Pole piece and battery cell thereof

Abstract

The utility model relates to the technical fields of battery discloses a kind of pole piece and its battery, with mutually perpendicular first direction, second direction and third direction, including foil layer and silicon-doped coating sequentially stacked along first direction, coating is equipped with first infiltration groove and second infiltration groove on the surface of foil layer in first direction, first infiltration groove and second infiltration groove respectively extend along second direction, the size of first infiltration groove in first direction is a μm, the size of second infiltration groove in first direction is b μm, the size of coating in first direction is c μm, wherein, c>b>a, the projection area of first infiltration groove in first direction is d mm 2 , the projection area of second infiltration groove in first direction is e mm 2 , wherein, d>e. The pole piece and its battery of the utility model, guarantee the electrolyte infiltration coverage of battery corner, solve the problem of large expansion of surface layer silicon-doped.

Description

Technical Field

[0001] This utility model relates to the technical field of batteries, and in particular to an electrode sheet and its cell. Background Technology

[0002] Currently, in existing technologies, laser drilling on the negative electrode sheet can significantly improve electrolyte wettability and reduce lithium plating during the charging and discharging process of lithium-ion batteries, thereby improving the cycle stability and cycle life of the cell. However, the negative electrode sheet drilling technology mainly involves straight lines parallel to the width direction. This drilling method may not cover the corners, failing to improve the corner lithium plating effect, which in turn affects the long-term cycle performance of the cell and cannot meet the development requirements of current silicon doping technology for the anode surface. Utility Model Content

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. It provides an electrode and its cell that ensure electrolyte wetting and coverage at the cell corners, thus solving the problem of large surface silicon doping expansion.

[0004] To achieve the above objectives, this utility model provides an electrode having three mutually perpendicular directions: a first direction, a second direction, and a third direction. It includes a foil layer and a silicon-doped coating layer stacked sequentially along the first direction. The coating layer has a first wetting groove and a second wetting groove on its surface opposite to the foil layer in the first direction. The first and second wetting grooves extend along the second direction, respectively. The dimension of the first wetting groove in the first direction is a μm, the dimension of the second wetting groove in the first direction is b μm, and the dimension of the coating layer in the first direction is c μm, where c > b > a. The projected area of ​​the first wetting groove in the first direction is d mm. 2 The projected area of ​​the second immersion tank in the first direction is emm. 2 , where d > e.

[0005] As a preferred embodiment, the first impregnation tank includes a plurality of first sub-impregnation tanks, the projection shape of the first sub-impregnation tanks in the first direction is polygonal, and the plurality of first sub-impregnation tanks are sequentially connected along the second direction to form a first impregnation tank group.

[0006] As a preferred embodiment, the first impregnation tank is provided with a plurality of first impregnation tank groups, and the plurality of first impregnation tank groups are connected sequentially along the third direction.

[0007] As a preferred embodiment, the second impregnation tank includes a plurality of second sub-impregnation tanks, the projection shape of the second sub-impregnation tanks in the first direction is polygonal, and the plurality of second sub-impregnation tanks are connected sequentially along the second direction to form a second impregnation tank group.

[0008] As a preferred embodiment, the second impregnation tank is provided with a plurality of second impregnation tank groups, which are connected sequentially along the third direction.

[0009] As a preferred embodiment, the coating has a first end face in the second direction, the distance between the end point of the first impregnation tank in the second direction and the first end face is L1 mm, 4.3≥L1≥1.7, and the distance between the end point of the second impregnation tank in the second direction and the first end face is L2 mm, 4.3≥L2≥1.7.

[0010] As a preferred embodiment, the coating has a second end face arranged opposite to the first end face in the second direction, the distance between the end point of the first impregnation tank in the second direction and the second end face is L3mm, 9≥L3≥5, and the distance between the end point of the second impregnation tank in the second direction and the second end face is L4mm, 9≥L4≥5.

[0011] As a preferred embodiment, the coating has a third end face in the third direction, the minimum distance between the end point of the first impregnation groove in the third direction and the third end face is W1 mm, 1≥W1≥0.5, and the minimum distance between the end point of the second impregnation groove in the third direction and the third end face is W2 mm, 1≥W2≥0.5.

[0012] As a preferred embodiment, the projection shapes of the first sub-immersion tank and the second sub-immersion tank in the first direction are regular polygons.

[0013] A battery cell includes a positive electrode, a separator, and the electrode, wherein the electrode is a negative electrode, and the positive electrode, the separator, and the electrode are sequentially stacked and wound to form the battery cell.

[0014] Compared with the prior art, the electrode sheet and its battery cell of this utility model have the following advantages: They include a foil layer and a coating layer stacked sequentially along a first direction. A first wetting groove and a second wetting groove are respectively formed on the surface of the coating layer facing away from the foil layer. The first and second wetting grooves extend along a second direction to ensure that the battery cell has both a first and a second wetting groove in the corner area, thereby reducing lithium plating at the corner, improving battery life, safety, and cycle stability. The dimensions of the first and second wetting grooves in the first direction are equal to their depths. The depth of the first wetting groove is less than the depth of the second wetting groove, ensuring the supporting strength of the coating. By increasing the depth of the second wetting groove, the electrolyte wetting depth is increased. Both the first and second wetting grooves can fully wet the electrolyte, optimizing the wettability of the electrolyte, enhancing ion conduction efficiency, and thus improving the battery's charge / discharge performance and power density. The depth of the second wetting groove is less than the depth of the coating, preventing the foil layer from being punctured and ensuring a high yield rate. Since the projected area of ​​the first immersion tank in the first direction is larger than that of the second immersion tank in the first direction, it can provide a larger expansion space on the surface of the coating, thereby reducing the overall expansion rate of the silicon-doped cell. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of the first and second immersion tanks in this embodiment of the present invention, where they are triangular.

[0016] Figure 2 This is a schematic diagram of the structure on the coating when the second immersion tank of this utility model is triangular.

[0017] Figure 3 This is a schematic diagram of the structure on the coating when the first immersion tank of this utility model is triangular.

[0018] Figure 4 This is an embodiment of the present utility model. Figure 1 A schematic diagram of the cross-sectional structure at point A in the diagram.

[0019] Figure 5 This is a schematic diagram of the overall structure of the first and second immersion tanks in this embodiment of the present invention, where both are square.

[0020] Figure 6 This is a schematic diagram of the structure on the coating when the second immersion tank of this utility model is square.

[0021] Figure 7 This is a schematic diagram of the structure on the coating when the first immersion tank of this utility model is square.

[0022] Figure 8 This is an embodiment of the present utility model. Figure 5A schematic diagram of the cross-sectional structure at point B in the diagram.

[0023] Figure 9 This is an embodiment of the present utility model. Figure 5 A schematic diagram of the cross-sectional structure at point C.

[0024] In the picture:

[0025] X, first direction; Y, second direction; Z, third direction;

[0026] 10. Foil layer;

[0027] 20. Coating; 21. First immersion tank; 22. First sub-immersion tank; 23. First immersion tank group; 24. Second immersion tank; 25. Second sub-immersion tank; 26. Second immersion tank group; 27. First end face; 28. Second end face; 29. ​​Third end face. Detailed Implementation

[0028] 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.

[0029] 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.

[0030] 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.

[0031] like Figures 1 to 9As shown, a preferred embodiment of the present invention provides an electrode sheet having mutually perpendicular first directions X, second directions Y, and third directions Z. It includes a foil layer 10 and a silicon-doped coating layer 20 stacked sequentially along the first direction X. The coating layer 20 has a first wetting groove 21 and a second wetting groove 24 on its surface away from the foil layer 10 in the first direction X. The first wetting groove 21 and the second wetting groove 24 extend along the second direction Y. The first wetting groove 21 has a dimension of a μm in the first direction X, the second wetting groove 24 has a dimension of b μm in the first direction X, and the coating layer 20 has a dimension of c μm in the first direction X, where c > b > a. The projected area of ​​the first wetting groove 21 in the first direction X is d mm². 2 The projected area of ​​the second immersion tank 24 in the first direction X is edmm. 2 , where d > e.

[0032] The electrode and its cell of this utility model include a foil layer 10 and a coating layer 20 stacked sequentially along a first direction X. A first wetting groove 21 and a second wetting groove 24 are respectively formed on the surface of the coating layer 20 away from the foil layer 10. The first wetting groove 21 and the second wetting groove 24 extend along a second direction Y to ensure that the cell has the first wetting groove 21 and the second wetting groove 24 in the corner area, thereby reducing the lithium plating phenomenon at the corner, improving the battery life, safety and cycle stability. The dimensions of the first wetting tank 21 and the second wetting tank 24 in the first direction X are equal to their depths. The depth of the first wetting tank 21 is less than the depth of the second wetting tank 24, which ensures the supporting strength of the coating 20. By increasing the depth of the second wetting tank 24, the electrolyte wetting depth is increased. Both the first and second wetting tanks 21 and 24 can fully wet the electrolyte, optimizing the wettability of the electrolyte and enhancing the ion conduction efficiency, thereby improving the charge-discharge performance and power density of the battery. The depth of the second wetting tank 24 is less than the depth of the coating 20, which prevents the foil layer 10 from being punctured and ensures the yield of the finished product. Since the projected area of ​​the first wetting tank 21 in the first direction X is larger than that of the second wetting tank 24 in the first direction X, a larger expansion space can be provided on the surface of the coating 20, thereby reducing the overall expansion rate of the silicon-doped cell.

[0033] The coating 20, mainly composed of negative electrode active materials (such as graphite, silicon-based materials, etc.), conductive agents, and binders, is the core region of the electrochemical reaction. Lithium ions intercalate / deintercalate into the active materials during charging and discharging, achieving energy storage and release. The foil layer 10 is responsible for conducting electrons generated by the active materials in the coating 20 to the external circuit, while simultaneously distributing the external current evenly across the coating 20. The foil layer 10 provides structural strength to the coating 20, supports the coating material, and ensures the integrity of the electrode during battery assembly (such as winding and stacking) and cycling.

[0034] As one embodiment, such as Figure 4 as well as Figures 8-9 As shown, coating 20 is a silicon-doped coating 20, comprising a first coating 20 and a silicon-doped second coating 20. In the first direction X, the first coating 20 is located between the foil layer 10 and the second coating 20. A first wetting groove 21 is formed in the second coating 20, and a second wetting groove 24 extends from the second coating 20 to the first coating 20. The second coating 20 is provided with both the first wetting groove 21 and the second wetting groove 24, increasing the expansion space on the surface of coating 20, thereby reducing the overall expansion rate of the silicon-doped cell.

[0035] As one embodiment, such as Figures 1 to 9 As shown, the first immersion tank 21 and the second immersion tank 24 are drilled by laser processing.

[0036] As one embodiment, such as Figure 4 and Figure 8 As shown, b≥2a, to ensure the wetting depth of the electrolyte, while also ensuring that the surface of coating 20 can provide a larger expansion space, thereby reducing the overall expansion rate of the silicon-doped cell.

[0037] Furthermore, such as Figure 1 , Figure 3 and Figure 7 As shown, the first immersion tank 21 includes multiple first sub-immersion tanks 22. The projection shape of the first sub-immersion tank 22 in the first direction X is polygonal. The multiple first sub-immersion tanks 22 are sequentially connected along the second direction Y to form a first immersion tank group 23. The first sub-immersion tank 22 is a sub-unit of the first immersion tank 21, and the projection of the first sub-immersion tank 22 in the first direction X is polygonal. The multiple polygonal first sub-immersion tanks 22 can be sequentially connected along the second direction Y to form the first immersion tank group 23, further increasing the area of ​​the first immersion tank 21, increasing the expansion space of the coating 20 surface, thereby reducing the overall expansion rate of the silicon-doped cell.

[0038] Furthermore, the first immersion tank 21 is provided with multiple first immersion tank groups 23, which are connected sequentially along the third direction Z. The first immersion tank 21 includes multiple first immersion tank groups 23. Arranging more first immersion tank groups 23 along the third direction Z further increases the area of ​​the first immersion tank 21, increases the expansion space on the surface of the coating 20, and thus reduces the overall expansion rate of the silicon-doped cell.

[0039] Furthermore, such as Figure 1 , Figure 2 and Figure 6As shown, the second immersion tank 24 includes multiple second sub-immersion tanks 25. The projection shape of each second sub-immersion tank 25 in the first direction X is polygonal. The multiple second sub-immersion tanks 25 are sequentially connected along the second direction Y to form a second immersion tank group 26. The second sub-immersion tank 25 is a sub-unit of the second immersion tank 24, and the projection of each second sub-immersion tank 25 in the first direction X is polygonal. The multiple polygonal second sub-immersion tanks 25 can be sequentially connected along the second direction Y to form a second immersion tank group 26, further increasing the area of ​​the second immersion tank 24, increasing the expansion space and electrolytic wetting space of the coating 20 surface, thereby reducing the overall expansion rate of the silicon-doped cell, optimizing the wettability of the electrolyte, enhancing the ion conduction efficiency, and thus improving the charge and discharge performance and power density of the battery.

[0040] Furthermore, such as Figure 2 and Figure 6 As shown, the second immersion tank 24 is provided with multiple second immersion tank groups 26, which are connected sequentially along the third direction Z. The second immersion tank 24 includes multiple second immersion tank groups 26. Arranging more second immersion tank groups 26 along the third direction Z further increases the area of ​​the second immersion tank 24, increases the expansion space of the coating 20 surface and the wetting space for electrolysis, thereby reducing the overall expansion rate of the silicon-doped cell, optimizing the wettability of the electrolyte, enhancing ion conduction efficiency, and thus improving the charge-discharge performance and power density of the battery.

[0041] As one embodiment, such as Figures 1 to 9 As shown, the polygon can be a triangle, quadrilateral, or hexagon. The second sub-immersion tank 25 has a shape and size in the first direction X that are twice the shape and size of the first sub-immersion tank 22 in the first direction X, which facilitates processing.

[0042] As one embodiment, such as Figures 1 to 9 As shown, the first immersion tank 21 and the second immersion tank 24 have the same shape.

[0043] Furthermore, such as Figures 2 to 3 and Figures 6 to 7 As shown, the coating 20 has a first end face 27 in the second direction Y. The distance between the end point of the first impregnation groove 21 in the second direction Y and the first end face 27 is L1mm, 4.3≥L1≥1.7. The distance between the end point of the second impregnation groove 24 in the second direction Y and the first end face 27 is L2mm, 4.3≥L2≥1.7. This ensures the support strength of the edge of the coating 20, prevents the coating 20 from falling off, and ensures the yield of the finished product.

[0044] Furthermore, such as Figures 2 to 3 and Figures 6 to 7As shown, the coating 20 has a second end face 28 arranged opposite to the first end face 27 in the second direction Y. The distance between the end point of the first impregnation groove 21 in the second direction Y and the second end face 28 is L3mm, 9≥L3≥5. The distance between the end point of the second impregnation groove 24 in the second direction Y and the second end face 28 is L4mm, 9≥L4≥5. The positions of L3 and L4 are the innermost layers of the wound cell. During the winding process, it needs to undergo two 180° bends, and this area is usually a single-sided coating area, that is, one side is the active material coating and the other side is the current collector exposed. If holes are drilled in this area of ​​L3 and L4 to form the first impregnation groove 21 or the second impregnation groove 24, it will further weaken the strength of the current collector, causing the stress to concentrate at the edge of the hole during bending, causing the active material to peel off from the current collector. The blank space at the head of the inner ring, that is, the area corresponding to L3 and L4, retains the complete current collector structure, which can disperse the bending stress and prevent the coating from falling off due to local deformation.

[0045] The L3 and L4 regions, set within appropriate dimensions, ensure the stiffness of the current collector and prevent lateral displacement during needle winding, reducing the misalignment rate by approximately 15%. The blank areas in the L3 and L4 regions provide rigid support, ensuring the concentricity of the core.

[0046] Furthermore, such as Figures 2 to 3 and Figures 6 to 7 As shown, the coating 20 has a third end face 29 in the third direction Z. The minimum distance between the endpoint of the first impregnation tank 21 in the third direction Z and the third end face 29 is W1 mm, where 1 ≥ W1 ≥ 0.5, ensuring the support strength of the coating 20 edge, preventing the coating 20 from falling off, and ensuring the processing yield. The minimum distance between the endpoint of the second impregnation tank 24 in the third direction Z and the third end face 29 is W2 mm, where 1 ≥ W2 ≥ 0.5, ensuring the support strength of the coating 20 edge, preventing the coating 20 from falling off, and ensuring the processing yield.

[0047] Furthermore, such as Figures 1 to 9 As shown, the projection shapes of the first sub-immersion tank 22 and the second sub-immersion tank 25 in the first direction X are regular polygons. The regular shapes of the first sub-immersion tank 22 and the second sub-immersion tank 25 reduce the processing difficulty and improve the product yield.

[0048] A battery cell includes a positive electrode, a separator, and an electrode sheet, wherein the electrode sheet is a negative electrode sheet, and the positive electrode, separator, and electrode sheet are sequentially stacked and wound to form a battery cell.

[0049] In summary, this utility model embodiment provides an electrode and its battery cell, including a foil layer 10 and a coating layer 20 stacked sequentially along a first direction X. A first wetting groove 21 and a second wetting groove 24 are respectively formed on the surface of the coating layer 20 facing away from the foil layer 10. The first wetting groove 21 and the second wetting groove 24 extend along a second direction Y to ensure that the battery cell has the first wetting groove 21 and the second wetting groove 24 in the corner area, thereby reducing the lithium plating phenomenon at the corner, improving the battery life, safety and cycle stability. The dimensions of the first wetting tank 21 and the second wetting tank 24 in the first direction X are equal to their depths. The depth of the first wetting tank 21 is less than the depth of the second wetting tank 24, which ensures the supporting strength of the coating 20. By increasing the depth of the second wetting tank 24, the electrolyte wetting depth is increased. Both the first and second wetting tanks 21 and 24 can fully wet the electrolyte, optimizing the wettability of the electrolyte and enhancing the ion conduction efficiency, thereby improving the charge-discharge performance and power density of the battery. The depth of the second wetting tank 24 is less than the depth of the coating 20, which prevents the foil layer 10 from being punctured and ensures the yield of the finished product. Since the projected area of ​​the first wetting tank 21 in the first direction X is larger than that of the second wetting tank 24 in the first direction X, a larger expansion space can be provided on the surface of the coating 20, thereby reducing the overall expansion rate of the silicon-doped cell.

[0050] 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. An electrode having a first direction, a second direction, and a third direction that are perpendicular to each other, characterized in that: The system comprises a foil layer and a silicon-doped coating stacked sequentially along the first direction. The coating has a first wetting groove and a second wetting groove on its surface opposite to the foil layer in the first direction. The first and second wetting grooves extend along the second direction, respectively. The first wetting groove has a dimension of a μm in the first direction, the second wetting groove has a dimension of b μm in the first direction, and the coating has a dimension of c μm in the first direction, where c > b > a. The projected area of ​​the first wetting groove in the first direction is d mm². 2 The projected area of ​​the second immersion tank in the first direction is emm. 2 , where d > e.

2. The electrode sheet according to claim 1, characterized in that: The first impregnation tank includes a plurality of first sub-impregnation tanks. The projection shape of the first sub-impregnation tanks in the first direction is polygonal. The plurality of first sub-impregnation tanks are connected sequentially along the second direction to form a first impregnation tank group.

3. The electrode sheet according to claim 2, characterized in that: The first impregnation tank is provided with a plurality of first impregnation tank groups, and the plurality of first impregnation tank groups are connected sequentially along the third direction.

4. The electrode sheet according to claim 2, characterized in that: The second immersion tank includes a plurality of second sub-immersion tanks. The projection shape of the second sub-immersion tanks in the first direction is polygonal. The plurality of second sub-immersion tanks are connected sequentially along the second direction to form a second immersion tank group.

5. The electrode sheet according to claim 4, characterized in that: The second impregnation tank is provided with a plurality of second impregnation tank groups, which are connected sequentially along the third direction.

6. The electrode sheet according to claim 1, characterized in that: The coating has a first end face in the second direction. The distance between the end point of the first impregnation tank in the second direction and the first end face is L1 mm, 4.3 ≥ L1 ≥ 1.

7. The distance between the end point of the second impregnation tank in the second direction and the first end face is L2 mm, 4.3 ≥ L2 ≥ 1.

7.

7. The electrode sheet according to claim 6, characterized in that: The coating has a second end face arranged opposite to the first end face in the second direction. The distance between the end point of the first impregnation tank in the second direction and the second end face is L3mm, 9≥L3≥5. The distance between the end point of the second impregnation tank in the second direction and the second end face is L4mm, 9≥L4≥5.

8. The electrode sheet according to claim 2, characterized in that: The coating has a third end face in the third direction. The minimum distance between the first impregnation tank at the end point in the third direction and the third end face is W1 mm, where 1 ≥ W1 ≥ 0.

5. The minimum distance between the second impregnation tank at the end point in the third direction and the third end face is W2 mm, where 1 ≥ W2 ≥ 0.

5.

9. The electrode sheet according to claim 4, characterized in that: The projection shapes of the first sub-immersion tank and the second sub-immersion tank in the first direction are regular polygons.

10. A battery cell, characterized in that: The battery cell includes a positive electrode, a separator, and an electrode as described in any one of claims 1-9, wherein the electrode is a negative electrode, and the positive electrode, the separator, and the electrode are sequentially stacked and wound to form the battery cell.

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