Battery cell and battery

Abstract

The utility model discloses a battery cell and a battery. The battery cell comprises a first pole piece, a diaphragm and a second pole piece which are sequentially laminated, wherein the polarities of the first pole piece and the second pole piece are opposite; the first pole piece comprises a first current collector, a first active layer arranged on at least one side of the first current collector, a first tab and first tab glue; a first tab groove is formed in the first active layer, and a part of the first tab is located in the first tab groove and connected with the first current collector; the first active layer comprises an inner side active layer, a middle active layer and an outer side active layer which are sequentially arranged around the first tab groove from inside to outside, the thickness of the middle active layer is smaller than that of the inner side active layer, and the thickness of the middle active layer is smaller than that of the outer side active layer; in the first direction, the first tab glue covers the first tab groove and the inner active layer, and at least part of the first tab glue is located on the middle active layer.

Description

Technical Field

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

[0002] For an electrode core with a middle-positioned tab structure, since the tab groove is formed in the active material layer coating area, when the adhesive tape for protecting the tab covers the tab groove, it will adhere to the outer surface of the active material layer, resulting in an increase in the ineffective thickness of the electrode core and a decrease in the energy density of the electrode core. If the thickness of the active material layer at the adhesive tape is reduced to reduce the increase in the ineffective thickness of the electrode core, in actual production, when using equipment to remove the active material, it is easy to scrape the current collector area exposed in the tab groove, which easily causes damage to the current collector. Summary of the Utility Model

[0003] In view of this, the embodiments of the present application are committed to providing an electrode core that can effectively solve the problem of easy damage to the current collector due to the removal of the active material layer while reducing the ineffective thickness of the electrode core.

[0004] On the one hand, the present application provides an electrode core, including a first electrode plate, a separator, and a second electrode plate that are sequentially stacked, and the polarities of the first electrode plate and the second electrode plate are opposite;

[0005] The first electrode plate includes a first current collector, a first active layer provided on at least one side of the first current collector, a first tab, and a first tab adhesive;

[0006] A first tab groove is provided on the first active layer, and a part of the first tab is located in the first tab groove and is connected to the first current collector;

[0007] The first active layer includes an inner active layer, a middle active layer, and an outer active layer that are sequentially arranged around the first tab groove from the inside to the outside. Among them, the thickness of the middle active layer is less than the thickness of the inner active layer, and the thickness of the middle active layer is less than the thickness of the outer active layer;

[0008] In the first direction, the first tab adhesive covers the first tab groove and the inner active layer, and at least a part is located on the middle active layer.

[0009] In a possible implementation manner, in the second direction, there is a spacing between the first tab groove and the edge of the first current collector, the inner active layer is arranged in a ring around the first tab groove, and along the second direction, the side of the inner active layer close to the edge of the first current collector is flush with the edge of the first current collector; or,

[0010] In the second direction, an opening is provided on one side of the first tab groove close to the edge of the first current collector, and the opening extends to the edge of the first current collector. The inner active layer is disposed around the first tab groove and is flush with the edge of the first current collector on the side close to the edge of the first current collector in the second direction.

[0011] In a possible implementation manner, the intermediate active layer is disposed around the inner active layer and is flush with the edge of the first current collector on the side close to the edge of the first current collector in the second direction.

[0012] In a possible implementation manner, the width of any section of the inner active layer in the circumferential direction of the first tab groove is 0.3 mm - 0.5 mm; and / or, along the circumferential direction of the inner active layer, the width of any section of the intermediate active layer disposed around it is 0.5 mm - 2 mm; and / or, the thickness of the inner active layer is the same as the thickness of the outer active layer.

[0013] In a possible implementation manner, along the second direction, a notch communicating with the first tab groove is formed at the edge of the first current collector.

[0014] In a possible implementation manner, a first thinning groove is provided on the second pole piece opposite to the first tab groove, and a first protective adhesive is provided in the first thinning groove.

[0015] In a possible implementation manner, the first thinning groove is a stepped groove. Along the thickness direction of the pole piece, the first thinning groove includes a step surface A and a step surface B arranged in sequence along the groove depth direction, and the first protective adhesive is provided on the step surface A.

[0016] In a possible implementation manner, a second thinning groove is provided on the first pole piece; the second thinning groove and the first tab groove are arranged on the first active layers on both sides of the first current collector, and at least partially overlap in the projection in the thickness direction of the pole piece;

[0017] The depth of the second thinning groove is less than the thickness of the first active layer, and a second protective adhesive is provided in the second thinning groove.

[0018] In a possible implementation manner, a second thinning groove and a second protective adhesive are provided on the first pole piece; the second thinning groove and the first tab groove are arranged on the first active layers on both sides of the first current collector, and at least partially overlap in the projection in the thickness direction of the pole piece; the depth of the second thinning groove is the same as the thickness of the first active layer,

[0019] The second protective adhesive is located on the first active layer and covers the second thinning groove.

[0020] In a possible implementation, a fifth protective glue is provided at a position of the second pole piece opposite to the second thinning groove, and a projection of the fifth protective glue in the thickness direction of the pole piece is located within a projection of the second protective glue.

[0021] In a possible implementation, the second pole piece includes a second current collector, a second active layer provided on at least one side of the second current collector, a second tab, and a second tab glue; a second tab groove is provided on the second active layer, a part of the second tab is located within the second tab groove and is connected to the second current collector, the second active layer includes a glue-containing active layer disposed around the second tab groove and a main active layer disposed around the glue-containing active layer, a thickness of the glue-containing active layer is less than a thickness of the main active layer, and a part of the second tab glue covers a section of the second tab located within the second tab groove and is partially located on the glue-containing active layer;

[0022] A third thinning groove is provided at a position of the first pole piece opposite to the second tab groove, and a third protective glue is provided within the third thinning groove.

[0023] In a possible implementation, a fourth thinning groove and a fourth protective glue located within the fourth thinning groove are further provided on the first pole piece. In the thickness direction of the battery cell, a projection of the fourth protective glue at least partially coincides with the second tab groove, and the fourth protective glue and the third protective glue are respectively located on two sections of the first pole piece, and the two sections are respectively located on two sides of the second pole piece section where the second tab groove is located; or,

[0024] A fourth protective glue is provided on the first pole piece, a welding groove and a sixth protective glue are provided on the second pole piece, the welding groove and the second tab groove are respectively located on two sides of the same section of the second current collector and at least partially coincide in the projection in the thickness direction, and the sixth protective glue covers an opening of the welding groove on the second active layer; a projection of the fourth protective glue in the thickness direction of the pole piece is located within a projection of the sixth protective glue.

[0025] According to the battery cell provided by the present application, the active material layer around the first tab groove is divided into an inner active layer, an intermediate active layer, and an outer active layer. The thickness of the intermediate active layer is relatively low, which is equivalent to forming a buried glue groove for accommodating the tab protective glue. Then, both sides of the first tab protective glue can be located on the intermediate active layer. In this way, compared with the first tab protective glue being located on the surface of the active material layer with a conventional thickness, the ineffective thickness of the battery cell can be reduced. At the same time, an inner active layer is provided between the intermediate active layer for reducing the thickness and the first tab groove, and there is a spacing from the first tab groove. During production, when removing the active material to form the intermediate active layer, the current collector in the first tab groove will not be removed, effectively avoiding the problem of damaging the current collector. While setting the buried glue groove to reduce the ineffective thickness of the battery cell, the problem of easily damaging the current collector in the tab groove during the production of the buried glue groove is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The figure shows a schematic diagram of the first active layer on the first pole piece in an embodiment of the present application;

[0027] Figure 2 The figure shows a schematic diagram of the notch on the first pole piece in an embodiment of the present application;

[0028] Figure 3 The figure shows a schematic diagram of the first type of setting of the battery cell in an embodiment of the present application;

[0029] Figure 4 The figure shows a schematic diagram of the first tab groove and the first tab glue in an embodiment of the present application;

[0030] Figure 5 The figure shows a schematic diagram of the second type of setting of the battery cell in an embodiment of the present application;

[0031] Figure 6 Shown is Figure 5 a partial enlarged view of;

[0032] Figure 7 The figure shows a schematic diagram of the third type of setting of the battery cell in an embodiment of the present application;

[0033] Figure 8 The figure shows a schematic diagram of the fourth type of setting of the battery cell in an embodiment of the present application.

[0034] Figure 1-8 In:

[0035] 100. First electrode tab; 101. First tab groove; 102. Second thinning groove; 103. Third thinning groove; 104. Fourth thinning groove; 105. Notch; 11. First tab; 12. First active layer; 121. Inner active layer; 122. Intermediate active layer; 123. Outer active layer; 13. First tab adhesive; 14. Second protective adhesive; 15. Third protective adhesive; 16. Fourth protective adhesive; 200. Second electrode tab; 21. Second tab; 22. Second active layer; 201. Second tab groove; 202. First thinning groove; 203. Welding groove; 23. Second tab adhesive; 24. First protective adhesive; 25. Fifth protective adhesive; 26. Sixth protective adhesive. Detailed implementation manners

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

[0037] Please refer to the attached Figure 1-8 As shown in the figure, an embodiment of the present application provides an electric core, which includes a first electrode tab 100, a separator, and a second electrode tab 200 that are sequentially stacked. The first electrode tab 100 and the second electrode tab 200 have opposite polarities. The first electrode tab 100 includes a first current collector, a first active layer 12 provided on at least one side of the first current collector, a first tab 11, and a first tab adhesive 13; the second electrode tab 200 includes a second current collector, a second active layer 22 provided on at least one side of the second current collector, a second tab 21, and a second tab adhesive 23. Among them, the first electrode tab 100 can be a positive electrode tab or a negative electrode tab. At the same time, a first tab groove 101 is provided on the first active layer 12, and a part of the first tab 11 is located in the first tab groove 101 and is connected to the first current collector; the first tab groove 101 is formed in the region of the current collector coated with the active material layer, such as the middle section. In this way, a tab-centered structure is formed, that is, the tab is located in the middle region of the current collector along its length direction rather than at the two ends, which is more conducive to rapid current transmission.

[0038] As Figure 1 shown, the periphery of the first tab groove 101 is the first active layer 12. At the same time, in the first direction (the first direction can be the length direction or the width direction of the electric core, as shown in the attached Figure 1For example, preferably, the first direction is the width direction of the tab, i.e., the direction perpendicular to the direction in which the tab extends from the current collector, and the second direction is the length direction of the tab, i.e., the direction in which the tab extends from the current collector. On the second direction, with the first tab groove 101 as the center, from the inside to the outside (i.e., from the inside to the outside of the first tab groove 101), the first active layer 12 includes an inner active layer 121, an intermediate active layer 122, and an outer active layer 123 that are sequentially arranged around the first tab groove 101. That is, the inner active layer 121 is adjacent to the first tab groove 101, and it can also be said that the inner active layer 121 forms the groove side wall of the first tab groove 101. The intermediate active layer 122 is located between the inner active layer 121 and the outer active layer 123.

[0039] Moreover, the thickness of the intermediate active layer 122 is less than the thickness of the inner active layer 121, and the thickness of the intermediate active layer 122 is less than the thickness of the outer active layer 123. That is, the intermediate active layer 122 is lower than the thickness of the surrounding active layers, so it forms a groove around the first tab groove 101.

[0040] The first tab adhesive 13 is used to cover the section of the first tab 11 located in the first tab groove 101, and the first tab adhesive 13 has a part (the area beyond the first tab groove 101) located on the surface of the first active layer 12. In this application, in the first direction, the first tab adhesive 13 covers the first tab groove 101 and the inner active layer 121, and at least a part is located on the intermediate active layer 122. The relatively lower intermediate active layer 122 forms a buried adhesive groove on the first active layer 12, accommodating the area of the first tab adhesive 13 that extends beyond the first tab groove 101 and the inner active layer 121.

[0041] In this way, compared with the case where the entire first active layer 12 has a conventional thickness and the first tab adhesive 13 is attached to the outer surface of the active layer, the ineffective thickness of the battery cell can be reduced, and the energy density of the battery cell can be prevented from decreasing. At the same time, an inner active layer 121 is provided between the intermediate active layer 122 for reducing the thickness and the first tab groove 101. The inner active layer 121 separates the first tab groove 101 and the intermediate active layer 122, that is, there is a distance between the buried adhesive groove and the first tab groove 101. In actual production, when removing the active material to form the intermediate active layer 122, the set removal area and the first tab groove 101 have an obvious distance. Even due to processing errors, dimension setting errors, or other error reasons, the current collector in the first tab groove 101 will not be removed, effectively avoiding the problem of damaging the current collector. While setting the buried adhesive groove to reduce the ineffective thickness of the battery cell, the problem of easily damaging the current collector in the tab groove during the production of the buried adhesive groove is solved.

[0042] It should be noted that the battery cell in the embodiment of the present application is preferably a wound core, that is, the first electrode tab 100, the separator (not shown in the figure), and the second electrode tab 200 are sequentially stacked and wound; alternatively, the battery cell in the embodiment of the present application may also be a stacked core, which is not limited here.

[0043] It should be noted that the process of scraping or laser cleaning is usually adopted to remove the active material to form the buried glue groove.

[0044] In some embodiments, the inner active layer 121 is disposed around the first tab groove 101. In the second direction (the second direction is the length direction of the tab, that is, the direction in which the tab extends out of the current collector), there is a distance between the first tab groove 101 and the edge of the first current collector (referring to the edge of the first current collector in the second direction), so the inner active layer 121 is annular and surrounds the first tab groove 101. In the second direction, the side of the inner active layer 121 close to the edge of the first current collector may be flush with the edge of the first current collector.

[0045] In still other embodiments, the side of the first tab groove 101 close to the edge of the first current collector has an opening for the first tab 11 to extend out. The first tab groove 101 is a U-shaped or U-shaped-like groove. The inner active layer 121 is disposed around the first tab groove 101 and is also U-shaped or U-shaped-like. For example, the inner active layer 121 has a first segment, a second segment, and a third segment that are sequentially connected end to end. The first segment and the third segment are located on both sides of the first tab groove 101 in the first direction, and the second segment is located on the side of the first tab groove 101 away from the opening in the second direction. In the second direction, the side of the inner active layer 121 close to the edge of the first current collector may be flush with the edge of the first current collector, that is, the edges of the first segment and the third segment away from the second segment are both flush with the edge of the first current collector.

[0046] The middle active layer 122 is disposed around the inner active layer 121 and is flush with the edge of the first current collector on the side close to the edge of the first current collector in the second direction. Specifically, the middle active layer 122 may be U-shaped or U-shaped-like, including a fourth segment, a fifth segment, and a sixth segment that are sequentially connected and disposed around the inner active layer 121. The fourth segment and the sixth segment are respectively located on both sides of the inner active layer 121 in the first direction, and the sides of the fourth segment and the sixth segment away from the fifth segment can both be flush with the edge of the first current collector. In this way, the area where the first tab glue 13 extends beyond the first tab groove 101 and the inner active layer 121 can be accommodated to the greatest extent, and the ineffective thickness of the battery cell can be reduced.

[0047] In some specific embodiments, the thickness of the inner active layer 121 may be 50 μm - 100 μm, and the width of any section of the inner active layer 121 in the circumferential direction of the first tab groove 101 may be 0.3 mm - 0.5 mm. For example, specifically 0.3 mm, 0.32 mm, 0.35 mm, 0.38 mm, 0.4 mm, 0.42 mm, 0.45 mm, 0.48 mm, 0.5 mm, etc., or any other arbitrary value within this range not listed.

[0048] The thickness of the middle active layer 122 is the thickness of the inner active layer 121 - the thickness of the first tab glue 13 + b, where b is ±2 μm. Along the circumferential direction of the inner active layer 121, the width of any section of the middle active layer 122 arranged around it is 0.5 mm - 2 mm, such as 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm, etc., or any other arbitrary value within this range not listed.

[0049] The thickness of the outer active layer 123 may be the same as that of the inner active layer 121. It should be noted that due to the error of the coating process or the cleaning process, the thickness difference between the outer active layer 123 and the inner active layer 121 within 15 μm can be considered as having the same thickness.

[0050] For the middle active layer 122, in the first direction, the width of the first section = the width of the third section = (the width of the first tab glue 13 - the width of the first tab groove 101 - the width of the inner active layer 121) / 2 + a; in the second direction, the length of the first section = the length of the third section = the length of the first tab glue 13 + a. Where 0.5 mm ≤ a ≤ 2 mm, or 0.5 mm ≤ a ≤ 1 mm.

[0051] As Figure 2 As shown, in some embodiments, in the second direction, a notch 105 communicating with the first tab groove 101 is formed at the edge of the first current collector. The edge of the current collector is likely to have burrs. The burrs on the current collector at the first tab groove 101 are likely to pierce the separator because there is no coverage of active material. In this application, the original edge of the first current collector at the first tab groove 101 is removed to form the notch 105, which can remove the burrs at the edge of the active layer at the edge of the electrode tab. In this way, on the basis of not increasing the ineffective thickness of the battery cell, the battery cell can be further prevented from short - circuiting.

[0052] As Figure 3As shown, in some embodiments, a first thinning groove 202 is provided on the second electrode tab 200 opposite to the first tab groove 101, and a first protective glue 24 is provided in the first thinning groove 202. The first protective glue 24 is opposite to the first tab 11, preventing the solder joint at the first tab 11 from piercing the separator and directly electrically connecting with the second electrode tab 200, resulting in a short circuit of the battery cell. The first thinning groove 202 accommodates the first protective glue 24 and is opposite to the first tab groove 101, which can balance the thicknesses of the first protective glue 24 and the first tab glue 13, reduce the overall thickness of the battery cell and the ineffective thickness of the battery cell.

[0053] In such embodiments, the depth of the first thinning groove 202 = the thickness of the first protective glue 24 + b, where b = ±2 μm.

[0054] As Figure 5 and Figure 6 As shown, in some embodiments, the first thinning groove 202 is a stepped groove. Along the thickness direction of the electrode tab, a step surface A and a step surface B are sequentially arranged in the first thinning groove 202, and the first protective glue 24 is arranged on the step surface A. In this way, the first protective glue 24 will not protrude from the first thinning groove 202, avoiding an increase in ineffective thickness; and the structure of the stepped groove can balance the thickness of the first tab glue 13 (i.e., the thickness of the area where the first tab glue 13 covers the first tab groove 101 and the inner active layer 121). At the same time, the active material is retained as much as possible, reducing the loss of the active material caused by grooving.

[0055] In such embodiments, it can be set that the groove depth of the step surface A (the depth from the groove opening to the step surface A) = the thickness of the first protective glue 24 + b; the groove depth of the first thinning groove 202 (the depth from the groove opening to the groove bottom) = the thickness of the first tab glue 13 + the thickness of the first protective glue 24 + the thickness of the first tab 11 protruding from the first tab groove 101 + b; where b = ±2 μm.

[0056] In the first direction, the width of the bottom of the first thinning groove 202 = the width of the first tab 11 + a, and / or, the width of the step surface B = the width of the inner active layer 121 + a, and / or, the width of the groove section where the step surface A is located (the groove section from the groove opening to the step surface A) = the width of the first protective glue 24 + a, where a > 0, or, 0.5 mm ≤ a ≤ 2 mm, or, 0.5 mm ≤ a ≤ 1 mm;

[0057] In some embodiments, a second thinning groove 102 is provided on the first pole piece 100; the second thinning groove 102 and the first tab groove 101 are arranged on the first active layer 12 on both sides of the first current collector, and at least partially overlap in the projection in the thickness direction of the pole piece; a second protective glue 14 is provided at the second thinning groove 102, and the projection of the second protective glue 14 in the thickness direction of the pole piece and the first tab 11 at least partially overlap. The setting of the second protective glue 14 can prevent the solder joint of the first tab 11 and the first current collector from protruding the active material on this side and piercing the separator, and the setting of the second thinning groove 102 can balance the thicknesses of the first tab glue 13, the first protective glue 24 and the second protective glue 14, and reduce the ineffective thickness of the battery cell.

[0058] As Figure 3 and Figure 5 shown, in some embodiments, if the first tab 11 and the first current collector are single-sided welded, the depth of the second thinning groove 102 is less than the thickness of the first active layer 12 on this side, and there is no need to expose the first current collector, and the second protective glue 14 can be located in the second thinning groove 102. In such embodiments, the depth of the second thinning groove 102 = the depth of the second protective glue 14 + b; where b = ±2 μm.

[0059] As Figure 7 and Figure 8 shown, in some embodiments, if the first tab 11 and the first current collector are double-sided welded, the depth of the second thinning groove 102 is the same as the thickness of the first active layer 12, and a part of the first current collector is exposed in the second thinning groove 102, and the welding of the first current collector and the first tab 11 on this side is performed from within the second thinning groove 102. At the same time, the second protective glue 14 is located on the first active layer 12 and covers the second thinning groove 102; in this way, it can prevent the solder joint on this side of the first current collector from piercing the separator. In such embodiments, the depth of the first thinning groove 202 + the depth of the second thinning groove 102 = the thickness of the first tab glue 13 + the thickness of the first protective glue 24 + the thickness of the second protective glue 14 + the thickness of the first tab 11 protruding from the first tab groove 101 + b; where b = ±2 μm.

[0060] In a further embodiment, a fifth protective glue 25 is provided at a position of the second pole piece 200 opposite to the second thinning groove 102, and the fifth protective glue 25 and the second thinning groove 102 at least partially overlap in the projection in the thickness direction of the pole piece. In this way, the safety can be further enhanced to prevent the solder joint from directly electrically connecting with the second tab 21 after piercing the separator.

[0061] The projection of the fifth protective glue 25 in the thickness direction of the pole piece is located within the projection of the second protective glue 14.

[0062] In such embodiments, it may be that the depth of the first thinning groove 202 + the depth of the second thinning groove 102 = the thickness of the first tab glue 13 + the thickness of the first protective glue 24 + the thickness of the second protective glue 14 + the thickness of the fifth protective glue 25 + the thickness of the first tab 11 protruding from the first tab groove 101 + b; where b = ±2 μm.

[0063] In the first direction, the width of the first thinning groove 202 = the width of the first protective glue 24 + a, and / or, the width of the second thinning groove 102 = the width of the second protective glue 14 + a; in the second direction, the length of the first thinning groove 202 = the length of the first protective glue 24 + a, and / or, the length of the second thinning groove 102 = the length of the second protective glue 14 + a; where 0.5 mm ≤ a ≤ 2 mm, or, 0.5 mm ≤ a ≤ 1 mm.

[0064] The second electrode sheet 200 includes a second current collector, a second active layer 22 provided on at least one side of the second current collector, a second tab 21, and a second tab glue 23. A second tab groove 201 is provided on the second active layer 22, and a part of the second tab 21 is located in the second tab groove 201 and is connected to the second current collector.

[0065] The second active layer 22 includes a glue-containing active layer provided around the second tab groove 201 and a main active layer provided around the glue-containing active layer. The thickness of the glue-containing active layer is less than the thickness of the main active layer, which is equivalent to forming a buried glue groove for accommodating the second tab glue 23 on the second electrode sheet 200. A part of the second tab glue 23 covers the section of the second tab 21 located in the second tab groove 201 and is partially (in the area beyond the second tab groove 201) located on the glue-containing active layer.

[0066] As Figure 3 shown, a third thinning groove 103 is provided at a position on the first electrode sheet 100 opposite to the second tab groove 201, and a third protective glue 15 is provided in the third thinning groove 103. The third protective glue 15 faces the second tab 21, and can prevent the solder joint of the second tab 21 and the second current collector from directly electrically connecting to the first electrode sheet 100 after piercing the separator, resulting in a short circuit of the battery cell. The third thinning groove 103 accommodates the third protective glue 15 and is opposite to the second tab groove 201, which can balance the thickness of the third protective glue 15 and the second tab glue 23, reduce the overall thickness of the battery cell and the ineffective thickness of the battery cell.

[0067] In such embodiments, the depth of the third thinning groove 103 = the depth of the third protective glue 15 + b; where b = ±2 μm.

[0068] As Figure 5As shown, the third thinning groove 103 is a stepped groove. Along the thickness direction of the electrode tab, a step surface C is provided in the third thinning groove 103, and the third protective adhesive 15 is disposed on the step surface C. In this way, the third protective adhesive 15 can be prevented from protruding out of the third thinning groove 103, avoiding an increase in the ineffective thickness. At the same time, the setting of the stepped groove can balance the thickness of the second tab adhesive 23 (i.e., the thickness of the region where the second tab adhesive 23 covers the second tab groove 201).

[0069] In such embodiments, it can be that the depth of the third thinning groove 103 = the thickness of the second tab adhesive 23 + the thickness of the third protective adhesive 15 + the thickness by which the second tab 21 protrudes from the second tab groove 201 + b; where b = ±2 μm.

[0070] In the first direction, the width of the bottom of the third thinning groove 103 = the width of the second tab 21 + a, and / or, the total width of the bottom + the two step surfaces C = the width of the third protective adhesive 15 + a, where a > 0, or, 0.5 mm ≤ a ≤ 2 mm, or, 0.5 mm ≤ a ≤ 1 mm;

[0071] In some embodiments, if the second tab 21 and the second current collector are welded on one side, then as Figure 3 and Figure 5 shown, a fourth thinning groove 104 and a fourth protective adhesive 16 located within the fourth thinning are further provided on the first electrode tab 100. In the thickness direction of the battery cell, the projection of the fourth protective adhesive 16 at least partially coincides with the second tab groove 201, and the fourth protective adhesive 16 and the third protective adhesive 15 are respectively located on two sections of the first electrode tab 100, and these two sections are respectively on both sides of the section of the second electrode tab 200 where the second tab groove 201 is located in the thickness direction of the battery cell. The setting of the fourth thinning groove 104 can reduce the content of the active material on the first electrode tab 100, balance the amount of the active material on the corresponding sections of the first electrode tab 100 and the second electrode tab 200 at the second tab 21, and balance the thickness of the fourth protective adhesive 16. The setting of the fourth protective adhesive 16 can reduce the amount of lithium ions precipitated on the section of the first electrode tab 100 opposite to the second tab groove 201, and can avoid the lithium precipitation phenomenon in the section of the second tab 21 where the second tab groove 201 is located.

[0072] In such embodiments, it can be that the depth of the third thinning groove 103 + the depth of the fourth thinning groove 104 = the thickness of the second tab adhesive 23 + the thickness of the third protective adhesive 15 + the thickness of the fourth protective adhesive 16 + the thickness by which the second tab 21 protrudes from the second tab groove 201 + b; where b = ±2 μm.

[0073] Or, in some other embodiments, if the second tab 21 and the second electrode tab 200 are welded on both sides, as Figure 7 and Figure 8As shown in the figure, a fourth protective adhesive 16 is provided on the first electrode tab 100, and a welding groove 203 and a sixth protective adhesive 26 are provided on the second electrode tab 200. The welding groove 203 and the second tab groove 201 are respectively located on both sides of the same section of the second current collector and at least partially overlap in the projection in the thickness direction. The sixth protective adhesive 26 covers the notch of the welding groove 203 on the second active layer 22. The fourth protective adhesive 16 faces the sixth protective adhesive 26, and it is possible that the projection of the fourth protective adhesive 16 in the thickness direction of the electrode tab is located within the projection of the sixth protective adhesive 26. In this way, it is possible to balance the thickness of each adhesive tape, prevent unnecessary ineffective thickness of the battery cell, and prevent the welding point from piercing the diaphragm and causing a short circuit.

[0074] In this embodiment, in the third direction, it is possible that the depth of the third thinning groove 103 + the depth of the welding groove 203 = the thickness of the sixth protective adhesive 26 + the thickness of the second tab adhesive 23 + the thickness of the third protective adhesive 15 + the thickness of the fourth protective adhesive 16 + the thickness of the second tab 21 protruding from the second tab groove 201 + b, where b = ±2 μm.

[0075] The basic principles of the present application have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, advantages, effects, etc. mentioned in the present application are only examples and not limitations. It cannot be considered that these advantages, advantages, effects, etc. are essential for each embodiment of the present application. In addition, the above-disclosed specific details are only for the purpose of illustration and easy understanding, rather than limitations. The above details do not limit the present application to necessarily adopt the above specific details to implement.

[0076] The components and devices involved in the present application are only illustrative examples and do not intend to require or imply that they must be connected, arranged, and configured in the manner shown in the drawings. As those skilled in the art will recognize, these components and devices can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open-ended words, meaning "including but not limited to", and can be used interchangeably with each other. The words "or" and "and" used here refer to the word "and / or" and can be used interchangeably with each other, unless the context clearly indicates otherwise. The word "such as" used here refers to the phrase "such as but not limited to" and can be used interchangeably with each other.

[0077] It should also be noted that in the devices and equipment of the present application, the components can be disassembled and / or recombined. These disassembly and / or recombination should be regarded as equivalent solutions of the present application.

[0078] The above description of the disclosed aspects enables any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of the present application. Thus, the present application is not intended to be limited to the aspects shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0079] It should be understood that the qualifiers "first", "second", "third", "fourth", "fifth" and "sixth" used in the description of the embodiments of the present application are only for more clearly elaborating the technical solutions and cannot be used to limit the protection scope of the present application.

[0080] The above description has been given for purposes of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub - combinations thereof.

[0081] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, etc. made within the spirit and principles of the present application shall be included within the protection scope of the present application.

Claims

1. A battery cell, characterized in that: It comprises a first pole piece, a diaphragm and a second pole piece which are stacked in sequence, wherein the first pole piece and the second pole piece have opposite polarities; The first pole piece includes a first current collector, a first active layer arranged on at least one side of the first current collector, a first pole ear and a first pole ear glue; A first electrode tab groove is provided on the first active layer, and a part of the first electrode tab is located in the first electrode tab groove and connected to the first current collector; The first active layer comprises an inner active layer, a middle active layer and an outer active layer which are sequentially arranged around the first tab groove from the inside to the outside, wherein the thickness of the middle active layer is smaller than the thickness of the inner active layer, and the thickness of the middle active layer is smaller than the thickness of the outer active layer; In the first direction, the first tab glue covers the first tab groove and the inner active layer, and is at least partially located on the middle active layer.

2. The battery cell according to claim 1, characterized in that: In the second direction, there is a distance between the first electrode tab groove and the edge of the first current collector, the inner active layer is arranged in a ring shape around the first electrode tab groove, and along the second direction, the side of the inner active layer close to the edge of the first current collector is flush with the edge of the first current collector; or, In the second direction, an opening is provided on one side of the first pole lug groove close to the edge of the first current collector, and the opening extends to the edge of the first current collector. The inner active layer is arranged around the first pole lug groove, and the side close to the edge of the first current collector in the second direction is flush with the edge of the first current collector.

3. The battery cell according to claim 1, characterized in that: The middle active layer is disposed around the inner active layer, and a side of the middle active layer close to the edge of the first current collector in the second direction is flush with the edge of the first current collector.

4. The battery cell according to claim 1, characterized in that: The width of any section of the inner active layer in the circumferential direction of the first electrode tab slot is 0.3 mm to 0.5 mm; and / or, Along the circumference of the inner active layer, the width of any section of the intermediate active layer arranged around it is 0.5 mm to 2 mm; and / or, The thickness of the inner active layer is consistent with the thickness of the outer active layer.

5. The battery cell according to claim 1, characterized in that: Along the second direction, a notch communicating with the first electrode tab groove is formed at the edge of the first current collector.

6. The battery cell according to claim 1, characterized in that: The second pole piece is provided with a first thinning groove which is arranged opposite to the first pole lug groove, and a first protective glue is provided in the first thinning groove.

7. The battery cell according to claim 6, characterized in that: The first thinning groove is a stepped groove. Along the thickness direction of the pole piece, the first thinning groove includes a step surface A and a step surface B sequentially arranged along the groove depth direction. The first protective glue is arranged on the step surface A.

8. The battery cell according to claim 1, characterized in that: A second thinning groove is provided on the first pole piece; the second thinning groove and the first pole lug groove are arranged on the first active layer on both sides of the first current collector, and their projections in the thickness direction of the pole piece at least partially overlap; The depth of the second thinning groove is less than the thickness of the first active layer, and a second protective glue is arranged in the second thinning groove.

9. The battery cell according to claim 1, characterized in that: A second skived groove and a second protective glue are provided on the first pole piece; the second skived groove and the first pole lug groove are arranged on the first active layer on both sides of the first current collector, and their projections in the thickness direction of the pole piece at least partially overlap; The depth of the second thinning groove is consistent with the thickness of the first active layer; The second protective glue is located on the first active layer and covers the second thinning groove.

10. The battery cell according to claim 9, characterized in that: A fifth protective glue is arranged at a position of the second pole piece opposite to the second thinning groove, and a projection of the fifth protective glue in the thickness direction of the pole piece is located within the projection of the second protective glue.

11. The battery cell according to claim 1, characterized in that: The second pole piece includes a second current collector, a second active layer arranged on at least one side of the second current collector, a second pole ear, and a second pole ear glue; a second pole ear groove is arranged on the second active layer, a part of the second pole ear is located in the second pole ear groove and connected to the second current collector, the second active layer includes a gel-containing active layer arranged around the second pole ear groove and a main active layer arranged around the gel-containing active layer, the thickness of the gel-containing active layer is less than the thickness of the main active layer, and the second pole ear glue partially covers the section of the second pole ear located in the second pole ear groove and is partially located on the gel-containing active layer; A third thinning groove is arranged on the first pole piece at a position opposite to the second pole lug groove, and a third protective glue is arranged in the third thinning groove.

12. The battery cell according to claim 11, characterized in that: The first pole piece is further provided with a fourth thinning groove and a fourth protective glue located in the fourth thinning groove, the projection of the fourth protective glue in the thickness direction of the battery cell at least partially overlaps with the second pole lug groove, and the fourth protective glue and the third protective glue are respectively located on two sections of the first pole piece, and the two sections are respectively located on both sides of the second pole piece section where the second pole lug groove is located; or, A fourth protective glue is provided on the first pole piece, and a welding groove and a sixth protective glue are provided on the second pole piece. The welding groove and the second pole lug groove are respectively located on both sides of the same section of the second current collector and their projections in the thickness direction at least partially overlap. The sixth protective glue covers the notch of the welding groove on the second active layer; the projection of the fourth protective glue in the thickness direction of the pole piece is located within the projection of the sixth protective glue.

13. A battery, characterized in that: A battery cell comprising the battery cell described in any one of claims 1 to 12.

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