Battery monomer, battery, power utilization device, cathode pole piece and manufacturing method of cathode pole piece

Abstract

The embodiment of the invention provides a battery monomer, a battery, a power utilization device, a cathode pole piece and a manufacturing method of the cathode pole piece. Wherein the battery monomer comprises a cathode pole piece, the cathode pole piece comprises a cathode current collector and a cathode active material layer arranged on the cathode current collector, the cathode active material layer comprises a first thinning area, and the first thinning area is located on the side edge, opposite to a cathode lug, of the cathode current collector; the anode pole piece and the cathode pole piece are arranged in a stacked mode in the first direction, the anode pole piece comprises an anode current collector and an anode active material layer arranged on the anode current collector, the anode active material layer comprises a second thinning area, and the second thinning area is arranged on the side edge, where the anode lug is arranged, of the anode current collector; the second thinning area and the first thinning area are at least partially overlapped. The first thinning area can reduce lithium ions deintercalated from the cathode active material layer of the cathode pole piece, so that the anode pole piece has enough large capacity to accommodate the lithium ions deintercalated from the cathode pole piece, the lithium precipitation phenomenon is further improved, and the performance of the battery is improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery cell, a battery, an electrical device, a cathode electrode and a manufacturing method thereof. Background Art

[0002] In some related technologies, the battery includes a battery cell, which includes an electrode assembly formed by winding a pole piece and a separator, and an injected electrolyte. After research, it was found that the battery may have the problem of lithium deposition, resulting in a decrease in battery performance. Summary of the invention

[0003] Some embodiments of the present application provide a battery cell, a battery, an electrical device, a cathode electrode plate and a manufacturing method thereof, which are used to alleviate the problem of battery performance degradation.

[0004] Some embodiments of the present application provide a battery cell, which includes: a cathode electrode sheet, including a cathode current collector and a cathode active material layer arranged on the cathode current collector, the cathode active material layer including a first thinning area, and the first thinning area is located on the side of the cathode current collector opposite to the cathode ear; and an anode electrode sheet, stacked with the cathode electrode sheet along a first direction, the anode electrode sheet includes an anode current collector and an anode active material layer arranged on the anode current collector, the anode active material layer including a second thinning area, and the second thinning area is arranged on the side of the anode current collector where the anode ear is arranged; the second thinning area at least partially overlaps with the first thinning area.

[0005] In the above embodiment, a first thinning zone is provided on the side of the cathode current collector opposite to the cathode ear, and the first thinning zone at least partially overlaps with the second thinning zone. The first thinning zone can reduce the lithium ions deintercalated from the cathode active material layer of the cathode electrode sheet, and change the CB value of the corresponding position of the first thinning zone, so that the unit area capacity of the anode electrode sheet can be greater than the unit area capacity of the cathode electrode sheet, so that the anode electrode sheet has a large enough capacity to accommodate the lithium ions deintercalated from the cathode electrode sheet, thereby improving the lithium plating phenomenon and improving the performance of the battery.

[0006] In some embodiments, a dimension W1 of the first thinning area along a second direction is less than or equal to a dimension W2 of the second thinning area along a second direction, wherein the second direction intersects the first direction, and the second direction is parallel to a direction in which the anode ear moves away from the anode current collector.

[0007] In the above embodiment, if the area of ​​the first thinning zone is too large, the energy density of the battery will be sacrificed. If the area of ​​the first thinning zone is too small, it will not be able to change the CB value. Therefore, the dimension W1 of the first thinning zone along the second direction is less than or equal to the dimension W2 of the second thinning zone along the second direction Y, which can not only meet the energy density requirements of the battery, but also has the effect of changing the CB value.

[0008] In some embodiments, W1∈[2,20]mm, W2∈[2,20]mm.

[0009] In the above embodiment, by setting the size range of the first thinning area and the second thinning area along the second direction, the CB value is changed while meeting the energy density requirement of the battery, thereby improving the lithium plating phenomenon and improving the performance of the battery.

[0010] In some embodiments, W1∈[3,8]mm, W2∈[3,10]mm.

[0011] In the above embodiment, by further limiting the size range of the first thinning area and the second thinning area along the second direction, the CB value can be changed while meeting the energy density requirement of the battery, thereby improving the lithium plating phenomenon and improving the performance of the battery.

[0012] In some embodiments, both the first thinning zone and the second thinning zone thin from a position far from the anode ear to a position close to the anode ear; a distance S1 between the position where the first thinning zone starts to thin and the anode ear is greater than or equal to a distance S2 between the position where the second thinning zone starts to thin and the anode ear.

[0013] In the above embodiment, along the direction of the anode ear away from the anode current collector, the position where the first thinning zone starts to thin is earlier than the position where the second thinning zone starts to thin, so that the cathode electrode sheet is thinned first in the area where the anode electrode sheet has not yet started to thin, thereby reducing the lithium ions deintercalated from the cathode active material layer of the cathode electrode sheet, and better changing the CB value of the corresponding position of the first thinning zone, so that the anode electrode sheet has a large enough capacity to accommodate the lithium ions deintercalated from the cathode electrode sheet, thereby improving the lithium plating phenomenon and improving the performance of the battery.

[0014] In some embodiments, a distance S3∈[0,5] mm between a position where the first thinning zone starts to be thinned and a position where the second thinning zone starts to be thinned.

[0015] In the above embodiment, by limiting the distance between the position where the first thinning area starts to thin and the position where the second thinning area starts to thin, the CB value can be changed while meeting the energy density requirements of the battery, thereby improving the lithium plating phenomenon and improving the performance of the battery.

[0016] In some embodiments, S3∈[0,3]mm.

[0017] In the above embodiment, by further limiting the distance between the position where the first thinning area starts to thin and the position where the second thinning area starts to thin, the CB value can be better changed while meeting the energy density requirements of the battery, thereby improving the lithium plating phenomenon and improving the performance of the battery.

[0018] In some embodiments, the cathode electrode plate further includes a first insulating layer, and the first insulating layer is disposed on a side of the first thinned region away from the cathode ear.

[0019] In the above embodiment, the first insulating layer is far away from the cathode ear relative to the first thinning area. In the operation of dividing the current collector into two to form two pole pieces, what is cut is the position where the first insulating layer of the current collector is located, rather than the cathode active material layer. This can reduce the phenomenon of burrs on the cathode active material layer and alleviate the problem of active material falling off caused by shearing the current collector to form pole pieces.

[0020] In some embodiments, the cathode active material layer further includes a third thinning region, and the third thinning region is located on a side of the cathode current collector where a cathode ear is disposed.

[0021] In the above embodiment, a third thinning area is arranged on the side of the cathode ear of the cathode current collector, which can increase the degree of wetting of the cathode electrode sheet by the electrolyte and change the CB value of the corresponding position of the third thinning area, so that the unit area capacity of the active material of the anode electrode sheet is greater than the unit area capacity of the active material of the cathode electrode sheet, so as to improve the lithium plating phenomenon and improve the performance of the battery.

[0022] In some embodiments, the cathode electrode further includes a second insulating layer, and the second insulating layer is located between the third thinned region and the cathode ear.

[0023] In the above embodiment, the second insulating layer is close to the cathode ear relative to the third thinning area. When shearing the cathode ear, if the shearing exceeds the cathode ear, the second insulating layer is sheared instead of the cathode active material layer, which can reduce the burr phenomenon of the cathode active material layer and alleviate the problem of active material falling off caused by shearing the cathode ear.

[0024] In some embodiments, the cathode active material layer further includes a fourth thinning region, and the fourth thinning region is located between a side of the cathode current collector where the cathode ear is disposed and a side opposite to the cathode ear.

[0025] In the above embodiment, the fourth thinning area can allow more electrolyte to pass through and can accommodate more electrolyte, so that the electrolyte can fully infiltrate the electrode piece in a short time, improve the wetting effect of the electrolyte on the electrode piece, and enable the active material to react more fully with the electrolyte, thereby alleviating the problem of insufficient electrolyte infiltration in the middle area of ​​the electrode assembly and improving the performance of the battery. The CB value of the corresponding position of the fourth thinning area can be changed, so that the unit area capacity of the active material of the anode electrode piece is greater than the unit area capacity of the active material of the cathode electrode piece, so as to improve the phenomenon of lithium precipitation and improve the performance of the battery.

[0026] In some embodiments, the cathode active material layer further includes a fifth thinning region, and the fifth thinning region is located in a corner area after the cathode electrode sheet is wound.

[0027] In the above embodiment, at the corner after the cathode electrode sheet is wound, there is curvature in the interface between the electrode sheets, which is easy to cause interface problems. The area of ​​the active material layer on the outer electrode sheet of the cathode electrode sheet and the anode electrode sheet is large. Therefore, the fifth thinning area is set at the corner after the cathode electrode sheet is wound, which can change the CB value at the corner, so that the unit area capacity of the anode electrode sheet is greater than the unit area capacity of the cathode electrode sheet, alleviate the lithium plating problem caused by insufficient capacity of the anode electrode sheet, and improve the performance of the battery.

[0028] Some embodiments of the present application provide a battery, which includes a box assembly and the above-mentioned battery cell, wherein the battery cell is disposed in the box assembly.

[0029] The battery includes the battery cell in the above embodiment, and therefore has the corresponding beneficial effects of the battery cell.

[0030] Some embodiments of the present application provide an electrical device comprising the above-mentioned battery.

[0031] The electrical device includes the battery in the above embodiment, and therefore has the corresponding beneficial effects of the battery.

[0032] Some embodiments of the present application provide a cathode electrode sheet, which includes: a cathode current collector; and a cathode active material layer, which is arranged on the cathode current collector, and the cathode active material layer includes a first thinning area, and the first thinning area is located on the side of the cathode current collector opposite to the cathode ear.

[0033] In the above embodiment, a first thinning zone is provided on the side of the cathode current collector opposite to the cathode ear, and the first thinning zone at least partially overlaps with the second thinning zone. The first thinning zone can reduce the lithium ions deintercalated from the cathode active material layer of the cathode electrode sheet, and change the CB value of the corresponding position of the first thinning zone, so that the unit area capacity of the anode electrode sheet can be greater than the unit area capacity of the cathode electrode sheet, so that the anode electrode sheet has a large enough capacity to accommodate the lithium ions deintercalated from the cathode electrode sheet, thereby improving the lithium plating phenomenon and improving the performance of the battery.

[0034] Some embodiments of the present application provide a method for manufacturing a cathode electrode sheet, which includes the following steps: preparing a current collector, wherein the current collector has a lug region on two opposite sides; coating an active material on a region of the current collector located between the two lug regions to form a cathode active material layer, and thinning the region of the cathode active material layer located between the two lug regions to form a thinned region; and dividing the current collector into two in the thinned region to form two cathode electrode sheets.

[0035] In the above embodiment, the current collector is divided into two from the middle area between the two pole ear areas of the current collector to form two cathode pole pieces, that is, the current collector is divided into two from the middle position of the two first thinning areas to form two cathode pole pieces, and the first thinning area of ​​each cathode pole piece is located on the side of the cathode current collector opposite to the cathode ear, which can increase the degree of wetting of the pole piece by the electrolyte and can change the CB value of the corresponding position of the first thinning area, so that the unit area capacity of the anode pole piece is greater than the unit area capacity of the cathode pole piece, thereby alleviating the lithium plating problem caused by insufficient capacity of the anode pole piece and improving the performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without paying creative work.

[0037] Figure 1 is a schematic structural diagram of a vehicle disclosed in some embodiments of the present application;

[0038] Figure 2 is a schematic diagram of an exploded structure of a battery disclosed in some embodiments of the present application;

[0039] Figure 3 is a schematic diagram of a battery cell disclosed in some embodiments of the present application;

[0040] Figure 4 is a schematic diagram of an electrode assembly disclosed in some embodiments of the present application;

[0041] Figure 5 is a side view schematic diagram of a stacked state of pole pieces of two polarities disclosed in some embodiments of the present application;

[0042] Figure 6 is a schematic diagram of an anode electrode sheet disclosed in some embodiments of the present application;

[0043] Figure 7 yes Figure 6 A schematic side view of the anode electrode piece shown;

[0044] Figure 8 is a schematic diagram of a first form of a cathode electrode sheet disclosed in some embodiments of the present application;

[0045] Fig. 9 yes Figure 8 A schematic side view of the cathode electrode piece shown;

[0046] Fig.10is a schematic diagram of a second form of a cathode electrode sheet disclosed in some embodiments of the present application;

[0047] Fig.11 yes Fig.10 A schematic side view of the cathode electrode piece shown;

[0048] Fig.12 is a side view schematic diagram of a third form of a cathode electrode piece disclosed in some embodiments of the present application;

[0049] Fig.13 is a side view schematic diagram of a fourth form of a cathode electrode piece disclosed in some embodiments of the present application;

[0050] Fig.14 is a side view schematic diagram of a fifth form of a cathode electrode piece disclosed in some embodiments of the present application;

[0051] Fig.15 is a schematic diagram of a first form of a current collecting member disclosed in some embodiments of the present application;

[0052] Fig.16 yes Fig.15 A schematic side view of the current collecting member shown;

[0053] Fig.17 It is a schematic diagram of a second form of the current collecting member disclosed in some embodiments of the present application.

[0054] In the drawings, the drawings are not drawn to scale.

[0055] Marking description: 10a-cathode pole piece; 1-cathode current collector; 11-first side; 12-second side; 13-third side; 14-fourth side; 15-first side; 16-second side; 2-cathode active material layer; 3a-thinning area; 31-first thinning area; 32-third thinning area; 33-fourth thinning area; 34-fifth thinning area; 4-tiling area; 5-cathode ear; 6-first insulating layer; 7-second insulating layer;

[0056] 10b-anode pole piece; 1'-anode current collector; 2'-anode active material layer; 3'-second thinning area; 4'-anode ear; 5'-third insulating layer;

[0057] 10-pole piece; 20-current collector; 30-ear area; 40-isolator;

[0058] 100-electrode assembly; 200-battery cell; 201-shell assembly; 201a-shell; 201b-end cover; 202-cathode terminal; 203-anode terminal; 204-explosion-proof valve; 300-battery; 301-box assembly; 301a-box; 301b-cover; 400-vehicle; 401-axle; 402-wheel; 403-motor; 404-controller. DETAILED DESCRIPTION

[0059] The following detailed description and drawings of the embodiments of the present application are used to illustrate the principles of the present application, but cannot be used to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

[0060] In the description of the present application, it should be noted that, unless otherwise specified, "multiple" means more than two; the terms "upper", "lower", "left", "right", "inside", "outside", etc., indicating the orientation or positional relationship, are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. "Vertical" is not strictly vertical, but is within the allowable error range. "Parallel" is not strictly parallel, but is within the allowable error range.

[0061] The directional words appearing in the following description are all directions shown in the figures, and do not limit the specific structure of this application. In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0062] With the popularization and promotion of new energy vehicles, the charging and discharging performance and endurance of new energy vehicles have attracted increasing attention and attention. As a rechargeable battery, power batteries are the power source of new energy vehicles and are widely used in the field of new energy vehicles.

[0063] In the manufacturing process of batteries, pole pieces and diaphragms with different polarities are generally wound or stacked, and then hot pressed to form electrode assemblies. Pole pieces are generally obtained by coating active materials on current collectors. Studies have found that the thickness of the active material layer on the pole piece affects the performance of the battery.

[0064] Based on this, some embodiments of the present application provide a battery cell, a battery, an electrical device, a cathode electrode plate and a method for manufacturing the same, which are used to improve the performance of the battery by setting the thickness of the cathode active material layer.

[0065] The battery of the present application can be used in electrical devices to provide electrical energy for the electrical devices, and the electrical devices can be mobile phones, portable devices, laptop computers, battery cars, electric cars, ships, spacecraft, electric toys and electric tools, etc. For example, spacecraft include airplanes, rockets, space shuttles and spacecrafts, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators and electric planers, etc.

[0066] refer to Figure 1 The electric device of the present application may be a vehicle 400. For example, a new energy vehicle, which may be a pure electric vehicle, a hybrid vehicle, or an extended-range vehicle.

[0067] The vehicle 400 includes an axle 401, a wheel 402 connected to the axle 401, a motor 403, a controller 404, and a battery 300. The motor 403 is used to drive the axle 401 to rotate, the controller 404 is used to control the operation of the motor 403, and the battery 300 can be arranged at the bottom, head or tail of the vehicle 400 to provide electrical energy for the operation of the motor 403 and other components in the vehicle.

[0068] refer to Figure 2 The battery 300 includes a box assembly 301 and at least one battery cell 200. The at least one battery cell 200 includes more than two battery cells 200. The multiple battery cells 200 can be connected in series, in parallel, or in mixed connection. Mixed connection refers to a mixture of series and parallel connection. The box assembly 301 is a hollow structure inside, and at least one battery cell 200 is accommodated in the box assembly 301.

[0069] The box assembly 301 may include two parts, which are respectively referred to as the box 301a and the cover 301b. The box 301a and the cover 301b are buckled together. After multiple battery cells 100a are connected in parallel, in series or in mixed series, they are placed in a closed chamber formed by the box 301a and the cover 301b buckled together.

[0070] refer to Figure 3, each battery cell 200 includes an electrode assembly 100 and a shell assembly 201. The electrode assembly 100 is disposed in the shell assembly 201. The shell assembly 201 includes a shell 201a and an end cap 201b. The shell 201a is determined according to the shape of one or more electrode assemblies 100 after being combined. For example, the shell 201a can be a hollow cuboid or a cube or a cylinder, and one of the surfaces of the shell 201a has an opening so that one or more electrode assemblies 100 can be placed in the shell 201a. For example, when the shell 201a is a hollow cuboid or a cube, one of the planes of the shell 201a is an open surface, that is, the plane does not have a shell wall so that the inside and outside of the shell 201a are connected. When the shell 201a is a hollow cylinder, the circular side of the shell 201a is an open surface, that is, the circular side does not have a shell wall so that the inside and outside of the shell 201a are connected. The end cap 201b is connected to the shell 201a at the opening of the shell 201a to form a closed housing for placing the electrode assembly 100. The shell assembly 201 is filled with electrolyte.

[0071] The end cap 201b is basically in the shape of a flat plate, and is provided with a cathode terminal 202, an anode terminal 203 and an explosion-proof valve 204. The cathode terminal 203 is connected to the cathode ear 5 of the cathode electrode 10a. The anode terminal 204 is connected to the anode ear 5' of the anode electrode 10b. The explosion-proof valve 204 can be a part of the flat surface of the end cap 201b, or can be welded to the flat surface of the end cap 201b. When the battery 400 generates too much gas, the gas expands and the gas pressure in the shell increases to a value exceeding the preset value, the explosion-proof valve 204 can be cracked to cause the inside and outside of the shell to communicate, and the gas is released outward through the crack of the explosion-proof valve 204, thereby avoiding an explosion.

[0072] refer to Figure 4 , the electrode assembly 100 includes a pole piece 10 and a separator 40. The pole piece 10 includes a cathode pole piece 10a and an anode pole piece 10b. The polarities of the cathode pole piece 10a and the anode pole piece 10b are opposite. The separator 40 is arranged between the cathode pole piece 10a and the anode pole piece 10b. The cathode pole piece 10a, the separator 40 and the anode pole piece 10b are stacked and wound in sequence to form the electrode assembly 100. Alternatively, the cathode pole piece 10a, the separator 40 and the anode pole piece 10b are stacked in sequence to form the electrode assembly 100. Among them, the separator 40 is made of insulating material.

[0073] refer to Figure 5 Some embodiments of the present application provide a battery cell, which includes a cathode electrode sheet 10a and an anode electrode sheet 10b.

[0074] The cathode electrode sheet 10 a includes a cathode current collector 1 and a cathode active material layer 2 disposed on the cathode current collector 1 . The cathode active material layer 2 includes a first thinned area 31 . The first thinned area 31 is located on the side of the cathode current collector 1 opposite to the cathode ear 5 .

[0075] The anode electrode sheet 10b and the cathode electrode sheet 10a are stacked along the first direction X, and the anode electrode sheet 10b includes an anode current collector 1' and an anode active material layer 2' arranged on the anode current collector 1', and the anode active material layer 2' includes a second thinning area 3', and the second thinning area 3' is arranged on the side of the anode current collector 1' where the anode ear 4' is arranged; the second thinning area 3' at least partially overlaps with the first thinning area 31.

[0076] The cathode current collector 1 and the anode current collector 1 ′ are structures or parts for collecting current, and in lithium-ion batteries they mainly refer to metal foils, such as copper foil and aluminum foil.

[0077] The anode active material layer 2' is formed by coating the anode active material on the anode current collector 1'. The anode active material includes at least one of lithium nickel cobalt manganese oxide, lithium iron phosphate, lithium nickel oxide, lithium nickel manganese oxide and lithium nickel iron manganese oxide, or carbon material (graphite, hard carbon, soft carbon, carbon nanotubes, graphene), wherein the graphite includes at least one of artificial graphite and natural graphite mesophase carbon microspheres.

[0078] The cathode active material layer 2 is formed by coating the cathode active material on the cathode current collector 1. The cathode active material includes at least one of lithium titanate, silicon negative electrode, silicon carbon negative electrode, lithium metal negative electrode material, tin-based negative electrode material, and tin oxide negative electrode material.

[0079] The cathode electrode sheet 10a, separator 40 and anode electrode sheet 10b are stacked and wound in sequence to form an electrode assembly 100. Alternatively, the cathode electrode sheet 10a, separator 40 and anode electrode sheet 10b are stacked in sequence to form an electrode assembly 100, and the electrode assembly 100 is placed in a housing assembly 201, and an electrolyte is injected into the housing assembly 201 to form a battery cell 200. The electrolyte soaks the active material on the electrode sheet, and the active material can react chemically with the electrolyte to charge the battery.

[0080] Since the current collector has a blank area for arranging the tabs, that is, an area where the active material is not coated, when the active material is coated on the current collector, the active material will form a thinning area with a slope at the transition position with the blank area, for example Figure 5 The second thinned region 3' of the anode active material layer 2'.

[0081] When the lithium-ion battery is charged, lithium ions will be deintercalated from the cathode active material layer 2 of the cathode electrode 10a, and these lithium ions will diffuse to the surface of the anode electrode 10b in the electrolyte and be embedded in the anode active material layer 2' of the anode electrode 10b. Since there is a second thinning area 3' at the position where the anode active material layer 2' is adjacent to the anode ear 4', the second thinning area 3' will cause the active material capacity of the anode electrode 10b to be insufficient, and there will not be enough embedding space to accommodate the lithium ions deintercalated from the cathode active material layer 2 of the cathode electrode 10a. The lithium ions can only be deposited on the surface of the anode electrode 10b, forming lithium deposition.

[0082] Therefore, in the embodiment of the present application, a first thinning zone 31 is provided on the side of the cathode current collector 1 opposite to the cathode ear 5, and the first thinning zone 31 at least partially overlaps with the second thinning zone 3'. The first thinning zone 31 can reduce the lithium ions deintercalated from the cathode active material layer 2 of the cathode electrode piece 10a, and change the CB (Cell Balance) value at the corresponding position of the first thinning zone 31, so that the unit area capacity of the anode electrode piece 10b can be greater than the unit area capacity of the cathode electrode piece 10a, that is, the CB value is ≥1, so that the anode electrode piece 10b has a large enough capacity to accommodate the lithium ions deintercalated from the cathode electrode piece 10a, thereby improving the lithium precipitation phenomenon and improving the performance of the battery.

[0083] Among them, CB value = capacity per unit area of ​​the anode electrode / capacity per unit area of ​​the cathode electrode.

[0084] In some embodiments, a dimension W1 of the first thinned region 31 along the second direction Y is less than or equal to a dimension W2 of the second thinned region 3' along the second direction Y, wherein the second direction Y intersects the first direction X, and the second direction Y is parallel to the direction in which the anode ear 4' moves away from the anode current collector 1'.

[0085] In the above embodiment, if the area of ​​the first thinning zone 31 is too large, the energy density of the battery will be sacrificed. If the area of ​​the first thinning zone 31 is too small, it will not be able to change the CB value. Therefore, the size W1 of the first thinning zone 31 along the second direction Y is less than or equal to the size W2 of the second thinning zone 3' along the second direction Y, which can not only meet the energy density requirements of the battery, but also has the effect of changing the CB value.

[0086] In some embodiments, W1∈[2,20]mm, W2∈[2,20]mm.

[0087] In the above embodiment, by setting the size range of the first thinned area 31 and the second thinned area 3' along the second direction Y, the CB value is changed while meeting the energy density requirement of the battery, thereby improving the lithium deposition phenomenon and improving the performance of the battery.

[0088] In some embodiments, W1∈[3,8]mm, W2∈[3,10]mm.

[0089] In the above embodiment, by further limiting the size range of the first thinned area 31 and the second thinned area 3' along the second direction Y, the CB value can be changed while meeting the energy density requirement of the battery, thereby improving the lithium deposition phenomenon and improving the battery performance.

[0090] In some embodiments, both the first thinning zone 31 and the second thinning zone 3' thin from a position far from the anode ear 4' to a position close to the anode ear 4'; the distance S1 between the position where the first thinning zone 31 starts to thin and the anode ear 4' is greater than or equal to the distance S2 between the position where the second thinning zone 3' starts to thin and the anode ear 4'.

[0091] In the above embodiment, along the direction of the anode ear 4' away from the anode current collector 1', the position where the first thinning zone 31 starts to thin is earlier than the position where the second thinning zone 3' starts to thin, or the first thinning zone 31 and the second thinning zone 3' start to thin from the same position, so as to thin the cathode electrode sheet 10a first in the area where the anode electrode sheet 10b has not started to thin, reduce the lithium ions deintercalated from the cathode active material layer 2 of the cathode electrode sheet 10a, and better change the CB value of the corresponding position of the first thinning zone 31, so that the CB value is ≥1, so that the anode electrode sheet 10b has a large enough capacity to accommodate the lithium ions deintercalated from the cathode electrode sheet 10a, thereby improving the lithium precipitation phenomenon and improving the performance of the battery.

[0092] In some embodiments, a distance S3∈[0,5] mm is provided between a position where the first thinning region 31 starts to be thinned and a position where the second thinning region 3 ′ starts to be thinned.

[0093] In the above embodiment, by limiting the distance between the position where the first thinning area 31 starts to thin and the position where the second thinning area 3' starts to thin, the CB value can be changed while meeting the energy density requirement of the battery, thereby improving the lithium deposition phenomenon and improving the performance of the battery.

[0094] In some embodiments, S3∈[0,3]mm.

[0095] In the above embodiment, by further limiting the distance between the position where the first thinning area 31 starts to thin and the position where the second thinning area 3' starts to thin, the CB value can be changed while meeting the energy density requirements of the battery, thereby improving the lithium plating phenomenon and improving the performance of the battery.

[0096] refer to Fig.10 and Fig.11 In some embodiments, the cathode electrode piece 10 a further includes a first insulating layer 6 , and the first insulating layer 6 is disposed on a side of the first thinned region 31 away from the cathode ear 5 .

[0097] In the above embodiment, the first insulating layer 6 is far away from the cathode ear 5 relative to the first thinning area 31. In the method for manufacturing the cathode electrode 10a provided in the subsequent embodiments of the present application, the current collector 20 is divided into two. In the operation of forming two electrodes, the position of the first insulating layer 6 of the current collector 20 is sheared instead of the cathode active material layer 2. This can reduce the phenomenon of burrs on the cathode active material layer 2 and alleviate the problem of active material falling off caused by shearing the current collector 20 to form a electrode.

[0098] The thickness of the first insulating layer 6 gradually decreases from the cathode ear 5 to the first thinned area 31 .

[0099] The first thinned area 31 is smoothly connected to the first insulating layer 6 to form an integral area, and the thickness of the integral area gradually becomes thinner from the cathode ear 5 to the first thinned area 31 .

[0100] refer to Figure 5 In some embodiments, the cathode active material layer 2 further includes a third thinning region 32 , and the third thinning region 32 is located on the side of the cathode current collector 1 where the cathode ear 5 is disposed.

[0101] In the above embodiment, the third thinning area 32 is provided on the side of the cathode current collector 1 where the cathode ear 5 is provided, which can improve the degree of electrolyte infiltration of the cathode electrode 10a, and can change the CB value of the corresponding position of the third thinning area 32, so that the unit area capacity of the active material of the anode electrode 10b is greater than the unit area capacity of the active material of the cathode electrode 10a, so as to improve the lithium precipitation phenomenon and improve the performance of the battery. In addition, the step stress of the side of the cathode current collector 1 can be reduced, the problem of stress concentration on the side of the cathode current collector 1 can be alleviated, the mutual squeezing force when the electrode expands can be reduced, and the phenomenon of electrode collapse can be reduced.

[0102] The thickness of the third thinned region 32 gradually becomes thinner in a direction from the first thinned region 31 to the cathode ear 5 .

[0103] In some embodiments, the width of the third thinned region 32 is W3∈[2, 20] mm, optionally, W3∈[3, 15] mm.

[0104] refer to Figure 8 and Fig. 9 In some embodiments, the cathode electrode piece 10 a further includes a second insulating layer 7 , and the second insulating layer 7 is located between the third thinned region 32 and the cathode ear 5 .

[0105] In the above embodiment, the second insulating layer 7 is close to the cathode ear 5 relative to the third thinning area 32. When shearing the cathode ear 5, if the shearing exceeds the cathode ear 5, it is the second insulating layer 7 that is sheared instead of the cathode active material layer 2. This can reduce the burr phenomenon of the cathode active material layer 2 and alleviate the problem of active material falling off caused by shearing the cathode ear 5.

[0106] In some embodiments, the thickness of the second insulating layer 7 gradually decreases from the third thinning region 32 to the cathode ear 5 .

[0107] In some embodiments, the third thinned region 32 is smoothly transitioned to the second insulating layer 7 to form an integral region, and the thickness of the integral region gradually becomes thinner from the third thinned region 32 to the cathode ear 5 .

[0108] refer to Fig.12 and Fig.13 In some embodiments, the cathode active material layer 2 further includes a fourth thinning region 33 , and the fourth thinning region 33 is located between the side of the cathode current collector 1 where the cathode ear 5 is disposed and the side opposite to the cathode ear 5 .

[0109] In the above embodiment, the fourth thinning area 33 can allow more electrolyte to pass through and can accommodate more electrolyte, so that the electrolyte can fully infiltrate the electrode piece in a short time, improve the infiltration effect of the electrolyte on the electrode piece, and enable the active material to react more fully with the electrolyte, thereby alleviating the problem of insufficient electrolyte infiltration in the middle area of ​​the electrode assembly 100 and improving the performance of the battery. The CB value of the corresponding position of the fourth thinning area 33 can be changed, so that the unit area capacity of the active material of the anode electrode piece 10b is greater than the unit area capacity of the active material of the cathode electrode piece 10a, so as to improve the phenomenon of lithium precipitation and improve the performance of the battery.

[0110] In some embodiments, the ratio of the width W4 of the fourth thinned region 33 to the width of the entire cathode electrode piece 10 a is in the range of [5%, 50%].

[0111] refer to Fig.14 In some embodiments, the cathode active material layer 2 further includes a fifth thinning region 34, and the fifth thinning region 34 is located in a corner region after the cathode electrode sheet 10a is wound.

[0112] In the above embodiment, at the corner after the cathode electrode 10a is wound, there is a curvature in the interface between the electrodes, which is easy to cause interface problems. The area of ​​the active material layer on the outer electrode of the cathode electrode 10a and the anode electrode 10b is large. Therefore, the fifth thinning area 34 is provided at the corner after the cathode electrode 10a is wound, which can change the CB value at the corner, so that the unit area capacity of the anode electrode 10b is greater than the unit area capacity of the cathode electrode 10a, thereby alleviating the lithium plating problem caused by insufficient capacity of the anode electrode 10b and improving the performance of the battery.

[0113] refer to Figure 2 Some embodiments of the present application further provide a battery 300 , which includes a box assembly 301 and the battery cell 200 in the above embodiment, and the battery cell 200 is disposed in the box assembly 301 .

[0114] The battery 300 includes the battery cell 200 in the above embodiment, and therefore has the corresponding beneficial effects of the battery cell 200 .

[0115] refer to Figure 1 Some embodiments of the present application also provide an electrical device, which includes the battery 300 in the above embodiment.

[0116] The electrical device includes the battery 300 in the above embodiment, and therefore has the corresponding beneficial effects of the battery 300.

[0117] In some embodiments, the electric device includes a vehicle 400 .

[0118] refer to Figures 8 to 15 Some embodiments of the present application further provide a cathode electrode sheet 10a, which includes a cathode current collector 1 and a cathode active material layer 2.

[0119] The cathode active material layer 2 is disposed on the cathode current collector 1 . The cathode active material layer 2 includes a first thinned area 31 . The first thinned area 31 is located on a side of the cathode current collector 1 opposite to the cathode ear 5 .

[0120] In the above embodiment, a first thinning zone 31 is provided on the side of the cathode current collector 1 opposite to the cathode ear 5, and the first thinning zone 31 at least partially overlaps with the second thinning zone 3'. The first thinning zone 31 can reduce the lithium ions deintercalated from the cathode active material layer 2 of the cathode electrode sheet 10a, and change the CB (Cell Balance) value at the corresponding position of the first thinning zone 31, so that the unit area capacity of the anode electrode sheet 10b can be greater than the unit area capacity of the cathode electrode sheet 10a, that is, the CB value is ≥1, so that the anode electrode sheet 10b has a large enough capacity to accommodate the lithium ions deintercalated from the cathode electrode sheet 10a, thereby improving the lithium precipitation phenomenon and improving the performance of the battery.

[0121] refer to Figures 15 to 17 Some embodiments of the present application further provide a method for manufacturing a cathode electrode sheet 10a, which comprises the following steps:

[0122] A current collector 20 is prepared, and two opposite sides of the current collector 20 are respectively provided with tab areas 30;

[0123] Coating an active material on the region between the two tab regions 30 of the current collector 20 to form a cathode active material layer 2, and thinning the region between the two tab regions 30 to form a thinned region 3a; and

[0124] The current collector 20 is divided into two in the thinned area 3a to form two cathode pole pieces.

[0125] In the above embodiment, the current collector 20 is divided into two parts from the middle area between the two pole ear areas 30 of the current collector 20 to form two cathode pole pieces 10a, that is, the current collector 20 is divided into two parts from the middle position of the two first thinning areas 31 to form two cathode pole pieces 10a, and the first thinning area 31 of each cathode pole piece 10a is located on the side of the cathode current collector 1 opposite to the cathode ear 5, which can improve the degree of electrolyte infiltration of the pole piece 1, and can change the CB value of the corresponding position of the first thinning area 31, so that the unit area capacity of the anode pole piece 10b is greater than the unit area capacity of the cathode pole piece 10a, alleviate the lithium precipitation problem caused by the insufficient capacity of the anode pole piece 10b, and improve the performance of the battery. In addition, it can reduce the step stress on the side of the cathode current collector 1, alleviate the problem of stress concentration on the side of the cathode current collector 1, reduce the mutual squeezing force when the pole piece expands, and reduce the phenomenon of pole piece crushing.

[0126] Combine the following Figures 6 to 17 The cathode pole piece 10a and the anode pole piece 10b are described in detail.

[0127] refer to Figure 6 and Figure 7 In some embodiments, the anode electrode sheet 10b includes an anode current collector 1' and an anode active material layer 2' disposed on the anode current collector 1', the anode active material layer 2' includes a second thinning region 3', and the second thinning region 3' is disposed on the side of the anode current collector 1' where the anode ear 4' is disposed; the second thinning region 3' at least partially overlaps with the first thinning region 31.

[0128] In some embodiments, the anode electrode sheet 10b includes a third insulating layer 5', and the third insulating layer 5' is disposed on a side of the second thinned region 3' close to the anode ear 4'.

[0129] In the above embodiment, the third insulating layer 5' is close to the anode ear 4' relative to the second thinning area 3'. When the anode ear 4' is sheared, if the shearing exceeds the anode ear 4', it is the third insulating layer 5' that is sheared instead of the anode active material layer 2', which can reduce the phenomenon of burrs on the anode active material layer 2' and alleviate the problem of active material falling off caused by shearing the anode ear 4'.

[0130] refer to Figure 8 and Fig. 9 The cathode electrode sheet 10a includes a cathode current collector 1 and a cathode active material layer 2. The cathode active material layer 2 is disposed on the cathode current collector 1, and the cathode active material layer 2 includes a first thinning area 31, which is located on the side of the cathode current collector 1 opposite to the cathode ear 5.

[0131] The cathode active material layer 2 further includes a flat region 4 , and a thickness H1 of the first thinned region 31 is smaller than a thickness H2 of the flat region 4 .

[0132] The length extension direction of the cathode electrode piece 10a is parallel to the third direction Z. The width extension direction of the cathode electrode piece 10a is parallel to the second direction Y. The thickness extension direction of the cathode electrode piece 10a is parallel to the first direction X.

[0133] The third direction Z intersects the second direction Y and the first direction X respectively, and the second direction Y intersects the first direction X. Optionally, the third direction Z is perpendicular to the second direction Y and the first direction X respectively, and the second direction Y is perpendicular to the first direction X.

[0134] The thickness direction of the cathode active material layer 2 is consistent with the thickness direction of the cathode electrode sheet 10 a . The thickness of the first thinned area 31 is less than the thickness of the flat area 4 , and the first thinned area 31 is concave toward the cathode current collector 1 relative to the flat area 4 .

[0135] The cathode electrode sheet 10 a further includes a cathode ear 5 . The cathode ear 5 can be formed by not coating an active material on one side of the cathode current collector 1 , that is, leaving a blank.

[0136] The cathode active material layer 2 includes a first thinning area 31 and a flat area 4. The thickness H1 of the first thinning area 31 is less than the thickness H2 of the flat area 4, so that the first thinning area 31 can be recessed toward the cathode current collector 1 relative to the flat area 4. The first thinning area 31 can allow more electrolyte to pass through and can accommodate more electrolyte, so that the electrolyte can fully infiltrate the electrode in a short time, thereby improving the wetting effect of the electrolyte on the cathode electrode 10a, allowing the active material to react more fully with the electrolyte, thereby improving the performance of the battery.

[0137] Furthermore, when a lithium-ion battery is charged, lithium ions are deintercalated from the active material of the cathode electrode 10a, diffused in the electrolyte to the surface of the anode electrode 10b, and embedded in the active material of the anode electrode 10b. If the active material capacity of the anode electrode 10b is insufficient and there is not enough embedding space, the lithium ions deintercalated from the active material of the cathode electrode 10a cannot be embedded in the active material of the anode electrode 10b, and the lithium ions can only be precipitated on the surface of the anode electrode 10b, thereby forming a layer of gray material, which is called lithium precipitation.

[0138] Based on this, in the embodiment provided in the present application, the cathode active material layer 2 includes a first thinning area 31 and a flat area 4, and the thickness H1 of the first thinning area 31 is less than the thickness H2 of the flat area 4, which can change the CB (Cell Balance) value of the corresponding position of the first thinning area 31 so that the CB value is ≥1, so as to improve the lithium precipitation phenomenon and improve the performance of the battery.

[0139] Among them, CB value = capacity per unit area of ​​the anode electrode / capacity per unit area of ​​the cathode electrode.

[0140] Setting the first thinning area 31 on the cathode active material layer 2 of the cathode electrode 10a can make the unit area capacity of the anode electrode 10b greater than the unit area capacity of the cathode electrode 10a, so that the anode electrode 10b has a large enough capacity to accommodate the lithium ions extracted from the cathode electrode 10a, thereby improving the lithium plating phenomenon and improving the performance of the battery.

[0141] In some embodiments, the first thinned region 31 is disposed on the first side 11 of the cathode current collector 1 opposite to the cathode ear 5 .

[0142] The first thinning area 31 is located at the side of the cathode current collector 1, which can reduce the step stress on the side of the cathode current collector 1, alleviate the problem of stress concentration on the side of the cathode current collector 1, reduce the extrusion force generated by the sides of the pole piece squeezing each other when the pole piece expands, and reduce the phenomenon of pole piece crushing.

[0143] In some embodiments, the length extension direction of the first thinned region 31 is consistent with the side extension direction of the cathode current collector 1 where it is located.

[0144] The first thinning area 31 extends along the extension direction of the side of the cathode current collector 1 where it is set, which can reduce the step stress on the side of the cathode current collector 1, alleviate the problem of stress concentration on the side of the cathode current collector 1, reduce the mutual squeezing force when the pole piece expands, and reduce the phenomenon of pole piece crushing.

[0145] The thickness of the first thinned region 31 gradually decreases from the direction close to the cathode ear 5 to the direction far away from the cathode ear 5 .

[0146] In some embodiments, the extension direction of the first side 11 is parallel to the third direction Z.

[0147] refer to Fig.10 and Fig.11 In some embodiments, the cathode electrode piece 10 a further includes a first insulating layer 6 , which is disposed on the first side edge 11 , and the first insulating layer 6 is away from the cathode ear 5 relative to the first thinning area 31 .

[0148] The first insulating layer 6 is away from the cathode ear 5 relative to the first thinning area 31. In the process of dividing the current collector 20 into two to form two cathode pole pieces 10a, what is sheared is the position where the first insulating layer 6 of the current collector 20 is located, rather than shearing the cathode active material layer 2. This can reduce the phenomenon of burrs on the cathode active material layer 2 and alleviate the problem of active material falling off caused by shearing the current collector 20 to form pole pieces.

[0149] The thickness of the first insulating layer 6 gradually decreases from the cathode ear 5 to the first thinned area 31 .

[0150] The first thinned region 31 is smoothly connected to the first insulating layer 6 to form an integral region, and the thickness of the integral region gradually decreases from the cathode ear 5 to the first thinned region 31 .

[0151] In some embodiments, the cathode electrode 10a includes a cathode ear 5, which is connected to the second side 12 of the cathode current collector 1. The first side 11 and the second side 12 are two opposite sides of the cathode current collector 1. The extension direction of the second side 12 is parallel to the extension direction of the first side 11.

[0152] The cathode active material layer 2 further includes a third thinned region 32 located at the second side 12 .

[0153] The third thinning area 32 is provided on the second side 12 of the cathode current collector 1, which can improve the degree of electrolyte infiltration of the cathode electrode 10a, and can change the CB value of the corresponding position of the third thinning area 32, so that the unit area capacity of the active material of the anode electrode 10b is greater than the unit area capacity of the active material of the cathode electrode 10a, so as to improve the lithium precipitation phenomenon and improve the performance of the battery. In addition, the step stress of the side of the cathode current collector 1 can be reduced, the problem of stress concentration on the side of the cathode current collector 1 can be alleviated, the mutual squeezing force when the electrode expands can be reduced, and the phenomenon of electrode collapse can be reduced.

[0154] The thickness of the third thinned region 32 gradually becomes thinner in a direction from the first thinned region 31 to the cathode ear 5 .

[0155] In some embodiments, the extension direction of the second side 12 is parallel to the third direction Z.

[0156] In some embodiments, the cathode electrode 10 a further includes a second insulating layer 7 , which is disposed on the second side 12 , and the second insulating layer 7 is close to the cathode ear 5 relative to the third thinned area 32 .

[0157] The thickness of the second insulating layer 7 gradually decreases from the third thinning area 32 to the cathode ear 5 .

[0158] The third thinned area 32 is smoothly connected to the second insulating layer 7 to form an integral area, and the thickness of the integral area gradually becomes thinner in a direction from the third thinned area 32 to the cathode ear 5 .

[0159] The second insulating layer 7 is close to the cathode ear 5 relative to the third thinning area 32. When shearing the cathode ear 5, if the shearing exceeds the cathode ear 5, it is the second insulating layer 7 that is sheared instead of the cathode active material layer 2. This can reduce the burrs on the cathode active material layer 2 and alleviate the problem of active material falling off caused by shearing the cathode ear 5.

[0160] The cathode current collector 1 further includes a third side edge 13 and a fourth side edge 14 . The third side edge 13 and the fourth side edge 14 are two opposite sides of the cathode current collector 1 .

[0161] In the embodiment where the cathode electrode sheet 10 a is a square electrode sheet, the cathode current collector 1 includes a first side 11 , a second side 12 , a third side 13 and a fourth side 14 .

[0162] A thinning area may also be provided on the third side 13 and the fourth side 14. Providing the thinning area at the side of the cathode current collector 1 can reduce the step stress on the side of the cathode current collector 1, alleviate the problem of stress concentration on the side of the cathode current collector 1, reduce the mutual squeezing force when the pole piece expands, and reduce the phenomenon of pole piece crushing.

[0163] refer to Fig.12 and Fig.13 In some embodiments, the cathode active material layer 2 further includes a fourth thinning region 33 disposed between the first side edge 11 and the second side edge 12 .

[0164] The thickness of the fourth thinning zone 33 is less than the thickness of the flat area 4, which can make the fourth thinning zone 33 concave toward the cathode current collector 1 relative to the flat area 4. The fourth thinning zone 33 can allow more electrolyte to pass through and can accommodate more electrolyte, so that the electrolyte can fully infiltrate the electrode piece in a short time, thereby improving the wetting effect of the electrolyte on the cathode electrode piece 10a, allowing the active material to react more fully with the electrolyte, alleviating the problem of insufficient electrolyte infiltration in the middle area of ​​the electrode assembly 100, and improving the performance of the battery.

[0165] In some embodiments, the length extension direction of the fourth thinned region 33 is consistent with the extension direction of the first side 11 .

[0166] The extension direction of the first side 11 is parallel to the third direction Z, that is, the extension direction of the first side 11 is consistent with the length extension direction of the cathode electrode 10a, and the length extension direction of the fourth thinning area 33 is consistent with the extension direction of the first side 11. The fourth thinning area 33 can allow more electrolyte to pass through in the length direction of the cathode electrode 10a, and can accommodate more electrolyte, so that the electrolyte can fully infiltrate the electrode in a short time, thereby improving the wetting effect of the electrolyte on the cathode electrode 10a, allowing the active substance to react more fully with the electrolyte, alleviating the problem of insufficient electrolyte infiltration in the middle area of ​​the electrode assembly 100, and improving the performance of the battery.

[0167] In some embodiments, the fourth thinned area 33 is located between the first side 11 and the second side 12 .

[0168] Here, the middle between the first side 11 and the second side 12 refers to the exact middle in terms of geometric dimensions.

[0169] The electrode in the middle area of ​​the battery is a region that is difficult for the electrolyte to infiltrate. In the later stage of use, the electrolyte in this area is prone to be poor, resulting in interface problems. Therefore, the fourth thinning area 33 is located between the first side 11 and the second side 12, and an electrolyte transmission channel can be constructed to alleviate the problem of insufficient electrolyte infiltration in the middle area of ​​the electrode assembly 100, thereby improving the performance of the battery.

[0170] refer to Fig.14 In some embodiments, the cathode active material layer 2 further includes a fifth thinning region 34, and the fifth thinning region 34 is located in a corner region after the cathode electrode sheet 10a is wound.

[0171] At the corner after the cathode electrode 10a is wound, there is a curvature in the interface between the electrodes, which is easy to cause interface problems. The area of ​​the cathode active material layer on the outer electrode of the cathode electrode 10a and the anode electrode 10b is large. Therefore, the fifth thinning area 34 is set at the corner after the cathode electrode 10a is wound, which can change the CB value at the corner, so that the unit area capacity of the anode electrode is greater than the unit area capacity of the cathode electrode, alleviate the lithium plating problem caused by insufficient anode electrode capacity, and improve battery performance.

[0172] refer to Figures 11 to 13 In some embodiments, the cathode current collector 1 includes a first side surface 15 and a second side surface 16 that are opposite to each other, and a cathode active material layer 2 is disposed on at least one of the first side surface 15 and the second side surface 16 .

[0173] The cathode active material layer 2 is formed by coating an active material on the cathode current collector 1 . The active material can chemically react with the electrolyte to charge the battery.

[0174] refer to Fig.12 and Fig.13 In some embodiments, the first side 15 and the second side 16 are both provided with a cathode active material layer 2, and at least one of the cathode active material layer 2 on the first side 15 and the cathode active material layer 2 on the second side 16 has a first thinning area 31 and a flattening area 4.

[0175] refer to Fig.12 A first thinning region 31 and a flattening region 4 are provided on the cathode active material layer 2 on the first side 15 and the second side 16 of the cathode current collector 1 , and a third thinning region 32 and a fourth thinning region 33 are provided on the first side 15 and the second side 16 .

[0176] refer to Fig.13 A third thinning region 32 and a tiled region 4 are provided on the cathode active material layer 2 on the first side 15 of the cathode current collector 1, and a first thinning region 31, a third thinning region 32, and a fourth thinning region 33 and a tiled region 4 are provided on the cathode active material layer 2 on the second side 16 of the cathode current collector 1.

[0177] The first thinning area 31 can be optionally set on the first side 15 and the second side 16 of the cathode current collector 1, and the CB value of the position where the first thinning area 31 is set can be changed, so that the unit area capacity of the anode electrode piece is greater than the unit area capacity of the cathode electrode piece, thereby alleviating the lithium plating problem caused by insufficient anode electrode piece capacity and improving battery performance.

[0178] In some embodiments, the area of ​​the first thinned region 31 is smaller than the area of ​​the tiled region 4 .

[0179] The paving region 4 can be formed by coating an active material on the cathode current collector 1, and the first thinned region 31 can be formed by thinning the paving region 4. Alternatively, the first thinned region 31 and the paving region 4 are formed by coating active materials of different thicknesses, respectively.

[0180] The paved area 4 occupies most of the area of ​​the cathode current collector 1 and is used to increase the energy density of the battery and improve the battery performance. The first thinned area 31 is used to change the local CB value and to increase the storage capacity of the electrolyte and improve the wetting effect of the electrolyte.

[0181] In some embodiments, the ratio of the thickness H1 of the first thinned area 31 to the thickness H2 of the tiled area 4 is ≥70%. The thickness H1 of the first thinned area 31 is less than the thickness H2 of the tiled area 4.

[0182] If the thickness H1 of the first thinning area 31 is too thin, the energy density of the battery will be sacrificed. If the thickness H1 of the first thinning area 31 is too large, it will not be able to change the CB value and improve the electrolyte infiltration effect. Therefore, the ratio of the thickness H1 of the first thinning area 31 to the thickness H2 of the flat area 4 is ≥70%, which can not only meet the energy density requirements of the battery, but also has the effect of changing the CB value and improving the electrolyte infiltration effect.

[0183] In some embodiments, the thickness H1 of the first thinned area 31 is ≤50 um. Optionally, the thickness H1 of the first thinned area 31 is ≤15 um.

[0184] In some embodiments, the flattened area 4 is a normal area of ​​the cathode electrode piece 10a. The first thinned area 31 is a local thinned area of ​​the cathode electrode piece 10a.

[0185] The local thinning area can be thinned physically to reduce the cathode active material layer in the local area to change the CB value of the area. Alternatively, physical thinning is not required, but a material layer with different performance from the main area (such as high resistance, low gram capacity, etc.) is coated in the area where the cathode theoretically needs to be thinned. For example: an anode with better gram capacity or a cathode with lower gram capacity is coated in the area where the CB value needs to be changed, or a high-resistance coating or active material is set in the area, so that the cathode delithiation in the area is reduced, thereby changing the CB value of the area.

[0186] In addition to setting a thinning area at the edge position to change the CB at the edge position, a thinning area can also be set in the middle position of the cathode electrode piece 10a, because the middle position of the cathode electrode piece 10a is often an area where the electrolyte is not fully infiltrated. Thinning this area can change the CB value of this area to improve battery performance, and can also form a groove in this area with more liquid storage to improve the electrolyte infiltration effect. In addition, the corner area of ​​the cathode electrode piece 10a can also be thinned to alleviate the problem of battery cell infiltration and insufficient CB value at the corner.

[0187] refer to Fig.15 Some embodiments of the present application further provide an electrode assembly, which includes a cathode electrode piece 10a and an anode electrode piece 10b, wherein the polarity of the cathode electrode piece 10a is opposite to the polarity of the anode electrode piece 10b.

[0188] When a lithium-ion battery is charged, lithium ions are deintercalated from the active material of the cathode electrode 10a, diffused in the electrolyte to the surface of the anode electrode 10b, and embedded in the active material of the anode electrode 10b. If the active material capacity of the anode electrode 10b is insufficient and there is not enough embedding space, the lithium ions deintercalated from the active material of the cathode electrode 10a cannot be embedded in the active material of the anode electrode 10b, and the lithium ions can only be deposited on the surface of the anode electrode 10b, forming lithium deposition.

[0189] Therefore, setting the first thinning zone 31 at a position of the cathode electrode 10a away from the cathode ear 5 can change the CB (Cell Balance) value at the corresponding position of the first thinning zone 31, so that the unit area capacity of the anode electrode is greater than the unit area capacity of the cathode electrode, so that the anode electrode 10b has a large enough capacity to accommodate the lithium ions extracted from the cathode electrode 10a, thereby improving the lithium plating phenomenon and improving the performance of the battery.

[0190] The cathode pole piece 10a and the anode pole piece 10b are stacked, and the cathode ear 5 of the cathode pole piece 10a is arranged opposite to the anode ear 5' of the anode pole piece 10b.

[0191] A thinning zone is formed at the position of the anode electrode 10b close to the anode ear 5'. If the first thinning zone 31 is not set at the position of the cathode electrode 10a away from the cathode ear 5, it is possible that the active material capacity of the anode electrode 10b is insufficient and there is not enough embedding space, resulting in the lithium ions deintercalated from the active material of the cathode electrode 10a being unable to be embedded in the active material of the anode electrode 10b, forming lithium precipitation. Therefore, the first thinning zone 31 of the cathode electrode 10a is set on the first side 11 of the cathode current collector 1, which can reduce the amount of lithium ion deintercalation of the cathode electrode 10a, make the unit area capacity of the anode electrode greater than the unit area capacity of the cathode electrode, and make the anode electrode 10b have a large enough capacity to accommodate the lithium ions deintercalated from the cathode electrode 10a, thereby improving the lithium precipitation phenomenon and improving the performance of the battery.

[0192] exist Figure 5 In the embodiment shown, the width of the second thinning area 3' of the side where the anode ear 5' of the anode pole piece 10b is located is W2. The width of the first thinning area 31 corresponding to the first side of the cathode pole piece 10a is W1. The first side is a strip side. The width of the third thinning area 32 corresponding to the side (second side) where the cathode ear 5 of the cathode pole piece 10a is located is W3.

[0193] In some embodiments, the value range of W1 is (0, 30) mm.

[0194] In some embodiments, the value range of W2 is (0,30) mm.

[0195] In some embodiments, the value range of W3 is (0,30) mm.

[0196] In some embodiments, the value of W2 is greater than or equal to the value of W1.

[0197] In some embodiments, W2=W1+A.

[0198] Due to relevant design principles, the edge of the side where the anode ear 5' of the anode plate 10b is located exceeds the edge of the first side of the cathode plate 10a, and the exceeding portion of the first side of the anode plate 10b does not require the corresponding thinning of the first side of the cathode plate 10a, so theoretically, the thinning width W2 of the first side of the anode plate 10b is greater than the thinning width W1 of the second side of the cathode plate 10a.

[0199] Wherein, A is a constant, and the unit is millimeter. In some embodiments, A∈[0.2, 8], and optionally, the value range of A is [0.5, 5].

[0200] The limitation of A can guide the thinning width of the cathode electrode piece 10a in design. If the thinning width is too large, the energy of the battery will be sacrificed. If it is too small, it cannot cover the thinning width of the anode electrode piece 10b, thus failing to achieve the expected effect.

[0201] Some embodiments of the present application also provide a method for manufacturing a cathode electrode 10a, which comprises the following steps:

[0202] refer to Fig.16 and Fig.17 , preparing a current collecting member 20, and respectively setting tab regions 30 on opposite sides of the current collecting member 20;

[0203] An active material is coated on the area of ​​the current collector 20 between the two pole lug areas 30 to form a cathode active material layer 2, which includes a thinning area 3a (two first thinning areas 31) and a flat area 4, wherein the thickness H1 of the thinning area 3a is less than the thickness H2 of the flat area 4.

[0204] The current collector 20 is divided into two parts from the middle area between the two pole ear areas 30 of the current collector 20 to form two cathode pole pieces 10a, that is, the current collector 20 is divided into two parts from the middle position of the two first thinning areas 31 to form two cathode pole pieces 10a, and the first thinning area 31 of each cathode pole piece 10a is located at the first side 11 of the cathode current collector 1.

[0205] The thickness H1 of the first thinning area 31 is less than the thickness H2 of the paving area 4, which can change the CB value of the corresponding position of the first thinning area 31, so that the unit area capacity of the anode electrode is greater than the unit area capacity of the cathode electrode, alleviate the lithium precipitation problem caused by insufficient anode electrode capacity, and improve the performance of the battery. In addition, it can reduce the step stress on the side of the cathode current collector 1, alleviate the problem of stress concentration on the side of the cathode current collector 1, reduce the mutual squeezing force when the electrode expands, and reduce the phenomenon of electrode crushing. Furthermore, the first thinning area 31 is concave toward the cathode current collector 1 relative to the paving area 4, and the first thinning area 31 can allow more electrolyte to pass through, and can accommodate more electrolyte, so that the electrolyte can fully infiltrate the electrode in a short time, improve the wetting effect of the electrolyte on the cathode electrode 10a, and enable the active material to react more fully with the electrolyte, thereby improving the performance of the battery.

[0206] The current collector 20 is divided into two parts in the middle area between the two tab areas 30 of the current collector 20 to form two cathode plates 10a. The current collector 20 is cut in the middle area, so for each cathode plate 10a, the cut edge of the middle area of ​​the current collector 20 is the strip edge, that is, the first side edge 11, and the side edge corresponding to the cathode tab 5 of the cathode plate 10a is the second side edge 12.

[0207] refer to Fig.17 In some embodiments, an insulating material is coated on the middle area between the two tab areas 30 of the current collector 20 to form a first insulating layer 6, and the cathode active material layer 2 is located between the first insulating layer 6 and the tab area 30 on one side.

[0208] The current collector 20 is divided into two parts from the middle area between the two pole ear areas 30 of the current collector 20 to form two cathode pole pieces 10a, and an insulating material is coated on the middle area between the two pole ear areas 30 of the current collector 20 to form a first insulating layer 6. In the process of dividing the current collector 20 into two parts to form two cathode pole pieces 10a, what is sheared is the position where the first insulating layer 6 of the current collector 20 is located, rather than shearing the cathode active material layer 2. This can reduce the phenomenon of burrs on the cathode active material layer 2 and alleviate the problem of active material falling off caused by shearing the current collector 20 to form pole pieces.

[0209] In some embodiments, the first thinned region 31 is disposed between the cathode active material layer 2 and the first insulating layer 6 .

[0210] The first thinning area 31 is provided on the first side 11 of the cathode current collector 1, which can improve the degree of the electrode 1 being infiltrated by the electrolyte, and can change the CB value of the corresponding position of the first thinning area 31, so that the unit area capacity of the anode electrode is greater than the unit area capacity of the cathode electrode, thereby alleviating the lithium precipitation problem caused by insufficient anode electrode capacity and improving the performance of the battery. In addition, the step stress on the side of the cathode current collector 1 can be reduced, the problem of stress concentration on the side of the cathode current collector 1 can be alleviated, the mutual squeezing force when the electrode expands can be reduced, and the phenomenon of electrode collapse can be reduced.

[0211] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that: include: A cathode electrode sheet (10a), comprising a cathode current collector (1) and a cathode active material layer (2) disposed on the cathode current collector (1), wherein the cathode active material layer (2) comprises a first thinning region (31), and the first thinning region (31) is located on a side of the cathode current collector (1) opposite to the cathode ear (5); as well as An anode pole piece (10b) is stacked with the cathode pole piece (10a) along a first direction (X), the anode pole piece (10b) comprising an anode current collector (1') and an anode active material layer (2') arranged on the anode current collector (1'), the anode active material layer (2') comprising a second thinning region (3'), the second thinning region (3') being arranged on the side of the anode current collector (1') where the anode ear (4') is arranged; the second thinning region (3') at least partially overlaps with the first thinning region (31).

2. The battery cell according to claim 1, characterized in that: A dimension W1 of the first thinned area (31) along the second direction (Y) is less than or equal to a dimension W2 of the second thinned area (3') along the second direction (Y), wherein the second direction (Y) intersects with the first direction (X), and the second direction (Y) is parallel to a direction in which the anode ear (4') moves away from the anode current collector (1').

3. The battery cell according to claim 2, characterized in that: W1∈[2,20]mm, W2∈[2,20]mm.

4. The battery cell according to claim 3, characterized in that: W1∈[3,8]mm, W2∈[3,10]mm.

5. The battery cell according to claim 1, characterized in that: The first thinning zone (31) and the second thinning zone (3') both thin from a position away from the anode ear (4') to a position close to the anode ear (4'); a distance S1 between the position where the first thinning zone (31) starts to thin and the anode ear (4') is greater than or equal to a distance S2 between the position where the second thinning zone (3') starts to thin and the anode ear (4').

6. The battery cell according to claim 5, characterized in that: A distance S3∈[0,5] mm between a position where the first thinning zone (31) starts to thin and a position where the second thinning zone (3') starts to thin.

7. The battery cell according to claim 6, characterized in that: S3∈[0,3]mm.

8. The battery cell according to claim 1, characterized in that: The cathode electrode plate (10a) further comprises a first insulating layer (6), wherein the first insulating layer (6) is arranged on a side of the first thinned region (31) away from the cathode ear (5).

9. The battery cell according to any one of claims 1 to 8, characterized in that: The cathode active material layer (2) further comprises a third thinned region (32), and the third thinned region (32) is located on the side of the cathode current collector (1) where the cathode ear (5) is arranged.

10. The battery cell according to claim 9, characterized in that: The cathode electrode piece (10a) further comprises a second insulating layer (7), wherein the second insulating layer (7) is located between the third thinned area (32) and the cathode ear (5).

11. The battery cell according to claim 1, characterized in that: The cathode active material layer (2) further comprises a fourth thinned region (33), wherein the fourth thinned region (33) is located between the side of the cathode current collector (1) where the cathode ear (5) is arranged and the side opposite to the cathode ear (5).

12. The battery cell according to claim 1, characterized in that: The cathode active material layer (2) further comprises a fifth thinning region (34), and the fifth thinning region (34) is located at a corner region after the cathode electrode sheet (10a) is wound.

13. A battery, characterized in that: It comprises a box assembly (301) and a battery cell according to any one of claims 1 to 12, wherein the battery cell is arranged in the box assembly (301).

14. An electrical device, characterized in that: Comprising a battery according to claim 13.

15. A cathode electrode, characterized in that: include: Cathode current collector (1); as well as A cathode active material layer (2) is provided on the cathode current collector (1), and the cathode active material layer (2) comprises a first thinning area (31), wherein the first thinning area (31) is located on the side of the cathode current collector (1) opposite to the cathode ear (5).

16. A method for manufacturing a cathode electrode, comprising the following steps: A current collecting member (20) is prepared, wherein two opposite sides of the current collecting member (20) respectively have a tab area (30); An active material is coated on the region of the current collector (20) located between the two tab regions (30) to form a cathode active material layer (2), and a region of the cathode active material layer (2) located between the two tab regions (30) is thinned to form a thinned region (3a); as well as The current collecting member (20) is divided into two in the thinned area (3a) to form two cathode pole pieces.

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