Battery cell, battery, electric apparatus, cathode plate and manufacturing method therefor

Abstract

Provided are a battery cell (200), a battery (300), an electric apparatus, a cathode plate (10a) and a manufacturing method therefor. The battery cell (200) comprises: a cathode plate (10a), which comprises a cathode current collector (1) and a cathode active material layer (2) arranged on the cathode current collector (1), wherein the cathode active material layer (2) comprises a first thinned area (31), and the first thinned area (31) is located on the side edge of the cathode current collector (1) that is opposite a cathode tab (5); and an anode plate (10b), which is arranged such that the anode plate (10b) and the cathode plate (10a) are stacked in a first direction (X), wherein the anode plate (10b) comprises 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') comprises a second thinned area (3'), the second thinned area (3') is arranged on the side edge of the anode current collector (1') that is provided with an anode tab (4'), and the second thinned area (3') at least partially overlaps the first thinned area (31). The first thinned area (31) can reduce lithium ions de-intercalated from the cathode active material layer (2) of the cathode plate (10a), so that the anode plate (10b) has enough capacity to accommodate the lithium ions de-intercalated from the cathode plate (10a), thereby alleviating lithium plating and improving the performance of the battery.

Description

Battery cell, battery, electrical device, cathode plate and manufacturing method thereof

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202311157607.6, filed on September 8, 2023, entitled “Battery cell, battery, electrical device, cathode plate and manufacturing method thereof,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] 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

[0004] In some related technologies, batteries include battery cells, which include electrode assemblies formed by winding electrode sheets and separators, and injected electrolyte. Research has found that batteries can suffer from lithium plating, resulting in reduced battery performance.

[0005] Summary of the Invention

[0006] Some embodiments of the present application provide a battery cell, a battery, an electrical device, a cathode plate, and a manufacturing method thereof, for alleviating the problem of battery performance degradation.

[0007] Some embodiments of the present application provide a battery cell, which includes: a cathode electrode, 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 region, and the first thinning region is located on the side of the cathode current collector opposite to the cathode ear; and an anode electrode, stacked with the cathode electrode along a first direction, the anode electrode including 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 region, and the second thinning region is arranged on the side of the anode current collector where the anode ear is arranged; the second thinning region at least partially overlaps with the first thinning region.

[0008] 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 and the second thinning zone at least partially overlap. The first thinning zone can reduce the lithium ions deintercalated from the cathode active material layer of the cathode electrode, and change the CB value of the corresponding position of the first thinning zone, 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 has a sufficiently large capacity to accommodate the lithium ions deintercalated from the cathode electrode, thereby improving the lithium plating phenomenon and improving the performance of the battery.

[0009] In some embodiments, a dimension W1 of the first thinning region along the second direction is less than or equal to a dimension W2 of the second thinning region along the second direction, wherein the second direction intersects the first direction, and the second direction is parallel to the direction in which the anode ear moves away from the anode current collector.

[0010] 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.

[0011] In some embodiments, W1∈[2,20]mm, W2∈[2,20]mm.

[0012] 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.

[0013] In some embodiments, W1∈[3,8]mm, W2∈[3,10]mm.

[0014] 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 better changed while meeting the energy density requirements of the battery, thereby improving the lithium plating phenomenon and improving the battery performance.

[0015] In some embodiments, both the first thinning zone and the second thinning zone thin from a position away from the anode ear to a position close to the anode ear; the distance S1 between the position where the first thinning zone starts to thin and the anode ear is greater than or equal to the distance S2 between the position where the second thinning zone starts to thin and the anode ear.

[0016] 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 is thinned first in the area where the anode electrode has not yet started to thin, thereby reducing the lithium ions deintercalated from the cathode active material layer of the cathode electrode, and better changing the CB value of the corresponding position of the first thinning zone, so that the anode electrode has a large enough capacity to accommodate the lithium ions deintercalated from the cathode electrode, thereby improving the lithium plating phenomenon and improving the performance of the battery.

[0017] In some embodiments, a distance S3∈[0,5] mm between a position where the first thinning region starts to be thinned and a position where the second thinning region starts to be thinned.

[0018] 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 battery performance.

[0019] In some embodiments, S3∈[0,3]mm.

[0020] 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.

[0021] In some embodiments, the cathode electrode 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.

[0022] In the above embodiment, the first insulating layer is 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 cutting the current collector to form pole pieces.

[0023] In some embodiments, the cathode active material layer further includes a third thinned region, and the third thinned region is located on a side of the cathode current collector where the cathode ear is provided.

[0024] In the above embodiment, a third thinning area is provided on the side of the cathode ear of the cathode current collector, which can increase the degree of wetting of the cathode electrode by the electrolyte, and can 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 is greater than the unit area capacity of the active material of the cathode electrode, so as to improve the lithium plating phenomenon and improve the performance of the battery.

[0025] 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.

[0026] 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 phenomenon of burrs on the cathode active material layer and alleviate the problem of active material falling off due to shearing the cathode ear.

[0027] In some embodiments, the cathode active material layer further includes a fourth thinned region, and the fourth thinned region is located between a side of the cathode current collector where the cathode ear is provided and a side opposite to the cathode ear.

[0028] In the above embodiment, the fourth thinned region allows more electrolyte to pass through and can accommodate more electrolyte, allowing the electrolyte to fully infiltrate the electrode piece in a short period of time, improving the electrolyte's infiltration effect on the electrode piece, allowing the active material to more fully react with the electrolyte, alleviating the problem of insufficient electrolyte infiltration in the central area of ​​the electrode assembly, and improving battery performance. Furthermore, the CB value at the corresponding position of the fourth thinned region can be changed, making the unit area capacity of the active material of the anode electrode piece greater than the unit area capacity of the active material of the cathode electrode piece, thereby improving lithium plating and improving battery performance.

[0029] 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.

[0030] In the above embodiment, at the corner after the cathode electrode is wound, there is curvature in the interface between the electrode pieces, which easily causes interface problems. The area of ​​the active material layer on the electrode piece located on the outer layer of the cathode electrode piece and the anode electrode piece is large. Therefore, the fifth thinning zone is set at the corner after the cathode electrode piece is wound, which can change the CB value at the corner, so that the unit area capacity of the anode electrode piece is greater than the unit area capacity of the cathode electrode piece, alleviate the lithium plating problem caused by insufficient capacity of the anode electrode piece, and improve the performance of the battery.

[0031] 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.

[0032] The battery includes the battery cell in the above embodiment, and therefore has the corresponding beneficial effects of the battery cell.

[0033] Some embodiments of the present application provide an electrical device comprising the above-mentioned battery.

[0034] The electrical device includes the battery in the above embodiment, and therefore has the corresponding beneficial effects of the battery.

[0035] Some embodiments of the present application provide a cathode electrode, 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, which is located on the side of the cathode current collector opposite to the cathode ear.

[0036] 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 and the second thinning zone at least partially overlap. The first thinning zone can reduce the lithium ions deintercalated from the cathode active material layer of the cathode electrode, and change the CB value of the corresponding position of the first thinning zone, 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 has a sufficiently large capacity to accommodate the lithium ions deintercalated from the cathode electrode, thereby improving the lithium plating phenomenon and improving the performance of the battery.

[0037] Some embodiments of the present application provide a method for manufacturing a cathode electrode, which includes the following steps: preparing a current collector, wherein the current collector has a tab region on opposite sides; coating an active material on an area of ​​the current collector located between the two tab regions to form a cathode active material layer, and thinning the area of ​​the cathode active material layer located between the two tab regions to form a thinned area; and dividing the current collector into two in the thinned area to form two cathode electrodes.

[0038] 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. 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

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. 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 creative work.

[0040] FIG1 is a schematic structural diagram of a vehicle disclosed in some embodiments of the present application;

[0041] FIG2 is a schematic diagram of the exploded structure of a battery disclosed in some embodiments of the present application;

[0042] FIG3 is a schematic diagram of a battery cell disclosed in some embodiments of the present application;

[0043] FIG4 is a schematic diagram of an electrode assembly disclosed in some embodiments of the present application;

[0044] FIG5 is a side view schematic diagram of a stacked state of pole pieces of two polarities disclosed in some embodiments of the present application;

[0045] FIG6 is a schematic diagram of an anode electrode sheet disclosed in some embodiments of the present application;

[0046] FIG7 is a schematic side view of the anode electrode shown in FIG6;

[0047] FIG8 is a schematic diagram of a first form of a cathode electrode disclosed in some embodiments of the present application;

[0048] FIG9 is a schematic side view of the cathode electrode shown in FIG8;

[0049] FIG10 is a schematic diagram of a second form of a cathode electrode disclosed in some embodiments of the present application;

[0050] FIG11 is a schematic side view of the cathode electrode shown in FIG10;

[0051] FIG12 is a side view schematic diagram of a third form of a cathode electrode disclosed in some embodiments of the present application;

[0052] FIG13 is a side view schematic diagram of a fourth form of a cathode electrode disclosed in some embodiments of the present application;

[0053] FIG14 is a side view schematic diagram of a fifth form of a cathode electrode disclosed in some embodiments of the present application;

[0054] FIG15 is a schematic diagram of a first form of a current collecting member disclosed in some embodiments of the present application;

[0055] FIG16 is a schematic side view of the current collecting member shown in FIG15;

[0056] FIG17 is a schematic diagram of a second form of a current collecting member disclosed in some embodiments of the present application.

[0057] In the drawings, the drawings are not drawn to scale.

[0058] Marking instructions: 10a-cathode electrode; 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-flattening area; 5-cathode ear; 6-first insulating layer; 7-second insulating layer; 10b-anode electrode; 1'-anode current collector; 2'-anode active material layer; 3'-second thinning area; 4'- Anode ear; 5'-third insulating layer; 10-pole piece; 20-current collector; 30-pole ear area; 40-isolator; 100-electrode assembly; 200-battery cell; 201-housing assembly; 201a-housing; 201b-end cover; 202-cathode terminal; 203-anode terminal; 204-explosion-proof valve; 300-battery; 301-housing assembly; 301a-housing; 301b-cover; 400-vehicle; 401-axle; 402-wheel; 403-motor; 404-controller. DETAILED DESCRIPTION

[0059] The following detailed description of the embodiments of the present application is provided in conjunction with the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present application, but are not intended 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 this application, it should be noted that, unless otherwise specified, "multiple" means more than two; the terms "upper", "lower", "left", "right", "inside", "outside", etc., indicating directions or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on this 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 perpendicular, 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 are attracting 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] During battery manufacturing, pole pieces and separators of different polarities are typically wound or stacked, followed by subsequent processes such as hot pressing to form an electrode assembly. Pole pieces are typically made by coating active material onto a current collector. Research has found that the thickness of the active material layer on the pole piece affects battery performance.

[0064] Based on this, some embodiments of the present application provide a battery cell, a battery, an electrical device, a cathode electrode and a manufacturing method thereof, 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. For example, spacecraft include airplanes, rockets, space shuttles and spacecraft. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys and electric airplane toys. Electric tools include metal cutting power tools, grinding power tools, assembly power tools and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators and electric planers.

[0066] 1 , the power-consuming 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] Vehicle 400 includes an axle 401, wheels 402 connected to axle 401, a motor 403, a controller 404, and a battery 300. Motor 403 is used to drive axle 401, controller 404 is used to control the operation of motor 403, and battery 300 can be located at the bottom, front, or rear of vehicle 400 to provide power to motor 403 and other components of the vehicle.

[0068] Referring to Figure 2 , a battery 300 includes a housing assembly 301 and at least one battery cell 200. Each battery cell 200 includes two or more battery cells 200. These multiple battery cells 200 can be connected in series, parallel, or in a hybrid configuration. The housing assembly 301 is hollow, housing the at least one battery cell 200.

[0069] The housing assembly 301 includes two parts, referred to herein as the housing 301a and the cover 301b. The housing 301a and the cover 301b snap together. Multiple battery cells 100a are connected in parallel, series, or in a hybrid arrangement and then placed within the enclosed chamber formed by the housing 301a and the cover 301b.

[0070] 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 the one or more electrode assemblies 100 after being combined. For example, the shell 201a can be a hollow cuboid, cube, or 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 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 housing 201a at the opening of the housing 201a to form a closed shell for placing the electrode assembly 100. The housing assembly 201 is filled with electrolyte.

[0071] End cap 201b is essentially a flat plate, equipped with a cathode terminal 202, an anode terminal 203, and an explosion-proof valve 204. Cathode terminal 203 is connected to cathode ear 5 of cathode electrode 10a. Anode terminal 204 is connected to anode ear 5' of anode electrode 10b. Explosion-proof valve 204 can be part of the flat surface of end cap 201b or welded to the flat surface of end cap 201b. When excessive gas is generated by battery 400, the gas expands, raising the pressure within the housing to a value exceeding a preset value. The explosion-proof valve 204 can rupture, allowing the inside and outside of the housing to communicate with each other. Gas can then be released outward through the rupture of explosion-proof valve 204, thereby preventing an explosion.

[0072] Referring to Figure 4, the electrode assembly 100 includes electrode sheets 10 and separators 40. The electrode sheets 10 include a cathode electrode sheet 10a and an anode electrode sheet 10b. The cathode electrode sheet 10a and the anode electrode sheet 10b have opposite polarities. The separator 40 is disposed between the cathode electrode sheet 10a and the anode electrode sheet 10b. The cathode electrode sheet 10a, the separator 40, and the anode electrode sheet 10b are stacked and wound in sequence to form the electrode assembly 100. Alternatively, the cathode electrode sheet 10a, the separator 40, and the anode electrode sheet 10b are stacked in sequence to form the electrode assembly 100. The separator 40 is made of an insulating material.

[0073] 5 , some embodiments of the present application provide a battery cell including a cathode electrode sheet 10 a and an anode electrode sheet 10 b .

[0074] The cathode electrode 10 a includes a cathode current collector 1 and a cathode active material layer 2 provided 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. The anode electrode sheet 10b includes an anode current collector 1' and an anode active material layer 2' provided on the anode current collector 1'. The anode active material layer 2' includes a second thinning area 3'. The second thinning area 3' is provided on the side of the anode current collector 1' where the anode ear 4' is provided; 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 current collector 1' with an anode active material. 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 manganese iron nickel oxide, or a 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 microbeads.

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

[0080] Since there is a blank area on the current collector for setting the tabs, that is, the 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, such as the second thinning area 3' of the anode active material layer 2' in Figure 5.

[0081] When a lithium-ion battery is charging, lithium ions are deintercalated from the cathode active material layer 2 of the cathode electrode 10a. These lithium ions diffuse through the electrolyte to the surface of the anode electrode 10b and are embedded in the anode active material layer 2' of the anode electrode 10b. Because the anode active material layer 2' and the anode lug 4' are adjacent to the second thinning region 3', the active material capacity of the anode electrode 10b is insufficient. This second thinning region 3' lacks sufficient embedding space to accommodate the lithium ions deintercalated from the cathode active material layer 2 of the cathode electrode 10a. As a result, the lithium ions are forced to precipitate on the surface of the anode electrode 10b, forming lithium deposition.

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

[0083] Wherein, CB value = capacity per unit area of ​​anode electrode / capacity per unit area of ​​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 dimension W1 of the first thinning zone 31 along the second direction Y is less than or equal to the dimension 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 plating phenomenon and enhancing the battery performance.

[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 requirements of the battery, thereby improving the lithium plating phenomenon and enhancing the battery performance.

[0090] In some embodiments, both the first thinning zone 31 and the second thinning zone 3' start to thin from a position far away 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 that the cathode electrode 10a is thinned first in the area where the anode electrode 10b has not started to thin, thereby reducing the lithium ions deintercalated from the cathode active material layer 2 of the cathode electrode 10a, and better changing 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 10b has a large enough capacity to accommodate the lithium ions deintercalated from the cathode electrode 10a, thereby improving the lithium plating phenomenon and improving the performance of the battery.

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

[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 requirements of the battery, thereby improving the lithium plating phenomenon and improving the battery performance.

[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 better changed while meeting the energy density requirements of the battery, thereby improving the lithium plating phenomenon and improving the battery performance.

[0096] 10 and 11 , in some embodiments, the cathode electrode 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 away from the cathode ear 5 relative to the first thinning area 31. In the manufacturing method of the cathode electrode 10a provided in the subsequent embodiments of the present application, the current collector 20 is divided into two to form two electrodes. What is cut is the position where the first insulating layer 6 of the current collector 20 is located, rather than 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 cutting the current collector 20 to form an electrode.

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

[0099] 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 becomes thinner from the cathode ear 5 to the first thinned region 31 .

[0100] 5 , in some embodiments, the cathode active material layer 2 further includes 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 provided.

[0101] In the above embodiment, the third thinned region 32 is provided on the side of the cathode current collector 1 where the cathode ear 5 is provided. This can improve the degree of electrolyte wetting of the cathode electrode 10a and change the CB value at the position corresponding to the third thinned region 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, thereby improving lithium deposition and improving battery performance. Furthermore, 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 collapse.

[0102] The thickness of the third thinned region 32 gradually becomes thinner 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] 8 and 9 , in some embodiments, the cathode electrode 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 phenomenon of burrs on 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] 12 and 13 , in some embodiments, the cathode active material layer 2 further includes a fourth thinned region 33 , which is located between the side of the cathode current collector 1 where the cathode ear 5 is provided and the side opposite to the cathode ear 5 .

[0109] In the above embodiment, the fourth thinned region 33 allows more electrolyte to pass through and can accommodate more electrolyte, allowing the electrolyte to fully infiltrate the electrode sheet in a short period of time, improving the electrolyte's infiltration effect on the electrode sheet, allowing the active material to more fully react with the electrolyte, alleviating the problem of insufficient electrolyte infiltration in the central area of ​​the electrode assembly 100, and improving battery performance. Furthermore, the CB value at the corresponding position of the fourth thinned region 33 can be changed, making the unit area capacity of the active material of the anode electrode sheet 10b greater than the unit area capacity of the active material of the cathode electrode sheet 10a, thereby improving lithium plating and improving battery performance.

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

[0111] 14 , in some embodiments, the cathode active material layer 2 further includes a fifth thinned region 34 , and the fifth thinned region 34 is located at a corner region of the wound cathode electrode sheet 10 a .

[0112] In the above embodiment, at the corner after the cathode electrode 10a is wound, there is curvature in the interface between the electrodes, which easily causes 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 zone 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] 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. 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 thus has the corresponding beneficial effects of the battery cell 200 .

[0115] 1 , some embodiments of the present application further 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 correspondingly possesses the beneficial effects of the battery 300 .

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

[0118] 8 to 15 , some embodiments of the present application further provide a cathode electrode sheet 10 a , 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 region 31 . The first thinned region 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 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 10b can be greater than the unit area capacity of the cathode electrode 10a, that is, the CB value is ≥1, so that the anode electrode 10b has a sufficiently large capacity to accommodate the lithium ions deintercalated from the cathode electrode 10a, thereby improving the lithium plating phenomenon and improving the performance of the battery.

[0121] 15 to 17 , some embodiments of the present application further provide a method for manufacturing a cathode electrode 10 a , which includes the following steps:

[0122] Prepare a current collecting member 20, wherein the current collecting member 20 has a tab region 30 on two opposite sides thereof;

[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 of the cathode active material layer 2 to form a thinned region 3a; and

[0124] The current collecting member 20 is divided into two at the thinned area 3 a 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 tab 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. 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 tab 5, which can improve the degree of electrolyte infiltration of the pole piece 1 and change the CB value at 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, thereby alleviating the lithium plating problem caused by insufficient capacity of the anode pole piece 10b and improving 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 pieces expand, and reduce the phenomenon of pole piece crushing.

[0126] The cathode electrode piece 10 a and the anode electrode piece 10 b are described in detail below with reference to FIG. 6 to FIG. 17 .

[0127] 6 and 7 , in some embodiments, the anode electrode 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 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'. This can reduce the occurrence of burrs on the anode active material layer 2' and alleviate the problem of active material falling off due to shearing the anode ear 4'.

[0130] 8 and 9 , the cathode electrode 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 includes a first thinned region 31 located on the side of the cathode current collector 1 opposite 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 10a. The thickness of the first thinned area 31 is less than the thickness of the flat area 4. The first thinned area 31 is recessed relative to the flat area 4 toward the cathode current collector 1.

[0135] The cathode electrode 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 it 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, which can make the first thinning area 31 concave 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, and improving the performance of the battery.

[0137] Furthermore, when a lithium-ion battery is charging, lithium ions are deintercalated from the active material of the cathode electrode 10a. These lithium ions diffuse through the electrolyte to the surface of the anode electrode 10b and then embed into the active material of the anode electrode 10b. If the active material capacity of the anode electrode 10b is insufficient and there is insufficient space for embedding, the lithium ions deintercalated from the active material of the cathode electrode 10a cannot embed into the active material of the anode electrode 10b. Instead, the lithium ions are deposited on the surface of the anode electrode 10b, forming a layer of gray material called lithium deposition.

[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. The CB (Cell Balance) value of the corresponding position of the first thinning area 31 can be changed so that the CB value is ≥1, thereby improving the lithium plating phenomenon and improving the performance of the battery.

[0139] Wherein, CB value = capacity per unit area of ​​anode electrode / capacity per unit area of ​​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 sufficiently large capacity to accommodate the lithium ions deintercalated 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 on 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 pieces squeezing each other when the pole pieces expand, 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 close to the cathode lug 5 to far away from the cathode lug 5 .

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

[0147] 10 and 11 , in some embodiments, the cathode electrode 10 a further includes a first insulating layer 6 . The first insulating layer 6 is disposed on the first side 11 , and the first insulating layer 6 is away from the cathode ear 5 relative to the first thinned region 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 cut is the position where the first insulating layer 6 of the current collector 20 is located, rather than cutting 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 cutting 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 region 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 tab 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 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] Providing a third thinned region 32 on the second side 12 of the cathode current collector 1 can improve the degree of electrolyte wetting of the cathode electrode 10a and change the CB value at the location corresponding to the third thinned region 32, making the active material capacity per unit area of ​​the anode electrode 10b greater than that of the cathode electrode 10a, thereby improving lithium deposition and enhancing battery performance. Furthermore, it can reduce 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 collapse.

[0154] The thickness of the third thinned region 32 gradually becomes thinner 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 . The second insulating layer 7 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 region 32 to the cathode ear 5 .

[0158] The third thinned region 32 is smoothly connected 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 .

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

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

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

[0163] 12 and 13 , in some embodiments, the cathode active material layer 2 further includes a fourth thinned region 33 disposed between the first side 11 and the second side 12 .

[0164] The thickness of the fourth thinning area 33 is less than the thickness of the flat area 4, which can make the fourth thinning area 33 concave toward the cathode current collector 1 relative to the flat area 4. 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 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, 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, and allowing 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.

[0167] In some embodiments, the fourth thinned region 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 an area that is difficult for the electrolyte to penetrate. In the later stages of use, the electrolyte in this area is prone to become poor, leading to interface problems. Therefore, the fourth thinning area 33 is located between the first side 11 and the second side 12, and can construct an electrolyte transmission channel to alleviate the problem of insufficient electrolyte penetration in the middle area of ​​the electrode assembly 100 and improve the performance of the battery.

[0170] 14 , in some embodiments, the cathode active material layer 2 further includes a fifth thinned region 34 , and the fifth thinned region 34 is located at a corner region of the wound cathode electrode sheet 10 a .

[0171] At the corner after the cathode electrode 10a is wound, there is a curvature in the interface between the electrodes, which can easily 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] 11 to 13 , in some embodiments, the cathode current collector 1 includes a first side surface 15 and a second side surface 16 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] 12 and 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 tiled area 4 .

[0175] 12 , a first thinning region 31 and a flattened 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] 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 , 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] A first thinning area 31 can be optionally provided 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 provided can be changed, 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 plating problem caused by insufficient anode electrode 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 tiled 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 tiled region 4. Alternatively, the first thinned region 31 and the tiled region 4 can be formed by coating active materials of different thicknesses.

[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 infiltration effect of the electrolyte.

[0181] In some embodiments, the ratio of the thickness H1 of the first thinned region 31 to the thickness H2 of the tiled region 4 is ≥70%. The thickness H1 of the first thinned region 31 is smaller than the thickness H2 of the tiled region 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 flattened 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 region 31 is ≤50 um. Optionally, the thickness H1 of the first thinned region 31 is ≤15 um.

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

[0185] The local thinning area can be changed by physically thinning the cathode active material layer in the local 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 providing a thinned area at the edge to change the CB at the edge, a thinned area can also be provided in the middle of the cathode plate 10a. This is because the middle of the cathode plate 10a is often an area with insufficient electrolyte wetting. Thinning this area can not only change the CB value in this area to improve battery performance, but also form a groove in this area to provide more liquid storage and improve electrolyte wetting. In addition, the corner area of ​​the cathode plate 10a can also be thinned to alleviate the problem of battery cell wetting and insufficient CB value in the corner.

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

[0188] When a lithium-ion battery is charging, lithium ions are deintercalated from the active material of the cathode electrode 10a. These lithium ions diffuse through the electrolyte to the surface of the anode electrode 10b and are 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 insufficient 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. The lithium ions can only be deposited on the surface of the anode electrode 10b, forming lithium deposition.

[0189] Therefore, a first thinning zone 31 is set at a position of the cathode electrode 10a away from the cathode ear 5, which can change the CB (Cell Balance) value of the corresponding position of the first thinning zone 31, and can make the unit area capacity of the anode electrode 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 deintercalated 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 near 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, the active material capacity of the anode electrode 10b may be insufficient and there may not be 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 plating. 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 plating phenomenon and improving the performance of the battery.

[0192] In the embodiment shown in FIG5 , the width of the second thinned region 3' on the side where the anode tab 5' of the anode plate 10b is located is W2. The width of the first thinned region 31 corresponding to the first side of the cathode plate 10a is W1. The first side is a striped side. The width of the third thinned region 32 corresponding to the side where the cathode tab 5 of the cathode plate 10a is located (the second side) 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. The exceeding part of the first side of the anode plate 10b does not require the corresponding thinning of the first side of the cathode plate 10a. Therefore, in theory, 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 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 10b, thus failing to achieve the expected effect.

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

[0202] 16 and 17 , a current collecting member 20 is prepared, and tab regions 30 are provided on opposite sides of the current collecting member 20 ;

[0203] Active material is coated on the area of ​​the current collector 20 located between the two tab 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, and 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 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 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 flattened 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 plating 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 flattened 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, improve the infiltration 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 region between the two tab regions 30 of the current collector 20, forming two cathode plates 10a. The current collector 20 is cut in the middle region. Therefore, for each cathode plate 10a, the cut edge in the middle region of the current collector 20 is the dividing edge, that is, the first side edge 11, and the side corresponding to the cathode tab 5 of the cathode plate 10a is the second side edge 12.

[0207] 17 , in some embodiments, an insulating material is coated on the middle region between the two tab regions 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 region 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 cut is the position where the first insulating layer 6 of the current collector 20 is located, rather than cutting 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 cutting 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] Providing a first thinned region 31 on the first side 11 of the cathode current collector 1 can improve the degree of electrolyte infiltration of the electrode 1 and change the CB value at the location corresponding to the first thinned region 31, making the unit area capacity of the anode electrode greater than the unit area capacity of the cathode electrode, alleviating the lithium deposition problem caused by insufficient anode electrode capacity and improving battery performance. Furthermore, 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 collapse.

[0211] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and components may be substituted with equivalents without departing from the scope of the present application. In particular, the various technical features described 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 encompasses all technical solutions within the scope of the claims.

Claims

1. A battery cell, comprising: 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, wherein a dimension W1 of the first thinning zone (31) along a second direction (Y) is less than or equal to a dimension W2 of the second thinning zone (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'). The battery cell according to claim 2 , wherein W1∈[2,20]mm, W2∈[2,20]mm. The battery cell according to claim 2 or 3, wherein W1∈[3,8]mm, W2∈[3,10]mm.

5. A battery cell according to any one of claims 1 to 4, wherein 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'); and a distance S1 between a 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 a position where the second thinning zone (3') starts to thin and the anode ear (4').

6. The battery cell according to claim 5, wherein 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. The battery cell according to claim 6 , wherein S3∈[0,3]mm.

8. The battery cell according to any one of claims 1 to 7, wherein the cathode electrode sheet (10a) further comprises a first insulating layer (6), and the first insulating layer (6) is arranged on a side of the first thinned area (31) away from the cathode ear (5).

9. The battery cell according to any one of claims 1 to 8, wherein the cathode active material layer (2) further comprises a third thinning area (32), and the third thinning area (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, wherein the cathode electrode sheet (10a) further comprises a second insulating layer (7), and the second insulating layer (7) is located between the third thinned area (32) and the cathode ear (5).

11. The battery cell according to any one of claims 1 to 10, wherein the cathode active material layer (2) further comprises a fourth thinning area (33), and the fourth thinning area (33) is located between the side of the cathode current collector (1) where the cathode ear (5) is provided and the side opposite to the cathode ear (5).

12. The battery cell according to any one of claims 1 to 11, wherein the cathode active material layer (2) further comprises a fifth thinning area (34), and the fifth thinning area (34) is located in a corner area after the cathode electrode sheet (10a) is wound.

13. A battery, comprising 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 comprising the battery according to claim 13.

15. A cathode electrode, comprising: 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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