Electrode sheet, winding core, and battery cell

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] The present application relates to the technical field of batteries, for example, electrode sheets, winding cores, and battery cells. [Background technology]

[0002] In the battery cells of the related art, full-tab electrode sheets are often adopted, and when manufacturing the battery cells, the full-tab electrode sheet is first wound to form a winding core, and then the full tabs of the winding core are rolled or stamped flat, and then welded to a bus plate, and finally assembled to manufacture the battery cell. However, in the process of rolling or stamping flat, the full tabs are likely to overlap or become misaligned, which results in the end of the winding core not being flat, and the stability of welding with the bus plate is reduced, which further affects the performance of the entire battery product.

[0003] The electrode sheet in the related art generally adopts an electrode sheet with multiple tabs, that is, a full tab in the electrode sheet is formed into multiple single tabs at intervals by laser die cutting, and the multiple tabs are transformed into an annular shape, that is, into the end surface of the winding core, in the process of flattening or stamping the tabs. The smaller the width of the tab, the higher the conformity of the end surface consisting of multiple tabs, but the width of the tab cannot be made infinitesimal, so that in the actual process of bending the tab (i.e., the process of flattening or stamping the tab), there is an internal stress inside the tab, which causes the tab to warp during the bending process, and the resulting distortion seriously affects the effect of flattening or stamping the tab, and even affects the effect of welding with the subsequent bus plate, and further affects the performance of the entire battery product. Summary of the Invention [Problem to be solved by the invention]

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

[0005] The present application provides a winding core having the above-mentioned electrode sheet provided thereon, so that the winding core after being flattened has a high flatness at its end surface, ensuring the stability of the welding with the bus plate, and further ensuring the performance of the battery cell.

[0006] The present application 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 a first aspect, the present embodiment comprises: An electrode sheet body; An electrode sheet is provided comprising: a plurality of tabs provided on an edge of the electrode sheet body, the plurality of tabs being spaced apart along a first direction, each tab having a notch at one end remote from the electrode sheet body.

[0008] In one embodiment, if the length of the tab in the first direction is d1 and the height of the tab 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 a 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, d1 ranges from 0 to 10 mm and / or h1 ranges from 0 to 20 mm.

[0010] As an optional aspect, if the width of the notch in the first direction is d2, then d2 / d1 can take a value range of 0.01 to 0.3, and if the height of the notch in the second direction is h2, then h2 / h1 can take a value range of 0.3 to 0.9.

[0011] In one embodiment, d2 has a value range of 0 to 5 mm and / or h2 has a value range of 0 to 19.9 mm.

[0012] In one embodiment, the tab includes two first oblique sides spaced apart along the first direction, and if an included angle between the first oblique sides and a top side 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 a radius of a winding core formed by winding the electrode sheet, The tab further includes a base and two second hypotenuses between the two first hypotenuses, the two second hypotenuses and the base jointly enclose 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 connected to both ends of the base, and when an included angle between the second hypotenuses and the base is β, the range of β is α-20° to α+10°.

[0013] In one embodiment, α ranges from 10° to 90° and / or β ranges from 10° to 90°.

[0014] In one embodiment, if the distance between two adjacent tabs along the first direction is d3, then d3 / d1 has a value range of 0.1-5.

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

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

[0017] In a second aspect, an embodiment of the present application provides a winding core including a separator, a positive electrode sheet, a separator, and a negative electrode sheet, which are sequentially stacked, wherein the positive electrode sheet and / or the negative electrode sheet is an electrode sheet according to any one of the above aspects; The winding core is formed by winding the separator, the positive electrode sheet, the separator and the negative electrode sheet, which are stacked in this order.

[0018] In a third aspect, an embodiment of the present application provides a battery cell including the above-mentioned winding core, a bus plate welded to the winding core, and a case in which the winding core and the bus plate are enclosed. Effect 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 of the tab that is separated from the electrode sheet body, so that the internal stress of the tab can be released through the notch, the degree of warping distortion of the tab is reduced, and the flatness and consistency of the end face of the battery cell after the tab is flattened is improved, the stability of welding with the subsequent bus plate is ensured, and the performance of the battery product is further ensured.

[0021] Since the winding core according to the present application is provided with the above-mentioned electrode sheet, the winding core after being flattened has a high flatness at its end surface, which ensures the stability of the welding with the bus plate and further ensures the performance of the battery product.

[0022] Since the battery cell according to the present application is provided with the above-described winding core, the performance of the battery cell can be guaranteed. [Brief description of the drawings]

[0023] [Figure 1] FIG. 2 is a structural schematic diagram in which a full tab is provided on an electrode sheet main body according to an embodiment of the present application. [Diagram 2] FIG. 2 is a structural schematic diagram of an electrode sheet according to an embodiment of the present application. [Diagram 3] 1A to 1C are schematic structural diagrams of different types of tabs according to an embodiment of the present application. [Figure 4] FIG. 2 is a partially enlarged view of an electrode sheet according to an embodiment of the present application. [Diagram 5]FIG. 2 is a structural schematic diagram of a core according to an embodiment of the present application. [Figure 6] FIG. 2 is a structural schematic diagram of a battery cell according to an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] In the description of this application, unless otherwise clearly specified and limited, the terms "connected", "connected" and "fixed" should be understood in a broad sense, for example, may be fixedly connected, detachably connected, or integrated, may be mechanically connected, may be electrically connected, may be directly connected, may be indirectly connected via an intermediate medium, may be internal communication between two elements, or may be an interaction relationship between two elements. A person skilled in the art can understand the specific meaning of the above terms in the present application according to the specific situation.

[0025] In this application, unless otherwise expressly specified and limited, a first feature being "above" or "below" a second feature may include direct contact between the first feature and the second feature, or may include contact between the first feature and the second feature through another feature between them without direct contact. Furthermore, a first feature being "above," "above," and "on the upper surface" of a second feature may include the first feature being directly above and diagonally above the second feature, or may simply indicate that the horizontal height of the first feature is higher than that of the second feature. A first feature being "below," "below," and "on the lower surface" of a second feature may include the first feature being directly below and diagonally below the second feature, or may simply indicate that the horizontal height of the first feature is lower than that of the second feature.

[0026] In the description of the present embodiment, the orientations and positional relationships of the terms "upper", "lower", "left", "right", etc. are based on the orientations and positional relationships shown in the drawings, and are merely for ease of description and simplification of operation, and do not indicate or imply that such devices or elements must have a specific orientation, be configured and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first" and "second" are merely for distinction in the description, and do not have any special meaning.

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

[0028] The above-mentioned electrode sheet has multiple tabs 20 on the edges of the electrode sheet body 10, which can reduce the requirements for equipment required to flatten the tabs 20. Compared with flattening the full tabs 30, the above-mentioned arrangement can reduce the situation in which the tabs 20 overlap or interfere with each other, and can ensure the flatness of the tabs 20 after they are flattened or hammered flat, which is advantageous for the stability of welding to the subsequent bus plate.

[0029] As shown in FIG. 2, in this embodiment, each of the tabs 20 has a notch 22 at one end away from the electrode sheet body 10. The internal stress is the stress that remains inside the object after the external load is removed, and it can be understood that it is caused by the uneven change in volume of the macro or micro structure inside the material. In the case of a metal tab 20, in the process of kneading or flattening the tab 20, the external load causes the tab 20 to bend, 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, due to the internal stress, the tab 20 tends to recover before deformation, but some atoms cannot return to the equilibrium position against the resistance force, and the interaction force between atoms continues to exist, resulting in the phenomenon of warping deformation. Therefore, by providing the notch 22, the restraint force experienced by the outside of the atoms at the edge of the notch 22 is nearly zero, so that the atoms can move freely to their equilibrium position, and a significant 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, thereby achieving the effect of weakening or releasing the stress, and finally improving the warping deformation of the tab 20, enhancing the flatness and conformity of the end surface of the winding core after the tab 20 is rolled flat, ensuring the stability of the welding with the subsequent bus plate, and further ensuring the performance of the battery cell.

[0030] As shown in FIG. 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 further be any one of three structure types shown in FIG. 3. FIG. 3 only shows three structure types of the tab 20, and in other embodiments, the shape of the tab 20 and the notch 22 may further be a trapezoid, a semicircular shape, an arch shape, or other shapes, and is not specifically limited here. In this embodiment, the tab 20 and the notch 22 are described as a parallelogram shape as an example.

[0031] For battery cells of different models, the size of the tab is different, that is, the size of the tab needs to be reasonably designed according to the radius of the battery cell to ensure the performance of battery cells of different models. As shown in FIG. 4, 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, 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 radius of the battery cell, and after the radius of the battery cell is determined, A1 is approximated to a constant, and does not need to be specifically limited here, and may be flexibly selected according to actual needs. The performance of the battery cell can be guaranteed by reasonably designing d1 and h1. Exemplarily, 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] Exemplarily, as shown in FIG. 4, the length d1 of the single tab 20 in the first direction can range from 0 to 10 mm. By setting the length d1 of the tab 20 in the first direction within the above range, the needs of battery cells with different radii can be met, and as long as the mathematical relationship between d1 and r is satisfied, any value within the above range can be selected for d1, while reducing the situation in which the tabs 20 overlap or interfere with each other, and ensuring the flatness of the tabs 20 after being kneaded or hammered flat. Exemplarily, the length d1 of the single tab 20 in the first direction can 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] Exemplarily, the height h1 of the tab 20 in the second direction is in the range of 0 to 20 mm. By setting the height h1 of the tab 20 in the second direction within the above range, it is not only possible to meet the needs of battery cells with different radii, but also possible to reduce the situation in which the tabs 20 overlap or interfere with each other after being kneaded or hammered flat, and ensure the flatness of the tabs 20 after being kneaded or hammered flat. Exemplarily, the height h1 of the tab 20 in the second direction may be 4 mm, 8 mm, 12 mm, 16 mm, or 20 mm, as long as the ratio between h1 and r is satisfied.

[0034] As shown in Fig. 4, the tab 20 has two first oblique sides 21 spaced apart along the first direction, and the angle between the first oblique sides 21 and the top side 11 of the electrode sheet main body 10 to which the tab is connected is α, and for battery cells of different model numbers, 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 x d1) / (π x 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 is approximated to a constant, and does not need to be specifically limited here, but can be flexibly selected according to actual needs.

[0035] For example, the angle α between the first oblique side 21 and the top side 11 of the electrode sheet body 10 can be in the range of 10° to 90°, and when α=90°, the tab 20 is rectangular. By reasonably setting the angle α of the tab 20, firstly, the needs of battery cells with different radii can be met and the performance of the battery cell can be guaranteed, and secondly, when the tab 20 is flattened, the binding force between the metals is smaller, thereby reducing the situation in which the tabs 20 overlap or interfere with each other, effectively preventing the edge of the tab 20 from being warped outward, ensuring the flatness of the tab 20 after being flattened or hammered outward, preventing the edge of the outwardly warped tab 20 from scratching and damaging the inner wall of the battery case, and at the same time reducing the generation of metal chips, and preventing the metal chips from remaining inside the battery, causing the battery to short circuit and causing a decrease in the production yield of the battery. Exemplarily, the angle α between the first oblique side 21 and the top side 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. FIG. 4 only shows the case where the first oblique side 21 is inclined toward the positive direction of X, and in other embodiments, the first oblique side 21 may be inclined toward the negative direction of X. In combination with FIG. 2 and FIG. 4, the tabs 20 are distributed at equal intervals on the upper edge of the electrode sheet body 10 along the first direction, which is advantageous for subsequent rolling and flattening. Based on this, if the distance between two adjacent tabs 20 along the first direction is d3, the range of d3 / d1 is 0.1 to 5. Within this ratio range, it is not only possible to ensure the performance of the battery cell, but also to effectively reduce the binding force between metals, reduce the situation in which the tabs 20 overlap or interfere with each other, and ensure the flatness of the tabs 20 after being kneaded or hammered flat. For example, the ratio of d3 to d1 may be 1.5, 2, 2.5, 3, 3.5, 4, or 4.5, etc.

[0036] Exemplarily, the distance d3 between two adjacent tabs 20 is in the range of 0 to 20 mm. By setting the distance d3 between two adjacent tabs 20 within the above range, it is not only possible to ensure the performance of the battery cell, but also to effectively reduce the binding force between metals, reduce the situation in which the tabs 20 overlap or interfere with each other, and ensure the flatness of the tabs 20 after being kneaded or hammered flat. Exemplarily, 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 the electrode sheet of this embodiment, the shape, length, and height of the tabs 20 and the distance between two adjacent tabs 20 can be designed, which makes it easier to process the tabs 20. When the tabs 20 are flattened, the binding force between the metals is smaller, thereby reducing the situation in which the tabs 20 overlap or interfere with each other, and ensuring the flatness of the tabs 20 after being flattened or hammered flat, which is favorable for the stability of welding with the subsequent bus plate, and ensuring the overall performance of the battery cell.

[0037] Preferably, as shown in FIG. 4, the notch 22 is located at the center of the tab 20 along the first direction, so that the tabs 20 on both sides of the notch 22 are evenly distributed, and the effect of releasing internal stress is better.

[0038] 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 d2 / d1 is 0.01 to 0.3, and the range of h2 / h1 is 0.3 to 0.9, and within the above ratio ranges, it is possible to effectively release the internal stress of the tab 20 and improve the warpage deformation of the tab 20 under the premise of ensuring the performance of the battery cell. Exemplarily, the ratio of d2 to d1 may be 0.1, 0.15, 0.2, 0.25, or 0.28, etc., 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, etc.

[0039] Exemplarily, the width d2 of the notch 22 in the first direction is in the range of 0 to 5 mm. By setting the width d2 of the notch 22 in the first direction within the above range, it is possible to better release the internal stress of the tab 20 and reduce the degree of distortion of the tab 20, on the premise that the performance of the battery cell is guaranteed. Exemplarily, 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 proportional relationship between d2 and d1 is satisfied.

[0040] Exemplarily, the height h2 of the notch 22 in the second direction ranges from 0 to 19.9 mm. By setting the height h2 of the notch 22 in the second direction within the above range, it is possible to better release the internal stress of the tab 20 and reduce the degree of distortion of the tab 20, on the premise that the performance of the battery cell is guaranteed. Exemplarily, the height h2 of the notch 22 in the second direction may be 4 mm, 8 mm, 12 mm, 16 mm, or 19 mm, as long as the proportional relationship between h2 and h1 is satisfied.

[0041] The tab 20 further has a base 221 and two second oblique sides 222 between the two first oblique sides 21, and the two second oblique sides 222 and the base 221 jointly surround and close the notch 22, the base 221 is parallel to the first direction, the two second oblique sides 222 are parallel to each other, and the two second oblique sides 222 are connected to both ends of the base 221, respectively, and the included angle between the second oblique sides 222 and the base 221 is β, and the range of 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 warpage deformation of the tab 20 can be improved. Exemplarily, β may be α-10°, α-5°, α, α+5°, or α+10°, etc.

[0042] Exemplarily, the included angle β between the second oblique side 222 and the base side 221 is in the range of 10° to 90°. By setting the included angle β within the above range, the internal stress of the tab 20 can be better released, the degree of distortion of the tab 20 can be reduced, the flatness and conformity of the end surface of the winding core after the tab 20 is flattened can be improved, the stability of welding with the subsequent bus plate can be guaranteed, and the performance of the battery cell can be further improved. Exemplarily, the included angle β can be 20°, 30°, 40°, 50°, 60°, 70°, or 80°, as long as the relationship between β and α is satisfied. FIG. 4 shows only the case where the second oblique side 222 is inclined toward the positive direction of X, and in other embodiments, the second oblique side 222 can be inclined toward the negative direction of X. Preferably, the included angle β and the included angle α are usually equal to each other in order to facilitate processing during actual production.

[0043] 5, the present embodiment further provides a winding core including a separator 5, a positive electrode sheet 6, a separator 5, and a negative electrode sheet 4, which are sequentially stacked, and the positive electrode sheet 6 and / or the negative electrode sheet 4 adopt the above-mentioned electrode sheet. When manufacturing the winding core, the separator 5, the positive electrode sheet 6, the separator 5, and the negative electrode sheet 4 are sequentially stacked and then wound to form a winding core, in which the tabs 20 of the positive electrode sheet 6 and the tabs 20 of the negative electrode sheet 4 are respectively located at both ends of the winding core, and the tabs 20 at both ends are kneaded or punched flat, and then welded to the corresponding bus plates, and finally assembled to manufacture a battery cell.

[0044] Because the electrode sheet is provided on the winding core of this embodiment, the end surface of the winding core after being rolled flat has a high degree of flatness, ensuring the stability of the welding to the bus plate and further ensuring the performance of the battery cell.

[0045] As shown in Fig. 6, this embodiment further provides a battery cell including the above-mentioned winding core 3, 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. The winding core 3 is inserted into the case and sealed to form the battery cell. Other configurations and operation 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 above-mentioned winding core, the performance of the battery cell can be guaranteed. [Explanation of symbols]

[0046] Reference Signs List 10 Electrode sheet body, 11 Top edge, 20 Tab, 21 First hypotenuse, 22 Notch, 221 Bottom edge, 222 Second hypotenuse, 30 Full tab, 1 Bus plate, 2 Case, 3 Winding core, 4 Negative electrode sheet, 5 Separator, 6 Positive electrode sheet.

Claims

1. An electrode sheet body (10); a plurality of tabs (20) provided at an edge of the electrode sheet body (10), the plurality of tabs being spaced apart along a first direction, each of the tabs having a notch (22) at one end remote from the electrode sheet body (10); Electrode sheet.

2. 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 x r + 1.15, h1 / r = 0.2 to 0.9, r is the radius of a 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. The electrode sheet according to claim 1 .

3. At least one of the size setting conditions is included: d1 is in the range of 0 to 10 mm; and h1 is in the range of 0 to 20 mm. The electrode sheet according to claim 2 .

4. If the width of the notch (22) in the first direction is d2, the range of values ​​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 values ​​of h2 / h1 is 0.3 to 0.

9. The electrode sheet according to claim 2 .

5. At least one of the size setting conditions includes: d2 has a value range of 0 to 5 mm; and h2 has a value range of 0 to 19.9 mm. The electrode sheet according to claim 4 .

6. The tab (20) has two first oblique sides (21) spaced apart along the first direction, and if an included angle between the first oblique side (21) and the top side (11) of the electrode sheet main body (10) to which the tab (20) is connected is α, then α=90°-(180×d1) / (π×A2), where A2 is a constant related to the radius of a winding core formed by winding the electrode sheet, The tab (20) further comprises a base (221) and two second oblique sides (222) disposed between the two first oblique sides (21), the two second oblique sides (222) and the base (221) jointly surround and close the notch (22), the base (221) is parallel to the first direction, the two second oblique sides (222) are parallel to each other, and the two second oblique sides (222) are respectively connected to both ends of the base (221), and if an included angle between the second oblique sides (222) and the base (221) is β, the range of β is α-20° to α+10°. The electrode sheet according to claim 2 .

7. At least one of the size setting conditions is included: the range of α is 10° to 90°; and the range of β is 10° to 90°. The electrode sheet according to claim 6 .

8. If the distance between two adjacent tabs (20) along the first direction is d3, then d3 / d1 has a value range of 0.1 to 5; The electrode sheet according to claim 2 .

9. The range of values ​​for d3 is 0 to 20 mm. The electrode sheet according to claim 8.

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

11. The battery includes a separator, a positive electrode sheet, a separator, and a negative electrode sheet, which are laminated in this order, and at least one of the positive electrode sheet and the negative electrode sheet employs the electrode sheet according to any one of claims 1 to 9; The winding core is formed by winding the separator, the positive electrode sheet, the separator, and the negative electrode sheet, which are stacked in this order. Roll core.

12. a winding core according to claim 11, a bus plate welded to the winding core, and a case in which the winding core and the bus plate are enclosed. Battery cell.

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