A positive electrode sheet and a battery cell thereof
By designing embossed and tilted regions with specific structures on the positive electrode, the problem of cell degradation caused by insufficient electrolyte was solved, and the long-term cycle performance of the cell was improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ZHEJIANG LIWINON ENERGY TECHNOLOGY CO LTD
- Filing Date
- 2025-06-16
- Publication Date
- 2026-07-14
AI Technical Summary
The concave and convex textures formed on the positive electrode sheet by the traditional positive electrode embossing process cannot effectively improve the electrolyte retention of the inner winding of the cell, resulting in insufficient electrolyte, which can easily cause the cell to drain rapidly and affect long-term cycle performance.
The positive electrode sheet is designed with a vertical edge area and an embossed area. The embossed area has a first inclined area and a second inclined area with opposite inclination directions to form a first groove. The embossed area has a first embossed area and a second embossed area with different diameters. The first embossed area and the second embossed area are arranged alternately, and the inclined areas are arranged alternately to increase the central wetting space and improve the liquid retention.
By optimizing the embossing design, the wetting space and electrolyte retention capacity of the electrolyte are increased, preventing cell leakage and improving the long-term cycle performance of the cells.
Smart Images
Figure CN224501896U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the technical field of batteries, and in particular to a positive electrode sheet and its cell. Background Technology
[0002] In existing technologies, positive electrode embossing is a technique that mechanically presses specific concave and convex patterns onto the surface of the battery's positive electrode sheet. Embossing on the positive electrode sheet can significantly improve electrolyte wettability during the charging and discharging process of lithium-ion batteries, reduce lithium plating at corners, and thus improve the cell's cycle stability and lifespan. However, traditional embossing methods involve embossing on the positive electrode surface, primarily creating uniformly distributed concave circles of the same depth and diameter. This type of embossing has little effect on improving electrolyte retention within the inner winding of the cell, easily leading to insufficient electrolyte and causing the cell to "drain," which in turn affects the cell's long-term cycle performance. Utility Model Content
[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. It provides a positive electrode sheet and its cell, which increases the electrolyte retention in the middle of the inner winding of the cell, preventing the cell from failing due to insufficient electrolyte and improving the long-term cycle performance of the cell.
[0004] To achieve the above objectives, this utility model provides a positive electrode sheet having a first direction, a second direction, and a third direction perpendicular to each other, including an edge region and an embossed region. The edge region surrounds the embossed region. The embossed region has a first inclined region and a second inclined region with opposite inclination directions. The first inclined region and the second inclined region intersect to form a first groove. The first groove has a plurality of circular first embossing and second embossing. The first groove, the first embossing, and the second embossing are recessed to the same side in the first direction. The diameter of the first embossing is smaller than the diameter of the second embossing. The first embossing and the second embossing are arranged at intervals.
[0005] As a preferred embodiment, the embossed area includes an edge embossed portion and a central embossed portion. The edge embossed portion is disposed at both ends of the central embossed portion in the second direction. The edge embossed portion is formed by a plurality of first embossed patterns arranged at intervals along the third direction. The central embossed portion includes an embossed subgroup, which is formed by a plurality of first embossed patterns and second embossed patterns arranged alternately at intervals along the third direction.
[0006] As a preferred embodiment, multiple embossed subgroups are provided, and the multiple embossed subgroups are spaced apart along the second direction. The first embossing and the second embossing of adjacent embossed subgroups are arranged alternately and spaced apart along the second direction.
[0007] As a preferred embodiment, the distance 'a' between adjacent first embossings is set at 250-350 micrometers.
[0008] As a preferred embodiment, the minimum distance b between the first embossing and the second embossing is set at 50-150 micrometers.
[0009] As a preferred embodiment, the diameter of the first embossed pattern is X1, and the diameter of the second embossed pattern is X2, wherein 4≥X2 / X1≥2.
[0010] As a preferred embodiment, the dimension of the edge region in the second direction is W mm, where 1 ≥ W ≥ 0.5.
[0011] As a preferred embodiment, the dimension of the edge region at one end in the third direction is L1mm, 10≥L1≥4; and / or the dimension of the edge region at the other end in the third direction is L2mm, 4.5≥L2≥1.5.
[0012] As a preferred embodiment, the first inclined region is provided with a first bridge surface, and adjacent first embossing patterns in the first inclined region are connected through the first bridge surface, and the first embossing pattern and the second embossing pattern in the first inclined region are connected through the first bridge surface.
[0013] The second inclined region is provided with a second bridge surface. Adjacent first embossing patterns in the second inclined region are connected through the second bridge surface. The first embossing pattern and the second embossing pattern in the second inclined region are connected through the second bridge surface. The inclination directions of the first bridge surface and the second bridge surface are opposite.
[0014] A battery cell includes a negative electrode, a separator, and a positive electrode, wherein the positive electrode, the separator, and the negative electrode are sequentially stacked and wound to form the battery cell.
[0015] Compared with existing technologies, the positive electrode sheet and its battery cell of this utility model have the following advantages: It includes an edge region and an embossed region. The embossed region contains a first embossed region and a second embossed region with different diameters. The first and second embossed regions are concave along a first direction, guiding the electrolyte to diffuse rapidly and reducing wetting dead zones. The diameter of the first embossed region is smaller than that of the second embossed region. The first and second embossed regions are arranged alternately, shortening the distance between them and improving wetting uniformity. The embossed region includes a first inclined region and a second inclined region with opposite inclination directions. The first and second inclined regions intersect to form a first groove. The deepest part of the first groove is located in the middle of the embossed region. The middle of the embossed region is a region where electrolyte penetration is slow and difficult. By increasing the wetting space in the middle of the embossed region, the liquid retention volume and amount in the middle of the embossed region are increased, avoiding battery cell failure due to insufficient electrolyte and improving the long-term cycle performance of the battery cell. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present utility model.
[0017] Figure 2 This is an embodiment of the present utility model. Figure 1 The cross-sectional view at point AA.
[0018] Figure 3 This is an embodiment of the present utility model. Figure 1 The cross-sectional view at point BB.
[0019] Figure 4 This is a schematic diagram of the edge embossed part and the middle embossed part of an embodiment of this utility model.
[0020] Figure 5 This is a schematic diagram of the embossed seed assembly according to an embodiment of the present invention.
[0021] In the picture:
[0022] 10. Edge area;
[0023] 20. Embossed area; 21. First inclined area; 22. First bridge surface; 23. Second inclined area; 24. Second bridge surface; 25. First groove; 26. First embossing; 27. Second embossing; 28. Edge embossed part; 29. Central embossed part; 30. Embossed sub-group; 31. First embossed area; 32. Second embossed area; 33. Third embossed area;
[0024] X, first direction; Y, second direction; Z, third direction. Detailed Implementation
[0025] The specific embodiments of this utility model will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this utility model, but are not intended to limit its scope.
[0026] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" used to indicate the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.
[0027] In the description of this utility model, it should be understood that the terms "connected," "linked," and "fixed," etc., used in this utility model should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or a welded connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly defined. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0028] like Figures 1 to 2 As shown, a preferred embodiment of the present invention provides a positive electrode sheet having mutually perpendicular first directions X, second directions Y, and third directions Z, including an edge region 10 and an embossed region 20. The edge region 10 is arranged around the embossed region 20. The embossed region 20 has a first inclined region 21 and a second inclined region 23 with opposite inclination directions. The first inclined region 21 and the second inclined region 23 intersect to form a first groove 25. The first groove 25 has a plurality of circular first embossings 26 and second embossings 27. The first groove 25, the first embossings 26 and the second embossings 27 are recessed towards the same side in the first direction X. The diameter of the first embossings 26 is smaller than the diameter of the second embossings 27. The first embossings 26 and the second embossings 27 are arranged at intervals.
[0029] A battery cell includes a negative electrode, a separator, and a positive electrode, wherein the positive electrode, the separator, and the negative electrode are sequentially stacked and wound to form the battery cell.
[0030] The positive electrode sheet and its cell of this utility model include an edge region 10 and an embossed region 20. First embossing 26 and second embossing 27 with different diameters are pressed into the embossed region 20. The first embossing 26 and second embossing 27 are recessed along a first direction X to guide the rapid diffusion of the electrolyte and reduce wetting dead zones. The diameter of the first embossing 26 is smaller than the diameter of the second embossing 27. The first embossing 26 and second embossing 27 are arranged alternately to shorten the distance between them and improve wetting uniformity. The embossed area 20 includes a first inclined area 21 and a second inclined area 23 with opposite inclination directions. The first inclined area 21 and the second inclined area 23 intersect to form a first groove 25. The deepest part of the first groove 25 is located in the middle of the embossed area 20. The middle part of the embossed area 20 is a region where electrolyte penetration is slow and difficult. By increasing the wetting space in the middle of the embossed area 20, the liquid retention volume and liquid retention amount in the middle of the embossed area 20 are increased, avoiding cell draining due to insufficient electrolyte and improving the long-term cycle performance of the cell.
[0031] Among them, "cell drop" usually refers to a sudden and sharp drop in voltage or capacity of a battery during the cycle (especially in the middle and later stages).
[0032] Furthermore, the embossed area 20 includes an edge embossed portion 28 and a central embossed portion 29. The edge embossed portion 28 is disposed at both ends of the central embossed portion 29 in the second direction Y. The edge embossed portion 28 is formed by a plurality of first embossed pieces 26 arranged at intervals along the third direction Z. The central embossed portion 29 includes an embossed subgroup 30, which is formed by a plurality of first embossed pieces 26 and second embossed pieces 27 arranged alternately along the third direction Z. Only first embossed pieces 26 are provided in the edge embossed portion 28, while the central embossed portion 29 is provided with alternating first embossed pieces 26 and second embossed pieces 27. The diameter of the first embossed piece 26 is smaller than that of the second embossed piece 27. The embossed area 20 is provided with only first embossed pieces 26 at both ends in the second direction Y, and the second embossed pieces 27 are provided in the central embossed portion 29, so that there can be a larger gradient in the second direction Y toward the center of the embossed area 20, which helps the electrolyte to flow from the edge of the embossed portion to the center.
[0033] Furthermore, multiple embossed flower groups 30 are provided, spaced apart along the second direction Y. The first embossed flower 26 and the second embossed flower 27 of adjacent embossed flower groups 30 are arranged alternately along the second direction Y. Each embossed flower group 30 includes a second embossed flower 27 with a larger diameter. Providing multiple embossed flower groups 30 helps to further increase the wetting space of the central embossed area 20, thereby improving the liquid retention volume and amount in the central part of the embossed area 20.
[0034] Furthermore, the distance 'a' between adjacent first embossings 26 is set at 250-350 micrometers. If the spacing between the first embossings 26 is too small, the current collector (aluminum foil / copper foil) between adjacent first embossing areas 31 will be overstretched, forming weak areas that are prone to breakage or microcracks during slitting, winding, or charging and discharging.
[0035] In one embodiment, the distance a between adjacent first embossings 26 is set at 300 micrometers.
[0036] Furthermore, the minimum distance b between the first embossing 26 and the second embossing 27 is set to 50-150 micrometers. Shortening the distance between the first embossing 26 and the second embossing 27 allows the first embossing 26, which is easier to wet with electrolyte at the edge, to effectively retain electrolyte while delivering electrolyte to the second embossing 27, which is more difficult to wet in the middle, thus ensuring the electrolyte retention in the middle of the positive electrode sheet.
[0037] Furthermore, the diameter of the first embossing 26 is X1, and the diameter of the second embossing 27 is X2, wherein 4≥X2 / X1≥2, thereby increasing the immersion space of the embossing area 20 and improving the liquid retention volume and amount in the middle of the embossing area 20.
[0038] Furthermore, the dimension of the edge region 10 in the second direction Y is W mm, where 1 ≥ W ≥ 0.5. If the dimension of the edge region 10 in the second direction Y is too small, the first embossing 26 will be too close to the edge, which may easily lead to insufficient adhesion between the coating and the current collector (aluminum foil / copper foil), causing peeling or microcracks.
[0039] Furthermore, the dimension of the edge region 10 at one end in the third direction Z is L1 mm, where 10 ≥ L1 ≥ 4; and / or the dimension of the edge region 10 at the other end in the third direction Z is L2 mm, where 4.5 ≥ L2 ≥ 1.5. If the dimension of the edge region 10 in the third direction Z is too small, the second embossing 27 will be too close to the edge, which may easily lead to insufficient adhesion between the coating and the current collector (aluminum foil / copper foil), causing peeling or microcracks. Since the edge region 10 cannot contribute to the capacity but occupies battery volume and reduces the overall energy density, L1 and L2 should not be set too large.
[0040] Furthermore, the first inclined region 21 is provided with a first bridge surface 22, and adjacent first embossing 26 in the first inclined region 21 are connected through the first bridge surface 22, and the first embossing 26 and the second embossing 27 in the first inclined region 21 are connected through the first bridge surface 22.
[0041] The second inclined region 23 is provided with a second bridge surface 24. Adjacent first embossed patterns 26 in the second inclined region 23 are connected by the second bridge surface 24. The first embossed patterns 26 and second embossed patterns 27 in the second inclined region 23 are also connected by the second bridge surface 24. The inclination directions of the first bridge surface 22 and the second bridge surface 24 are opposite. Electrode electrolyte is transported between adjacent first embossed patterns 26 and between first embossed patterns 26 and second embossed patterns 27, respectively, through the first bridge surface 22 and the second bridge surface 24. The first bridge surface 22 and the second bridge surface 24 are inclined toward the side with the greatest depth of the first groove 25, so that the electrolyte at the edge can be more easily transported to the side with the greater depth of the first groove 25 through the inclined first bridge surface 22 and the second bridge surface 24.
[0042] In one embodiment, the embossing area 20 is provided with a first embossing area 31, a second embossing area 32, and a third embossing area 33 with gradually decreasing embossing depth along the third direction Z. The first embossing area 31 is close to the winding start point of the positive electrode sheet, and the third embossing area 33 is far away from the winding start point. By setting the first embossing area 31, the second embossing area 32, and the third embossing area 33, the wetting space of the inner ring embossing area 20 of the battery cell is increased, the liquid retention volume and liquid retention amount inside the embossing area 20 are improved, and the wetting of the electrolyte in the inner ring of the battery cell is guaranteed.
[0043] In summary, this utility model embodiment provides a positive electrode sheet and its battery cell, including an edge region 10 and an embossed region 20. A first embossed pattern 26 and a second embossed pattern 27 with different diameters are formed in the embossed region 20. The first embossed pattern 26 and the second embossed pattern 27 are recessed along a first direction X to guide the rapid diffusion of the electrolyte and reduce wetting dead zones. The diameter of the first embossed pattern 26 is smaller than the diameter of the second embossed pattern 27. The first embossed pattern 26 and the second embossed pattern 27 are arranged alternately to shorten the distance between them and improve wetting uniformity. The embossed area 20 includes a first inclined area 21 and a second inclined area 23 with opposite inclination directions. The first inclined area 21 and the second inclined area 23 intersect to form a first groove 25. The deepest part of the first groove 25 is located in the middle of the embossed area 20. The middle part of the embossed area 20 is a region where electrolyte penetration is slow and difficult. By increasing the wetting space in the middle of the embossed area 20, the liquid retention volume and liquid retention amount in the middle of the embossed area 20 are increased, avoiding cell draining due to insufficient electrolyte and improving the long-term cycle performance of the cell.
[0044] The above are merely preferred embodiments of this utility model. It should be noted that, for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of this utility model, and these improvements and substitutions should also be considered within the protection scope of this utility model.
Claims
1. A positive electrode sheet having a first direction, a second direction, and a third direction that are perpendicular to each other, characterized in that: It includes an edge area and an embossed area. The edge area surrounds the embossed area. The embossed area has a first inclined area and a second inclined area with opposite inclination directions. The first inclined area and the second inclined area intersect to form a first groove. The first groove has a plurality of circular first embossing and second embossing. The first groove, the first embossing, and the second embossing are recessed to the same side in the first direction. The diameter of the first embossing is smaller than the diameter of the second embossing. The first embossing and the second embossing are arranged at intervals.
2. The positive electrode sheet according to claim 1, characterized in that: The embossed area includes an edge embossed portion and a central embossed portion. The edge embossed portion is disposed at both ends of the central embossed portion in the second direction. The edge embossed portion is formed by a plurality of first embossed patterns arranged at intervals along the third direction. The central embossed portion includes an embossed subgroup, which is formed by a plurality of first embossed patterns and second embossed patterns arranged alternately at intervals along the third direction.
3. The positive electrode sheet according to claim 2, characterized in that: The embossing subgroups are provided in multiple ways, and the multiple embossing subgroups are spaced apart along the second direction. The first embossing and the second embossing of adjacent embossing subgroups are arranged alternately and spaced apart along the second direction.
4. The positive electrode sheet according to claim 1, characterized in that: The distance 'a' between adjacent first embossed flowers is set at 250-350 micrometers.
5. The positive electrode sheet according to claim 1, characterized in that: The minimum distance b between the first embossing and the second embossing is set at 50-150 micrometers.
6. The positive electrode sheet according to claim 1, characterized in that: The diameter of the first embossed flower is X1, and the diameter of the second embossed flower is X2, wherein 4≥X2 / X1≥2.
7. The positive electrode sheet according to claim 1, characterized in that: The dimension of the edge region in the second direction is W mm, where 1 ≥ W ≥ 0.
5.
8. The positive electrode sheet according to claim 2, characterized in that: The dimension of the edge region at one end in the third direction is L1mm, 10≥L1≥4; and / or the dimension of the edge region at the other end in the third direction is L2mm, 4.5≥L2≥1.
5.
9. The positive electrode sheet according to claim 1, characterized in that: The first inclined region is provided with a first bridge surface, and adjacent first embossings in the first inclined region are connected through the first bridge surface. The first embossings and the second embossings in the first inclined region are connected through the first bridge surface. The second inclined region is provided with a second bridge surface. Adjacent first embossing patterns in the second inclined region are connected through the second bridge surface. The first embossing pattern and the second embossing pattern in the second inclined region are connected through the second bridge surface. The inclination directions of the first bridge surface and the second bridge surface are opposite.
10. A battery cell, characterized in that: The battery cell includes a negative electrode, a separator, and a positive electrode as described in any one of claims 1-9, wherein the negative electrode, the separator, and the positive electrode are sequentially stacked and wound to form the battery cell.