Electrode sheets, winding cores, and battery cells

Abstract

To provide an electrode sheet capable of reducing the situation where tabs overlap each other or are out of position, releasing the internal stress of the tabs, weakening the distortion of the tabs, improving the flatness and conformity of the end faces of battery cells, and ensuring the stability of welding to a bus plate.SOLUTION: An electrode sheet includes an electrode sheet body 10, and a plurality of tabs 20 provided on the edge of the electrode sheet body, the plurality of tabs being spaced apart along a first direction, each having a notch 22 formed at one end remote from the electrode sheet body.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This application relates to the technical field of batteries, for example, electrode sheets, wound cores, and battery cells.

Background Art

[0002] In battery cells in related technologies, full-tab electrode sheets are often adopted. During the manufacture of battery cells, first, the full-tab electrode sheet is wound to form a wound core, and then the full tabs of the wound core are flattened by rubbing or pressing flat. After that, they are welded to the bus plate and finally assembled to manufacture the battery cell. However, in the process of flattening the full tabs by rubbing or pressing flat, the situation where they overlap or shift in position easily occurs. As a result, the end of the wound core does not become flat, the stability of welding with the bus plate is reduced, and further affects the performance of the entire battery product.

[0003] Electrode sheets in related technologies usually adopt electrode sheets with multiple tabs. That is, with respect to the full tabs on the electrode sheet, a plurality of single tabs are formed at intervals by laser die-cutting. In the process of flattening the tabs by rubbing or pressing flat, the plurality of tabs are annular, that is, they become the end face of the wound core. The smaller the width of the tab, the higher the conformity of the end face composed of the plurality of tabs. However, the width of the tab cannot be infinitely small. Therefore, in the actual bending process of the tab (that is, the process of flattening the tab by rubbing or pressing flat), internal stress exists inside the tab. Due to this internal stress, the tab will warp and deform during the bending process, and the generated strain seriously affects the effect of flattening the tab by rubbing or pressing flat, and even affects the effect of subsequent welding with the bus plate, and further affects the performance of the entire battery product.

Summary of the Invention

Problems to be Solved by the Invention

[0004] This invention provides an electrode sheet that can reduce situations in which tabs overlap or are misaligned, release internal stress in the tabs, weaken tab distortion, improve the flatness and consistency of the end faces of the battery cells, and ensure the stability of welding to the bus plate.

[0005] This invention provides a winding core, and since the electrode sheet is provided, the winding core after the flattening process has a high degree of flatness at the end face, ensuring the stability of the welding with the bus plate and further guaranteeing the performance of the battery cell.

[0006] This invention provides a battery cell, and since the above-mentioned winding core is provided, the performance of the battery cell can be guaranteed. [Means for solving the problem]

[0007] In the first aspect, the embodiments of the present application are as follows: Electrode sheet body and The present invention provides an electrode sheet comprising: a plurality of tabs provided on the edge of the electrode sheet body, spaced apart along a first direction, and each tab having a notch at one end away from the electrode sheet body.

[0008] In one embodiment, if the length of the tab in the first direction is d1 and the height in the second direction is h1, then d1 = A1 × r + 1.15, and h1 / r = 0.2 to 0.9, where r is the radius of the winding core formed by winding the electrode sheet, A1 is a constant related to the radius of the winding core, and the second direction is perpendicular to the first direction.

[0009] In one embodiment, the range of d1 is 0 to 10 mm, and / or the range of h1 is 0 to 20 mm.

[0010] As an example of a selectable configuration, if the width of the notch in the first direction is d2, the range of d2 / d1 is 0.01 to 0.3, and if the height of the notch in the second direction is h2, the range of h2 / h1 is 0.3 to 0.9.

[0011] In one embodiment, the take range of d2 is 0 to 5 mm, and / or the take range of h2 is 0 to 19.9 mm.

[0012] In one embodiment, the tab has two first hypotenuses spaced apart along the first direction, and if the angle between the first hypotenuses and the top edge of the electrode sheet body to which the tab is connected is α, then α = 90° - (180 × d1) / (π × A2), where A2 is a constant related to the radius of the core formed by winding the electrode sheet. The tab further comprises a base and two second hypotenuses provided between the two first hypotenuses, the two second hypotenuses and the base jointly enclose and close to form the notch, the base is parallel to the first direction, the two second hypotenuses are parallel to each other, and the two second hypotenuses are each connected to both ends of the base, and if the angle between the second hypotenuses and the base is β, the range of β is α-20° to α+10°.

[0013] In one embodiment, the range of values ​​for α is 10° to 90°, and / or the range of values ​​for β is 10° to 90°.

[0014] In one embodiment, if the distance between two adjacent tabs along the first direction is d3, then the range of values ​​for d3 / d1 is 0.1 to 5.

[0015] In one embodiment, the value range of d3 is 0 to 20 mm.

[0016] In one embodiment, along the first direction, the notch is located at the central position of the tab.

[0017] In a second aspect, the embodiment of the present application provides a winding core comprising sequentially stacked separators, a positive electrode sheet, a separator, and a negative electrode sheet, wherein the positive electrode sheet and / or the negative electrode sheet employ the electrode sheet described in any one of the above items. The core is formed by winding the separator, the positive electrode sheet, the separator, and the negative electrode sheet that are sequentially laminated.

[0018] On the third side, an embodiment of the present application provides a battery cell including the above-mentioned core, a bus plate welded to the core, and a case in which the core and the bus plate are enclosed.

Advantages of the Invention

[0019] The beneficial effects of the present application are as follows.

[0020] In the electrode sheet according to the present application, a notch is provided at one end separated from the electrode sheet body of the tab, so that the internal stress of the tab can be released through the notch, the degree of warpage distortion of the tab is reduced, the flatness and consistency of the end face of the battery cell after the tab is flattened are improved, the stability of welding with the subsequent bus plate is ensured, and furthermore, the performance of the battery product is ensured.

[0021] / / 这里似乎原文有误,推测是想表示换行,所以我按照换行处理了 In the core according to the present application, since the above-mentioned electrode sheet is provided, the core after being flattened has a high flatness of the end face, the stability of welding with the bus plate is ensured, and furthermore, the performance of the battery product is ensured.

[0022] In the battery cell according to the present application, since the above-mentioned core is provided, the performance of the battery cell can be ensured.

Brief Description of the Drawings

[0023] [Figure 1] It is a structural schematic diagram of an electrode sheet body provided with a full tab according to an embodiment of the present application. [Figure 2] It is a structural schematic diagram of an electrode sheet according to an embodiment of the present application. [Figure 3] It is a structural schematic diagram of different types of tabs according to an embodiment of the present application. [Figure 4] It is a partially enlarged view of an electrode sheet according to an embodiment of the present application. [Figure 5]It is a schematic structural diagram of a core according to an embodiment of the present application. [Figure 6] It is a schematic structural diagram of a battery cell according to an embodiment of the present application.

Mode for Carrying Out the Invention

[0024] In the description of the present application, unless otherwise clearly specified and limited, the terms "connected", "connected to", and "fixed" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated, a mechanical connection, an electrical connection, directly connected, or indirectly connected through an intermediate medium, or it may be the internal communication between two elements or the interaction relationship between two elements. Those skilled in the art can understand the specific meaning of the above terms in the present application according to the specific situation.

[0025] In the present application, unless otherwise clearly specified and limited, the fact that the first feature is "above" or "below" the second feature may include direct contact between the first feature and the second feature, or the first feature and the second feature do not directly contact, and may include contact through other features therebetween. Further, the fact that the first feature is "above", "above and above", and "upper surface" of the second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the horizontal height of the first feature is higher than that of the second feature. The fact that the first feature is "below", "below and below", and "lower surface" of the second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the horizontal height of the first feature is lower than that of the second feature.

[0026] In the description of this embodiment, the orientation and positional relationship terms such as "above", "below", "left", "right", etc. are based on the orientation and positional relationship shown in the drawings, and are only for facilitating the explanation and simplifying the operation, and do not indicate or imply that such a device or element must have a specific orientation and be configured and operated in a specific orientation. Therefore, it cannot be understood as limiting the present application. Also, the terms "first" and "second" are only for the purpose of distinction in the description and do not include any special meaning.

[0027] As shown in Figure 2, this embodiment provides an electrode sheet comprising an electrode sheet body 10 and tabs 20, wherein a plurality of tabs 20 are provided on the upper edge of the electrode sheet body 10, and the plurality of tabs 20 are spaced apart along the first direction, and the specific number of tabs 20 can be adaptively selected according to actual needs and is not specifically limited here. As shown in Figure 1, the tabs 20 are obtained by laser die-cutting full tabs 30 provided on the electrode sheet body 10. Before die-cutting, the electrode sheet consisting of the electrode sheet body 10 and full tabs 30 is a rectangular foil material. The electrode sheet may be a positive electrode sheet and / or a negative electrode sheet, and if the electrode sheet is a positive electrode sheet, the base material of the positive electrode sheet may be aluminum foil, and if the electrode sheet is a negative electrode sheet, the base material of the negative electrode sheet may be copper foil. For ease of understanding, the length direction of the electrode sheet body 10 is defined as the first direction, and the width direction of the electrode sheet body 10 is defined as the second direction.

[0028] The electrode sheet described above reduces the equipment requirements for flattening the tabs 20 by providing multiple tabs 20 on the edge of the electrode sheet body 10. Compared to flattening a full tab 30, providing the tabs as described above reduces situations where the tabs 20 overlap or interfere with each other, and ensures the flatness of the tabs 20 after they have been flattened or hammered, which is advantageous for the stability of welding with the subsequent bus plate.

[0029] As shown in Figure 2, in this embodiment, a notch 22 is provided at one end of each tab 20 away from the electrode sheet body 10. Internal stress is the stress that remains inside an object after an external load has been removed, and it can be understood that this is caused by a non-uniform change in volume in the macroscopic or microscopic structure inside the material. In the case of a metal tab 20, during the process of flattening or hammering the tab 20, the external load bends the tab 20, and due to the interaction between atoms, the tab 20 spontaneously generates internal stress to resist the action of the external force. After the external force is removed, the internal stress causes the tab 20 to tend to recover to its pre-deformation state, but some atoms cannot return to their equilibrium position against the resistance force, and the interaction force between atoms continues to exist, causing the phenomenon of warping deformation. Therefore, by providing the notch 22, the restraining force on the outside of the atoms at the edge of the notch 22 becomes almost zero, allowing the atoms to move freely to the equilibrium position. As a result, a considerable portion of the internal stress in the area near the notch 22 is rapidly released, causing the tab 20 to lose the driving force for warping deformation and achieving stress reduction or release. This ultimately improves the warping deformation of the tab 20, increasing the flatness and consistency of the end face of the core after the tab 20 has been flattened, ensuring the stability of the welding with the subsequent bus plate, and further guaranteeing the performance of the battery cell.

[0030] As shown in Figure 2, in one embodiment, the tab 20 may have a parallelogram structure, and the shape of the notch 22 in the tab 20 may also be a parallelogram. In another embodiment, the shape of the tab 20 and the notch 22 may be any one of the three structural forms shown in Figure 3. Figure 3 shows only three of the structural forms of the tab 20, and in other embodiments, the shape of the tab 20 and the notch 22 may be trapezoidal, semicircular, arched, or other shapes, and is not specifically limited here. In this embodiment, the case where the tab 20 and the notch 22 are parallelograms will be explained as an example.

[0031] The tab sizes differ for different battery cell types; that is, the tab size needs to be rationally designed according to the radius of the battery cell to guarantee the performance of different battery cell types. As shown in Figure 4, if the length of tab 20 in the first direction is d1 and the height in the second direction is h1, then d1 = A1 × r + 1.15, and h1 / r = 0.2 to 0.9, where r is the radius of the winding core formed by winding the electrode sheet, and A1 is a constant related to the radius of the winding core. A1 is related to the selection of the battery cell radius, and after the radius of the battery cell is determined, A1 approximates a constant and does not need to be specifically limited here; it can be flexibly selected according to the actual needs. By rationally designing d1 and h1, the performance of the battery cell can be guaranteed. Exemplary, the ratio of h1 to r may be 0.25, 0.35, 0.45, 0.55, 0.65, 0.75, or 0.85, etc.

[0032] Exemplary, as shown in Figure 4, the range of values ​​for the length d1 of a single tab 20 in the first direction is 0 to 10 mm. By setting the length d1 of the tab 20 in the first direction within this range, the needs of battery cells of different radii can be met, and any value within this range can be selected for d1 as long as the mathematical relationship between d1 and r is satisfied. At the same time, it is possible to reduce situations in which the tabs 20 overlap or interfere with each other and to ensure the flatness of the tabs 20 after they have been flattened or hammered. Exemplary, the length d1 of a single tab 20 in the first direction may be 2 mm, 4 mm, 6 mm, 8 mm, or 10 mm, as long as the mathematical relationship between d1 and r is satisfied.

[0033] Exemplary, the range of values ​​for the height h1 of tab 20 in the second direction is 0 to 20 mm. By setting the height h1 of tab 20 in the second direction within the above range, it is possible not only to meet the needs of battery cells of different radii, but also to reduce situations in which the tabs 20 overlap or interfere with each other after being flattened or hammered, thereby ensuring the flatness of the tabs 20 after being flattened or hammered. Exemplary, the height h1 of tab 20 in the second direction may be 4 mm, 8 mm, 12 mm, 16 mm, or 20 mm, as long as the ratio relationship between h1 and r is satisfied.

[0034] As shown in Figure 4, the tab 20 has two first hypotenuses 21 spaced apart along the first direction, and the angle between the first hypotenuses 21 and the top edge 11 of the electrode sheet body 10 to which the tab is connected is α. For different types of battery cells, α is related to the length d1 of a single tab 20 in the first direction and the radius of the winding core, that is, α must satisfy the formula α = 90° - (180 × d1) / (π × A2), where A2 is a constant related to the radius of the winding core. A2 is related to the selection of the radius of the winding core, and after the radius of the winding core is determined, A2 approximates a constant and does not need to be specifically limited here, and can be flexibly selected according to actual needs.

[0035] For example, the range of the angle α between the first hypotenuse 21 and the top edge 11 of the electrode sheet body 10 is 10° to 90°, and when α = 90°, the tab 20 is rectangular. By rationally setting the angle α of the tab 20, firstly, the needs of battery cells of different radii can be met and the performance of the battery cells can be guaranteed. Secondly, when the tab 20 is flattened, the constraint force between the metals becomes smaller, thereby reducing situations in which the tabs 20 overlap or interfere with each other, effectively preventing eversion of the edges of the tab 20, and guaranteeing the flatness after the tab 20 is flattened or hammered. This prevents everted edges of the tab 20 from scratching and damaging the inner wall of the battery case, and at the same time reduces the generation of metal shavings, preventing metal shavings from remaining inside the battery, causing a short circuit and reducing the battery production yield. For example, the angle α between the first hypotenuse 21 and the top edge 11 of the electrode sheet body 10 may be 20°, 30°, 40°, 50°, 60°, 70°, or 80°, as long as the mathematical relationship between α and d1 is satisfied. Figure 4 shows only the case where the first hypotenuse 21 is inclined toward the positive direction of X; in other embodiments, the first hypotenuse 21 may be inclined toward the negative direction of X. In conjunction with Figures 2 and 4, the multiple tabs 20 are distributed at equal intervals along the first direction on the upper edge of the electrode sheet body 10, which is advantageous for subsequent winding and flattening. With this in mind, if the distance between two adjacent tabs 20 along the first direction is d3, then the range of d3 / d1 is 0.1 to 5. Within this ratio range, not only can the performance of the battery cells be guaranteed, but the restraining force between the metals can also be effectively reduced, decreasing situations in which the tabs 20 overlap or interfere with each other, and ensuring the flatness of the tabs 20 after they have been flattened or hammered. For example, the ratio of d3 to d1 may be 1.5, 2, 2.5, 3, 3.5, 4, or 4.5, etc.

[0036] Exemplary, the range of values ​​for the distance d3 between two adjacent tabs 20 is 0 to 20 mm. By setting the distance d3 between two adjacent tabs 20 within the above range, not only can the performance of the battery cell be guaranteed, but the constraint force between the metals can also be effectively reduced, the situations in which the tabs 20 overlap or interfere with each other can be reduced, and the flatness of the tabs 20 after being flattened or hammered can also be guaranteed. Exemplary, the distance d3 between two adjacent tabs 20 may be 4 mm, 8 mm, 12 mm, 16 mm, or 20 mm, as long as the ratio relationship between d3 and d1 is satisfied. In this embodiment, the electrode sheet allows for easy processing of the tabs 20 by designing the shape, length, height, and distance between adjacent tabs 20. Furthermore, when the tabs 20 are flattened, the restraining force between the metals is reduced, thereby reducing situations where the tabs 20 overlap or interfere with each other. This ensures the flatness of the tabs 20 after they are flattened or hammered, which is advantageous for the stability of welding with the subsequent bus plate and guarantees the overall performance of the battery cell.

[0037] Preferably, as shown in Figure 4, the notch 22 is located in the center of the tab 20 along the first direction. By providing it in this way, the tabs 20 on both sides of the notch 22 are evenly distributed, resulting in a better effect of releasing internal stress.

[0038] As shown in Figure 4, the width of the notch 22 in the first direction is d2, the height of the notch 22 in the second direction is h2, the range of values ​​for d2 / d1 is 0.01 to 0.3, and the range of values ​​for h2 / h1 is 0.3 to 0.9. If the ratios are within the above ranges, the internal stress of the tab 20 can be effectively released and the warping deformation of the tab 20 can be improved, provided that the performance of the battery cell is guaranteed. For example, the ratio of d2 to d1 may be 0.1, 0.15, 0.2, 0.25, or 0.28, and the ratio of h2 to h1 may be 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, or 0.8.

[0039] For example, the range of width d2 of the notch 22 in the first direction is 0 to 5 mm. By setting the width d2 of the notch 22 in the first direction within the above range, the internal stress of the tab 20 can be better released and the degree of strain of the tab 20 can be reduced, while ensuring the performance of the battery cell. For example, the width d2 of the notch 22 in the first direction may be 1 mm, 2 mm, 3 mm, 4 mm, or 5 mm, as long as the ratio relationship between d2 and d1 is satisfied.

[0040] For example, the range of height h2 in the second direction of the notch 22 is 0 to 19.9 mm. By setting the height h2 in the second direction of the notch 22 within the above range, the internal stress of the tab 20 can be better released and the degree of strain of the tab 20 can be reduced, while ensuring the performance of the battery cell. For example, the height h2 in the second direction of the notch 22 may be 4 mm, 8 mm, 12 mm, 16 mm, or 19 mm, as long as the ratio relationship between h2 and h1 is satisfied.

[0041] The tab 20 further has a base 221 and two second hypotenuses 222 provided between two first hypotenuses 21. The two second hypotenuses 222 and the base 221 jointly enclose and close a notch 22. The base 221 is parallel to the first direction, the two second hypotenuses 222 are parallel to each other, and the two second hypotenuses 222 are each connected to both ends of the base 221. If the angle between the second hypotenuses 222 and the base 221 is β, then the range of values ​​for β is α-20° to α+10°. By setting β within the above range, the internal stress of the tab 20 can be better released, and the warping deformation of the tab 20 can be improved. Exemplaryly, β may be α-10°, α-5°, α, α+5°, or α+10°, etc.

[0042] Exemplary, the range of values ​​for the angle β between the second hypotenuse 222 and the base 221 is 10° to 90°. By setting the angle β within the above range, the internal stress of the tab 20 is better released, the degree of strain of the tab 20 is reduced, the flatness and consistency of the end face of the winding core after the tab 20 has been flattened is improved, the stability of welding with the subsequent bus plate is ensured, and the performance of the battery cell can be further improved. Exemplary, the angle β may be 20°, 30°, 40°, 50°, 60°, 70°, or 80°, as long as the relationship between β and α is satisfied. Figure 4 shows only the case where the second hypotenuse 222 is inclined toward the positive direction of X, but in other embodiments, the second hypotenuse 222 may be inclined toward the negative direction of X. Preferably, in actual production, the angle β and the angle α are usually made equal to facilitate processing.

[0043] This embodiment further provides a winding core comprising sequentially stacked separators 5, positive electrode sheet 6, separator 5, and negative electrode sheet 4, as shown in Figure 5, wherein the positive electrode sheet 6 and / or negative electrode sheet 4 employ the electrode sheets described above. During the manufacture of the winding core, the separators 5, positive electrode sheet 6, separator 5, and negative electrode sheet 4 are sequentially stacked, and then wound to form a winding core. The tabs 20 of the positive electrode sheet 6 and the tabs 20 of the negative electrode sheet 4 are located at both ends of the winding core, and the tabs 20 at both ends are flattened by crumpling or hammering, then welded to the corresponding bus plate, and finally assembled to manufacture a battery cell.

[0044] In this embodiment, the core is provided with the electrode sheet described above. As a result, the core after the flattening process has a high degree of flatness at its end face, ensuring the stability of the welding to the bus plate and further guaranteeing the performance of the battery cell.

[0045] This embodiment further provides a battery cell comprising the winding core 3 described above, a bus plate 1 welded to the winding core 3, and a case 2 in which the winding core 3 and the bus plate 1 are enclosed, as shown in Figure 6. The battery cell is formed when the winding core 3 is placed in the case and sealed. The other components and operating processes of the battery cell are all known to those skilled in the art and will not be described in detail here. Since the battery cell of this embodiment is provided with the winding core described above, the performance of the battery cell can be guaranteed. [Explanation of symbols]

[0046] 10... Electrode sheet body, 11... Top edge, 20... Tab, 21... First hypotenuse, 22... Notch, 221... Base edge, 222... Second hypotenuse, 30... Full tab, 1... Bath plate, 2... Case, 3... Core, 4... Negative electrode sheet, 5... Separator, 6... Positive electrode sheet.

Claims

1. Electrode sheet body (10) and An electrode sheet comprising: a plurality of tabs (20) provided on the edge of the electrode sheet body (10), spaced apart along a first direction, and each tab (20) having a notch (22) at one end away from the electrode sheet body (10); If the length of the tab (20) in the first direction is d1 and the height in the second direction is h1, then d1 = A1 × r + 1.15, h1 / r = 0.2 to 0.9, where r is the radius of the core formed by winding the electrode sheet, A1 is a constant predetermined according to the radius r of the core, the second direction is perpendicular to the first direction, and the units of d1, h1 and r are all millimeters. Electrode sheet.

2. The size setting includes at least one of the following conditions: the range of values ​​for d1 is 0 to 10 mm, and the range of values ​​for h1 is 0 to 20 mm. The electrode sheet according to claim 1.

3. If the width of the notch (22) in the first direction is d2, the range of d2 / d1 is 0.01 to 0.3, and if the height of the notch (22) in the second direction is h2, the range of h2 / h1 is 0.3 to 0.9, and both d2 and h2 are in millimeters. The electrode sheet according to claim 1.

4. At a minimum, the size setting includes at least one of the following conditions: the range of d2 is 0 to 5 mm, and the range of h2 is 0 to 19.9 mm. The electrode sheet according to claim 3.

5. The tab (20) has two first hypotenuses (21) spaced apart along the first direction, and if the angle between the first hypotenuses (21) and the top edge (11) of the electrode sheet body (10) to which the tab (20) is connected is α, then α = 90° - (180 × d1) / (π × A2), where A2 is a constant predetermined according to the radius r of the winding core. The tab (20) further comprises a base (221) and two second hypotenuses (222) provided between the two first hypotenuses (21), the two second hypotenuses (222) and the base (221) jointly enclose and close to form the notch (22), the base (221) is parallel to the first direction, the two second hypotenuses (222) are parallel to each other, and the two second hypotenuses (222) are each connected to both ends of the base (221), and if the angle between the second hypotenuses (222) and the base (221) is β, the range of β is α-20° to α+10°. The electrode sheet according to claim 1.

6. At a minimum, the size setting includes at least one of the following conditions: the range of values ​​for α is 10° to 90°, and the range of values ​​for β is 10° to 90°. The electrode sheet according to claim 5.

7. If the distance between two adjacent tabs (20) along the first direction is d3, then the range of values ​​for d3 / d1 is 0.1 to 5, and the unit of d3 is millimeters. The electrode sheet according to claim 1.

8. The value range for d3 is 0 to 20 mm. The electrode sheet according to claim 7.

9. Along the first direction, the notch (22) is located at the central position of the tab (20), The electrode sheet according to any one of claims 1 to 8.

10. A winding core comprising sequentially stacked separators, a positive electrode sheet, a separator, and a negative electrode sheet, wherein at least one of the positive electrode sheet and the negative electrode sheet is an electrode sheet as described in any one of claims 1 to 8, The winding core is formed by winding sequentially stacked separators, positive electrode sheets, separators, and negative electrode sheets. Core.

11. The invention comprises a core as described in claim 10, a bus plate welded to the core, and a case in which the core and the bus plate are enclosed. Battery cell.

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