Positive plate, battery cell and battery

Abstract

The utility model discloses a positive plate, a battery cell and a battery, which are applied to the technical field of batteries, a first insulating layer is arranged along the side edge, close to a first tab, of a current collector and is in contact with a first active substance layer along a second direction to form a first edge; the second insulating layer is arranged along the side edge, close to the first tab, of the current collector and is in contact with the second active substance layer in the second direction to form a second edge; the projection positions of the first side and the second side in the first direction have a first distance along the second direction, and the first distance is greater than or equal to the width of the projection of the side surface of the first active material layer connected with the first insulating layer along the first direction in the second direction; and / or the first spacing is greater than or equal to the width of the projection of the side surface of the second active material layer connected with the second insulating layer along the first direction in the second direction. By reducing the width of the side surface of the active material layer, the positive electrode active layer has a larger effective area, so that the energy density of the battery can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a positive electrode sheet, a battery core and a battery. Background Art

[0002] With the rapid development of 5G and the increasing application of electronic products, fast charging and high energy density remain the mainstream research directions of battery technology. From the perspective of electrode structure, the larger the effective coating area / coating amount on the positive electrode, the more conducive it is to improving battery energy density. Therefore, how to provide a positive electrode with a larger effective coating area is an urgent problem that technicians in this field need to solve. Utility Model Content

[0003] The purpose of the utility model is to provide a positive electrode sheet with a larger effective coating area; the utility model also provides a battery core and a pole sheet with a larger capacity.

[0004] In order to solve the above technical problems, the utility model provides a positive electrode sheet, comprising a current collector, a first active material layer, a second active material layer, a first insulating layer, a second insulating layer, and a first tab;

[0005] The first active material layer is located on a first surface of the current collector, and the second active material layer is located on a second surface of the current collector, and the first surface and the second surface are arranged opposite to each other along a first direction; the first electrode tab protrudes from the current collector, and the first insulating layer is arranged along a side of the current collector close to the first electrode tab and contacts the first active material layer along a second direction to form a first side; the second insulating layer is arranged along a side of the current collector close to the first electrode tab and contacts the second active material layer along the second direction to form a second side;

[0006] The projections of the first side and the second side in the first direction are spaced apart from each other in the second direction. The projections of the first side and the second side in the first direction both extend along the third direction. The first spacing is greater than or equal to the width of the projection of the side surface of the first active material layer in contact with the first insulating layer in the second direction along the first direction.

[0007] And / or, the first distance is greater than or equal to a width of a projection of a side surface of the second active material layer in contact with the second insulating layer along the first direction in the second direction.

[0008] Optionally, along the third direction, the first insulating layer contacts the first active material layer to form a third side, and the second insulating layer contacts the second active material layer to form a fifth side, and the third side and the fifth side are located on one side of the first electrode tab along the third direction;

[0009] And / or, along the third direction, the first insulating layer contacts the first active material layer to form a fourth side, the second insulating layer contacts the second active material layer to form a sixth side, and the fourth side and the sixth side are located on the other side of the first electrode tab along the third direction;

[0010] The projections of the third side, the fourth side, the fifth side and the sixth side in the first direction all extend along the second direction.

[0011] Optionally, projections of the third side and the fifth side in the first direction have a second spacing along the third direction, and the second spacing is greater than or equal to a width of a projection of a side surface of the first active material layer and the first insulating layer in contact along the third direction along the first direction in the third direction;

[0012] And / or, the projections of the fourth side and the sixth side in the first direction have a third spacing along the third direction, and the third spacing is greater than or equal to the width of the projection of the side surface of the first active material layer and the first insulating layer connected along the third direction along the first direction in the third direction.

[0013] Optionally, the projection of the first active material layer in the first direction covers the projection of the second active material layer in the first direction;

[0014] And / or, the projection of the first insulating layer in the first direction covers the projection of the second insulating layer in the first direction.

[0015] Optionally, the first spacing is not greater than 2.0 mm;

[0016] and / or, the second spacing is not greater than 2.0 mm;

[0017] And / or, the third spacing is not greater than 2.0 mm.

[0018] Optionally, the thickness of the first insulating layer is smaller than the thickness of the first active material layer;

[0019] And / or, the thickness of the second insulating layer is smaller than the thickness of the second active material layer.

[0020] Optionally, the ratio of the thickness of the first insulating layer to the thickness of the first active material layer is in a range of 0.2 to 1.0;

[0021] And / or, a ratio of the thickness of the second insulating layer to the thickness of the second active material layer is in a range of 0.2 to 1.0.

[0022] Optionally, a width of a projection of a side surface of the first active material layer and the first insulating layer in contact with each other along the second direction along the first direction is not greater than 1.0 mm in the second direction;

[0023] and / or, a projection of a side surface of the second active material layer and the second insulating layer in contact with each other in the second direction along the first direction has a width in the second direction of no more than 1.0 mm;

[0024] and / or a projection of a side surface of the first active material layer and the first insulating layer in contact along the third direction along the first direction has a width in the third direction of no more than 1.0 mm;

[0025] And / or, the width of a projection along the first direction of a side surface of the second active material layer and the second insulating layer that is in contact with each other along the third direction is no greater than 1.0 mm.

[0026] Optionally, the angle between the side surface of the first active material layer in contact with the first insulating layer and the current collector satisfies: 10°≤α≤70°;

[0027] And / or, an angle between the side surface of the second active material layer in contact with the second insulating layer and the current collector is in a range of 10° to 70°.

[0028] The present invention further provides a battery cell, comprising a negative electrode sheet and a positive electrode sheet as described in any one of the above items, wherein the negative electrode sheet is arranged opposite to the positive electrode sheet.

[0029] Optionally, a projection of a side surface of the first active material layer in contact with the first insulating layer in the first direction is located within a projection of the negative electrode sheet in the first direction;

[0030] And / or, a projection of a side surface of the second active material layer in contact with the second insulating layer in the first direction is located within a projection of the negative electrode sheet along the first direction.

[0031] The utility model also provides a battery, comprising the battery core as described in any one of the above items.

[0032] The present invention provides a positive electrode sheet, comprising a current collector, a first active material layer, a second active material layer, a first insulating layer, a second insulating layer, and a first electrode tab; the first active material layer is located on the first surface of the current collector, the second active material layer is located on the second surface of the current collector, and the first surface and the second surface are arranged opposite to each other along a first direction; the first electrode tab protrudes from the current collector, the first insulating layer is arranged along the side of the current collector close to the first electrode tab and contacts the first active material layer along the second direction to form a first edge; the second insulating layer is arranged along the side of the current collector close to the first electrode tab and contacts the second active material layer along the second direction to form a second edge; the projection positions of the first edge and the second edge in the first direction have a first spacing along the second direction, the projections of the first edge and the second edge in the first direction both extend along a third direction, the first spacing is greater than or equal to the width of the projection of the side surface of the first active material layer and the first insulating layer in contact along the first direction in the second direction; and / or the first spacing is greater than or equal to the width of the projection of the side surface of the second active material layer and the second insulating layer in contact along the first direction in the second direction.

[0033] After coating, the active material layer is thinned at its edges due to slurry casting, forming a thinned area. This thinned area will be cleaned by using a scraper to physically scrape it off, forming a narrower thinned area.

[0034] By forming a first spacing, the stability of the cleaning process can be ensured when cleaning the edge of the active material layer; and by limiting the width of the projection of each active material layer side along the first direction in the second direction to be less than the above-mentioned first spacing, the cleaning effect can be ensured while limiting the width of the thinning area at the edge of the active material layer, so that the active material layer has a larger effective area, thereby improving the battery energy density.

[0035] The present invention also provides a battery cell and a battery, which also have the above-mentioned beneficial effects and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 A schematic structural diagram of a positive electrode sheet provided in an embodiment of the present utility model;

[0038] Figure 2 A schematic top view of the structure of a first specific positive electrode sheet provided by an embodiment of the present utility model;

[0039] Figure 3 A schematic top view of the structure of a second specific positive electrode sheet provided in an embodiment of the present utility model;

[0040] Figure 4 A schematic top view of the structure of a third specific positive electrode sheet provided in an embodiment of the present utility model;

[0041] Figure 5 A schematic structural diagram of a fourth specific positive electrode sheet provided in an embodiment of the present utility model;

[0042] Figure 6 The present invention is a structural diagram of a battery cell provided in an embodiment of the present invention.

[0043] In the figure: 1. current collector, 11. first electrode tab, 21. first active material layer, 22. second active material layer, 23. first side, 24. second side, 25. third side, 26. fourth side, 27. fifth side, 28. sixth side, 31. first insulating layer, 32. second insulating layer, 4. negative electrode sheet, 41. negative electrode active layer. DETAILED DESCRIPTION

[0044] The core of this utility model is to provide a positive electrode sheet. Because the active material layer of the positive electrode sheet is in a slurry state before coating and has a certain degree of fluidity, after coating the positive electrode active layer, the slurry casting will form a thickness reduction zone. Within this thickness reduction zone, the coating thickness at the edge of the electrode sheet differs from the coating thickness in the center of the electrode sheet. In other words, the positive electrode coating amount in this thickness reduction zone is relatively small, which will have a certain impact on the energy density of the battery cell. How to remove or reduce the size of the thickness reduction zone is also one of the current research directions.

[0045] The present invention provides a positive electrode sheet, including a current collector, a first active material layer, a second active material layer, a first insulating layer, a second insulating layer, and a first electrode tab; the first active material layer is located on the first surface of the current collector, the second active material layer is located on the second surface of the current collector, and the first surface and the second surface are arranged opposite to each other along the first direction; the first electrode tab protrudes from the current collector, the first insulating layer is arranged along the side of the current collector close to the first electrode tab and contacts the first active material layer along the second direction to form a first edge; the second insulating layer is arranged along the side of the current collector close to the first electrode tab and contacts the second active material layer along the second direction to form a second edge; the projection positions of the first edge and the second edge in the first direction have a first spacing along the second direction, the projections of the first edge and the second edge in the first direction both extend along the third direction, the first spacing is greater than or equal to the width of the projection of the side surface of the first active material layer and the first insulating layer in contact along the first direction in the second direction; and / or the first spacing is greater than or equal to the width of the projection of the side surface of the second active material layer and the second insulating layer in contact along the first direction in the second direction.

[0046] By forming a first spacing, the stability of the cleaning process can be ensured when cleaning the edge of the active material layer; and by limiting the width of the projection of each active material layer side along the first direction in the second direction to be less than the above-mentioned first spacing, the width of the thinning area at the edge of the active material layer is limited, so that the active material layer has a larger effective area, thereby improving the battery energy density.

[0047] To help those skilled in the art better understand the present invention, the present invention is further described below in conjunction with the accompanying drawings and specific embodiments. Obviously, the embodiments described are only a portion of the present invention, not all of the embodiments. All other embodiments derived by those skilled in the art based on the embodiments of the present invention without inventive effort are also within the scope of protection of the present invention.

[0048] Please refer to Figures 1 to 4 , Figure 1 A schematic structural diagram of a positive electrode sheet provided in an embodiment of the present utility model; Figure 2 A schematic top view of the structure of a first specific positive electrode sheet provided by an embodiment of the present utility model; Figure 3 A schematic top view of the structure of a second specific positive electrode sheet provided in an embodiment of the present utility model; Figure 4 This is a schematic top view of the structure of a third specific positive electrode sheet provided in an embodiment of the present utility model.

[0049] See also Figure 1In one embodiment of the present invention, a positive electrode sheet is provided, comprising a current collector 1, a first active material layer 21, a second active material layer 22, a first insulating layer 31, a second insulating layer 32, and a first electrode tab 11; the first active material layer 21 is located on the first surface of the current collector 1, the second active material layer 22 is located on the second surface of the current collector 1, and the first surface and the second surface are arranged opposite to each other along a first direction; the first electrode tab 11 protrudes from the current collector 1, the first insulating layer 31 is arranged along the side of the current collector 1 close to the first electrode tab 11, and contacts the first active material layer 21 along the second direction to form a first edge 23; the second insulating layer 31 is arranged along the second direction to form a first edge 23; the second insulating layer 31 is arranged along the second direction to form a first edge 23; the first active material layer 21 is located on the first surface of the current collector 1, and the second active material layer 22 is located on the second surface of the current collector 1, and the first surface and the second surface are arranged opposite to each other along a first direction; the first electrode tab 11 protrudes from the current collector 1, and the first insulating layer 31 is arranged along the side of the current collector 1 close to the first electrode tab 11, and contacts the first active material layer 21 along the second direction to form a first edge 23; the second insulating layer 31 is arranged along the second direction to form a first edge 23; the first active material layer 21 is located on the first surface of the current collector 1, and the second active material layer 22 is located on the second surface of the current collector 1 2 is arranged along the side of the current collector 1 close to the first electrode tab 11 and contacts the second active material layer 22 along the second direction to form a second side 24; the first side 23 and the second side 24 have a first spacing along the second direction at the projection position in the first direction, the projections of the first side 23 and the second side 24 in the first direction both extend along the third direction, and the first spacing is greater than or equal to the width of the projection of the side surface of the first active material layer 21 and the first insulating layer 31 in contact with each other along the first direction in the second direction; and / or the first spacing is greater than or equal to the width of the projection of the side surface of the second active material layer 22 and the second insulating layer 32 in contact with each other along the first direction in the second direction.

[0050] The current collector 1 is typically sheet-shaped and has a first surface and a second surface facing each other. In this embodiment, the first and second surfaces are arranged relative to each other along a first direction, which is the thickness direction of the positive electrode sheet. An active material layer is provided on the surface of the current collector 1. The active material layer is made of a material that primarily participates in the positive electrode reaction of the positive electrode sheet. The active material layer located on the first surface is the first active material layer 21, and the active material layer located on the second surface is the second active material layer 22.

[0051] In this embodiment, the edge of the current collector 1 is generally provided with a first tab 11, which protrudes from the edge of the current collector 1. For a battery cell with a jelly-roll structure, the first tab 11 generally protrudes from the current collector 1 along the width direction.

[0052] In this embodiment, an insulating layer is provided on the side of the active material layer facing the first electrode tab 11. The insulating layer located on the first surface is a first insulating layer 31, and the insulating layer located on the second surface is a second insulating layer 32. The first insulating layer 31 is provided along the side of the current collector 1 near the first electrode tab 11 and contacts the first active material layer 21 along the second direction, forming a first edge 23. The first direction is the thickness direction of the electrode sheet. For a winding core, the first direction is the same as the thickness direction of the winding core. The second direction is the width direction of the electrode sheet, i.e., the extension direction of the first electrode tab 11. For a winding core, the second direction is the length direction of the winding core. The side edge is the side near the electrode tab, where the first insulating layer 31 contacts the first active material layer 21. The projection of the first edge 23 along the thickness direction of the positive electrode sheet is the boundary between the first active material layer 21 and the first insulating layer 31, which is equivalent to the boundary between the first insulating layer 31 and the first active material layer 21 in a top view of the positive electrode sheet. Correspondingly, the second insulating layer 32 will contact the second active material layer 22, and the projection position of the above-mentioned second edge 24 along the thickness direction of the positive electrode sheet is the dividing line between the second active material layer 22 and the second insulating layer 32, which is equivalent to the dividing line between the second insulating layer 32 and the second active material layer 22 in the top view of the positive electrode sheet.

[0053] In this embodiment, the projection positions of the first side 23 and the second side 24 in the first direction have a first spacing along the second direction, the projections of the first side 23 and the second side 24 in the first direction both extend along the third direction, and the first spacing is greater than or equal to the width of the projection of the side surface of the first active material layer 21 and the first insulating layer 31 along the first direction in the second direction; and / or, the first spacing is greater than or equal to the width of the projection of the side surface of the second active material layer 22 and the second insulating layer 32 along the first direction in the second direction.

[0054] The side surface of the active material layer is the surface of the reduced thickness region of the active material layer, which typically forms an irregular slope, i.e., a slope. Specifically, in this embodiment, the side surface can be a cleaning surface, specifically the cleaning surface formed when removing the reduced thickness region at the edge of the positive electrode active material layer. In this embodiment, after coating, the active material layer is thinned at its edge due to slurry casting, thereby forming a reduced thickness region. However, one embodiment provided in this application cleans this reduced thickness region, specifically by physically scraping it with a scraper, i.e., removing part of the reduced thickness region to form a narrower reduced thickness region. The side surface is formed during the cleaning process. In this embodiment, the entire active material layer can be divided into a main region and a reduced thickness region based on the thickness uniformity of the active material layer. The main region is also commonly referred to as the effective region, and the reduced thickness region is closer to the tab than the main region. In the active material layer, the main region is generally a region with a relatively constant thickness, while the reduced thickness region is a region with a greater degree of thickness reduction, lower thickness uniformity, and a trend of decreasing thickness along the second direction. In this embodiment, the positions of the main region and the thickness reduction region can be located in the following manner: from the thickness reduction region to the main region, each 50 μm interval is used as a test point, and then the thickness of the active material layer is measured at each of the above measurement points using a device such as an electron microscope. The position where the thickness increase rate between two adjacent measurement points is less than 2% is the boundary between the edge region and the main region, and the area from the boundary point to the edge of the active material layer near the tab side is the area where the thickness reduction region is located. Of course, the above interval distance can be 10 μm or other values, which are not limited here.

[0055] From another perspective, the reduced thickness region in this application is specifically the area formed by the cleaning process. Therefore, in this embodiment, the slope of the reduced thickness region surface, which corresponds to the rate of change of the thickness at each measurement point, is significantly different from the rate of change of the thickness of the main region. For the curve formed by the thickness values ​​at each measurement point, the point where the slope suddenly changes corresponds to the starting position of the reduced thickness region close to the main region. In this embodiment, the surface of the reduced thickness region is determined to be the side surface of the active material layer. The surface of the reduced thickness region in the first active material layer 21 is determined to be the side surface of the first active material layer 21 where the first active material layer 21 is in contact with the first insulating layer 31; the surface of the reduced thickness region in the second active material layer 22 is determined to be the side surface of the second active material layer 22 where the second active material layer 22 is in contact with the second insulating layer 32.

[0056] In this embodiment, the first spacing is the spacing between the projection positions of the first side 23 and the second side 24 in the first direction along the second direction, that is, the spacing between the first side 23 and the second side 24 in the thickness direction of the positive electrode sheet along the direction pointing to the electrode ear. The projections of the first side 23 and the second side 24 in the first direction both extend along the third direction. For the electrode sheet, the third direction is the length direction of the positive electrode sheet. For the winding core, the third direction is the winding direction, that is, the width direction of the battery cell. The third direction can be perpendicular to both the first direction and the second direction. In this embodiment, the setting of the first spacing improves the stability of the cleaning process. Since the side surfaces of the first active material layer 21 and the side surfaces of the second active material layer 22 in this embodiment need to be obtained through a cleaning process, and for the first active material layer 21 and the second active material layer 22, it is specifically necessary to clean the first active material layer 21 and the second active material layer 22 in turn through two cleaning processes. To ensure the stability of the two cleaning processes, the position of the scraper is adjusted during the second cleaning process, resulting in a difference in the position of the side of the first active material layer 21 and the side of the second active material layer 22 in the first direction, thereby generating the above-mentioned first gap. Therefore, the setting of the above-mentioned first gap can improve the stability of the cleaning process, ensure thorough cleaning and prevent damage to the current collector.

[0057] In this embodiment, the side surface of the first active material layer 21 that contacts the first insulating layer 31 has a width in the second direction when projected along the first direction. The projection of the side surface in the first direction is generally rectangular, with two sides in the second direction, resulting in the aforementioned width. In this embodiment, the first spacing is required to be greater than or equal to the width of the side surface of the first active material layer 21. That is, the width of the reduced thickness region of the first active material layer 21 is required to be less than the first spacing. This limits the area of ​​the reduced thickness region, thereby increasing the effective area of ​​the active material layer and thereby improving the battery energy density. Correspondingly, in this embodiment, the side surface of the second active material layer 22 that contacts the second insulating layer 32 also has a width in the second direction when projected along the first direction. The projection of the side surface in the first direction is generally rectangular, with two sides in the second direction, resulting in the aforementioned width. In this embodiment, the first spacing is required to be greater than or equal to the width of the side surface of the second active material layer 22. That is, the width of the reduced thickness region of the second active material layer 22 is required to be less than the first spacing. This limits the area of ​​the reduced thickness region, thereby increasing the effective area of ​​the active material layer and thereby improving the battery energy density. That is, in this embodiment, the first spacing needs to be greater than or equal to the width of the projection of the side surface of the first active material layer 21 and the first insulating layer 31 along the first direction in the second direction; and / or the first spacing needs to be greater than or equal to the width of the projection of the side surface of the second active material layer 22 and the second insulating layer 32 along the first direction in the second direction.

[0058] like Figure 2 and Figure 3 As shown, in this embodiment, the positive electrode sheet may only have the first side 23 and the second side 24, that is, the active material layer is cleaned only along one direction during cleaning. Accordingly, in this embodiment, the active material layer can be cleaned along more directions, that is, more structures can be formed. Figure 4 As shown, in this embodiment, along the third direction, the first insulating layer 31 contacts the first active material layer 21 to form a third side 25, and the second insulating layer 32 contacts the second active material layer 22 to form a fifth side 27, and the third side 25 and the fifth side 27 are located on one side of the first electrode tab 11 along the third direction; and / or, along the third direction, the first insulating layer 31 contacts the first active material layer 21 to form a fourth side 26, and the second insulating layer 32 contacts the second active material layer 22 to form a sixth side 28, and the fourth side 26 and the sixth side 28 are located on the other side of the first electrode tab 11 along the third direction; wherein, the projections of the third side 25, the fourth side 26, the fifth side 27 and the sixth side 28 in the first direction all extend along the second direction.

[0059] The third and fourth sides 25 and 26 are similar to the first side 23 and serve as the boundary between the first insulating layer 31 and the first active material layer 21, as projected in the thickness direction (i.e., the first direction). The fifth and sixth sides 27 and 28 are similar to the second side 24 and serve as the boundary between the second insulating layer 32 and the second active material layer 22, as projected in the first direction. The projections of the third, fourth, fifth, and sixth sides 25, 26, 27, and 28 in the first direction all extend along the second direction and are parallel to the second direction. The third and fourth sides 25 and 26 are typically located on either side of the first electrode tab 11, while the fifth and sixth sides 27 and 28 are typically located on either side of the first electrode tab 11. The third and fifth sides 25 and 27 are typically located on one side of the first electrode tab 11 along the third direction, while the fourth and sixth sides 26 and 28 are typically located on the other side of the first electrode tab 11 along the point direction. Of course, depending on the structure of the current collector 1, only the third side 25 and the fifth side 27, or the fourth side 26 and the sixth side 28 may be formed. That is, in this embodiment, it is not necessary to clean the subsequent thinning areas of the active material layer on both sides of the current collector 1, depending on the specific situation. In this embodiment, when the third side 25 and the fifth side 27, and / or the fourth side 26 and the sixth side 28 are provided, it is equivalent to cleaning the edges of the current collector 1 at the edge of the first tab 11, so that the active material layer has a larger effective area.

[0060] In this embodiment, the projections of the third side 25 and the fifth side 27 in the first direction have a second spacing along the third direction, and the second spacing is greater than or equal to the width of the projection of the side surface of the first active material layer 21 and the first insulating layer 31 along the third direction along the first direction; and / or, the projections of the fourth side 26 and the sixth side 28 in the first direction have a third spacing along the third direction, and the third spacing is greater than or equal to the width of the projection of the side surface of the first active material layer 21 and the first insulating layer 31 along the third direction along the first direction.

[0061] Similar to the first spacing described above, the second spacing is the spacing between the projections of the third side 25 and the fifth side 27 in the first direction along the third direction. In this case, the side surfaces where the first active material layer 21 and the first insulating layer 31 meet include side surfaces whose longitudinal direction is in the second direction. The projections of these side surfaces along the first direction have a width along the third direction. The second spacing must be greater than or equal to this width to ensure a stable cleaning process while ensuring a sufficiently large effective area for the active material layer. Similarly, the side surfaces where the second active material layer 22 and the second insulating layer 32 meet also include side surfaces whose longitudinal direction is in the second direction. The projections of these side surfaces along the first direction also have a width along the third direction. The second spacing can also be greater than or equal to the width of the projections of the side surfaces where the second active material layer 22 and the second insulating layer 32 meet along the third direction along the first direction.

[0062] Similar to the first spacing described above, the third spacing is the spacing between the projections of the fourth side 26 and the sixth side 28 along the first direction along the third direction. In this case, the side surfaces where the first active material layer 21 and the first insulating layer 31 meet include side surfaces whose longitudinal sides are oriented in the second direction. The projections of these side surfaces along the first direction have a width along the third direction. The third spacing must be greater than or equal to this width to ensure a stable cleaning process while ensuring a sufficiently large effective area for the active material layer. Similarly, the side surfaces where the second active material layer 22 and the second insulating layer 32 meet also include side surfaces whose longitudinal sides are oriented in the second direction. The projections of these side surfaces along the first direction also have a width along the third direction. The third spacing can also be greater than or equal to the width of the projections of the side surfaces where the second active material layer 22 and the second insulating layer 32 meet along the third direction along the first direction.

[0063] In this embodiment, to ensure the stability of the cleaning process, the projection of the first active material layer 21 in the first direction covers the projection of the second active material layer 22 in the first direction; and / or the projection of the first insulating layer 31 in the first direction covers the projection of the second insulating layer 32 in the first direction. That is, after the cleaning process, in this embodiment, the size of the first active material layer 21 is generally larger than that of the second active material layer 22, and / or the size of the first insulating layer 31 is generally larger than that of the second insulating layer 32, to ensure the stability of the cleaning process.

[0064] The positive electrode sheet provided in this embodiment can ensure the stability of the cleaning process when cleaning the edge of the active material layer by forming a first spacing; and by limiting the width of the projection of each active material layer side along the first direction in the second direction to be less than the above-mentioned first spacing, thereby limiting the width of the thinning area at the edge of the active material layer, so that the active material layer has a larger effective area, thereby improving the battery energy density.

[0065] Please refer to Figure 5 , Figure 5 This is a schematic structural diagram of a fourth specific positive electrode sheet provided in an embodiment of the present utility model.

[0066] Different from the above embodiment, this embodiment further defines the specific structure of the positive electrode sheet based on the above embodiment. The remaining contents have been described in detail in the above embodiment and will not be repeated here.

[0067] See also Figure 4 In this embodiment, the first spacing is not greater than 2.0mm; and / or, the second spacing is not greater than 2.0mm; and / or, the third spacing is not greater than 2.0mm. Assuming that the above-mentioned first spacing is L1, the second spacing is L2, and the third spacing is L3, it is necessary to satisfy L1≤2.0mm, L2≤2.0mm, L3≤2.0mm. It should be noted that L1, L2 and L3 are all greater than 0. In this embodiment, by limiting the numerical values ​​of the above-mentioned first spacing, second spacing and third spacing, it is possible to ensure that each active material layer has a larger effective area while ensuring the stability of the cleaning process, thereby improving the battery energy density.

[0068] In this embodiment, the thickness of the first insulating layer 31 is less than that of the first active material layer 21; and / or the thickness of the second insulating layer 32 is less than that of the second active material layer 22. By limiting the thickness of the first insulating layer 31 and the second insulating layer 32, it is ensured that when the first insulating layer 31 is provided, it will not flow to the surface of the main area of ​​the first active material layer 21, and when the second insulating layer 32 is provided, it will not flow to the surface of the main area of ​​the second active material layer 22. In other words, the insulating layers are ensured not to block the surface of the main area of ​​the corresponding active material layer, thus preventing the insulating layers from affecting the thickness of the electrode and, consequently, the battery energy density.

[0069] Specifically, in this embodiment, the ratio of the thickness of the first insulating layer 31 to the thickness of the first active material layer 21 ranges from 0.2 to 1.0; and / or the ratio of the thickness of the second insulating layer 32 to the thickness of the second active material layer 22 ranges from 0.2 to 1.0. In this embodiment, assuming the thickness of the first active material layer 21 is H, the thickness of the second active material layer 22 is H', and assuming the thickness of the first insulating layer 31 is H1, and the thickness of the second insulating layer 32 is H1', ​​then generally, H1 = (0.2-1.0) × H; H1' = (0.2-1.0) × H'. In this case, the first edge 23 is located on the side of the first active material layer 21, and the second edge 24 is located on the side of the second active material layer 22.

[0070] In this embodiment, the width of the side surface of the first active material layer 21 and the first insulating layer 31 that are in contact along the second direction, projected along the first direction, in the second direction, is no greater than 1.0 mm; and / or the width of the side surface of the second active material layer 22 and the second insulating layer 32 that are in contact along the second direction, projected along the first direction, in the second direction, is no greater than 1.0 mm; and / or the width of the side surface of the first active material layer 21 and the first insulating layer 31 that are in contact along the third direction, projected along the first direction, in the third direction, is no greater than 1.0 mm; and / or the width of the side surface of the second active material layer 22 and the second insulating layer 32 that are in contact along the third direction, projected along the first direction, in the third direction, is no greater than 1.0 mm. Assuming the above width is W1, it is necessary to satisfy W1≤1.0 mm to ensure that each active material layer has a larger effective area while improving the bonding force between the electrode and the separator, improving the force uniformity of the cell formation, reducing the transmission distance, and thus improving the battery energy density.

[0071] In this embodiment, the angle between the side surface where the first active material layer 21 is connected to the first insulating layer 31 and the current collector 1 is in the range of 10° to 70°; and / or the angle between the side surface where the second active material layer 22 is connected to the second insulating layer 32 and the current collector 1 is in the range of 10° to 70°.

[0072] In this embodiment, the angle between the above-mentioned side surface of the first active material layer 21 and the current collector 1 is M, and the angle between the above-mentioned side surface of the second active material layer 22 and the current collector 1 is M'. In this embodiment, it is necessary to satisfy 10°≤M≤70° and 10°≤M'≤70° to ensure that each active material layer has a larger effective area, thereby improving the battery energy density.

[0073] In this embodiment, the first insulating layer 31 and the second insulating layer 32 typically include an insulating base material and a binder. The insulating base material is typically one or more of aluminum oxide, boehmite, magnesium oxide, and magnesium hydroxide; and the binder is typically one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl pyrrolidone, polyacrylic acid, polyacrylonitrile, lithium polyacrylate, polyamide, methacrylate, and sodium carboxymethyl cellulose. The specific materials of the first insulating layer 31 and the second insulating layer 32 are not specifically limited in this embodiment and will depend on the specific circumstances.

[0074] The positive electrode sheet provided in this embodiment can ensure the stability of the cleaning process when cleaning the edge of the active material layer by forming a first spacing; and by limiting the width of the projection of each active material layer side along the first direction in the second direction to be less than the above-mentioned first spacing, thereby limiting the width of the thinning area at the edge of the active material layer, so that the active material layer has a larger effective area, thereby improving the battery energy density.

[0075] A battery cell provided by an embodiment of the present invention is introduced below. The battery cell described below and the positive electrode sheet described above can be referred to in correspondence with each other.

[0076] Please refer to Figure 6 , Figure 6 The present invention is a structural diagram of a battery cell provided in an embodiment of the present invention.

[0077] See also Figure 6 In this embodiment, the battery cell includes a negative electrode sheet 4 and a positive electrode sheet as described in any of the above embodiments, with the negative electrode sheet 4 being disposed opposite the positive electrode sheet. Typically, the negative electrode sheets 4 and the positive electrode sheets are alternately stacked or wound to form a battery cell. The specific structure of the battery cell can be determined based on actual conditions and is not specifically limited here.

[0078] In this embodiment, the projection of the side surface of the first active material layer 21 that is in contact with the first insulating layer 31 in the first direction is located within the projection of the negative electrode sheet 4 along the first direction; and / or, the projection of the side surface of the second active material layer 22 that is in contact with the second insulating layer 32 in the first direction is located within the projection of the negative electrode sheet 4 along the first direction.

[0079] That is, in this embodiment, the projection of the negative electrode active layer 41 in the negative electrode sheet 4 along the thickness direction will extend beyond the thickness reduction area directly opposite the negative electrode sheet 4, that is, extend beyond the side of the first active material layer 21 and / or the second active material layer 22, ensuring that the negative electrode covers the positive electrode in the thickness reduction area and reducing the risk of lithium plating. In this embodiment, the distance between the first side 23 or the second side 24 and the edge of the negative electrode active layer 41 is F, and it is generally necessary to be greater than or equal to the width W1 of the thickness reduction area to ensure that the negative electrode sheet 4 covers the positive electrode sheet and reduce the risk of lithium plating.

[0080] The battery cell provided in this embodiment can have a larger capacity because it uses the positive electrode sheet provided in any of the above embodiments.

[0081] A battery provided by an embodiment of the present invention is introduced below. The battery described below and the battery cell described above can be referred to in correspondence with each other.

[0082] In this embodiment, the battery includes the cell provided in the above-described embodiment. The specific structure of the cell has been described in detail in the above-described embodiment and will not be further described here. The remaining components of the battery, such as the housing, can be found in the prior art and will not be further described here.

[0083] The battery provided in this embodiment can have a larger capacity because it uses the battery cell provided in the above embodiment.

[0084] This example uses a 785075 wound cell as a model. The width of the active layer of the positive electrode sheet is approximately 70mm, with an insulating layer of 1.0mm width left at the edge. The thickness of the main area of ​​the active material layer is approximately 60um. In this example, a blank group and an experimental group are set up for comparison, where:

[0085] In the blank group, after the positive electrode is rolled by the coating roller, a thickness reduction area will be formed at the edge of the electrode. The width of the thickness reduction area is about 5mm. The electrode is then transferred to winding after processes such as die-cutting.

[0086] In the experimental group, during the coating process, before applying the insulating layer, the positive electrode sheet was first transferred to the scraping process. Physical scraping was used to polarize the thinned areas at the edge of the electrode sheet to form the side surfaces of the active material layer. To ensure the formation of the above-mentioned side surfaces of the active material layer on both sides of the current collector 1, the thinned areas on both sides were scraped. To ensure process yield, the scraping distance of the positive electrode active layer 2 on both sides of the current collector 1 was different, forming the above-mentioned first spacing L, L of 0.5mm.

[0087] The width dimension W1 of the side of the active material layer is 0.6mm, and the angle M formed with the current collector 1 is approximately 6°. After the scraping is completed, the positive electrode sheet is transferred to the next process, where an insulating layer is coated on the edge of the positive electrode sheet. The insulating layer will flow to the above-mentioned side to ensure that there is no gap between the insulating layer and the corresponding positive electrode active layer on the current collector 1, preventing the current collector 1 from being exposed and creating a safety risk. The thickness H1 of the coated insulating layer is approximately 35μm. The thickness H1 of the insulating layer is less than the thickness H of the corresponding positive electrode active layer. This is mainly to prevent the thickness of the insulating layer from affecting the thickness of the entire positive electrode sheet, resulting in a thicker electrode sheet and affecting the energy density of the battery.

[0088] After the positive electrode sheets of the experimental group are processed, they are transferred to the winding process together with the positive electrode sheets of the blank group. The two positive electrode sheets are respectively wound together with the negative electrode sheet 4 and the separator to form a winding core. After the winding is completed, the edge of the negative electrode active layer 41 of the negative electrode sheet 4 falls on the insulating layer at the edge of the positive electrode sheet, and ensures that the edge of the negative electrode active layer 41 exceeds the edge of the above-mentioned side. The dimension F between the two is approximately 0.3 mm.

[0089] After capacity analysis of the aforementioned batteries, it was found that the experimental group had a 0.57% higher capacity than the blank group. Disassembly of the batteries also revealed better adhesion between the head and separator in the experimental group. This is primarily due to the fact that the side surface of the active material layer at the head of the experimental group's cells is much smaller than the thinning area of ​​the blank group's cells. Furthermore, due to the smaller side surface width, the thickness difference at the head is smaller, resulting in more uniform force during formation and better adhesion between the electrode and separator. This side surface arrangement increases the actual coating amount of the positive electrode material, thereby increasing the battery's capacity.

[0090] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0091] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.

[0092] The above describes in detail the positive electrode sheet, battery cell, and battery provided by the present invention. This article uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above examples is only intended to help understand the method and core concept of the present invention. It should be noted that for ordinary technicians in this technical field, without departing from the principles of the present invention, various improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A positive electrode sheet, characterized in that: It includes a current collector, a first active material layer, a second active material layer, a first insulating layer, a second insulating layer, and a first tab; The first active material layer is located on a first surface of the current collector, and the second active material layer is located on a second surface of the current collector, and the first surface and the second surface are arranged opposite to each other along a first direction; the first electrode tab protrudes from the current collector, and the first insulating layer is arranged along a side of the current collector close to the first electrode tab and contacts the first active material layer along a second direction to form a first side; the second insulating layer is arranged along a side of the current collector close to the first electrode tab and contacts the second active material layer along the second direction to form a second side; The projections of the first side and the second side in the first direction are spaced apart from each other in the second direction. The projections of the first side and the second side in the first direction both extend along the third direction. The first spacing is greater than or equal to the width of the projection of the side surface of the first active material layer in contact with the first insulating layer in the second direction along the first direction. And / or, the first distance is greater than or equal to a width of a projection of a side surface of the second active material layer in contact with the second insulating layer along the first direction in the second direction.

2. The positive electrode sheet according to claim 1, characterized in that Along the third direction, the first insulating layer contacts the first active material layer to form a third side, and the second insulating layer contacts the second active material layer to form a fifth side, and the third side and the fifth side are located on one side of the first electrode tab along the third direction; And / or, along the third direction, the first insulating layer contacts the first active material layer to form a fourth side, the second insulating layer contacts the second active material layer to form a sixth side, and the fourth side and the sixth side are located on the other side of the first electrode tab along the third direction; The projections of the third side, the fourth side, the fifth side and the sixth side in the first direction all extend along the second direction.

3. The positive electrode sheet according to claim 2, characterized in that: The projections of the third side and the fifth side in the first direction have a second distance along the third direction, and the second distance is greater than or equal to the width of the projection of the side surface of the first active material layer and the first insulating layer in contact along the third direction along the first direction in the third direction; And / or, the projections of the fourth side and the sixth side in the first direction have a third spacing along the third direction, and the third spacing is greater than or equal to the width of the projection of the side surface of the first active material layer and the first insulating layer connected along the third direction along the first direction in the third direction.

4. The positive electrode sheet according to claim 2, characterized in that The projection of the first active material layer in the first direction covers the projection of the second active material layer in the first direction; And / or, the projection of the first insulating layer in the first direction covers the projection of the second insulating layer in the first direction.

5. The positive electrode sheet according to claim 3, characterized in that: The first spacing is not greater than 2.0 mm; and / or, the second spacing is not greater than 2.0 mm; And / or, the third spacing is not greater than 2.0 mm.

6. The positive electrode sheet according to claim 1, characterized in that The thickness of the first insulating layer is smaller than the thickness of the first active material layer; And / or, the thickness of the second insulating layer is smaller than the thickness of the second active material layer.

7. The positive electrode sheet according to claim 6, characterized in that: The ratio of the thickness of the first insulating layer to the thickness of the first active material layer is in a range of 0.2 to 1.0; And / or, a ratio of the thickness of the second insulating layer to the thickness of the second active material layer is in a range of 0.2 to 1.

0.

8. The positive electrode sheet according to claim 3, characterized in that: The width of the projection of the side surface of the first active material layer and the first insulating layer in contact with each other in the second direction along the first direction is not greater than 1.0 mm in the second direction; and / or, a projection of a side surface of the second active material layer and the second insulating layer in contact with each other in the second direction along the first direction has a width in the second direction of no more than 1.0 mm; and / or a projection of a side surface of the first active material layer and the first insulating layer in contact along the third direction along the first direction has a width in the third direction of no more than 1.0 mm; And / or, the width of a projection along the first direction of a side surface of the second active material layer and the second insulating layer that is in contact with each other along the third direction is no more than 1.0 mm.

9. The positive electrode sheet according to claim 3, characterized in that: The angle between the side surface of the first active material layer in contact with the first insulating layer and the current collector is in a range of 10° to 70°; And / or, an angle between the side surface of the second active material layer in contact with the second insulating layer and the current collector is in a range of 10° to 70°.

10. A battery cell, characterized in that: The invention comprises a negative electrode sheet and a positive electrode sheet according to any one of claims 1 to 9, wherein the negative electrode sheet is arranged opposite to the positive electrode sheet.

11. The battery cell according to claim 10, characterized in that: The projection of the side surface of the first active material layer in contact with the first insulating layer in the first direction is located within the projection of the negative electrode sheet along the first direction; And / or, a projection of a side surface of the second active material layer in contact with the second insulating layer in the first direction is located within a projection of the negative electrode sheet along the first direction.

12. A battery, characterized in that: The invention comprises a battery cell according to any one of claims 10 to 11.

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