Pole piece and battery cell

Abstract

The utility model provides a pole piece and a battery cell, and relates to the technical field of batteries, the pole piece comprises a current collector and an active layer, the current collector comprises a first region and a second region, the active layer is coated on the first region, and the second region is provided with a tab; the second area of the current collector and the surface of the active layer are provided with a plurality of sunken structures which are sunken in the thickness direction of the pole piece. According to the pole piece, the sunken structure is arranged on the surface of the active layer, the efficiency of embedding lithium ions into the active layer from the surface of the active layer is improved, lithium precipitation on the surface of the active layer can be avoided, the sunken structure is arranged on the current collector, the overcurrent capacity at the tab is improved, and the fast charging capacity of the battery is further improved. Moreover, the sunken structure arranged on the surface of the active layer is easy to form in a physical processing mode, so that the quality and the size of the sunken structure are easier to control in the sunken structure forming process, the quality control difficulty in the pole piece manufacturing process is reduced, the product percent of pass is improved, and large-scale production and application are facilitated.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a pole piece and a battery cell. Background Art

[0002] With the development of social economy and science and technology, batteries are used more and more widely in electronic devices, and at the same time, electronic devices have higher and higher requirements for the fast charging performance of batteries.

[0003] In order to improve the fast charging capability of the battery, it is necessary to structurally adjust the existing electrode. Current solutions include chemical pore making, laser pore making, etc.

[0004] However, all of these solutions have their shortcomings. Among them, chemical pore creation is to add chemical substances such as pore-forming agents to produce chemical reactions to create holes in the active layer. This solution will introduce new substances, and the residual pore-forming agents will have the risk of deteriorating electrical properties. Laser pore creation is carried out by high-temperature ablation and dissolution of adhesive materials, and the ablation depth and hole size are random, which makes quality control in the manufacturing process difficult and easily leads to defective products. In addition, the above solutions have limited effect on improving the current capacity of the tabs of fast-charging batteries. Utility Model Content

[0005] In view of the above problems, the present application provides a pole piece and a battery cell, which improves the efficiency of lithium ions embedding from the surface of the active layer into the interior of the active layer, avoids lithium plating, and reduces the difficulty of quality control in the pole piece manufacturing process, improves the product qualification rate, and also improves the current capacity at the pole ear.

[0006] The present application provides a pole piece for a battery, the pole piece comprising a current collector and an active layer, the current collector comprising a first region and a second region, the active layer being coated on the first region, and the second region being provided with a pole ear; the second region of the current collector and the surface of the active layer are both provided with a plurality of recessed structures recessed along the thickness direction of the pole piece.

[0007] According to the pole piece of the present application, a recessed structure is provided on the surface of the active layer, which can shorten the distance between the surface and the interior of the active layer. When the pole piece is in the electrolyte, the electrolyte enters the recessed structure and quickly immerses into the interior of the negative electrode active layer around the recessed structure, thereby improving the efficiency of lithium ions transported from the positive electrode side to the negative electrode side being embedded in the interior of the active layer from the surface of the active layer, and avoiding lithium precipitation on the surface of the active layer. The recessed structure is provided in the second area of ​​the current collector, which can increase the connection contact area between the current collector and the pole ear, so as to improve the flow capacity at the pole ear, so as to further improve the fast charging capacity of the battery. In addition, the recessed structure provided on the surface of the active layer is easy to form by physical processing, so it is easier to control the quality and size of the recessed structure during the formation of the recessed structure, reduce the difficulty of quality control in the process of pole piece manufacturing, improve the product qualification rate, and facilitate large-scale production and application.

[0008] In some embodiments, a plurality of the concave structures are arranged in an array, and in a direction along the first direction and away from the tab, the arrangement density of the concave structures gradually decreases.

[0009] In some embodiments, the concave structures on the electrode tab include multiple columns, there is a gap between any two adjacent columns, and in a direction along the first direction and away from the tab, for any two adjacent gaps, the ratio of the width of the gap farther from the tab to the width of the gap closer to the tab is 1.01 - 1.2.

[0010] In some embodiments, the difference in depth between any two adjacent ones of the plurality of concave structures is less than or equal to 6 μm; and / or, the difference in aperture at the opening between any two adjacent ones of the plurality of concave structures is less than or equal to 200 μm; and / or, the ratio of the area of all the concave structures to the area of the electrode tab is 10% - 50%; and / or, among the plurality of concave structures, the concave structure closest to the edge of the electrode tab has a spacing from the edge of the electrode tab of 1 mm - 10 mm; and / or, the ratio of the depth of the concave structure to the width of the opening of the concave structure ranges from 0.1 - 0.9; and / or, the spacing between any two adjacent ones of the plurality of concave structures ranges from 50 μm - 200 μm; and / or, the inner wall of the concave structure includes a side wall and a bottom wall, the side wall is arranged obliquely relative to a reference plane, the reference plane is parallel to the plane where the surface of the active layer is located, and the angle between the side wall and the reference plane is 20° - 80°; and / or, the ratio of the depth of the concave structure on the active layer to the thickness of the active layer is 0.05 - 0.4.

[0011] In some embodiments, the active layer includes a uniform-thickness region and a thinning region, the thinning region is formed by a part of the active layer adjacent to the second region, and the thickness of the thinning region is less than the thickness of the uniform-thickness region; the concave structure in the uniform-thickness region is a first concave structure, the concave structure in the thinning region is a second concave structure, and the concave structure in the second region is a third concave structure.

[0012] In some embodiments, the area of the first concave structure is S1, the area of the second concave structure is S2, and the area of the third concave structure is S3, and S1, S2, and S3 satisfy: S1 < S2 < S3; and / or, the depth of the first concave structure is H1, the depth of the second concave structure is H2, and the depth of the third concave structure is H3, and H1, H2, and H3 satisfy: H1 < H2 < H3.

[0013] In some embodiments, the depth H1 of the first recessed structure has a value range of 5μm≤H1≤20μm; and / or, the depth H2 of the second recessed structure has a value range of 8μm≤H1≤25μm; and / or, the depth H3 of the third recessed structure has a value range of 10μm≤H1≤30μm; and / or, the ratio of the depth H3 of the third recessed structure to the depth H1 of the first recessed structure is in a range of 1.5-2; and / or, the ratio of the depth H2 of the second recessed structure to the depth H1 of the first recessed structure is in a range of 1.2-1.8.

[0014] In some embodiments, a ratio of a distance between the third recessed structure closest to the electrode tab and the electrode tab in the first direction to a length of the current collector is 0-0.002.

[0015] In some embodiments, a crest position and a trough position exist at an edge of the thinned region on a side facing the second region, and a spacing between the crest position and the trough position in the first direction is 0-3 mm.

[0016] In some embodiments, the recessed structure is formed by the pole piece through at least one of a pressing process and a carving process.

[0017] The second aspect of the present application also provides a battery cell, including: a first pole piece, a diaphragm, and a second pole piece, wherein the first pole piece, the diaphragm, and the second pole piece are stacked in sequence, and at least one of the first pole piece and the second pole piece is the pole piece described in the first aspect above.

[0018] According to the battery cell of the present application, by providing the above-mentioned pole piece, fast charging of the battery cell can be achieved, lithium plating can be avoided, and electrical performance can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 This is a schematic diagram of the structure of the pole piece of some embodiments of the present application;

[0021] Figure 2 This is a schematic diagram of the structure of the pole piece of some embodiments of the present application;

[0022] Figure 3 Partial structural schematic diagram of pole pieces of other embodiments of the present application;

[0023] Figure 4 Schematic diagram of the distribution of different regions of the pole pieces of some embodiments of the present application;

[0024] Figure 5 This is a schematic diagram of the structure of the pole piece of some embodiments of the present application.

[0025] Description of reference numerals:

[0026] 100-pole piece;

[0027] 1-current collector; 11-first region; 12-second region; 13-third recessed structure;

[0028] 2-active layer; 21-uniform thickness region; 22-thinning region; 23-recessed structure; 23a-first recessed structure; 23b-second recessed structure;

[0029] 3-Pole ear. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned purposes, features and advantages of the embodiments of the present application more obvious and understandable, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of this application.

[0031] With the development of social economy and science and technology, batteries are increasingly used in electronic devices, and electronic devices have higher and higher requirements for the fast charging performance of batteries. In order to improve the fast charging capability of batteries, it is necessary to regulate the structure of existing electrodes. The current solutions include chemical pore formation, laser pore formation, etc.

[0032] However, all of these solutions have their shortcomings. Among them, chemical pore creation is to add chemical substances such as pore-forming agents to produce chemical reactions to create holes in the active layer. This solution will introduce new substances, and the residual pore-forming agents will have the risk of deteriorating electrical properties. Laser pore creation is carried out by high-temperature ablation and dissolution of adhesive materials, and the ablation depth and hole size are random, which makes quality control in the manufacturing process difficult and easily leads to defective products. In addition, the above solutions have limited effect on improving the current capacity of the tabs of fast-charging batteries.

[0033] In view of this, the present application provides a pole piece and a battery cell, in which a recessed structure is arranged on the surface of the active layer, which can shorten the distance between the surface and the interior of the active layer. When the pole piece is in the electrolyte, the electrolyte enters the recessed structure and quickly immerses into the interior of the negative electrode active layer around the recessed structure, thereby improving the efficiency of lithium ions transported from the positive electrode side to the negative electrode side being embedded in the active layer from the surface of the active layer, and avoiding lithium precipitation on the surface of the active layer. The recessed structure is arranged in the second area of ​​the current collector, which can increase the connection contact area between the current collector and the pole ear to improve the flow capacity at the pole ear, so that the fast charging capacity of the battery can be further improved. In addition, the recessed structure arranged on the surface of the active layer is easy to form by physical processing, so it is easier to control the quality and size of the recessed structure during the formation of the recessed structure, reduce the difficulty of quality control in the process of pole piece production, improve the product qualification rate, and facilitate large-scale production and application.

[0034] The pole piece 100 according to the first embodiment of the present application is described below.

[0035] The pole piece 100 of this embodiment can be a positive pole piece or a negative pole piece, preferably a negative pole piece. The pole piece 100 can be used in a battery, and the battery can be a primary battery or a secondary battery. A primary battery refers to a battery that cannot be recharged and reused after the battery is discharged, and a secondary battery refers to a battery that can be recharged to activate the active material and continue to be used after the battery is discharged. The battery can be any one of a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, and a nickel-hydrogen battery. Of course, the embodiments of the present application are not limited to this.

[0036] For ease of description, the following description is made by taking the electrode 100 as being applied to a lithium battery and being a negative electrode as an example.

[0037] refer to Figure 1-Figure 5 The pole piece 100 may include a current collector 1 and an active layer 2, and the active layer 2 is coated on the surface of the current collector 1. For example, the current collector 1 may include a first surface and a second surface opposite to each other in the thickness direction. When the pole piece 100 is used as the pole piece 100 of a wound battery cell, the first surface and the second surface may be coated with the active layer 2; when the pole piece 100 is used as the pole piece 100 of a stacked battery cell, since the pole piece 100 and the positive electrode sheet are both multiple and alternately stacked, when the pole piece 100 is used as the topmost or bottommost pole piece, the active layer 2 may be provided only on the surface of one side of the current collector 1 facing the positive electrode sheet, while the first surface and the second surface of the other pole pieces 100 in the middle position may be coated with the active layer 2.

[0038] In some embodiments, reference Figure 2-Figure 5The current collector 1 may include a first region 11 and a second region 12, wherein the active layer 2 is coated on the first region 11, and the second region 12 is provided with a pole ear 3, that is, the second region 12 is an empty foil region of the current collector 1, and the pole ear 3 of the battery cell may be provided in the second region 12. In this way, the battery cell having the pole piece 100 is conveniently connected to the outside.

[0039] The second region 12 of the current collector 1 and the surface of the active layer 2 are both provided with a plurality of recessed structures 23. Optionally, only a portion of the second region 12 and the active layer 2 are each provided with a recessed structure 23, or the entire second region 12 and the active layer 2 are each provided with a recessed structure 23. The recessed structure 23 may be provided only on the active layer 2 on one side of the current collector 1, or on both sides of the current collector 1.

[0040] The recessed structure 23 can be recessed along the thickness direction of the pole piece 100, and the shape of the recessed structure 23 can be square, circular, triangular, multi-deformed or any other shape; the inner wall of the recessed structure 23 can be a straight inner wall, a curved inner wall, or an inner wall of any other shape; the shapes of any two recessed structures 23 can be the same or different; the spacing between any two adjacent recessed structures 23 can be the same or different; multiple recessed structures 23 can be arranged regularly or in disorder.

[0041] When the electrode 100 is in the electrolyte, the electrolyte enters the recessed structure 23 on the active layer 2 and quickly penetrates into the interior of the active layer 2 from the recessed structure 23. The recessed structure 23 serves as a partial transport channel for lithium ions, thereby improving the efficiency of lithium ions transported from the positive electrode side to the negative electrode side being embedded from the surface of the active layer 2 into the interior of the active layer 2, and avoiding lithium precipitation on the surface of the active layer 2, thereby greatly improving the fast charging capability of the battery using the electrode 100.

[0042] The recessed structure 23 is provided on the second region 12 of the current collector 1. On the one hand, it can increase the connection contact area between the current collector 1 and the pole tab 3, so as to improve the flow capacity at the pole tab 3 and reduce the heat generation at the pole tab 3; on the other hand, it can also increase the friction between the second region 12 of the current collector 1 and the pole tab 3, making it easier to weld the two, and improve the welding strength between the current collector 1 and the pole tab 3, and ensure the connection stability of the pole tab 3. In addition, the pole piece 100 can be pore-formed as a whole, and the recessed structure 23 can be formed on the second region 12 of the current collector and the active layer 2 simultaneously, eliminating the need to control the pore-forming area separately when pores are formed in only one of the two, thereby reducing the difficulty of the pore-forming process.

[0043] According to the pole piece 100 of the embodiment of the present application, a recessed structure 23 is provided on the surface of the active layer 2, which can shorten the distance between the surface and the interior of the active layer 2. When the pole piece 100 is in the electrolyte, the electrolyte enters the recessed structure 23 and quickly penetrates into the interior of the negative electrode active layer 2 around the recessed structure 23, thereby improving the efficiency of lithium ions transported from the positive electrode side to the negative electrode side from the surface of the active layer 2 to the interior of the active layer 2, and avoiding lithium precipitation on the surface of the active layer 2. The recessed structure 23 is provided in the second region 12 of the current collector 1, which can increase the connection contact area between the current collector 1 and the pole ear 3 to improve the current flow capacity at the pole ear 3, so that the fast charging capacity of the battery can be further improved. In addition, the recessed structure 23 provided on the surface of the active layer 2 is easy to be formed by physical processing, so it is easier to control the quality and size of the recessed structure 23 during the formation process of the recessed structure 23, reduce the difficulty of quality control in the production process of the pole piece 100, improve the product qualification rate, and facilitate large-scale production and application.

[0044] In some embodiments, reference Figure 1-Figure 3 The plurality of recessed structures 23 are arranged in an array on the pole piece 100. For example, all the recessed structures 23 including the recessed structures 23 on the current collector 1 and the active layer 2 can be arranged in a circular array, an annular array, a cross-shaped array, a square array or other arrays. In this way, the arrangement of the recessed structures 23 is diverse, and the arrangement is relatively simple and easy to process.

[0045] In some embodiments, in combination Figure 1-Figure 3 , the plurality of recessed structures 23 are arranged in an array, for example, in a plurality of rows and columns. Moreover, in the direction along the first direction (for example, the length direction) and away from the pole ear 3, the arrangement density of the recessed structures 23 gradually decreases. Taking the first side length direction as the length direction of the current collector 1 as an example, as Figure 1 As shown, when the tab 3 is arranged in the middle area of ​​the current collector 1, the arrangement interval between the columns gradually increases from the tab 3 toward the two ends of the current collector 1, and the density of the recessed structure 23 gradually decreases; Figure 2 As shown, when the pole lug 3 is arranged at one end of the current collector 1, the arrangement interval between the columns gradually increases in the direction from the end where the pole lug 3 is located to the other end, and the density of the recessed structure 23 gradually decreases. In this way, the distribution mode of the recessed structure 23 is adapted to the lithium ion density and migration rate at different distances from the pole lug 3 on the pole piece 100, which is conducive to improving the fast charging capability of the battery and reducing the process difficulty while ensuring no lithium precipitation.

[0046] Optionally, the recessed structure 23 can be constructed as a variable-size recessed structure 23 according to the requirements of the battery cell design, that is, the recessed structure can be variable-size along the length direction, width direction, thickness direction or any other angle of the pole piece 100 .

[0047] In some possible embodiments, the recessed structures 23 on the second region 12 and the recessed structures 23 on the active layer 2 may form arrays separately, and the array shape of the recessed structures 23 on the second region 12 may be the same as or different from the array shape of the recessed structures 23 on the active layer 2; or, the recessed structures 23 on the second region 12 and the recessed structures 23 on the active layer 2 together form an array, that is, a part of the array is formed by the recessed structures 23 on the second region 12, and the other part is formed by the recessed structures 23 on the active layer 2; or, the recessed structures 23 on the second region 12 and the recessed structures 23 on the active layer 2 are arranged using the same arrangement rule, or they may be arranged using different arrangement rules; or, the recessed structures 23 on the second region 12 and the recessed structures 23 on the active layer 2 are arranged as a whole according to one arrangement rule.

[0048] In some embodiments, reference Figure 1 and Figure 2 , there is a gap between any two adjacent columns, and, in the direction along the first direction and away from the pole lug 3, in any two adjacent gaps, the ratio of the width of a gap away from the pole lug 3 to the width of a gap close to the pole lug 3 is 1.01-1.2. In other words, in the direction along the first direction and away from the pole lug 3, the scaling factor of the width of adjacent gaps is 1.01-1.2. For example, in the direction along the first direction and away from the pole lug 3, the scaling factor of the width of adjacent gaps can be 1.01, 1.02, 1.05, 1.08, 1.1, 1.11, 1.12, 1.14, 1.15, 1.16, 1.18 or 1.2. Of course, the present application does not impose any restrictions on this. In any two adjacent intervals, the ratio of the width of a spacing away from the pole ear 3 to the width of a spacing close to the pole ear 3 can be reasonably selected within the above range according to actual needs. In this way, it can avoid that when it is less than 1.01, the recessed structure 23 is arranged too densely, which has limited effect on improving the efficiency of lithium ions embedded in the active layer 2 in the electrolyte and increases the process difficulty. It can also avoid that when it is greater than 1.2, when the total area of ​​the active layer 2 is constant, the number of recessed structures 23 is reduced, which is not conducive to improving the efficiency of lithium ions embedded in the active layer 2, thereby improving the fast charging capability of the battery.

[0049] In some embodiments, the depth difference between any two adjacent ones of the plurality of recessed structures 23 is less than or equal to 6 μm. For example, the depth difference between any two adjacent ones of the plurality of recessed structures 23 is 2 μm, 3 μm, 4 μm, 5 μm or 6 μm. Of course, the present application does not limit this. It is only necessary to ensure that the depth difference between any two adjacent ones of the plurality of recessed structures 23 is within the above range. It can ensure that the depth consistency of the plurality of recessed structures 23 is good. At the same time, the depth difference between adjacent recessed structures 23 is small, the liquid storage volume is close, and the contact area between each recessed structure 23 and the electrolyte is close, so that the current distribution of the electrode 100 is uniform.

[0050] In some embodiments, the difference in apertures between any two adjacent openings of the plurality of recessed structures 23 is less than or equal to 200 μm. In this way, the opening sizes of the plurality of recessed structures 23 can be kept consistent. At the same time, the difference in opening sizes of adjacent recessed structures 23 is small, the liquid storage amounts are close, and the contact areas between each recessed structure 23 and the electrolyte are close, so that the current distribution of the electrode 100 is uniform.

[0051] In some embodiments, the ratio of the sum of the areas of the recessed structures 23 on the active layer 2 to the area of ​​the active layer 2 is 10%-50%. For example, the ratio of the sum of the areas of all the recessed structures 23 on the active layer 2 to the area of ​​the active layer 2 can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% or 50%. Of course, the present application does not limit this. The ratio of the sum of the areas of all the recessed structures 23 on the active layer 2 to the area of ​​the active layer 2 is reasonably selected within the above range according to actual needs. In this way, when the ratio is too small, for example, less than 10%, the effect of setting the recessed structure 23 on improving the overall lithium ion migration efficiency of the pole piece 100 is poor. When the ratio is too large, for example, greater than 50%, the active material of the active layer 2 is greatly reduced, which affects the battery energy density and reduces the battery capacity.

[0052] In some embodiments, among the multiple recessed structures 23, the recessed structure 23 closest to the edge of the pole piece 100 has a spacing of 1mm-10mm from the edge of the pole piece 100, and the recessed structure 23 closest to the edge of the pole piece 100 has a spacing of 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm or 10mm from the edge of the pole piece 100. Of course, the present application does not limit this, and among the multiple recessed structures 23, the spacing between the recessed structure 23 closest to the edge of the pole piece 100 and the edge of the pole piece 100 can be reasonably selected within the above range according to actual needs. For example, when the multiple recessed structures 23 are arranged in a rectangular array, the distance between a row or a column of recessed structures 23 as the rectangular edge and the corresponding edge of the pole piece 100 is 1mm-10mm; when the multiple recessed structures 23 are arranged in an array of other shapes, the recessed structure 23 closest to the edge of the pole piece 100 on the array contour line is 1mm-10mm from the edge of the pole piece 100 on the side where it is located. In this way, it can be ensured that the distribution range of the recessed structures 23 in various regions on the active layer 2 is relatively wide and uniform, which is conducive to ensuring that the current distribution in various regions on the pole piece 100 is relatively uniform.

[0053] In some embodiments, the ratio of the depth of the recessed structure 23 to the width of the opening of the recessed structure 23 is in the range of 0.1-0.9. For example, the ratio of the depth of the recessed structure 23 to the width of the opening of the recessed structure 23 can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or 0.9. Of course, the present application does not impose any limitation on this. The ratio of the depth of the recessed structure 23 to the width of the opening of the recessed structure 23 can be reasonably selected within the above range according to actual needs. For example, when the recessed structure 23 is circular, the ratio of the depth of the recessed structure 23 to the diameter of the opening of the recessed structure 23 is 0.1-0.9. In this way, it can be prevented that when the ratio is too small, for example, less than 0.1, the depth of the recessed structure 23 is insufficient, and the electrolyte has insufficient penetration power from the surface of the active layer 2 to the inner layer of the active layer 2, which has limited improvement on the battery's dynamic performance; it can also be prevented that when the ratio is too large, for example, greater than 0.9, the depth of the recessed structure 23 is too large, the lithium ions migrated from the positive electrode side cannot be quickly embedded in the active layer 2, but have a tendency to lithium precipitation, and cause a large loss of active materials, and increase processing costs.

[0054] In some embodiments, the spacing between any two adjacent ones of the plurality of recessed structures 23 ranges from 50 μm to 200 μm. For example, the spacing between any two adjacent ones of the plurality of recessed structures 23 ranges from 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 120 μm, 140 μm, 150 μm, 160 μm, 180 μm, 190 μm or 200 μm. Of course, the present application does not limit this, and the spacing between any two adjacent ones of the plurality of recessed structures 23 can be reasonably selected within the above range according to actual needs. In this way, it is possible to prevent the spacing between any two adjacent recessed structures 23 from being too small, for example, less than 50 μm, and the recessed structures 23 from being arranged too densely, resulting in a large loss of active materials, great processing difficulty, high processing cost and reduced battery capacity. It is also possible to prevent the spacing between any two adjacent recessed structures 23 from being too large, for example, greater than 200 μm, and the recessed structures 23 from being arranged at a low density, resulting in limited improvement in the fast charging capability of the battery and easy occurrence of lithium plating.

[0055] In some embodiments, the inner wall of the recessed structure 23 may include a side wall and a bottom wall, the side wall is arranged obliquely relative to the reference plane, the reference plane is parallel to the plane where the surface of the active layer 2 is located, and the angle between the side wall and the reference plane is 20°-80°. For example, the angle between the side wall and the reference plane can be 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75° or 80°. Of course, the present application does not limit this, and the angle between the side wall and the reference plane can be reasonably selected within the above range according to actual needs. In this way, the surface area of ​​the inner wall of the recessed structure 23 can be increased, thereby increasing the contact area between the inner wall of the recessed structure 23 and the electrolyte, so that lithium ions can be embedded into the active layer 2 more quickly.

[0056] In some embodiments, the ratio of the depth of the recessed structure 23 on the active layer 2 to the thickness of the active layer 2 is 0.05-0.4. For example, the ratio of the depth of the recessed structure 23 on the active layer 2 to the thickness of the active layer 2 is 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35 or 0.4. Of course, the present application is not limited to this. The ratio of the depth of the recessed structure 23 on the active layer 2 to the thickness of the active layer 2 can be reasonably selected within the above range according to actual needs. In this way, it is possible to prevent the ratio of the depth of the recessed structure 23 on the active layer 2 to the thickness of the active layer 2 from being too small, for example, less than 0.05, in which case the depth of the recessed structure 23 is insufficient, and the electrolyte has insufficient penetration power from the surface of the active layer 2 to the inner layer of the active layer 2, resulting in limited improvement in the battery's dynamic performance; it is also possible to prevent the ratio from being too large, for example, greater than 0.4, in which case the depth of the recessed structure 23 is too large, and the lithium ions migrating from the positive electrode side cannot be quickly embedded in the active layer 2, but instead have a tendency to lithium precipitation, resulting in a large loss of active materials and increased processing costs.

[0057] In some embodiments, in combination with Figure 4 and Figure 5 , the active layer 2 may include a uniform-thickness region 21 and a thinning region 22. The thinning region 22 is formed by the part of the active layer 2 adjacent to the second region 12. The thickness of the thinning region 22 is lower than that of the uniform-thickness region 21. For example, the thickness of each part of the thinning region 22 may be the same and less than that of the uniform-thickness region 21; alternatively, the uniform-thickness region 21 may gradually thin towards the second region 12 to form the thinning region 22. At this time, the surface of the thinning region 22 is an inclined surface compared with the surface of the uniform-thickness region 21. It should be noted that the thinning region 22 may be a trailing tail formed at the contact boundary between the active material and the current collector 1 during the coating process.

[0058] Referring to Figure 5 , it is defined here that the concave structure 23 of the uniform-thickness region 21 is the first concave structure 23a, the concave structure 23 of the thinning region 22 is the second concave structure 23b, and the concave structure 23 of the second region 12 of the current collector 1 is the third concave structure 13. It can be understood that the existence of the third concave structure 13 can increase the friction between the empty foil area and the tab 3, improve the welding strength of the tab 3, and is beneficial to improving the cycle reliability of the connection of the tab 3; the existence of the second concave structure 23b can reduce the covering area of the positive electrode tab corresponding to the thinning region 22 on the negative wire bonding tab, and improve the problem of lithium deposition at the edge of the electrode tab; the existence of the third concave structure 13 can increase the space for storing electrolyte inside the battery, improve the liquid retention capacity of the battery, and improve the wetting efficiency of the battery. The sufficient electrolyte between the electrode tabs improves the kinetic performance of the electrode tabs, which is beneficial to the battery to achieve fast charging and discharging.

[0059] Among them, the area of the first concave structure 23a is S1, the area of the second concave structure 23b is S2, and the area of the third concave structure 13 is S3. S1, S2, and S3 satisfy: S1 < S2 < S3. Since the position with a smaller thickness on the electrode tab 100 has a smaller strength and a lower ability to resist deformation, and the second region 12 has the smallest thickness compared with the active layer 2, when using the same pore-forming process such as stamping to form pores, the punched area on the part with a smaller thickness is more likely to drive the surrounding area to deform, resulting in the largest area of the third concave structure 13 on the current collector 1 and the smallest area of the first concave structure 23a in the uniform-thickness region 21, which is easy to perform the pore-forming process on the electrode tab 100. In this way, the requirements for the pore-forming accuracy of different parts can be simplified, and the process difficulty and processing cost can be reduced.

[0060] The depth of the first concave structure 23a is H1, the depth of the second concave structure 23b is H2, and the depth of the third concave structure 13 is H3. H1, H2, and H3 satisfy: H1 < H2 < H3. In this way, it is easy to perform the pore-forming process on the electrode sheet 100. Since the position with a smaller thickness on the electrode sheet 100 has a smaller strength and a lower ability to resist deformation, and the second region 12 has the smallest thickness compared to the active layer 2. When using the same pore-forming process, such as stamping, the punched area on the part with a smaller thickness is more likely to drive the surrounding area to deform, so that the depth of the third concave structure 13 on the current collector 1 is the largest, and the depth of the first concave structure 23a in the thickness-uniform region 21 is the smallest, making it easy to perform the pore-forming process on the electrode sheet 100. In this way, the requirements for the pore-forming accuracy of different parts can be simplified, and the process difficulty and processing cost can be reduced.

[0061] In some embodiments, the value range of the depth H1 of the first concave structure 23a is: 5μm ≤ H1 ≤ 20μm. For example, the value of the depth H1 of the first concave structure 23a can be 5μm, 6μm, 8μm, 10μm, 12μm, 15μm, 18μm, or 20μm. Of course, the present application does not limit this, and the depth H1 of the first concave structure 23a can be reasonably selected within the above range according to actual needs. In this way, when the depth of the first concave structure 23a in the thickness-uniform region 21 is too small, such as less than 5μm, the depth of the first concave structure 23a is insufficient, and the driving force for the electrolyte to penetrate from the surface of the active layer 2 to the inner layer of the active layer 2 is insufficient, resulting in limited improvement in the kinetic performance of the battery. It can also prevent the depth of the first concave structure 23a from being too large, such as greater than 20μm. When the depth of the first concave structure 23a is too large, the lithium ions migrated from the positive electrode side cannot be quickly embedded in the active layer 2, but instead tend to deposit lithium, and it also leads to a large loss of active material and an increase in processing cost.

[0062] In some embodiments, the depth H2 of the second recessed structure 23b has a value range of 8μm≤H1≤25μm. For example, the depth H2 of the second recessed structure 23b can be 8μm, 10μm, 12μm, 15μm, 18μm, 20μm, 22μm, 24μm or 25μm. Of course, the present application does not impose any restrictions on this. The depth H1 of the second recessed structure 23b can be reasonably selected within the above range according to actual needs. In this way, it is possible to prevent the depth of the second recessed structure 23b in the thinning area 22 from being too small, for example, when it is less than 8μm, the depth of the second recessed structure 23b is insufficient, and the electrolyte has insufficient penetration power from the surface of the active layer 2 to the inner layer of the active layer 2, which has limited improvement on the battery's dynamic performance; it is also possible to prevent the depth of the second recessed structure 23b from being too large, for example, when it is greater than 25μm, the depth of the second recessed structure 23b is too large, and the lithium ions migrating from the positive electrode side cannot be quickly embedded in the active layer 2, but instead have a tendency to lithium precipitation, and cause a large loss of active materials, which increases the processing cost. In addition, the processing difficulty is relatively low.

[0063] In some embodiments, the depth H3 of the third recessed structure 13 has a value range of 10μm≤H1≤30μm. For example, the depth H3 of the third recessed structure 13 may be 10μm, 12μm, 15μm, 18μm, 20μm, 22μm, 24μm, 25μm, 28μm or 30μm. Of course, the present application does not limit this. The depth H3 of the third recessed structure 13 may be reasonably selected within the above range according to actual needs. In this way, it is possible to prevent the depth of the third recessed structure 13 of the second region 12 from being too small, for example, less than 10μm, and the depth of the third recessed structure 13 is insufficient, which has limited effect on improving the connection between the tab 3 and the current collector 1. It is also possible to prevent the depth of the third recessed structure 13 from being too large, for example, greater than 30μm, and the depth of the third recessed structure 13 is too large, which may cause the current collector 1 to rupture, increase the internal resistance, and cause serious heat generation.

[0064] In some embodiments, the ratio of the depth H3 of the third recessed structure 13 to the depth H1 of the first recessed structure 23a is in the range of 1.5-2. For example, the ratio of the depth H3 of the third recessed structure 13 to the depth H1 of the first recessed structure 23a can be 1.5, 1.6, 1.7, 1.8, 1.9 or 2. Of course, the present application does not limit this. The ratio of the depth H3 of the third recessed structure 13 to the depth H1 of the first recessed structure 23a can be reasonably selected within the above range according to actual needs. If the ratio of the depth H3 of the third recessed structure 13 to the depth H1 of the first recessed structure 23a is too small, the effect of improving the kinetic performance of lithium ions will not be obvious. If it is too large, the mechanical properties of the empty foil area of ​​the current collector 1 and the uniform thickness area 21 of the active layer 2 will be destroyed, resulting in problems such as poor welding, powdering and flakes when applying the paste.

[0065] The ratio of the depth H2 of the second recessed structure 23b to the depth H1 of the first recessed structure 23a is in the range of 1.2-1.8. For example, the ratio of the depth H2 of the second recessed structure 23b to the depth H1 of the first recessed structure 23a can be 1.2, 1.3, 1.4, 1.5, 1.6, 1.7 or 1.8. Of course, the present application does not limit this. The ratio of the depth H2 of the second recessed structure 23b to the depth H1 of the first recessed structure 23a can be reasonably selected within the above range according to actual needs. If the ratio of the depth H2 of the second recessed structure 23b to the depth H1 of the first recessed structure 23a is too small, the effect of improving the kinetic performance of lithium ions will not be obvious. If it is too large, the mechanical properties of the thinning area 22 and the uniform thickening area 21 of the active layer 2 will be destroyed, resulting in problems such as powder and flake falling when applying the paste.

[0066] In some embodiments, the current collector 1 corresponding to the second recessed structure 23b has a recess, and the direction of the recess is the same as the recessed direction of the second recessed structure 23b, and the current collector 1 corresponding to the third recessed structure 13 has a recess, and the direction of the recess is the same as the recessed direction of the third recessed structure 13. In other words, the current collector 1 covered by the active layer 2 can be deformed in the same direction as the active layer 2 during the pore-forming process of the active layer 2.

[0067] In some embodiments, the ratio of the distance between the third recessed structure 13 closest to the pole tab 3 and the pole tab 3 in the first direction to the length of the current collector 1 is 0-0.002, wherein, if the ratio is too small, it will lead to high process difficulty and high equipment processing cost; if the ratio is too large, it will lead to the improvement effect of the processed pole piece 100 in terms of dynamic performance is not obvious, and in addition, it can also prevent the recessed structure 23 on the second region 12 and the pole tab 3 from having a large distance, which has an insignificant effect on improving the connection reliability between the pole tab 3 and the current collector 1. That is, when the ratio is within the above range, the best improvement effect can be achieved.

[0068] It should be noted that, when the ratio of the distance between the third recessed structure 13 closest to the pole lug 3 and the pole lug 3 in the first direction to the length of the current collector 1 is 0, the distance recessed structure 23 on the second region 12 of the current collector 1 can be arranged close to the pole lug 3, that is, the distance from the pole lug 3 is 0.

[0069] In some embodiments, there are crest positions and trough positions on the edge of the thinning region 22 facing the second region 12, and the spacing between the crest positions and the trough positions in the first direction is 0-3 mm. For example, the spacing between the crest positions and the trough positions in the first direction can be 0, 1 mm, 2 mm or 3 mm, wherein when the spacing between the crest positions and the trough positions in the first direction is 0, the edge of the thinning region 22 facing the second region 12 can be a straight line; when the spacing between the crest positions and the trough positions in the first direction is not 0, the edge of the thinning region 22 facing the second region 12 can be wavy or other irregular curve shapes. At this time, since the recessed structures 23 are arranged in an array, a part of the recessed structure 23 at the edge of the active layer 2 or the edge of the second region 12 may be in the second region 12, and the other part may be on the active layer 2.

[0070] In some embodiments, the recessed structure 23 is formed by the pole piece 100 through at least one of a pressing process and a carving process. In this way, the recessed structure 23 is formed in a relatively simple manner and is easy to process.

[0071] The battery cell of the second embodiment of the present application is described below.

[0072] The battery cell of this embodiment includes: a first electrode sheet, a separator and a second electrode sheet. One of the first electrode sheet and the second electrode sheet is a positive electrode sheet and the other is a negative electrode sheet. For example, the first electrode sheet is a positive electrode sheet and the second electrode sheet is a negative electrode sheet, or the second electrode sheet is a positive electrode sheet and the first electrode sheet is a negative electrode sheet. At least one of the first electrode sheet and the second electrode sheet is the electrode sheet 100 in the above embodiment. When the battery cell is a laminated battery cell, there are multiple first and second electrode sheets, and the first electrode sheet, the separator and the second electrode sheet are alternately stacked in sequence; when the battery cell is a wound battery cell, the first electrode sheet, the separator and the second electrode sheet are stacked and wound in sequence.

[0073] According to the battery cell of the embodiment of the present application, by providing the pole piece 100 of the above embodiment, it is possible to achieve fast charging of the battery cell, avoid lithium plating, and improve electrical performance.

[0074] The electrical performance effect when the negative electrode sheet of the battery cell in this embodiment is provided with a recessed structure 23 is described below in conjunction with specific embodiments.

[0075] The following uses the negative electrode sheet of the battery cell using the electrode sheet 100 of the first aspect as an example, and the processing method thereof is as follows:

[0076] The surface of the pole piece 100 can be processed by stamping die pressing, engraving machine engraving and other processing techniques. Among them, the processing parts of the mold or engraving machine can be rigid structural parts, such as metal parts, ceramic parts and other materials with sufficient hardness (hardness of 2-10), and the shape of the processing parts can be cylindrical, truncated cone, square cone, cone, tetrahedron, etc. The processing parts are used to apply a force to the surface of the pole piece 100, and the force is perpendicular to the pole piece 100. The vibration frequency of the processing parts is 2000HZ-5000HZ, preferably, the vibration frequency is 3000HZ-4800H, so that the processing efficiency is higher. After each hole-making step is completed, a visual inspection system is used to detect the contour and depth of the recessed structure 23 to ensure that the size of the recessed structure 23 meets the process requirements.

[0077] Lithium deposition test of electrode 100: The battery with the above-mentioned electrode 100 is charged to 4.35V at 2C, 2.5C and 3C at 25°C, left to stand for 10 minutes, and then discharged to 3.0V at 0.7C. The above groups of batteries are tested for 20 cycles, and the lithium deposition of the battery electrode 100 is dissected and observed.

[0078] Wetting time test: Take the processed electrode 100, place it on a horizontal surface, use a pipette to take the electrolyte for the battery cell, and drop it quantitatively on the surface of the electrode 100. Use a stopwatch to time it. The time from the electrolyte starting to contact the surface of the electrode 100 to the time it completely disappears is the electrolyte infiltration time.

[0079] Weight loss rate of the pole piece 100: the initial weight of the pole piece 100 to be processed is W0, and the weight after the hole making process is W1, and the weight loss rate = (W0-W1) / W0*100%.

[0080] Cell capacity loss rate: Take the cells after capacity division, and obtain the capacities of the cells in the comparison group (comparison group 1 and comparison group 2) and the experimental group (including experimental groups 1-4) as Q0 and Qi, respectively. Capacity loss rate = (Q0-Wi) / Q0*100%.

[0081] The manufacturing steps of the battery of comparison group 1 are as follows:

[0082] Preparation of negative electrode sheet: Graphite, styrene butadiene latex (SBR), sodium carboxymethyl cellulose (CMC), and conductive carbon black were added to deionized water at a mass ratio of 96.90:1.3:1.3:0.5, and stirred evenly to prepare negative electrode slurry; the prepared negative electrode slurry was evenly coated on a copper foil with a thickness of 6 μm (i.e., negative electrode current collector), and the coating weight was 7.38 mg / cm 2 After drying and compaction, the electrode 100 is obtained, and the compaction density is 1.70g / cm 3 , coating thickness 93μm;

[0083] Preparation of positive electrode sheet: LiCoO2, PVDF and conductive agent were added to N-methylpyrrolidone (NMP) at a mass ratio of 97.8:1.1:1.1, stirred evenly to form positive electrode slurry, and coated on a positive current collector with a thickness of 9 μm using an extrusion coater or a transfer coater, with a coating weight of 13.63 mg / cm 2 , compacted density 4.13g / cm 3 , the thickness after rolling is 75μm;

[0084] Diaphragm: Polypropylene microporous membrane is used as the diaphragm;

[0085] Preparation of lithium-ion battery electrolyte: lithium hexafluorophosphate (LiPF6) with a concentration of 1M is used as lithium salt, a mixture of ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) is used as non-aqueous organic solvent (wherein the mass ratio is EC: DMC: EMC = 3: 4: 3), and an additive containing 3wt% fluoroethylene carbonate (FEC) and 1wt% vinylene carbonate is added;

[0086] Lithium-ion battery assembly: The prepared pole piece, separator and positive electrode piece are stacked and wound to obtain a lithium-ion battery cell, the cell is loaded into a shell, the prepared lithium-ion battery electrolyte is injected, sealed, and the lithium-ion battery of comparison group 1 is assembled after the processes of formation and capacity.

[0087] Comparison group 2

[0088] The difference between the battery cells in comparison group 2 and comparison group 1 is that the surface of the pole piece in comparison group 2 is laser ablated, with a processing depth of 30 μm, an opening size of 60 μm, and a recessed structure spacing of 100 μm.

[0089] Experimental Group 1

[0090] The difference between the battery cells in the experimental group 1 and the comparative group 1 is that the surface of the pole piece 100 is mechanically engraved, the processing depth is 10 μm, the opening size is 60 μm, and the spacing between the recessed structures 23 is 100 μm.

[0091] Experimental Group 2

[0092] The difference from the battery cell of the experimental group 1 is that the depth of the recessed structure 23 of the pole piece 100 in the experimental group 2 is 20 μm.

[0093] Experimental Group 3

[0094] The difference from the battery cell of the experimental group 1 is that the depth of the recessed structure 23 of the pole piece 100 in the experimental group 3 is 30 μm.

[0095] Experimental Group 4

[0096] The difference from the battery cell of the experimental group 1 is that the depth of the recessed structure 23 of the pole piece 100 in the experimental group 3 is 40 μm.

[0097] Table 1 Performance test comparison between experimental group and control group

[0098]

[0099] By analyzing the above data and comparing the comparison group 1 with the experimental group, it can be seen that after the electrode 100 is subjected to the pore-forming treatment, the electrolyte infiltration efficiency of the electrode is significantly improved, the battery performance is significantly improved, and there is no lithium deposition in the electrode 100 during the fast charging process;

[0100] Comparing the comparative group 2 with the experimental group, it can be seen that: the pole piece 100 after mechanical engraving has no weight loss rate and capacity loss of the battery cell, indicating that after the pole piece 100 is laser ablated, the change of the microstructure of the active layer 2 and the local failure of the adhesive may be affected, thereby affecting the integrity of the conductive network between the particles;

[0101] In addition, compared with the experimental group, in the processing process of the pole piece 100, the laser ablation scheme of the control group 2 is uncontrollable due to the uncontrollability of the laser spot during the ablation process, and the ablated opening size is irregular, which cannot be detected by the visual system, resulting in uncontrollable quality of the processing process. The pole pieces 100 of the experimental group are all mechanically engraved, with regular opening sizes, and the processing depth can be controlled mechanically to ensure its consistency, thereby ensuring the stability of the pole piece 100 processing process and the controllable product quality.

[0102] From the comparison of experimental groups 1-4, it can be seen that with the increase of processing depth, the infiltration efficiency of the electrolyte is significantly improved, and the problem of fast lithium charging is significantly improved.

[0103] The battery of the third embodiment of the present application is described below.

[0104] The battery of this embodiment can be a primary battery or a secondary battery. A primary battery refers to a battery that cannot be recharged and reused after the battery is discharged, and a secondary battery refers to a battery that can be recharged to activate the active material and continue to be used after the battery is discharged. The battery can be any one of a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, and a nickel-hydrogen battery. Of course, the embodiment of the present application is not limited to this. The battery may include: a housing and a battery cell in the above embodiment, the battery cell is arranged in the housing, and the battery cell can be connected to the positive and negative electrodes on the housing through the pole ear 3.

[0105] The battery of this embodiment, by providing the battery cells of the above-mentioned embodiment, can achieve fast charging and avoid lithium plating, which is beneficial to improving electrical performance, thereby enhancing user experience.

[0106] The following describes an electrical device according to an embodiment of the fourth aspect of the present application.

[0107] The power-consuming device of this embodiment may be a mobile phone, a tablet computer, a laptop computer, a new energy vehicle, a smart watch, a communication base station, etc. The power-consuming device may include: a device body and the battery in the above embodiment. The device body has a battery compartment, the battery may be arranged in the battery compartment, and the battery is electrically connected to the device body.

[0108] According to the electric device of the embodiment of the present application, by setting the battery in the above embodiment, since the battery has a fast charging capability, the charging speed of the electric device can be increased, which is beneficial to improving the user experience.

[0109] The various embodiments or implementation methods in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referenced to each other.

[0110] It should be noted that the embodiments represented by "one embodiment", "an embodiment", "an exemplary embodiment", "some embodiments", etc. mentioned in the specification may include specific features, structures or characteristics, but not every embodiment may include the specific features, structures or characteristics. In addition, such phrases do not necessarily refer to the same embodiment. In addition, when describing specific features, structures or characteristics in conjunction with an embodiment, it is within the knowledge of those skilled in the art to implement such features, structures or characteristics in conjunction with other embodiments that are explicitly or not explicitly described.

[0111] In general, terms should be understood, at least in part, by the context in which they are used. For example, the term "one or more" as used herein may be used to describe any feature, structure, or characteristic in a singular sense, or may be used to describe a combination of features, structures, or characteristics in a plural sense, depending, at least in part, on the context. Similarly, terms such as "a," "an," or "the" may also be understood to convey singular usage or to convey plural usage, depending, at least in part, on the context.

[0112] It should be easily understood that “on,” “above,” and “over” in the present disclosure should be interpreted in the broadest manner, so that “on” not only means “directly on something,” but also includes the meaning of “on something” with intervening features or layers therebetween, and “above” or “over” not only includes the meaning of “above” or “over,” but also may include the meaning of “above” or “over something” with no intervening features or layers therebetween (i.e., directly on something).

[0113] Additionally, cavity-relative terms, such as "below," "below," "beneath," "above," "above," etc., may be used herein for ease of description to describe the relationship of one element or feature relative to other elements or features as shown in the figures. Cavity-relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation shown in the figures. The device may have other orientations (rotated 90 degrees or at other orientations), and the cavity-relative descriptors used herein may likewise be interpreted accordingly.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A pole piece, characterized in that: The electrode includes a current collector and an active layer. The current collector includes a first region and a second region. The active layer is coated on the first region, and a tab is provided on the second region. A plurality of concave structures recessed in the thickness direction of the electrode are provided on both the second region of the current collector and the surface of the active layer.

2. The pole piece according to claim 1, characterized in that: The plurality of concave structures are arranged in an array. In the direction along the first direction and away from the tab, the arrangement density of the concave structures gradually decreases.

3. The pole piece according to claim 2, characterized in that: The concave structures on the electrode include multiple columns, and there is a gap between any two adjacent columns. Moreover, in the direction along the first direction and away from the tab, for any two adjacent gaps, the ratio of the width of the gap farther from the tab to the width of the gap closer to the tab is 1.01 - 1.

2.

4. The pole piece according to claim 1, characterized in that: The difference in depth between any two adjacent ones of the plurality of concave structures is less than or equal to 6 μm; and / or The difference in aperture at the opening between any two adjacent ones of the plurality of concave structures is less than or equal to 200 μm; and / or The ratio of the sum of the areas of the concave structures on the active layer to the area of the active layer is 10% - 50%; and / or Among the plurality of concave structures, the distance between the concave structure closest to the edge of the electrode and the edge of the electrode is 1 mm - 10 mm; and / or The ratio range of the depth of the concave structure to the width of the opening of the concave structure is 0.1 - 0.9; and / or The value range of the distance between any two adjacent ones of the plurality of concave structures is 50 μm - 200 μm; and / or The inner wall of the concave structure includes a side wall and a bottom wall. The side wall is inclined with respect to a reference plane parallel to the plane where the surface of the active layer is located, and the included angle between the side wall and the reference plane is 20° - 80°; and / or The ratio of the depth of the concave structure on the active layer to the thickness of the active layer is 0.05 - 0.

4.

5. The electrode according to claim 1, wherein The active layer includes a uniform - thickness region and a thinning region, and the thickness of the thinning region is less than the thickness of the uniform - thickness region; The concave structure in the uniform - thickness region is the first concave structure, the concave structure in the thinning region is the second concave structure, and the concave structure in the second region is the third concave structure.

6. The electrode according to claim 5, wherein The area of the first concave structure is S1, the area of the second concave structure is S2, and the area of the third concave structure is S3. S1, S2, and S3 satisfy: S1 < S2 < S3; and / or The depth of the first concave structure is H1, the depth of the second concave structure is H2, and the depth of the third concave structure is H3. H1, H2, and H3 satisfy: H1 < H2 < H3.

7. The electrode according to claim 5, wherein The value range of the depth H1 of the first concave structure is: 5 μm ≤ H1 ≤ 20 μm; and / or The value range of the depth H2 of the second concave structure is: 8 μm ≤ H1 ≤ 25 μm; and / or The depth H3 of the third recessed structure is in the range of 10 μm ≤ H1 ≤ 30 μm; and / or, The ratio of the depth H3 of the third recessed structure to the depth H1 of the first recessed structure is in the range of 1.5-2; and / or, The ratio of the depth H2 of the second recessed structure to the depth H1 of the first recessed structure is in the range of 1.2-1.

8.

8. The pole piece according to claim 5, characterized in that: The ratio of the distance between the third recessed structure closest to the electrode tab and the electrode tab in the first direction to the length of the current collector is 0-0.

002.

9. The pole piece according to claim 5, characterized in that: There are crest positions and trough positions at an edge of the thinned area on a side facing the second area, and the spacing between the crest positions and the trough positions in the first direction is 0-3 mm.

10. A battery cell, characterized in that: include: A first pole piece, a diaphragm and a second pole piece, wherein the first pole piece, the diaphragm and the second pole piece are stacked in sequence, At least one of the first pole piece and the second pole piece is the pole piece according to any one of claims 1-9.

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