Cylindrical battery and battery pack

Abstract

The utility model relates to the technical field of batteries, in particular to a cylindrical battery and a battery pack. The end surfaces of the electrode plates in the axial direction of the roll core are connected with a plurality of tab groups, and the tab groups are distributed along the radial direction of the roll core; the tab group comprises a plurality of sub-tab groups; each sub tab group comprises at least one tab distributed along the circumferential direction of the roll core; the tab comprises a connecting part and a bending part; the number of the sub-tab groups is N, and the bending part of the tab in the (n + 1) th sub-tab group is laminated on one side, deviating from the electrode plate, of the bending part of the tab in the nth sub-tab group; the number of the tab groups is I, the bending part of the tab of the Nth sub-tab group in the ith tab group has a first orthographic projection L1 on the reference plane, the bending part of the tab of the sub-tab group in the (i + 1) th tab group has a second orthographic projection L2 on the reference plane, and the first orthographic projection and the second orthographic projection are not overlapped. According to the invention, the thickness of the tab stack is reduced, the energy density of the battery is improved, and the welding tension is improved.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and particularly to a cylindrical battery and a battery pack. Background Art

[0002] With the rapid development of new energy vehicles, the cylindrical batteries for energy storage of new energy vehicles have also been rapidly iterated. The all-pole-ear cylindrical battery cell has become one of the directions of the next-generation battery technology. The all-pole-ear cylindrical battery has the advantages of large energy, high manufacturing efficiency, low internal resistance, and excellent rate performance, and has received extensive attention in the fields of energy storage and power.

[0003] The all-pole-ear battery cell has significant advantages in terms of internal resistance and rate performance, but the all-pole-ear battery cell also introduces some new technical problems. For example, there is a problem of highly compressing the pole ear height of the all-pole-ear. A relatively thick pole ear will increase the internal resistance of the battery and reduce the energy density of the battery. Summary of the Utility Model

[0004] The present application provides a cylindrical battery and a battery pack to solve the technical problem that the relatively thick pole ear affects the battery performance.

[0005] The present application provides a cylindrical battery, including:

[0006] A housing; and

[0007] A wound core disposed in the housing; the wound core is formed by laminating and winding electrode sheets and a separator layer. Multiple groups of pole ear groups are connected to the end faces of the electrode sheets in the axial direction of the wound core, and each group of pole ear groups is distributed radially along the wound core; each group of pole ear groups includes multiple groups of sub-pole ear groups, and each group of sub-pole ear groups is distributed radially along the wound core; each group of sub-pole ear groups includes at least one pole ear distributed circumferentially along the wound core; the pole ear includes a connecting portion and a bending portion, the connecting portion connects the bending portion and the electrode sheet, and the bending portion extends radially along the wound core toward the axial direction of the wound core;

[0008] In the pole ear group, the groups of sub-pole ear groups are numbered in the direction from the axial direction of the wound core toward the outside of the wound core. The number of groups of sub-pole ear groups is N. The bending portion of the pole ear in the (n + 1)-th group of sub-pole ear groups is laminated on the side of the bending portion of the pole ear in the n-th group of sub-pole ear groups away from the electrode sheet, where n is 1, 2, 3,..., N - 1;

[0009] The wound core has a reference plane perpendicular to its axial direction. The groups of pole ear groups are numbered in the direction from the axial direction of the wound core toward the outside of the wound core. The number of groups of pole ear groups is I. The bending portion of the pole ear of the N-th group of sub-pole ear groups in the i-th group of pole ear groups has a first orthographic projection L1 on the reference plane, and the bending portion of the pole ear of the sub-pole ear group in the (i + 1)-th group of pole ear groups has a second orthographic projection L2 on the reference plane m. The first orthographic projection and the second orthographic projection do not overlap, where i is 1, 2, 3,..., I - 1.

[0010] As an alternative embodiment of this solution, the orthographic projections of the bent portions of the tabs of each sub-tab group in the (i + 1)-th tab group on the reference plane m do not overlap with the first orthographic projection L1.

[0011] As an alternative embodiment of this solution, the flattened height of the tabs in the k-th sub-tab group in the (i + 1)-th tab group is less than the flattened height of the tabs in the N-th sub-tab group in the i-th tab group.

[0012] As an alternative embodiment of this solution, the flattened heights of the tabs in the same sub-tab group are the same.

[0013] As an alternative embodiment of this solution, the flattened heights of the tabs of each sub-tab group in the same tab group increase one by one along the direction from the axial direction of the winding core towards the outside of the winding core.

[0014] As an alternative embodiment of this solution, the electrode sheet includes a positive electrode sheet and a negative electrode sheet;

[0015] In the tab group, the distance between the tabs in two adjacent sub-tab groups is equal to or greater than the sum of the thicknesses of one layer of positive electrode sheet, one layer of negative electrode sheet, and two layers of separator.

[0016] As an alternative embodiment of this solution, taking the end of the connecting portion of the same tab away from the bent portion as the root, the distance between the roots of the tabs in the N-th sub-tab group in the i-th tab group and the roots of the tabs in the k-th sub-tab group in the (i + 1)-th tab group is greater than or equal to the distance between the roots of the tabs in two adjacent sub-tab groups in the i-th tab group.

[0017] As an alternative embodiment of this solution, the number of sub-tab groups in each tab group is a, where 2 ≤ a ≤ 20.

[0018] As an alternative embodiment of this solution, the number of tabs in each sub-tab group is b, where 1 ≤ b ≤ 100.

[0019] On the other hand, the present application provides a battery pack, including the cylindrical battery as described above.

[0020] One of the above technical solutions has the following advantages or beneficial effects:

[0021] By setting the first set of tab groups and N sets of sub-tab groups, the bent portions of the tabs in the (n + 1)-th set of sub-tab groups are stacked on the bent portions of the tabs in the n-th set of sub-tab groups, and the orthographic projection of the bent portion of the tab in the N-th set of sub-tab groups in the i-th set of tab groups on the reference plane does not overlap with the orthographic projection of the bent portion of the tab in the sub-tab group in the (i + 1)-th set of tab groups on the reference plane. In this way, it can be ensured that when the battery cell is in the wound state, every N layers of the sub-tab groups form a set of tab groups, and the tabs in the sub-tab group in the (i + 1)-th set of tab groups will not be stacked on the tabs in the N-th set of sub-tab groups in the i-th set of tab groups. Thus, when the tabs are flattened and stacked to a certain height, the tabs are re-stacked, thereby reducing the stacked thickness of the tabs and further increasing the energy density of the battery. The increase in energy density can increase the battery's endurance time and improve the application performance of the battery in energy storage and mobile devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The following will, with reference to the drawings, make the technical solutions and other beneficial effects of the present application obvious through a detailed description of the specific embodiments of the present application.

[0023] Figure 1 is a cross-sectional view of the core provided in Embodiment 1 of the present application;

[0024] Figure 2 is a schematic structural diagram of multiple sets of tab groups provided in Embodiment 1 of the present application;

[0025] Figure 3 is a schematic structural diagram of a set of tab groups provided in Embodiment 1 of the present application;

[0026] Figure 4 is a schematic diagram of the electrode sheet in the unfolded state provided in Embodiment 1 of the present application;

[0027] Figure 5 is a schematic diagram of the electrode sheet and the separator provided in Embodiment 1 of the present application;

[0028] Figure 6 is a cross-sectional view of the core provided in Embodiment 2 of the present application;

[0029] Figure 7 is a schematic diagram of the electrode sheet in the unfolded state provided in Embodiment 2 of the present application;

[0030] Figure 8 is a cross-sectional view of the core provided in Embodiment 3 of the present application;

[0031] Figure 9 is a schematic diagram of the electrode sheet in the unfolded state provided in Embodiment 3 of the present application;

[0032] Figure 10 is a cross-sectional view of the core provided in Embodiment 4 of the present application;

[0033] Figure 11 It is a schematic diagram of the electrode sheet provided in Embodiment 4 of the present application in the unfolded state.

[0034] Reference numerals:

[0035] 10. Core; 11. Electrode sheet; 110. Positive electrode sheet; 120. Negative electrode sheet; 12. Ear group; 13. Sub-ear group; 14. Ear; 141. Connection part; 142. Bending part; 15. First non-polar ear part; 16. Second non-polar ear part. Detailed implementation manners

[0036] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0037] In the description of the present application, it should be noted that unless otherwise clearly defined and limited, the term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the front and rear associated objects without special instructions.

[0038] The present application provides a cylindrical battery and a battery pack, which will be described in detail below. It should be noted that the description order of the following embodiments does not limit the preferred order of the embodiments of the present application. And in the following embodiments, each embodiment is described with emphasis. For the parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0039] The full-tab cell has significant advantages in terms of internal resistance and rate performance, but there are also some new technical problems with the full-tab cell. For example, the problem of the height compression of the tabs of the full-tab cell after being flattened. The thickness of the tabs of the existing full-tab cell is relatively thick after being flattened, resulting in an increase in the internal resistance of the battery and thus a decrease in the energy density of the battery.

[0040] Therefore, the present application provides a cylindrical battery and a battery pack. The cylindrical battery is a full-tab cylindrical battery. The tabs of the cylindrical battery will be re-stacked after being flattened to a certain height, which can reduce the thickness of the tabs after being flattened, help reduce the internal resistance of the battery, and improve the energy density of the battery. The cylindrical battery of the present application will be elaborated in detail below.

[0041] Specifically, the present application provides a battery pack, which includes a plurality of cylindrical batteries. The cylindrical battery includes a housing (not shown in the figure) and a winding core 10, and the winding core 10 is disposed in the housing. The winding core 10 is formed by laminating and winding electrode sheets 11 and a separator.

[0042] Please refer to Figures 1 to 5 , Figure 1 which is a cross-sectional view of a cylindrical battery cell in the axial direction in an embodiment of the present application, Figure 2 and Figure 1 is an enlarged view of some tabs in the cylindrical battery in Figure 3 and Figure 1 is a cross-sectional view of a set of tab groups in the embodiment shown in Figure 4 and Figure 1 is a schematic structural view of the winding core in the unfolded state in the embodiment shown in Figure 5 and Figure 1 is a schematic view of the electrode sheet and the separator in the embodiment shown in

[0043] In one embodiment, a plurality of sets of tab groups 12 are connected to the end face of the electrode sheet 11 in the axial direction of the winding core 10, and each set of tab groups 12 is distributed radially along the winding core 10; each set of tab groups 12 includes a plurality of sets of sub-tab groups 13, and each set of sub-tab groups 13 is distributed radially along the winding core 10; each set of sub-tab groups 13 includes at least one tab 14 distributed circumferentially along the winding core 10. The tab 14 includes a connecting portion 141 and a bending portion 142. The connecting portion 141 is connected to the electrode sheet 11, and the bending portion 142 is connected to one end of the connecting portion 141 away from the electrode sheet 11. The bending portion 142 extends radially along the winding core 10 towards the axial direction of the winding core 10.

[0044] In the tab group 12, the sets of sub-tab groups 13 are numbered in the direction from the axial direction of the winding core 10 towards the outside of the winding core 10. The number of sets of sub-tab groups 13 is N. The bending portion 142 of the tab 14 in the (n + 1)-th set of sub-tab groups 13 is laminated on the side of the bending portion 142 of the tab 14 in the n-th set of sub-tab groups 13 away from the electrode sheet 11, where n is 1, 2, 3,..., N - 1.

[0045] The winding core 10 has a reference plane m perpendicular to its axial direction. The sets of tab groups 12 are numbered in the direction from the axial direction of the winding core 10 towards the outside of the winding core 10. The number of sets of tab groups 12 is I. The bending portion 142 of the tab 14 in the N-th set of sub-tab groups 13 in the i-th set of tab groups 12 has a first orthographic projection L1 on the reference plane m, and the bending portion 142 of the tab 14 in the sub-tab group 13 in the (i + 1)-th set of tab groups 12 has a second orthographic projection L2 on the reference plane m. The first orthographic projection L1 and the second orthographic projection L2 do not overlap, where i is 1, 2, 3,..., I - 1.

[0046] Since the bent portions 142 of the tabs 14 in the (n + 1)-th sub-tab group 13 are stacked on the side of the bent portions 142 of the tabs 14 in the n-th sub-tab group 13 that is away from the electrode sheet 11, and the first orthographic projection L1 and the second orthographic projection L2 do not overlap, it can be ensured that when the battery cell is in the wound state, every N layers of the sub-tab groups 13 form a tab group 12, and the tabs 14 in the (n + 1)-th sub-tab group 13 will not be stacked on the n-th sub-tab group 13. Thus, when the number of layers after the tabs 14 are flattened reaches a certain height, the tabs 14 are re-stacked, thereby reducing the stacked thickness of the tabs 14 and further increasing the energy density of the battery. Energy density (Wh / L) = Capacity * Plateau voltage / Volume / 1000, where Capacity is the energy stored in the battery; Plateau voltage depends on the type of battery. For example, the plateau voltage of an iron battery is 3.2V, while the plateau voltage of a ternary lithium battery is generally 3.7V; the calculation of Volume varies according to the shape of the battery. The volume calculation formula for a cylindrical battery is πr 2 ×h. When the number of stacked layers remains unchanged, that is, r remains unchanged, the fewer the number of stacked layers of the tabs, the smaller h is, and then the greater the energy density of the battery cell is.

[0047] Furthermore, the orthographic projections of the bent portions 142 of the tabs 14 in each sub-tab group 13 in the (i + 1)-th tab group 12 on the reference plane m do not overlap with the first orthographic projection L1. This can ensure that the tabs 14 in each tab group 12 in the circumferential direction of the wound core 10 do not overlap with the tabs 14 in the previous tab group 12 in the radial direction, so as to ensure that the upper surfaces of the N-th sub-tab groups 13 in each tab group 12 of the wound core 10 are on the same plane as much as possible. When welding the current collector plate to the tabs 14, the contact area between the tabs 14 and the current collector plate can be increased, the welding area can be increased, thereby significantly improving the welding consistency, increasing the welding pull force, and further improving the comprehensive capabilities such as the over-current capacity, cycle performance, self-discharge, and reliability of the battery cell.

[0048] It is not difficult to understand that in this embodiment, Figures 1 to 4 only five tab groups 12 are schematically shown, and the case where each tab group 12 includes three sub-tab groups 13 Figures 1 to 4 is only used as an example for illustration and does not limit the technical scope of the present application. In this embodiment, the number of sub-tab groups 13 in each tab group 12 is a, where 2 ≤ a ≤ 20; the number of tabs 14 in each sub-tab group 13 is b, where 1 ≤ b ≤ 100. In other embodiments, the number of sub-tab groups 13 and the number of tabs 14 can be set as needed and are not limited herein.

[0049] Specifically, after the electrode sheet 11 is wound and before the tabs 14 are flattened, the tabs 14 have a flattened height in the axial direction of the wound core 10. This flattened height is the sum of the lengths of the bent portions 142 and the connecting portions 141, that isFigure 5 The distance between the end of the middle tab 14 far from the electrode sheet 11 and the reference plane m; the flattened height of the tab 14 in the first sub-tab group 13 of the (i + 1)-th tab group 12 is less than the flattened height of the tab 14 in the N-th sub-tab group 13 of the i-th tab group 12.

[0050] In addition, the flattened heights of the tabs 14 in the same sub-tab group 13 are the same, so that it can be ensured that the tabs 14 in the same sub-tab group 13 are in the same plane in the circumferential direction after being flattened, so as to ensure the flatness of the stacked sub-tab groups 13 and tab groups 12, and further achieve a good welding effect.

[0051] To ensure that the tabs 14 in each sub-tab group 13 in the same tab group 12 are stacked layer by layer, the outer diameter of the core 10 and the flattened heights of each sub-tab group 13 in the same tab group 12 increase one by one along the axial direction of the core 10 towards the outside of the core 10.

[0052] Further, in this embodiment, taking the end of the connecting portion 141 of the same tab 14 far from the bent portion 142 as the root, it can be understood that the root is the part where the tab 14 is connected to the foil of the electrode sheet 11, and the plane where the tab 14 is connected to the foil of the electrode sheet 11 is the reference plane m. As the number of winding turns of the core 10 increases, the circumference of each turn also gradually increases. Therefore, the distance between the roots of the tabs 14 in the N-th sub-tab group 13 of the i-th tab group 12 and the roots of the tabs 14 in the first sub-tab group 13 of the (i + 1)-th tab group 12 is greater than the distance between the roots of the tabs 14 in two adjacent sub-tab groups 13 in the i-th tab group 12.

[0053] Refer to Figure 4 and Figure 5 , the electrode sheet 11 includes a positive electrode sheet 110 and a negative electrode sheet 120, and the separator is arranged between the electrode sheet 11 and the negative electrode sheet 120. When the core 10 is in the unfolded state, when there is no tabless area between two adjacent sub-tab groups 13 in the same tab group 12, in the same tab group 12, the distance between the tabs 14 in two adjacent sub-tab groups 13 is equal to the sum of the thicknesses of one layer of the positive electrode sheet 110, one layer of the negative electrode sheet 120 and two layers of the separator. If the distance between the tabs 14 in two adjacent sub-tab groups 13 is H, the thickness of the positive electrode sheet 110 is H1, the thickness of the negative electrode sheet 120 is H2, and the thickness of the separator is H3, then, H = H1 + H2 + 2 * H3.

[0054] In addition, the distance between the root of the pole lug 14 of the Nth sub-pole lug group 13 in the i-th pole lug group 12 and the root of the pole lug 14 of the first sub-pole lug group 13 in the i+1th pole lug group 12 is greater than the sum of the thickness of a layer of positive electrode sheet 110, a layer of negative electrode sheet 120 and two layers of separator. If the distance between the root of the pole lug 14 of the Nth sub-pole lug group 13 in the i-th pole lug group 12 and the root of the pole lug 14 of the first sub-pole lug group 13 in the i+1th pole lug group 12 is W, then W>H1+H2+2H3. That is to say, when the winding core 10 is in the unfolded state, there is a non-polar lug area between two adjacent pole lug groups 12, and the electrode sheet 11 between the two adjacent pole lug groups 12 is the first non-polar lug area 15. Further, the flattened length C1 of the first non-polar lug portion 15 can be the length of one winding of the electrode sheet 11 and the separator or the length of multiple windings, which is not limited here. It should be noted that the length of the non-polar lug region between the i-th group of polar lugs 12 and the i+1-th group of polar lugs 12 is adjusted according to the flattened height of the polar lugs 14 in the first group of sub-polar lug groups 13 in the i+1-th group of polar lugs 12 to ensure that the i+1-th group of polar lugs 12 is not stacked on the i-th group of polar lugs 12.

[0055] By setting the above structure and the first non-polar ear portion 15, the number of polar ears 14 can be reduced, thereby reducing the thickness of the polar ears 14 after stacking. A height tester is used to measure the total thickness T of the polar ear layer after flattening, and the total thickness T of the polar ear layer is the distance from the bending portion 142 to the reference plane m. After the polar ear 14 is flattened, the collector plate is welded to the polar ear 14, the battery cell is clamped with a clamp, and the collector plate is stretched along the side away from the battery cell in the axial direction of the battery cell using a tensile tester, and the change in tension during the stretching process is recorded. The maximum value of the tension during the stretching process is the welding tension F. Taking the example of stacking 10 layers of polar ears 14 along the axial direction of the winding core 10 toward the outside of the winding core 10, the total thickness of the polar ear layer T is measured to be 0.21 mm and the welding tension F is 32.6 N using the polar ear structure provided in the present application. However, taking the example of stacking 10 layers of the tabs 14 along the axial direction of the winding core 10 toward the outside of the winding core 10, using the currently existing stacked tab structure, the total thickness of the tab layer is measured to be T = 2.03 mm, and the welding tension F = 20.2N.

[0056] It can be seen that, when the number of stacked layers of the tabs 14 is the same, by adopting the cylindrical battery structure provided by the present application, the total thickness of the tab layer can be greatly reduced, and the welding tension can be increased, thereby improving the energy density of the battery cell. Energy density (Wh / liter) = capacity * platform voltage / volume / 1000, where capacity is the energy stored in the battery; platform voltage depends on the type of battery, for example, the platform voltage of an iron battery is 3.2V, while the platform voltage of a ternary lithium battery is generally 3.7V; the calculation of volume varies according to the shape of the battery, and the cylindrical volume calculation formula is πr 2×h, when the number of stacked layers remains unchanged, that is, r remains unchanged, the smaller the total thickness of the tab layer, the smaller h, and the greater the energy density of the battery cell. The increase in energy density can increase the battery life and improve the application performance of the battery in energy storage and mobile devices.

[0057] In another embodiment, see Figure 6 and Figure 7 , the spacing between the tabs 14 in two adjacent sub-tab groups 13 is equal to the sum of the thickness of a layer of positive electrode sheet 110, a layer of negative electrode sheet 120 and two layers of separator, and the spacing between the root of the tab 14 of the Nth sub-tab group 13 in the i-th tab group 12 and the root of the tab 14 of the 1st sub-tab group 13 in the i+1th tab group 12 is equal to the sum of the thickness of a layer of positive electrode sheet 110, a layer of negative electrode sheet 120 and two layers of separator. That is, H = H1 + H2 + H3, and W = H1 + H2 + H3. That is to say, when the winding core 10 is in the unfolded state, there is no tab-free area between the two adjacent tab groups 12, and there is no tab-free area between the two adjacent sub-tab groups 13.

[0058] By setting the above structure, a height tester is used to measure the total thickness T of the tab layer after flattening, and the total thickness T of the tab layer is the distance from the bent portion 142 to the reference plane m. After the tab 14 is flattened, the collector is welded to the tab 14, the battery cell is clamped by a fixture, and the collector is stretched along the side away from the battery cell in the axial direction of the battery cell by a tensile tester, and the change of tension during the stretching process is recorded. The maximum value of the tension during the stretching process is the welding tension F. Taking the tab 14 stacked in 10 layers along the axial direction of the winding core 10 toward the outside of the winding core 10 as an example, the total thickness T of the tab layer is measured to be 0.20mm, and the welding tension F is 33.4N using the tab structure provided in the present application. However, also taking the tab 14 stacked in 10 layers along the axial direction of the winding core 10 toward the outside of the winding core 10 as an example, using the existing layered tab structure, the total thickness T of the tab layer is measured to be 2.03mm, and the welding tension F is 20.2N. It can be seen that, when the number of stacked layers of the tabs 14 is the same, by adopting the cylindrical battery structure provided by the present application, the total thickness of the tab layer can be greatly reduced, and the welding tension can be increased, thereby improving the energy density of the battery cell. The increase in energy density can increase the battery life and improve the application performance of the battery in energy storage and mobile devices.

[0059] In other embodiments, see Figure 8 and Figure 9, the spacing between the tabs 14 in two adjacent sub-tab groups 13 is greater than the sum of the thickness of a layer of positive electrode sheet 110, a layer of negative electrode sheet 120 and two layers of separator, and the spacing between the root of the tab 14 of the Nth sub-tab group 13 in the i-th tab group 12 and the root of the tab 14 of the 1st sub-tab group 13 in the i+1th tab group 12 is equal to the sum of the thickness of a layer of positive electrode sheet 110, a layer of negative electrode sheet 120 and two layers of separator. That is, H>H1+H2+H3, and W=H1+H2+H3. That is to say, when the winding core 10 is in the unfolded state, there is no tab-free region between the two adjacent tab groups 12, there is a tab-free region between the two adjacent sub-tab groups 13, and the electrode sheet 11 between the two adjacent sub-tab groups 13 is the second tab-free portion 16. Further, the flattened length C2 of the second non-polar lug portion 16 can be the length of one winding of the electrode sheet 11 and the diaphragm or the length of multiple windings, which is not limited here. It should be noted that the length of the non-polar lug area between the nth group of sub-polar lug groups 13 and the n+1th group of sub-polar lug groups 13 is adjusted according to the height difference between adjacent sub-polar lug groups 13 in the same polar lug group 12 to ensure that the polar lugs 14 in the n+1th group of sub-polar lug groups 13 can be stacked on the polar lugs 14 in the nth group of sub-polar lug groups 13.

[0060] By setting the above structure and the second non-polar ear portion 16, the number of the pole ears 14 can be further reduced, thereby reducing the thickness of the pole ears 14 after stacking. The total thickness T of the pole ear layer after flattening is measured by a height tester, and the total thickness T of the pole ear layer is the distance from the bending portion 142 to the reference plane m. After the pole ear 14 is flattened, the collector plate is welded to the pole ear 14, the battery cell is clamped by a clamp, and the collector plate is stretched along the side away from the battery cell in the axial direction of the battery cell by a tensile tester, and the change of tension during the stretching process is recorded. The maximum value of the tension during the stretching process is the welding tension F. Taking the example of stacking 10 layers of pole ears 14 along the axial direction of the winding core 10 toward the outside of the winding core 10, the total thickness of the pole ear layer T is measured to be 0.20 mm and the welding tension F is 31.5N using the pole ear structure provided in the present application. However, taking the example of stacking 10 layers of the tabs 14 along the axial direction of the core 10 toward the outside of the core 10, the currently existing stacked tab structure is used, and the total thickness of the tab layer is measured to be T = 2.03 mm, and the welding tension F = 20.2 N. It can be seen that when the number of stacked layers of the tabs 14 is the same, by adopting the cylindrical battery structure provided by the present application, the total thickness of the tab layer can be greatly reduced, and the welding tension can be increased, thereby improving the energy density of the battery cell. The increase in energy density can increase the battery life and improve the application performance of the battery in energy storage and mobile devices.

[0061] In another embodiment, see Figure 10 and Figure 11, the distance between the tabs 14 in two adjacent sub-tab groups 13 is greater than the sum of the thicknesses of one layer of the positive electrode sheet 110, one layer of the negative electrode sheet 120, and two layers of the separator, and the distance between the roots of the tabs 14 of the Nth sub-tab group 13 in the ith tab group 12 and the roots of the tabs 14 of the 1st sub-tab group 13 in the (i + 1)th tab group 12 is greater than the sum of the thicknesses of one layer of the positive electrode sheet 110, one layer of the negative electrode sheet 120, and two layers of the separator. That is, H > H1 + H2 + H3, and W > H1 + H2 + H3.

[0062] That is to say, in the unfolded state of the core 10, there is a tabless area between two adjacent tab groups 12, and the electrode sheet 11 between two adjacent tab groups 12 is the first tabless part 15. Further, the flattened length C1 of the first tabless part 15 can be the length of one turn of winding the electrode sheet 11 and the separator, or can be the length of multiple turns of winding, which is not limited here. It should be noted that the length of the tabless area of the tabs 14 between the ith tab group 12 and the (i + 1)th tab group 12 is adjusted according to the flattened height of the tabs 14 in the first sub-tab group 13 of the (i + 1)th tab group 12. At the same time, there is also a tabless area between two adjacent sub-tab groups 13, and the electrode sheet 11 between two adjacent sub-tab groups 13 is the second tabless part 16. Further, the flattened length C2 of the second tabless part 16 can be the length of one turn of winding the electrode sheet 11 and the separator, or can be the length of multiple turns of winding, which is not limited here. It should be noted that the length of the tabless area between the nth sub-tab group 13 and the (n + 1)th sub-tab group 13 is adjusted according to the height difference between two adjacent sub-tab groups 13 in the same tab group 12, so as to ensure that the tabs 14 in the (n + 1)th sub-tab group 13 can be stacked on the tabs 14 in the nth sub-tab group 13.

[0063] By setting the above structure, by setting the first non-polar ear portion 15 and the second non-polar ear portion 16, the number of pole ears 14 can be further reduced, thereby reducing the thickness of the pole ears 14 after stacking. The total thickness T of the pole ear layer after flattening is measured by a height tester. The total thickness T of the pole ear 14 layer is the distance from the bending portion 142 to the reference plane m. After the pole ear 14 is flattened, the collector plate is welded to the pole ear 14, the battery cell is clamped by a clamp, and the collector plate is stretched along the side away from the battery cell in the axial direction of the battery cell by a tensile tester, and the change of tension during the stretching process is recorded. The maximum value of the tension during the stretching process is the welding tension F. Taking the example of stacking 10 layers of pole ears 14 along the axial direction of the winding core 10 toward the outside of the winding core 10, the total thickness T of the pole ear layer is measured by the pole ear structure provided in the present application, which is 0.21 mm, and the welding tension F is 32.1N. However, taking the example of stacking 10 layers of the tabs 14 along the axial direction of the core 10 toward the outside of the core 10, the currently existing stacked tab structure is used, and the total thickness of the tab layer is measured to be T = 2.03 mm, and the welding tension F = 20.2 N. It can be seen that when the number of stacked layers of the tabs 14 is the same, by adopting the cylindrical battery structure provided by the present application, the total thickness of the tab layer can be greatly reduced, and the welding tension can be increased, thereby improving the energy density of the battery cell. The increase in energy density can increase the battery life and improve the application performance of the battery in energy storage and mobile devices.

[0064] In addition, the present application also provides a battery pack, which includes the above-mentioned cylindrical battery. The battery pack has high energy density and welding tension, long battery life and good application performance in energy storage and mobile devices.

[0065] The above description is only a partial implementation method of the embodiments of the present application and does not constitute any form of limitation on the application. The protection scope of the embodiments of the present application is not limited thereto. Any simple modifications, equivalent changes and modifications that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the embodiments of the present application should be covered within the protection scope of the embodiments of the present application.

Claims

1. A cylindrical battery, characterized in that: The cylindrical battery comprises: a housing; and A winding core (10) is arranged in the shell; the winding core (10) is formed by stacking and winding an electrode sheet (11) and a diaphragm; the electrode sheet (11) is connected to a plurality of pole lug groups (12) on the axial end surface of the winding core (10); each of the pole lug groups (12) is distributed along the radial direction of the winding core (10); the pole lug group (12) includes a plurality of sub-pole lug groups (13); each of the sub-pole lug groups (13) is distributed along the radial direction of the winding core (10); each of the sub-pole lug groups (13) includes at least one pole lug (14) distributed along the circumference of the winding core (10); the pole lug (14) includes a connecting portion (141) and a bending portion (142); the connecting portion (141) connects the bending portion (142) and the electrode sheet (11); the bending portion (142) extends along the radial direction of the winding core (10) toward the axial direction of the winding core (10); In the pole lug group (12), each of the sub-pole lug groups (13) is numbered along the direction from the axial direction of the winding core (10) toward the outside of the winding core (10), the number of the sub-pole lug groups (13) is N, the bent portion (142) of the pole lug (14) in the n+1th sub-pole lug group (13) is stacked on the side of the bent portion (142) of the pole lug (14) in the nth sub-pole lug group (13) away from the electrode sheet (11), and n is 1, 2, 3, ..., N-1; The winding core (10) has a reference plane (m) perpendicular to its axial direction, and each of the pole lug groups (12) is numbered along the direction from the axial direction of the winding core (10) toward the outside of the winding core (10), the number of the pole lug groups (12) is I, the bending portion (142) of the pole lug (14) of the Nth sub-pole lug group (13) in the i-th pole lug group (12) has a first orthographic projection L1 on the reference plane (m), and the bending portion (142) of the pole lug (14) of the sub-pole lug group (13) in the i+1-th pole lug group (12) has a second orthographic projection L2 on the reference plane (m), the first orthographic projection does not overlap with the second orthographic projection, and i is 1, 2, 3, ..., I-1.

2. The cylindrical battery according to claim 1, characterized in that: The orthographic projections of the bent portions (142) of the pole tabs (14) of each sub-pole tab group (13) in the (i+1)th pole tab group (12) on the reference plane (m) do not overlap with the first orthographic projection L1.

3. The cylindrical battery according to claim 1, characterized in that: The flattened height of the pole lug (14) in the first sub-pole lug group (13) in the (i+1)th pole lug group (12) is smaller than the flattened height of the pole lug (14) in the Nth sub-pole lug group (13) in the i-th pole lug group (12).

4. The cylindrical battery according to claim 1, characterized in that: The flattened heights of the pole tabs (14) in the same pole tab group (13) are the same.

5. The cylindrical battery according to claim 1, characterized in that: The flattened heights of the pole tabs (14) of each sub-pole tab group (13) in the same pole tab group (12) increase gradually along the direction from the axial direction of the winding core (10) toward the outside of the winding core (10).

6. The cylindrical battery according to claim 1, characterized in that: The electrode sheet (11) comprises a positive electrode sheet and a negative electrode sheet; In the electrode tab group (12), the distance between the electrode tabs (14) in two adjacent sub-electrode tab groups (13) is equal to or greater than the sum of the thicknesses of one positive electrode sheet, one negative electrode sheet and two layers of the separator.

7. The cylindrical battery according to claim 1, characterized in that: Taking the end of the connecting portion (141) of the same pole lug (14) away from the bending portion (142) as the root, the distance between the root of the pole lug (14) of the Nth sub-pole lug group (13) in the i-th pole lug group (12) and the root of the pole lug (14) of the 1st sub-pole lug group (13) in the (i+1)th pole lug group (12) is greater than or equal to the distance between the roots of the pole lugs (14) in two adjacent sub-pole lug groups (13) in the i-th pole lug group (12).

8. The cylindrical battery according to claim 1, characterized in that: The number of sub-electrode tab groups (13) in each group of the electrode tab groups (12) is a, 2≤a≤20.

9. The cylindrical battery according to claim 1, characterized in that: The number of the pole tabs (14) in each of the sub-pole tab groups (13) is b, and 1≤b≤100.

10. A battery pack, characterized in that: Comprising a cylindrical battery as described in any one of claims 1-9.

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