 31 , which is used to be electrically connected to other structures later, such as a busbar, so as to output current.

[0037] The housing 1 comprises a housing body and a cover plate 3 . The pole assembly 31 can be arranged on the housing body or on the cover plate 3 .

[0038] The winding core body 222 is formed by winding the pole piece. In this embodiment, the winding core body 222 specifically refers to: when in an unfolded state, the area outside the thinned area 224 is removed along the width direction of the pole piece.

[0039] The width of a single pole lug 221 refers to the width of a single pole lug 221 along the length direction of the cylindrical winding core 2 when the cylindrical winding core 2 is in an unfolded state. When measuring, the winding core body 222 can be flattened, and the size of the pole lug 221 measured along the length direction of the pole piece is the width of the pole lug 221.

[0040] The structure of a single pole ear 221 can be various, for example, it can be a rectangle (for example Figure 4 As shown), it can also be a trapezoid (for example Figure 7 ), or a special shape thereof.

[0041] Among them, since there are many structural forms of a single pole ear 221, there are differences in the measurement methods of the width E of a single pole ear 221: when a single pole ear 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 a single pole ear 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.

[0042] The battery provided by the embodiment of the present invention achieves good alignment of the pole lugs by controlling the relationship between the number of winding layers and the thickness difference of the winding core body 222, ensuring that the pole lugs have sufficient welding area in the future and ensuring the current capacity. In addition, by limiting the value range of the width E of a single pole lug 221 to 2mm≤E≤9mm; each pole lug 221 is a small pole lug with a smaller width. Since the cylindrical winding core 2 leads to multiple pole lugs 221 from the winding core body 222, slits are set between adjacent pole lugs 221, so that after the cylindrical winding core 2 is wound, multiple pole lugs 221 can be overlapped with each other to form a pole lug area 21, ensuring sufficient welding area. If a single large pole lug is used, the pole lug is prone to wrinkles or even folds during the winding process of the cylindrical winding core 2, which is not conducive to ensuring the welding area. Therefore, the large pole lug is cut into multiple small pole lugs by setting a slit to avoid wrinkles during the winding process. However, due to the difference in electrode thickness, the pole ears are prone to misalignment during winding. At the same time, due to the use of small pole ears, there are gaps between the pole ears, which will increase 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 serious misalignment and cause insufficient subsequent electrical connection area.

[0043] In this embodiment, the width E of a single pole ear 221 may be 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 8 mm, 9 mm, etc.

[0044] In this embodiment, the shell 1 has an opening formed on one side along the axial direction, the cover plate 3 is disposed on the opening of the shell 1, and the cylindrical winding core 2 is disposed in the shell 1. As a variation, the shell 1 may also have openings formed on both sides along the axial direction, and the cover plate 3 is disposed on the opening of the shell 1.

[0045] The cylindrical winding core 2 includes a pole piece 22 , which can be specifically divided into a positive pole piece and a negative pole piece. The cylindrical winding core 2 is formed by stacking the positive pole piece, the negative pole piece and the separator, and then winding them.

[0046] After the cylindrical core 2 is wound, a plurality of tabs 221 are stacked to form a tab area 21 , which is used to be electrically connected to the pole assembly 31 or the shell 1 , thereby conducting the current of the cylindrical core 2 to the outside of the battery.

[0047] 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 pole lug area 21 .

[0048] In this embodiment, the pole piece 22 includes a plurality of pole tabs 221, and the pole piece 22 is wound to form a winding core. Each layer of the winding core includes a plurality of pole tabs 221. The plurality of pole tabs 221 located in the pole tab area 21 of the same layer of the winding core form a single-layer pole tab group 223. When the thickness consistency of the pole piece is good, after the cylindrical winding core 2 is wound, the gaps between the layers along the radial direction are consistent, and the adjacent single-layer pole tab groups 223 are well aligned, which can effectively ensure the effective area of ​​the pole tab area 21, and further ensure the welding area of ​​the pole tab area 21 and the pole column. On the contrary, when the thickness of the pole piece is uneven, that is, when the difference between the maximum thickness and the minimum thickness of the winding core body 222 is large, the alignment of the radially adjacent single-layer pole tab groups 223 is poor. When the number of winding layers is relatively large, the staggered layers of the pole tabs will be further aggravated, which will easily cause the effective area of ​​the pole tab area 21 to be insufficient, reduce the welding area of ​​the pole tab area 21 and the pole column, and easily cause insufficient current capacity. By comprehensively controlling the difference d between the maximum thickness and the minimum thickness of the core body 222 and the relationship with the number of winding layers n of the cylindrical core 2, the alignment of the tabs in the radial direction of the battery cell can be ensured as much as possible, effectively reducing the occurrence of tab misalignment.

[0049] When d·n is too large, that is, the difference between the maximum thickness and the minimum thickness of the winding 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 pole ears in the radial direction of the battery cell, which reduces the welding area of ​​the pole ear area 21 and the pole, and easily causes insufficient current capacity.

[0050] When d·n is too small, if the difference between the maximum thickness and the minimum thickness of the winding core body 222 is small, the production process control conditions are strictly required, the process is difficult to implement, and the production cost is greatly increased. If the number of winding layers is small, it is easy to cause low battery energy density.

[0051] The electrode sheet 22 includes a positive electrode sheet and a negative electrode sheet; the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, and the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. There is no particular limitation on the positive electrode current collector, as long as it has conductivity and does not cause adverse chemical changes in the battery, and can use, for example: stainless steel, aluminum, nickel, titanium, fired carbon, or aluminum or stainless steel that has been surface-treated with one of carbon, nickel, titanium, silver, etc. The negative electrode 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.

[0052] The positive electrode active substance includes positive electrode active materials, which include nickel-cobalt-manganese ternary materials, lithium iron phosphate materials, lithium manganese iron phosphate materials, etc.; the negative electrode active substance includes negative electrode active materials, which include artificial graphite, natural graphite, silicon-based materials, etc.

[0053] After the active material is coated on the current collector, it is formed on the current collector through a rolling process, and there will be a phenomenon that the thickness of the core body 222 is uneven. In order to obtain the thickness of the core body 222, so as to obtain the maximum thickness and minimum thickness of the core body 222, in the specific measurement process, the core body 222 can be flattened and a certain area of ​​the middle area, the first section area, and the tail section area can be taken (such as Figure 5 The X1 area, X2 area, and X3 area shown in the figure are measured several times (such as Figure 5 As shown in the figure, the circles in the X1 area, X2 area, and X3 area represent random measurement points), and the maximum thickness and minimum thickness of each of these areas are determined (such as Figure 6 As shown, the maximum thickness in the X1 region is d1 and the minimum thickness is d2); then the maximum thickness in these regions is subtracted from the minimum thickness to obtain the difference d between the maximum thickness and the minimum thickness of the core body 222. Specifically, in this embodiment, the area of ​​the middle region, the first section region, and the last section region can be 2500mm 2 ; 50 measurement sites were randomly selected in the middle area, midsection area, and tail area.

[0054] In some embodiments, there are multiple tabs 221 on the same layer.

[0055] Multiple means greater than or equal to two.

[0056] Since the cylindrical winding core 2 has multiple tabs 221 extending from the winding core body 222, slits are provided between adjacent tabs 221 so that after the cylindrical winding core 2 is wound, multiple tabs 221 can be overlapped to form a tab area 21, ensuring sufficient welding area. At the same time, since there are gaps between the tabs, the risk of misalignment will be aggravated, so the relationship between the thickness difference d and the number of winding layers n needs to be strictly controlled to avoid serious misalignment.

[0057] In some embodiments, the difference d between the maximum thickness and the minimum thickness of the core body 222 satisfies: 0.002 mm ≤ d ≤ 0.012 mm.

[0058] In this embodiment, the difference d between the maximum thickness and the minimum thickness of the core body 222 may be 0.002 mm, 0.005 mm, 0.008 mm, 0.010 mm, 0.011 mm, 0.012 mm, etc.

[0059] By controlling the difference d between the maximum thickness and the minimum thickness of the core body 222, after the cylindrical core 2 is wound, the gap between the radial layers is uniform, thereby ensuring good alignment of the tabs, ensuring that the tabs have sufficient welding area in the future, and ensuring the current capacity.

[0060] When the difference d between the maximum thickness and the minimum thickness of the core body 222 exceeds the upper limit, the thickness consistency of the core body 222 is poor, which may easily cause an increase in the gap between the front and rear layers after winding, and further lead to poor alignment of the pole ears in the radial direction of the battery cell, resulting in excessive overlapping areas between the pole ears 221, and reducing the effective area of ​​the pole ear area 21, that is, the subsequent welding area between the pole ear area 21 and the pole is reduced, which may easily lead to insufficient current capacity.

[0061] When the difference d between the maximum thickness and the minimum thickness of the core body 222 exceeds the lower limit, strict control conditions are imposed on the production process, the process is difficult to implement, and the production cost is greatly increased.

[0062] In some embodiments, the dimension of the tab 221 along the radial direction is H, which satisfies: 240≤H / d≤5000.

[0063] The smaller the dimension H of the pole ear 221 along the radial direction, the more stringent the precision requirement between the staggered layers. When the dimension H of the pole ear 221 along the radial direction is smaller, the flow cross-sectional area is smaller. At this time, the difference d needs to be smaller to ensure the consistency of the pole piece thickness, thereby reducing the risk of subsequent staggered layers and avoiding insufficient flow.

[0064] In some embodiments, the tab 221 includes a positive tab and a negative tab, and the positive tab and the negative tab are located on the same side of the winding 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 shell 1, and satisfies: 0.12≤d·n≤0.8.

[0065] The positive electrode tab and the negative electrode tab are located on the same side of the winding core body 222 along the axial direction. The positive and negative electrode tabs are output from the same side, so that the pole and the shell 1 are used as output poles respectively, and are electrically connected to the positive and negative electrode tabs respectively, so that the current path of the subsequent electrical connection is shorter and the impedance is lower. When the positive and negative electrode tabs are output from different sides, the current path of one side of the tab needs to pass through the shell, the current path is longer, and the impedance is larger.

[0066] Since the positive electrode tab and the negative electrode tab are located on the same side of the winding core body 222 along the axial direction, the positive electrode tab and the negative electrode tab need to jointly occupy the area of ​​the same side end surface of the winding core body 222, resulting in a smaller area for each tab to be set. Therefore, the range of d·n is further preferably 0.12≤d·n≤0.8, so as to further ensure the alignment of the tabs, ensure that the tabs have sufficient welding area in the future, and ensure the current capacity.

[0067] In some embodiments, the diameter of the cylindrical winding core 2 is D, satisfying: 40 mm ≤ D ≤ 56 mm.

[0068] When the positive electrode tab and the negative electrode tab are located on the same side of the winding core body 222 along the axial direction, the tab staggered layers will aggravate the insufficient current carrying capacity of the positive and negative electrodes. Therefore, the diameter of the cylindrical winding core 2 needs to be set larger to increase the setting area of ​​the positive and negative tabs, thereby ensuring the current carrying capacity.

[0069] In this embodiment, the diameter D of the cylindrical winding core 2 can be 40 mm, 42 mm, 45 mm, 47 mm, 49 mm, 50 mm, 52 mm, 56 mm, etc.

[0070] In some embodiments, the dimension of the tab 221 along the radial direction is H, and the diameter of the cylindrical winding core 2 is D, which satisfies: 0.05≤H / D≤0.25.

[0071] It should be noted that when measuring the radial dimension H of the tab 221 , it can be the distance from one end of the tab 221 close to the core body 222 to the other end away from the core body 222 along the width direction of the core after the cylindrical core 2 is unfolded.

[0072] When the positive and negative pole ears are on the same side, the positive and negative ears share the same battery cell end face, and their respective flow areas are relatively small; therefore, the range of H / D needs to be controlled; H / D cannot be too small, otherwise, more ear layers will need to be set, which will increase the risk of subsequent misalignment; in addition, H / D cannot be too large, otherwise it will cause the ear size to increase in the radial direction, and the risk of ear folding during winding will increase. In addition, since the positive and negative ears are on the same side, the ears are too long in the radial direction, and the positive and negative ears in the inner layer closest to the middle of the winding core are prone to overlap, posing a risk of short circuit. Further explanation of the overlap between the positive and negative ears: Because the ears are vertical at first, they will be flattened and folded back onto the end face later. If the ears are too long, the risk of the innermost positive and negative ears overlapping increases.

[0073] In some embodiments, the shape of the tab 221 is rectangular, satisfying: 0.002 mm ≤ d ≤ 0.008 mm;

[0074] Alternatively, the shape of the tab 221 is a trapezoid, satisfying: 0.002 mm ≤ d ≤ 0.01 mm.

[0075] When the shape of the pole lug 221 is rectangular, in the same layer, the gap between the pole lugs is larger, and the probability of subsequent displacement deviation will be greater, so the range of d needs to be smaller.

[0076] When the shape of the tab 221 is a trapezoid, in the same layer, the gap between the tabs is smaller, and the probability of subsequent displacement deviation will be smaller, so the range d can be slightly larger.

[0077] In some embodiments, a plurality of tabs 221 are stacked to form a tab region 21 . Along the radial direction, the tab region 21 is configured in a fan shape, satisfying: 0.003 mm≤d≤0.012 mm.

[0078] The tab area 21 is constructed in a fan shape, which can be easily matched with the shape of the battery cell. By stacking multiple tabs 221 to form the tab area 21, the risk of tab misalignment can be reduced and the allowable range of d can be larger.

[0079] Further, in this embodiment, the range of d can preferably be: 0.003mm≤d≤0.0085mm.

[0080] Further, in this embodiment, the range of d can preferably be: 0.0035 mm≤d≤0.011 mm.

[0081] In some other embodiments, the tab 221 includes a positive tab and a negative tab, and the positive tab and the negative tab are respectively located on both sides of the core body 222 along the axial direction; the dimension of the tab 221 along the radial direction is H, and the diameter of the cylindrical core 2 is D, satisfying: 0.03≤H / D≤0.2.

[0082] In this embodiment, the positive electrode tab and the negative electrode tab are respectively located on both sides of the winding core body 222 along the axial direction; that is, the positive and negative electrode tabs are on different sides, so that the positive electrode tab and the negative electrode tab do not need to occupy the area of ​​the same side end surface of the winding core body 222 together, ensuring that the area of ​​the positive electrode tab and the negative electrode tab is increased, and H / D can be set relatively small to reduce the overlapping size of the tabs between adjacent layers, and avoid the tab area being too thick after the tabs are folded. Because the tabs are first cut out on the pole piece during the battery cell processing, the tabs are first upright, and then the tabs will be folded back. If H is too large, the tabs will overlap a large size after folding, resulting in an increase in the thickness of the tabs of the battery assembly. In addition, the risk of tab folding will also increase when the tabs are wound.

[0083] In some embodiments, the shape of the tab 221 is rectangular, satisfying: 0.003 mm ≤ d ≤ 0.0085 mm;

[0084] Alternatively, the shape of the tab 221 is a trapezoid, satisfying: 0.0035 mm ≤ d ≤ 0.011 mm.

[0085] Since the positive and negative ears can be set on different end faces of the battery cell, the positive and negative areas can be set larger. Therefore, for the solution in which the positive and negative ears are output on different sides, compared with the solution in which the positive and negative ears are output on the same side, the difference d between the maximum thickness and the minimum thickness of the core body 222 can be appropriately increased to reduce the restrictions on the process conditions during the electrode processing and improve production efficiency.

[0086] In some embodiments, 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: 0.002 mm≤d≤0.01 mm.

[0087] Due to the existence of the thickness difference d, after winding, the tabs of different winding layers may be misaligned. When m is relatively small, for example, when m is 1 or 2, after winding, the overall risk of misalignment of the tabs is relatively small. 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 relatively large, for example, when m is greater than or equal to 3, after winding, the overall risk of misalignment is likely to increase, resulting in a larger circumferential distance between the outermost tab and the innermost tab; and the welding of the tab and the pole assembly mainly relies on the welding of the middle part of the area together. When the risk of misalignment increases, the effective welding area is reduced, affecting the overcurrent; therefore, it is necessary to more accurately control the value range of d to reduce the further increase of the risk of misalignment.

[0088] Additionally, the difference between the number of the outermost tabs 221 and the number of the innermost tabs 221 is m, and the condition that m is less than or equal to 8 is also satisfied.

[0089] By limiting the upper limit of m to avoid too many layers, the thickness difference of the pole piece needs to be limited too strictly, resulting in overly strict pole piece processing conditions.

[0090] In some embodiments, in combination Figure 3 As shown, along the radial direction, the angle between the outermost pole lug 221 and the innermost pole lug 221 and the line connecting the axis of the cylindrical winding core 2 is A, which satisfies: 0°<A≤18°.

[0091] It should be noted that, along the radial direction, the outermost pole lug and the innermost pole lug refer to the outermost edge pole lug and the innermost edge pole lug, respectively.

[0092] By limiting the angles between the lines connecting the outermost tab and the innermost tab and the axis of the cylindrical winding core 2, the tab misalignment distance is controlled within a certain range to avoid subsequent impact on the tab flow area.

[0093] In some embodiments, the thickness of the core body 222 is C, which satisfies: C ≥ 0.080 mm; and satisfies: 0.12 ≤ d·n ≤ 0.8.

[0094] When the thickness C of the core body 222 is ≥ 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 in the radial direction is relatively large, the risk of misalignment of the tabs increases, and the alignment of the radially adjacent single-layer tab groups 223 is poor. Therefore, a smaller value of d·n is required.

[0095] In addition, when the thickness is relatively large, the consistency of the electrode thickness will be more difficult to control during the rolling process.

[0096] In some embodiments, the cylindrical core 2 includes a thinning area 224 , and the difference between the maximum thickness and the minimum thickness of the cylindrical core 2 in the thinning area 224 is F, which satisfies: 8 μm≤F≤60 μm.

[0097] Combination Figure 6 As shown, the thinning area 224 refers to some areas in the coating of the pole piece 22, in which the coated material will be thinner than other areas, forming a gradient distribution structure. The thickness of the thinning area is one of the important parameters affecting battery performance. First, after the pole piece is thinned, the internal resistance of the battery can be reduced, and the discharge performance and charging speed of the battery can be improved. Secondly, appropriate thinning can increase the specific surface area of ​​the positive electrode piece, which is beneficial to increase the contact area between the electrode material and the electrolyte, thereby improving the energy density and cycle life of the battery. However, if the thickness of the thinning area is too thin, it will also lead to a decrease in the mechanical strength of the pole piece and increase the safety risk of the battery.

[0098] Since the thinning area is closer to the root of the pole ear, the pole ear will undergo a folding process later, and the pole ear will start to fold back from the position close to the root. If the thickness difference in the thinning area is relatively large, the risk of misalignment of the pole ears between different layers will increase. When the difference F between the maximum thickness and the minimum thickness of the winding core body 222 in the thinning area exceeds the upper limit, the thickness consistency of the winding core body 222 in the thinning area is poor, which will cause individual pole ears and the previous pole ears to not be distributed radially, thereby increasing the degree of misalignment of the pole ears, reducing the effective area of ​​the pole ear area 21, that is, the subsequent welding area of ​​the pole ear area 21 and the pole column is reduced, which is easy to cause insufficient current capacity.

[0099] When the difference F between the maximum thickness and the minimum thickness of the core body 222 in the thinning area exceeds the lower limit, strict control conditions are imposed on the production process, the process is difficult to implement, and the production cost is greatly increased.

[0100] In some embodiments, the number n of winding layers of the cylindrical winding core 2 satisfies: n≤200.

[0101] When the number of winding layers n of the cylindrical winding core 2 exceeds the upper limit, the number of winding layers of the cylindrical winding core 2 is relatively large. Due to the accumulation of errors, the misalignment of the tabs will be further aggravated, which will easily cause the effective area of ​​the tab area 21 to be insufficient, and the welding area of ​​the tab area 21 and the pole column to be reduced, which will easily cause insufficient current capacity. When the number of winding layers n of the cylindrical winding core 2 exceeds the lower limit, it is easy to cause low battery energy density.

[0102] In some embodiments, in combination Figure 3As shown, the cylindrical core 2 includes a positive electrode sheet and a negative electrode sheet. After the cylindrical core 2 is wound, multiple pole tabs 221 of the positive electrode sheet are stacked to form a positive electrode tab area, and multiple pole tabs 221 of the negative electrode sheet are stacked to form a negative electrode tab area. The positive electrode tab area and the negative electrode tab area are located on the same side of the cylindrical core 2 along the axial direction, and the positive electrode tab area and the negative electrode tab area are spaced apart from each other.

[0103] Obviously, the above embodiments are only examples for clear explanation, and are not intended to limit the implementation methods. Although the embodiments of the present invention are described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the present invention.

Claims

1. A battery, characterized in that: include: A housing (1), wherein a pole assembly (31) is arranged on the housing (1); A cylindrical winding core (2), the cylindrical winding core (2) comprising a winding core body (222) and a plurality of pole ears (221); the pole ears (221) are used to be electrically connected to the pole column assembly (31) or the shell (1); the plurality of pole ears (221) are distributed in multiple layers along the radial direction of the winding core body (222); When the cylindrical winding core (2) is in an unfolded state, along the length direction of the cylindrical winding core (2), the width of a single pole ear (221) is E, satisfying: 2mm≤E≤9mm; The difference between the maximum thickness and the minimum thickness of the winding core body (222) is d, the number of winding layers of the winding core body (222) is n, and the following conditions are satisfied: 0.08≤d·n≤0.9; The pole lug (221) comprises a positive pole lug and a negative pole lug, and the positive pole lug and the negative pole lug are respectively located on both sides of the winding core body (222) along the axial direction; the size of the pole lug (221) along the radial direction is H, and the diameter of the cylindrical winding core (2) is D, which satisfies: 0.03≤H / D≤0.2; The cylindrical winding core (2) comprises a thinned area.

2. The battery according to claim 1, characterized in that There are multiple pole tabs (221) on the same layer.

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

4. The battery according to claim 1, characterized in that The dimension of the pole lug (221) along the radial direction is H, which satisfies: 240≤H / d≤5000.

5. The battery according to claim 1, characterized in that A plurality of the pole lugs (221) are stacked to form a pole lug region (21); along the radial direction, the pole lug region (21) is constructed in a fan shape, satisfying the following condition: 0.003 mm ≤ d ≤ 0.012 mm.

6. The battery according to claim 1, characterized in that The shape of the pole ear (221) is rectangular, satisfying: 0.003mm≤d≤0.0085mm; Alternatively, the shape of the pole ear (221) is a trapezoid, satisfying: 0.0035 mm ≤ d ≤ 0.011 mm.

7. The battery according to claim 1, 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, satisfying: m is greater than or equal to 3; and satisfying: 0.002mm≤d≤0.01mm.

8. The battery according to claim 1, characterized in that In the radial direction, the angle between the lines connecting the outermost pole lug (221) and the innermost pole lug (221) and the axis of the cylindrical winding core (2) is A, satisfying: 0°<A≤18°.

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

8.

10. The battery according to claim 1, characterized in that The difference between the maximum thickness and the minimum thickness of the cylindrical winding core (2) in the thinning area is F, which satisfies: 8μm≤F≤60μm.

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