WO2024103224A1 - 极片、电极组件、电池单体、电池及用电设备 - Google Patents

极片、电极组件、电池单体、电池及用电设备 Download PDF

Info

Publication number
WO2024103224A1
WO2024103224A1 PCT/CN2022/131740 CN2022131740W WO2024103224A1 WO 2024103224 A1 WO2024103224 A1 WO 2024103224A1 CN 2022131740 W CN2022131740 W CN 2022131740W WO 2024103224 A1 WO2024103224 A1 WO 2024103224A1
Authority
WO
WIPO (PCT)
Prior art keywords
functional layer
active material
pole piece
current collector
area
Prior art date
Application number
PCT/CN2022/131740
Other languages
English (en)
French (fr)
Inventor
许虎
金海族
牛少军
赵丰刚
曾毓群
Original Assignee
宁德时代新能源科技股份有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 宁德时代新能源科技股份有限公司 filed Critical 宁德时代新能源科技股份有限公司
Priority to PCT/CN2022/131740 priority Critical patent/WO2024103224A1/zh
Publication of WO2024103224A1 publication Critical patent/WO2024103224A1/zh

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes

Definitions

  • the purpose of the embodiments of the present application is to provide a pole piece, an electrode assembly, a battery cell, a battery and an electrical device, which are intended to improve the problem of low energy density of batteries in related technologies.
  • the conductive agent includes at least one of acetylene black, activated carbon, carbon black, conductive graphite, and carbon nanotubes.
  • the active material of the functional layer can be the same as the active material of the active material layer, so that the functional layer can not only facilitate the capillary effect, so that the electrolyte can quickly infiltrate the thinned area through the functional layer, so that the thinned area can play a role, but also the functional layer itself can play the same role as the active material layer, which is conducive to improving the energy density of the battery cell.
  • the particle size of the powder particles of the active material material of the functional layer is larger than the particle size of the powder particles of the active material material of the active material layer, so that the particles of the functional layer are larger than the particles of the thinned area, and have a larger impedance, so that the lithium ion release rate of the thinned area is slower, so that the lithium ions that need to be embedded in the negative electrode per unit time are reduced, so that it is more difficult to precipitate lithium, which is conducive to ensuring the performance of the battery cell.
  • the electrode sheet is a negative electrode sheet
  • the functional layer includes active material
  • the gram capacity of the active material of the functional layer is M 1
  • the gram capacity of the active material of the active material layer is M 2
  • 1.01 ⁇ M 1 /M 2 ⁇ 5 is satisfied.
  • the electrode is a positive electrode
  • the functional layer includes active material
  • the gram capacity of the active material of the functional layer is M 1
  • the gram capacity of the active material of the main region is M 2
  • 0.3 ⁇ M 1 /M 2 ⁇ 1.01 is satisfied.
  • the gram capacity of the active material material of the functional layer is less than the gram capacity of the active material material of the active material layer, so that the CB value of the electrode in the functional area can be improved, and the positive electrode can release less lithium ions, so it is not easy to precipitate lithium, which is beneficial to ensure the performance of the battery cell.
  • the gram capacity of the active material material of the functional layer is equal to or slightly greater than the gram capacity of the active material material of the active material layer, so that the functional layer can not only be conducive to the capillary effect, so that the electrolyte can quickly infiltrate the thinning area through the functional layer, so that the thinning area can play a role, but also the functional layer itself can play the same role as the active material layer, which is beneficial to improve the energy density of the battery cell.
  • the minimum thickness of the functional layer is h, satisfying: 1 ⁇ m ⁇ h ⁇ 80 ⁇ m.
  • the minimum thickness of the functional layer is limited to 1-80 ⁇ m, so that after the pole piece is wound or stacked to form an electrode assembly, the gap between the functional layer and the separator is small, which is conducive to the capillary effect, and at the same time, the pole piece will not be too thick, so that the battery cell has a higher energy density. If h ⁇ 1 ⁇ m, the minimum thickness of the functional layer is thin, and the improvement of the capillary effect is not obvious. If h > 80 ⁇ m, the minimum thickness of the functional layer is thicker, indicating that the overall functional layer is thicker, which will make the pole piece thicker, and may reduce the energy density of the battery cell.
  • the length of the functional layer in the first direction is L 1
  • the length of the thinned area in the first direction is L 2 , satisfying: 0.8 ⁇ L 1 /L 2 ⁇ 1.5.
  • the length of the functional layer in the first direction is 0.8 to 1.5 times the length of the thinned area in the first direction.
  • the functional layer can substantially or completely cover the thinned area along the first direction, so that the gap between the functional layer and the isolation film is small after the pole pieces are wound or stacked to form an electrode assembly, which is conducive to the capillary effect.
  • the functional layer along the thickness direction of the current collector, the functional layer has a first surface away from the current collector, the maximum distance between the first surface and the current collector is T 1 , the thickness of the main region is T 2 , and 0.8 ⁇ T 1 /T 2 ⁇ 1.1 is satisfied.
  • the maximum distance between the first surface and the current collector is 0.8 to 1.1 times the thickness of the main area.
  • the first surface is basically flush with the surface of the main area away from the current collector, which is conducive to the capillary effect, and at the same time, the pole piece will not be too thick, so that the battery cell has a higher energy density. If T 1 ⁇ 0.8T 2 , after the pole piece is wound or stacked to form a battery cell, the gap between the functional layer and the isolation membrane is relatively large, and the electrolyte infiltration speed of the thinned area is relatively slow.
  • the functional layer exceeds the distance of the surface of the main area away from the current collector by a large distance.
  • the distance between the main area and the isolation membrane increases, which slows down the infiltration speed of the main area.
  • the space occupied by the pole piece increases, and there is also a risk of reducing the energy density of the battery cell.
  • the maximum distance between the first surface and the current collector is 0.9 to 1.01 times the thickness of the main region.
  • the first surface is basically flush with the surface of the main region away from the current collector, and both the main region and the thinned region can be quickly wetted, while the pole piece is not too thick, so that the battery cell has a higher energy density.
  • the thinning zone has a second surface
  • the functional layer is arranged on the second surface, and along the direction from the main zone to the thinning zone, the distance between the second surface and the current collector in the thickness direction of the current collector gradually decreases.
  • the thickness of the thinned area gradually decreases along the direction from the main area to the thinned area, which is helpful to reduce the stress at the junction of the active material layer and the pole ear.
  • the second surface is an arc surface.
  • the second surface intersects with the current collector at a first edge, and the functional layer covers the first edge.
  • the functional layer covers a portion of the pole ear portion.
  • the root of the pole lug can be reinforced, thereby reducing the risk of deformation and wrinkles at the root of the pole lug.
  • the functional layer has a third surface away from the main region, the third surface intersects the current collector at a second edge, the distance between the second edge and the first edge is L 3 , satisfying: 0 ⁇ L 3 ⁇ 5mm.
  • the distance between the second edge and the first edge is 0-5 mm, so that the functional layer can have a sufficient area to be coated on the pole ear portion, and play a role in reinforcing the root of the pole ear, and at the same time, the functional layer will not affect the length of the pole ear. If L 3 > 5 mm, the area of the pole ear portion covered by the functional layer is large, which will affect the forming of the pole ear.
  • the distance between the second edge and the first edge is between 1 and 2 mm, so that the functional layer can have a good reinforcement effect on the pole ear portion while not easily affecting the forming of the pole ear.
  • the functional layer has a first surface, a third surface and a fourth surface, the fourth surface is in contact with the second surface, the first surface is parallel or flush with the surface of the main region away from the current collector along the thickness direction of the current collector, the first surface intersects with the fourth surface, the third surface connects the first surface and the fourth surface, and the third surface is perpendicular to the first surface.
  • the third surface has a large length in the thickness direction.
  • the gap between the functional layer and the isolation membrane is small, which is conducive to the capillary effect, so that the electrolyte can quickly infiltrate the thinned area through the functional layer, so that the thinned area can play a role, which is conducive to improving the energy density of the battery cell.
  • the first surface is flush with a surface of the main region that is away from the current collector along the thickness direction of the current collector.
  • the first surface is flush with the surface of the main area away from the current collector in the thickness direction.
  • the gap between the main area and the isolation membrane is equal to the gap width between the first surface and the isolation membrane, which can ensure that the electrolyte quickly infiltrates the thinned area without increasing the thickness of the pole piece, and can greatly improve the energy density of the battery cell.
  • the effect of setting the functional layer in this way is relatively ideal.
  • the third surface intersects with the current collector.
  • the third surface intersects with the current collector, indicating that the functional layer covers the edge of the thinning area in the direction from the main area to the thinning area, and has a good liquid retention effect.
  • the functional layer has a first surface, a third surface, a fourth surface and a fifth surface, the fourth surface is bonded to the second surface, the first surface is parallel or flush with the surface of the main region away from the current collector along the thickness direction of the current collector, the fifth surface is bonded to the current collector, the third surface connects the fifth surface and the first surface, and the fourth surface connects the first surface and the fifth surface.
  • the functional layer can be formed after the fluid dries, when the functional layer is set in a more ideal manner, the functional layer may flow to form the above-mentioned shape. At this time, the functional layer also has a good liquid retention effect, which can make the thinned area be quickly infiltrated so that the thinned area can play a role.
  • the third surface is an arc surface.
  • setting the third surface as an arc surface is beneficial to reducing stress concentration.
  • the active material layer is provided on two opposite surfaces of the current collector along the thickness direction, and the functional layer is provided on the thinned area of each active material layer.
  • active material layers are arranged on both sides of the current collector, and functional layers are arranged on the thinned area of each active material layer, so that the pole pieces can be formed into an electrode assembly by winding or stacking.
  • an embodiment of the present application further provides an electrode assembly, which includes the above-mentioned electrode piece.
  • an embodiment of the present application further provides a battery cell, wherein the battery cell includes the above-mentioned electrode assembly.
  • an embodiment of the present application further provides a battery, comprising the above-mentioned battery cell.
  • an embodiment of the present application further provides an electrical device, wherein the electrical device comprises the above-mentioned battery, and the battery is used to provide electrical energy to the electrical device.
  • FIG1 is a schematic diagram of the structure of a vehicle provided in some embodiments of the present application.
  • FIG2 is an exploded view of a battery provided in some embodiments of the present application.
  • FIG3 is an exploded view of a battery cell provided in some embodiments of the present application.
  • FIG4 is a schematic diagram of the structure of an electrode assembly provided in some embodiments of the present application.
  • FIG5 is a schematic diagram of the structure of a pole piece provided in some embodiments of the present application.
  • FIG6 is a schematic diagram of the structure of pole pieces provided in other embodiments of the present application.
  • FIG7 is a schematic diagram of the structure of pole pieces provided in some other embodiments of the present application.
  • FIG8 is a schematic diagram of the structure of pole pieces provided in some further embodiments of the present application.
  • Icons 10-casing; 11-first part; 12-second part; 20-battery cell; 21-end cap; 22-electrode assembly; 221-negative electrode sheet; 222-positive electrode sheet; 223-separation membrane; 23-shell; 24-pole sheet; 241-current collector; 2411-ear portion; 242-active material layer; 2421-main body area; 2422-thinning area; 24221-second surface; 243-functional layer; 2431-first surface; 2432-third surface; 2434-fifth surface; 100-battery; 200-controller; 300-motor; 1000-vehicle.
  • the terms “installed”, “connected”, “connected”, and “attached” 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 a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements.
  • installed 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 a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements.
  • a and/or B can represent: A exists alone, A and B exist at the same time, and B exists alone.
  • the character "/" in this application generally indicates that the associated objects before and after are in an "or" relationship.
  • battery cells may include lithium-ion secondary battery cells, lithium-ion primary battery cells, lithium-sulfur battery cells, sodium-lithium-ion battery cells, sodium-ion battery cells or magnesium-ion battery cells, etc., and the embodiments of the present application do not limit this.
  • Battery cells may be cylindrical, flat, rectangular or other shapes, etc., and the embodiments of the present application do not limit this. Battery cells are generally divided into three types according to the packaging method: cylindrical battery cells, square battery cells and soft-pack battery cells, and the embodiments of the present application do not limit this.
  • the battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.
  • the battery mentioned in the present application may include a battery module or a battery pack.
  • the battery generally includes a box for encapsulating one or more battery cells. The box can prevent liquid or other foreign matter from affecting the charging or discharging of the battery cells.
  • the battery cell includes an electrode assembly and an electrolyte, and the electrode assembly includes a positive electrode sheet, a negative electrode sheet and a separator.
  • the battery cell mainly relies on the movement of metal ions between the positive electrode sheet and the negative electrode sheet to work.
  • the positive electrode sheet includes a positive electrode collector and a positive electrode active material layer.
  • the positive electrode active material layer is coated on the surface of the positive electrode collector.
  • the positive electrode collector not coated with the positive electrode active material layer protrudes from the positive electrode collector coated with the positive electrode active material layer.
  • the positive electrode collector not coated with the positive electrode active material layer serves as a positive electrode ear.
  • the material of the positive electrode collector can be aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide, etc.
  • the negative electrode sheet includes a negative electrode collector and a negative electrode active material layer.
  • the negative electrode active material layer is coated on the surface of the negative electrode collector.
  • the negative electrode collector not coated with the negative electrode active material layer protrudes from the negative electrode collector coated with the negative electrode active material layer.
  • the negative electrode collector not coated with the negative electrode active material layer serves as a negative electrode ear.
  • the material of the negative electrode collector can be copper, and the negative electrode active material can be carbon or silicon, etc.
  • the number of positive pole ears is multiple and stacked together, and the number of negative pole ears is multiple and stacked together.
  • the material of the isolation film can be PP (polypropylene) or PE (polyethylene).
  • the electrode assembly can be a winding structure or a laminated structure, and the embodiments of the present application are not limited thereto.
  • Batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the continuous expansion of battery application areas, its market demand is also constantly expanding.
  • the pole piece includes a current collector and an active material layer disposed on the surface of the current collector.
  • the portion of the current collector where the active material layer is not disposed is the pole ear portion, which is used to form the pole ear. Due to the height difference between the active material layer and the pole ear portion, stress will be concentrated at the junction of the active material layer and the pole ear portion during rolling, causing the active material layer to fall off and cracks to form on the current collector. In order to release stress, the thickness of the active material layer at one end close to the pole ear portion is usually reduced, thereby forming a thinning area with a smaller thickness.
  • the gap between the thinned area and the isolation membrane is large, which is not conducive to the capillary action, resulting in the thinned area being difficult to be wetted, the amount of electrolyte in the thinned area is small or there is no electrolyte, making the thinned area unable to function (the thinned area cannot contribute to the electrochemical reaction).
  • the thinned area of the positive electrode sheet cannot function, the energy density of the battery cell is reduced.
  • the thinned area of the negative electrode sheet cannot function, lithium deposition will occur, which will affect the performance of the battery cell and reduce the energy density of the battery cell. As a result, the energy density of the battery cell is low.
  • an embodiment of the present application provides a pole piece, which includes a current collector, an active material layer and a functional layer.
  • the active material layer is arranged on the surface of the current collector.
  • the active material layer includes a main body area and a thinning area, the thinning area is arranged at one end of the main body area along a first direction, and the thickness of the main body area is greater than the thickness of the thinning area.
  • the current collector has a pole ear portion that extends beyond the thinning area in a direction away from the main body area.
  • the functional layer is arranged on the surface of the thinning area away from the current collector, and the functional layer is configured to allow electrolyte to pass through.
  • the pole piece is provided with a functional layer allowing electrolyte to pass through on the thinned area of the active material layer.
  • the gap between the functional layer and the isolation membrane is small, which is conducive to the capillary action, so that the electrolyte can quickly infiltrate the thinned area through the functional layer, so that the thinned area can play a role, which is conducive to improving the energy density of the battery cell.
  • the smaller gap makes the lithium ion transmission path shorter, which can reduce the risk of lithium plating and improve the performance of the battery cell.
  • the electrical equipment may be vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and electric tools, etc.
  • 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.
  • the embodiments of the present application do not impose any special restrictions on the above-mentioned electrical equipment.
  • the following embodiments are described by taking the electric device as a vehicle 1000 as an example.
  • FIG. 1 is a schematic diagram of the structure of a vehicle 1000 provided in some embodiments of the present application.
  • the vehicle 1000 may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc.
  • a battery 100 is provided inside the vehicle 1000, and the battery 100 may be provided at the bottom, head or tail of the vehicle 1000.
  • the battery 100 may be used to power the vehicle 1000, for example, the battery 100 may be used as an operating power source for the vehicle 1000.
  • the vehicle 1000 may also include a controller 200 and a motor 300, and the controller 200 is used to control the battery 100 to power the motor 300, for example, for the starting, navigation and driving power requirements of the vehicle 1000.
  • the battery 100 can not only serve as an operating power source for the vehicle 1000, but also serve as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.
  • FIG. 2 is an exploded view of a battery 100 provided in some embodiments of the present application.
  • the battery 100 includes a box 10 and a battery cell 20, and the battery cell 20 is contained in the box 10.
  • the box 10 is used to provide a storage space for the battery cell 20, and the box 10 can adopt a variety of structures.
  • the box 10 may include a first part 11 and a second part 12, and the first part 11 and the second part 12 cover each other, and the first part 11 and the second part 12 jointly define a storage space for accommodating the battery cell 20.
  • the second part 12 may be a hollow structure with one end open, and the first part 11 may be a plate-like structure, and the first part 11 covers the open side of the second part 12, so that the first part 11 and the second part 12 jointly define a storage space; the first part 11 and the second part 12 may also be hollow structures with one side open, and the open side of the first part 11 covers the open side of the second part 12.
  • the box 10 formed by the first part 11 and the second part 12 can be in a variety of shapes, such as a cylinder, a cuboid, etc.
  • the battery 100 there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a mixed connection.
  • a mixed connection means that the multiple battery cells 20 are both connected in series and in parallel.
  • the multiple battery cells 20 may be directly connected in series, in parallel, or in a mixed connection, and then the whole formed by the multiple battery cells 20 is accommodated in the box 10; of course, the battery 100 may also be a battery module formed by connecting multiple battery cells 20 in series, in parallel, or in a mixed connection, and then the multiple battery modules are connected in series, in parallel, or in a mixed connection to form a whole, and accommodated in the box 10.
  • the battery 100 may also include other structures, for example, the battery 100 may also include a busbar component for realizing electrical connection between the multiple battery cells 20.
  • Each battery cell 20 may be a secondary battery cell or a primary battery cell, or a lithium-sulfur battery cell, a sodium-ion battery cell, or a magnesium-ion battery cell, but is not limited thereto.
  • the battery cell 20 may be cylindrical, flat, rectangular, or in other shapes.
  • FIG 3 is an exploded view of a battery cell 20 provided in some embodiments of the present application.
  • the battery cell 20 refers to the smallest unit constituting the battery 100.
  • the battery cell 20 includes an end cap 21, an electrode assembly 22, a housing 23 and other functional components.
  • the end cap 21 refers to a component that covers the opening of the shell 23 to isolate the internal environment of the battery cell 20 from the external environment.
  • the shape of the end cap 21 can be adapted to the shape of the shell 23 to match the shell 23.
  • the end cap 21 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the end cap 21 is not easily deformed when squeezed and collided, so that the battery cell 20 can have a higher structural strength and the safety performance can also be improved.
  • Functional components such as electrode terminals (not shown in the figure) can be provided on the end cap 21. The electrode terminal can be used to electrically connect to the electrode assembly 22 for outputting or inputting electrical energy of the battery cell 20.
  • the material of the end cap 21 can also be a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiment of the present application does not impose special restrictions on this.
  • an insulating member can also be provided on the inner side of the end cap 21, and the insulating member can be used to isolate the electrical connection components in the shell 23 from the end cap 21 to reduce the risk of short circuit.
  • the insulating member may be plastic, rubber, or the like.
  • the shell 23 is a component used to cooperate with the end cap 21 to form the internal environment of the battery cell 20, wherein the formed internal environment can be used to accommodate the electrode assembly 22, the electrolyte and other components.
  • the shell 23 and the end cap 21 can be independent components, and an opening can be set on the shell 23, and the internal environment of the battery cell 20 is formed by covering the opening with the end cap 21 at the opening.
  • the end cap 21 and the shell 23 can also be integrated.
  • the end cap 21 and the shell 23 can form a common connection surface before other components are put into the shell, and when the interior of the shell 23 needs to be encapsulated, the end cap 21 covers the shell 23.
  • the shell 23 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the shell 23 can be determined according to the specific shape and size of the electrode assembly 22.
  • the material of the shell 23 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiment of the present application does not impose any special restrictions on this.
  • FIG. 4 is a schematic diagram of the structure of the electrode assembly 22 provided in some embodiments of the present application.
  • the electrode assembly 22 is a component in the battery cell 20 where an electrochemical reaction occurs.
  • One or more electrode assemblies 22 may be included in the housing 23.
  • the electrode assembly 22 is mainly formed by winding or stacking a positive electrode sheet 222 and a negative electrode sheet 221, and a separator 223 is usually provided between the positive electrode sheet 222 and the negative electrode sheet 221.
  • the parts of the positive electrode sheet 222 and the negative electrode sheet 221 with active materials constitute the main body of the electrode assembly 22, and the parts of the positive electrode sheet 222 and the negative electrode sheet 221 without active materials each constitute a pole ear.
  • the positive pole ear and the negative pole ear may be located together at one end of the main body or at both ends of the main body respectively.
  • the positive electrode active material and the negative electrode active material react with the electrolyte, and the pole ear connects the electrode terminal to form a current loop.
  • Figure 5 is a schematic diagram of the structure of the pole piece 24 provided in some embodiments of the present application.
  • the embodiment of the present application provides a pole piece 24, which includes a current collector 241, an active material layer 242 and a functional layer 243.
  • the active material layer 242 is arranged on the surface of the current collector 241.
  • the active material layer 242 includes a main body area 2421 and a thinning area 2422.
  • the thinning area 2422 is arranged at one end of the main body area 2421 along the first direction, and the thickness of the main body area 2421 is greater than the thickness of the thinning area 2422.
  • the current collector 241 has a pole ear portion 2411 that extends beyond the thinning area 2422 in a direction away from the main body area 2421.
  • the functional layer 243 is arranged on the surface of the thinning area 2422 away from the current collector 241, and the functional layer 243 is configured to allow the electrolyte to pass through.
  • the electrode sheet 24 can be used as the negative electrode sheet 221 of the electrode assembly 22, or as the positive electrode sheet 222 of the electrode assembly 22.
  • only the negative electrode sheet 221 can use the electrode sheet 24
  • only the positive electrode sheet 222 can use the electrode sheet 24
  • both the negative electrode sheet 221 and the positive electrode sheet 222 can use the electrode sheet 24.
  • the main body region 2421 is the main part of the active material layer 242, which realizes the main function of the active material layer 242.
  • the thinned region 2422 is a thinned portion of the active material layer 242 toward one end of the pole ear portion 2411.
  • the thinned region 2422 is located at one end of the main body region 2421 along the first direction.
  • the thickness of the main area 2421 is greater than the thickness of the thinned area 2422 means that the minimum thickness of the main area 2421 is greater than the maximum thickness of the thinned area 2422. In other words, the thickness at any position of the main area 2421 is greater than the thickness at any position of the thinned area 2422.
  • the first direction may be the A direction shown in FIG5
  • the thickness direction may be the B direction shown in FIG5 .
  • the pole ear portion 2411 is a portion of the current collector 241 where the active material layer 242 is not disposed.
  • the pole ear portion 2411 is used to form a pole ear.
  • the portion of the current collector 241 where the active material layer 242 is disposed and the pole ear portion 2411 are arranged along a first direction.
  • the functional layer 243 has gaps that allow the electrolyte to pass through.
  • the functional layer 243 may be a ceramic layer, a polymer layer, or other condensed material layer that allows the electrolyte to pass through.
  • the pole piece 24 is provided with a functional layer 243 that allows electrolyte to pass through on the thinned area 2422 of the active material layer 242.
  • the gap between the functional layer 243 and the isolation membrane 223 is small, which is conducive to the capillary action, so that the electrolyte can pass through the functional layer 243 and quickly infiltrate the thinned area 2422, so that the thinned area 2422 can play a role, which is conducive to improving the energy density of the battery cell 20.
  • the smaller gap shortens the path for lithium ion transmission, which can reduce the risk of lithium plating and improve the performance of the battery cell 20 .
  • the ability of the functional layer 243 to store electrolyte is stronger than that of the active material layer 242 .
  • the ability to store electrolyte can be measured by testing the infiltration time. The faster the infiltration speed, the stronger the ability to store electrolyte. In addition, it can also be measured by testing the volatilization time. The slower the volatilization speed, the stronger the ability to store electrolyte.
  • the ability of the functional layer 243 to store electrolyte is stronger than that of the active material layer 242 , so that during infiltration, the electrolyte can quickly flow through the functional layer 243 to the thinned area 2422 , and after the infiltration is completed, the electrolyte in the functional layer 243 is more difficult to volatilize.
  • the functional layer 243 can store electrolyte, so that lithium ions can enter the isolation film 223 or the thinned area 2422 through the electrolyte stored in the functional layer 243 .
  • the electrolyte can be easily stored in the functional layer 243 , so that lithium ions can enter the isolation membrane 223 or the thinned area 2422 through the electrolyte stored in the functional layer 243 , thereby reducing the risk of lithium plating and improving the performance of the battery cell 20 .
  • the functional layer 243 includes at least one of vinylidene fluoride polymer, hexafluoropropylene polymer, vinylidene fluoride-hexafluoropropylene polymer, polyacrylic acid, polystyrene butadiene copolymer, polyvinyl alcohol, polyacrylate, polyurethane, chlorinated rubber, and epoxy resin.
  • the functional layer 243 further includes a conductive agent.
  • the conductive agent can improve the conductive effect of the functional layer 243. Since the main material of the functional layer 243 is a polymer, and the polymer has poor or no conductive ability, the conductive ability of the functional layer 243 is enhanced by adding a conductive agent to facilitate the passage of lithium ions.
  • the conductivity of the functional layer 243 is enhanced, so that lithium ions are easily transported.
  • the conductive agent includes at least one of acetylene black, activated carbon, carbon black, conductive graphite, and carbon nanotubes.
  • Acetylene black, activated carbon, carbon black, conductive graphite and carbon nanotubes have good conductive effects, especially acetylene black, which not only has good conductive effects but also has low costs.
  • the electrode sheet 24 is a negative electrode sheet 221.
  • the functional layer 243 includes active material, and the powder particles with a particle size greater than D 1 account for 50% of the volume distribution of the active material material of the functional layer 243.
  • the powder particles with a particle size greater than D 2 account for 50% of the volume distribution of the active material material of the active material layer 242, satisfying: 1 ⁇ D 2 /D 1 ⁇ 25.
  • D 1 indicates that the powder particles with a particle size larger than D 1 account for 50% of the active material volume distribution of the functional layer 243 , that is, 50% of the powder particles with a particle size larger than D 1 in the active material volume distribution of the functional layer 243 .
  • D 2 indicates that 50% of the powder particles in the active material volume distribution of the active material layer 242 have a particle size larger than D 2 , that is, 50% of the powder particles in the active material volume distribution of the active material layer 242 have a particle size larger than D 2 .
  • the active material of the functional layer 243 can be the same as the active material of the active material layer 242, so that the functional layer 243 can not only facilitate the capillary action, so that the electrolyte can quickly infiltrate the thinned area 2422 through the functional layer 243, so that the thinned area 2422 can function, but also the functional layer 243 can play the same role as the active material layer 242, which is conducive to improving the energy density of the battery cell 20.
  • the particle size of the powder particles of the active material of the functional layer 243 is smaller than the particle size of the powder particles of the active material of the active material layer 242, so that the particles of the functional layer 243 are smaller than the particles of the thinned area 2422, and the electrolyte in the thinned area 2422 is not easy to be discharged, so that the functional layer 243 can play a better liquid retention effect on the thinned area 2422, so that the thinned area 2422 can function, which is conducive to improving the energy density of the battery cell 20.
  • the particles of the functional layer 243 are smaller than those of the thinned area 2422 , and their dynamics are better, so that the functional layer in this area has a higher lithium deposition window, thereby reducing the risk of lithium deposition and helping to ensure the performance of the battery cell 20 .
  • the functional layer 243 has better liquid retention capability and better kinetics, has a higher lithium deposition window, is less prone to lithium deposition, and is beneficial to ensuring the performance of the battery cell 20 .
  • the electrode sheet 24 is a positive electrode sheet 222.
  • the functional layer 243 includes active material, and the powder particles with a particle size greater than D1 account for 50% of the volume distribution of the active material material of the functional layer 243.
  • the powder particles with a particle size greater than D2 account for 50% of the volume distribution of the active material material of the active material layer 242, satisfying: 1 ⁇ D1 / D2 ⁇ 30 .
  • the active material of the functional layer 243 can be the same as the active material of the active material layer 242.
  • the functional layer 243 can not only facilitate the capillary effect, so that the electrolyte can quickly infiltrate the thinned area 2422 through the functional layer 243, so that the thinned area 2422 can play a role, but also the functional layer 243 itself can play the same role as the active material layer 242, which is conducive to improving the energy density of the battery cell 20.
  • the particle size of the powder particles of the active material material of the functional layer 243 is larger than the particle size of the powder particles of the active material material of the active material layer 242.
  • the particles of the functional layer 243 are larger than the particles of the thinned area 2422 and have a larger impedance, so that the lithium ion release rate of the thinned area 2422 is slower, so that the lithium ions that need to be embedded in the negative electrode sheet 221 per unit time are reduced, so that it is more difficult to precipitate lithium, which is conducive to ensuring the performance of the battery cell 20.
  • the electrode sheet 24 is a negative electrode sheet 221.
  • the functional layer 243 includes active material, and the gram capacity of the active material of the functional layer 243 is M1 .
  • the gram capacity of the active material of the active material layer 242 is M2 , which satisfies: 1.01 ⁇ M1 / M2 ⁇ 5 .
  • Gram capacity refers to the ratio of the capacitance that can be released by the active material to the mass of the active material.
  • M1 represents the gram capacity of the active material of the functional layer 243 .
  • M2 represents the gram capacity of the active material of the active material layer 242 .
  • M 1 /M 2 represents the ratio of the gram capacity of the active material of the functional layer 243 to the gram capacity of the active material of the active material layer 242 .
  • the gram capacity of the active material of the functional layer 243 is greater than the gram capacity of the active material of the active material layer 242.
  • the CB value Cell balance, cell balance rate, CB value is equal to the unit active capacity of the negative electrode sheet 221 divided by the unit active capacity of the positive electrode sheet 222) of the electrode sheet 24 in the functional area can be improved, and the space for embedding lithium ions in the negative electrode sheet 221 is increased, so that lithium is less likely to be deposited, which is beneficial to ensuring the performance of the battery cell 20.
  • the space of the negative electrode sheet 221 for inserting lithium ions can be increased, thereby preventing lithium from being easily deposited, and the CB value will not be too large, thereby significantly increasing the cost.
  • the electrode 24 is a positive electrode 222
  • the functional layer 243 includes active material
  • the gram capacity of the active material of the functional layer 243 is M 1
  • the gram capacity of the active material of the main region 2421 is M 2
  • 0.3 ⁇ M 1 /M 2 ⁇ 1.01 is satisfied.
  • the gram capacity of the active material of the functional layer 243 is less than the gram capacity of the active material of the active material layer 242, so that the CB value of the electrode 24 in the functional area can be improved, and the positive electrode 222 can release less lithium ions, so it is not easy to precipitate lithium, which is beneficial to ensure the performance of the battery cell 20.
  • the gram capacity of the active material of the functional layer 243 is equal to or slightly greater than the gram capacity of the active material of the active material layer 242, so that the functional layer 243 can not only facilitate the capillary effect, so that the electrolyte can quickly infiltrate the thinned area 2422 through the functional layer 243, so that the thinned area 2422 can play a role, but also the functional layer 243 itself can play the same role as the active material layer 242, which is beneficial to improve the energy density of the battery cell 20.
  • the gram capacity of the active material of the functional layer 243 is relatively large, and the functional layer 243 itself can also play the same role as the active material layer 242 , which is beneficial to improving the energy density of the battery cell 20 .
  • the minimum thickness of the functional layer 243 is h, satisfying: 1 ⁇ m ⁇ h ⁇ 80 ⁇ m.
  • the minimum thickness of the functional layer 243 refers to the thickness of the functional layer 243 at its thinnest position. Referring to FIG5 , along the first direction, the functional layer 243 at one end in the direction from the thinning area 2422 to the main area 2421 is at its thinnest position, and the minimum thickness of the functional layer 243 is also the thickness at the thinnest position.
  • the minimum thickness of the functional layer 243 is limited to 1-80 ⁇ m, so that after the pole piece 24 is wound or stacked to form the electrode assembly 22, the gap between the functional layer 243 and the isolation film 223 is small, which is conducive to the capillary effect. At the same time, the pole piece 24 will not be too thick, so that the battery cell 20 has a higher energy density. If h ⁇ 1 ⁇ m, the minimum thickness of the functional layer 243 is thin, and the improvement of the capillary effect is not obvious. If h > 80 ⁇ m, the minimum thickness of the functional layer 243 is thick, indicating that the functional layer 243 is thicker as a whole, which will make the pole piece 24 thicker, which may reduce the energy density of the battery cell 20.
  • the length of the functional layer 243 in the first direction is L 1
  • the length of the thinned region 2422 in the first direction is L 2 , satisfying: 0.8 ⁇ L 1 /L 2 ⁇ 1.5.
  • the length of the functional layer 243 in the first direction refers to the distance between both ends of the functional layer 243 along the first direction.
  • the length of the thinned region 2422 in the first direction refers to the distance between two ends of the thinned region 2422 along the first direction.
  • L1 / L2 refers to the ratio of the length of the functional layer 243 in the first direction to the length of the thinned area 2422 in the first direction.
  • the length of the functional layer 243 in the first direction is 0.8 to 1.5 times the length of the thinned area 2422 in the first direction. In this way, the functional layer 243 can substantially or completely cover the thinned area 2422 along the first direction, so that the gap between the functional layer 243 and the isolation film 223 is small after the pole piece 24 is wound or stacked to form the electrode assembly 22, which is conducive to the capillary effect.
  • the functional layer 243 has a first surface 2431 away from the current collector 241 .
  • the maximum distance between the first surface 2431 and the current collector 241 is T 1
  • the thickness of the main region 2421 is T 2 , satisfying: 0.8 ⁇ T 1 /T 2 ⁇ 1.1.
  • the first surface 2431 is a surface of the functional layer 243 that is away from the current collector 241 along the thickness direction of the current collector 241 .
  • T1 represents the maximum distance between the first surface 2431 and the current collector 241 , which can also be understood as the maximum value of the total thickness of the thinned region 2422 and the functional layer 243 .
  • T2 represents the thickness of the main region 2421 , which can also be understood as the distance from the surface of the main region 2421 away from the current collector 241 to the current collector 241 along the thickness direction.
  • T1 /T2 represents the ratio of the maximum distance between the first surface 2431 and the current collector 241 to the thickness of the main region 2421.
  • the maximum distance between the first surface 2431 and the current collector 241 is 0.8 to 1.1 times the thickness of the main body region 2421.
  • the first surface 2431 is substantially flush with the surface of the main body region 2421 away from the current collector 241, which is conducive to the capillary effect and at the same time prevents the pole piece 24 from being too thick, so that the battery cell 20 has a higher energy density. If T 1 ⁇ 0.8T 2 , after the pole piece 24 is wound or stacked to form the battery cell 20, the gap between the functional layer 243 and the isolation film 223 is relatively large, and the electrolyte infiltration speed of the thinned area 2422 is relatively slow.
  • the functional layer 243 is farther away from the surface of the main region 2421 away from the current collector 241 along the direction from the current collector 241 to the active material layer 242.
  • the distance between the main region 2421 and the isolation film 223 increases, which slows down the wetting speed of the main region 2421.
  • the space occupied by the pole piece 24 increases, and there is a risk of reducing the energy density of the battery cell 20.
  • 0.9 ⁇ T 1 /T 2 ⁇ 1.01.
  • the maximum distance between the first surface 2431 and the current collector 241 is 0.9 to 1.01 times the thickness of the main region 2421.
  • the first surface 2431 is substantially flush with the surface of the main region 2421 away from the current collector 241, and both the main region 2421 and the skived region 2422 can be quickly wetted, while the pole piece 24 is not too thick, so that the battery cell 20 has a higher energy density.
  • the skived region 2422 has a second surface 24221, and the functional layer 243 is disposed on the second surface 24221.
  • the distance between the second surface 24221 and the current collector 241 in the thickness direction of the current collector 241 gradually decreases.
  • a distance between the second surface 24221 and the current collector 241 in the thickness direction of the current collector 241 gradually decreases along the direction from the main area 2421 to the thinning area 2422” can also be understood as the thickness of the thinning area 2422 gradually decreases along the direction from the main area 2421 to the thinning area 2422.
  • the second surface 24221 is an arc surface.
  • Figure 6 is a schematic diagram of the structure of the pole piece 24 provided in some other embodiments of the present application.
  • Figure 7 is a schematic diagram of the structure of the pole piece 24 provided in some other embodiments of the present application.
  • Figure 8 is a schematic diagram of the structure of the pole piece 24 provided in some other embodiments of the present application.
  • the second surface 24221 intersects with the current collector 241 at the first edge.
  • the functional layer 243 covers the first edge.
  • the first edge is formed by the intersection of the second surface 24221 and the surface of the current collector 241 where the active material layer 242 is disposed.
  • the first edge can also be understood as the edge of the thinned region 2422 along the direction from the main region 2421 to the thinned region 2422 .
  • the functional layer 243 wrapping the first edge can also be understood as the functional layer 243 covering the first edge.
  • the functional layer 243 covers the first edge, thereby reducing the risk of the thinned area 2422 falling off and causing powder to fall off.
  • the functional layer 243 covers a portion of the electrode ear portion 2411 .
  • the functional layer 243 covering a portion of the pole lug portion 2411 can also be understood as: a portion of the functional layer 243 is disposed on the pole lug portion 2411 .
  • the root of the pole ear portion 2411 can be reinforced, thereby reducing the risk of deformation and wrinkles at the root of the pole ear.
  • the functional layer 243 has a third surface 2432 away from the main region 2421.
  • the third surface 2432 intersects the current collector 241 at a second edge, and the distance between the second edge and the first edge is L 3 , satisfying: 0 ⁇ L 3 ⁇ 5 mm.
  • the second edge is formed by the intersection of the third surface 2432 and the surface of the current collector 241 where the active material layer 242 is disposed.
  • L3 represents the distance between the second edge and the first edge along the first direction.
  • the distance between the second edge and the first edge is 0-5 mm, so that the functional layer 243 can have a sufficient area to be coated on the pole ear portion 2411, and play a role in reinforcing the root of the pole ear, and at the same time, the functional layer 243 will not affect the length of the pole ear. If L3 >5mm, the functional layer 243 covers a larger area of the pole ear portion 2411, which will affect the formation of the pole ear.
  • the distance between the second edge and the first edge is between 1 and 2 mm, so that the functional layer 243 can have a good reinforcement effect on the pole ear portion 2411 while not easily affecting the forming of the pole ear.
  • the functional layer 243 does not cover a large enough range of the first edge, and the effect of reducing the shedding of powder in the thinning area 2422 is not very good.
  • the functional layer 243 covers a large area of the pole ear portion 2411, and the production cost increases.
  • the functional layer 243 has a first surface 2431, a third surface 2432, and a fourth surface.
  • the fourth surface is in contact with the second surface 24221.
  • the first surface 2431 is parallel or flush with the surface of the main region 2421 that is away from the current collector 241 along the thickness direction of the current collector 241.
  • the first surface 2431 intersects with the fourth surface, the third surface 2432 connects the first surface 2431 and the fourth surface, and the third surface 2432 is perpendicular to the first surface 2431.
  • the functional layer 243 is disposed on the second surface 24221 , and the fourth surface thereof is in contact with the second surface 24221 , so that the electrolyte can infiltrate the skived area 2422 after passing through the functional layer 243 .
  • the first surface 2431 is the surface of the functional layer 243 away from the current collector 241 along the thickness direction.
  • the first surface 2431 is parallel or flush with the surface of the main region 2421 away from the current collector 241 along the thickness direction of the current collector 241, so that the width of the gap between the functional layer 243 and the isolation film 223 is consistent, which is more conducive to the capillary effect.
  • the third surface 2432 has a large length. In this way, after the pole piece 24 is wound or stacked to form the electrode assembly 22, the gap between the functional layer 243 and the isolation film 223 is small, which is conducive to the capillary action, so that the electrolyte can quickly infiltrate the thinned area 2422 through the functional layer 243, so that the thinned area 2422 can play a role, which is conducive to improving the energy density of the battery cell 20.
  • the first surface 2431 is flush with a surface of the main region 2421 that is away from the current collector 241 along the thickness direction of the current collector 241 .
  • the first surface 2431 is flush with the surface of the main area 2421 away from the current collector 241 in the thickness direction.
  • the gap between the main area 2421 and the isolation film 223 is equal to the gap width between the first surface 2431 and the isolation film 223, which can ensure that the electrolyte quickly infiltrates the thinned area 2422 without increasing the thickness of the pole piece 24, and can greatly improve the energy density of the battery cell 20.
  • the effect of setting the functional layer 243 in this way is more ideal.
  • the third surface 2432 intersects with the current collector 241 .
  • the third surface 2432 intersects with the current collector 241 , indicating that the functional layer 243 covers the edge of the skived area 2422 in the direction from the main area 2421 to the skived area 2422 , and has a good liquid retention effect.
  • the third surface 2432 intersects with the second surface 24221.
  • the functional layer 243 does not cover the edge of the skived area 2422 in the direction from the main area 2421 to the skived area 2422, but the electrolyte can still infiltrate most of the skived area 2422, so that the skived area 2422 can play a role and improve the energy density of the battery cell 20.
  • the functional layer 243 has a first surface 2431, a third surface 2432, a fourth surface, and a fifth surface 2434.
  • the fourth surface is in contact with the second surface 24221.
  • the first surface 2431 is parallel to or flush with the surface of the main region 2421 that is away from the current collector 241 along the thickness direction of the current collector 241.
  • the fifth surface 2434 is in contact with the current collector 241, and the third surface 2432 connects the fifth surface 2434 and the first surface 2431.
  • the fourth surface connects the first surface 2431 and the fifth surface 2434.
  • the fifth surface 2434 is attached to the current collector 241 , including the fifth surface 2434 being attached to the pole ear portion 2411 , so that the functional layer 243 can reinforce the root of the pole ear portion 2411 and reduce the risk of deformation and wrinkles at the root of the pole ear.
  • the functional layer 243 can be formed after the fluid dries, when the functional layer 243 is set in a more ideal manner, the functional layer 243 may flow to form the above-mentioned shape. At this time, the functional layer 243 also has a good liquid retention effect, which can make the thinned area 2422 quickly infiltrated, so that the thinned area 2422 can play a role.
  • the first surface 2431 is flush with a surface of the main region 2421 that is away from the current collector 241 along the thickness direction of the current collector 241 .
  • the first surface 2431 is flush with the surface of the main area 2421 that is away from the current collector 241 in the thickness direction.
  • the gap between the main area 2421 and the isolation membrane 223 is equal to the gap width between the first surface 2431 and the isolation membrane 223, which can ensure that the electrolyte quickly infiltrates the thinned area 2422 without increasing the thickness of the pole piece 24, thereby greatly improving the energy density of the battery cell 20.
  • the third surface 2432 is an arc surface.
  • the second surface 24221 may also be a wavy arc surface, which is also helpful in reducing stress concentration.
  • two opposite surfaces of the current collector 241 along the thickness direction are both provided with active material layers 242 , and a functional layer 243 is provided in the thinned region 2422 of each active material layer 242 .
  • the current collector 241 includes two surfaces disposed opposite to each other in the thickness direction, and active material layers 242 are disposed on both surfaces.
  • Each active material layer 242 has a thinned area 2422 , and a functional layer 243 is disposed on each thinned area 2422 .
  • Active material layers 242 are disposed on both sides of the current collector 241 , and a functional layer 243 is disposed on the thinned region 2422 of each active material layer 242 , so that the pole pieces 24 can be wound or stacked to form an electrode assembly 22 .
  • the embodiment of the present application further provides an electrode assembly 22 , and the electrode assembly 22 includes the above-mentioned electrode piece 24 .
  • the electrode assembly 22 includes a positive electrode sheet 222, a negative electrode sheet 221 and a separator 223.
  • the positive electrode sheet 222, the separator 223 and the negative electrode sheet 221 are wound or stacked to form the electrode assembly 22.
  • At least one of the positive electrode sheet 222 and the negative electrode sheet 221 is the electrode sheet 24 mentioned above.
  • the embodiment of the present application further provides a battery cell 20 , and the battery cell 20 includes the above-mentioned electrode assembly 22 .
  • the embodiment of the present application further provides a battery 100 , and the battery 100 includes the above-mentioned battery cell 20 .
  • the embodiment of the present application further provides an electric device, which includes the above-mentioned battery 100, and the battery 100 is used to provide electric energy to the electric device.
  • FIGS. 3 to 8 please refer to FIGS. 3 to 8 .
  • the embodiment of the present application provides a pole piece 24, which includes a current collector 241, an active material layer 242 and a functional layer 243.
  • the active material layer 242 is arranged on the surface of the current collector 241.
  • the active material layer 242 includes a main body area 2421 and a thinning area 2422, and the thinning area 2422 is arranged at one end of the main body area 2421 along the first direction, and the thickness of the main body area 2421 is greater than the thickness of the thinning area 2422.
  • the current collector 241 has a pole ear portion 2411 that extends beyond the thinning area 2422 in a direction away from the main body area 2421.
  • the functional layer 243 is arranged on the surface of the thinning area 2422 away from the current collector 241, and the functional layer 243 is configured to allow the electrolyte to pass through.
  • the pole piece 24 is provided with a functional layer 243 that allows electrolyte to pass through on the thinned area 2422 of the active material layer 242, so that after the pole piece 24 is wound or stacked to form the electrode assembly 22, the gap between the functional layer 243 and the isolation film 223 is small, which is conducive to the capillary effect, so that the electrolyte can quickly infiltrate the thinned area 2422 through the functional layer 243, so that the thinned area 2422 can play a role, which is conducive to improving the energy density of the battery cell 20.
  • the smaller gap makes the path of lithium ion transmission shorter, which can reduce the risk of lithium precipitation and improve the performance of the battery cell 20.
  • the skived area 2422 has a second surface 24221, and the functional layer 243 is disposed on the second surface 24221.
  • the distance between the second surface 24221 and the current collector 241 in the thickness direction of the current collector 241 gradually decreases.
  • the second surface 24221 intersects with the current collector 241 at a first edge, and the functional layer 243 covers the first edge.
  • the functional layer 243 covers a portion of the pole ear portion 2411.
  • the root of the pole ear portion 2411 can be reinforced, reducing the risk of deformation and wrinkles at the root of the pole ear.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

本申请提供了一种极片、电极组件、电池单体、电池及用电设备，涉及电池领域。极片包括集流体、活性物质层和功能层。活性物质层设置于集流体的表面。活性物质层包括主体区和削薄区，削薄区设置于主体区沿第一方向的一端，主体区的厚度大于削薄区的厚度。沿第一方向，集流体具有沿背离主体区的方向超出于削薄区的极耳部。功能层设置于削薄区背离集流体的表面，功能层被配置为允许电解液通过。该极片在活性物质层的削薄区上设置有允许电解液通过的功能层，这样极片卷绕或层叠形成电极组件后，功能层与隔离膜之间的间隙较小，有利于毛细作用的发挥，使电解液能够经过功能层快速浸润削薄区，使得削薄区能够发挥作用，有利于提升电池单体的能量密度。

Description

极片、电极组件、电池单体、电池及用电设备 技术领域
本申请涉及电池领域，具体而言，涉及一种极片、电极组件、电池单体、电池及用电设备。
背景技术
电池在新能源领域应用甚广，例如电动汽车、新能源汽车等，新能源汽车、电动汽车已经成为汽车产业的发展新趋势。电池技术的发展要同时考虑多方面的设计因素，例如，循环寿命、放电容量、充放电倍率等性能参数，另外，还需要考虑电池的能量密度。然而，目前，电池单体的能量密度较低。
发明内容
本申请实施例的目的在于提供一种极片、电极组件、电池单体、电池及用电设备，其旨在改善相关技术中电池的能量密度较低的问题。
第一方面，本申请实施例提供了一种极片，所述极片包括集流体、活性物质层和功能层，所述活性物质层设置于所述集流体的表面，所述活性物质层包括主体区和削薄区，所述削薄区设置于所述主体区沿第一方向的一端，所述主体区的厚度大于所述削薄区的厚度，沿所述第一方向，所述集流体具有沿背离所述主体区的方向超出于所述削薄区的极耳部；所述功能层设置于所述削薄区背离所述集流体的表面，所述功能层被配置为允许电解液通过。
在上述技术方案中，该极片在活性物质层的削薄区上设置有允许电解液通过的功能层，这样极片卷绕或层叠形成电极组件后，功能层与隔离膜之间的间隙较小，有利于毛细作用的发挥，使得电解液能够经过功能层快速浸润削薄区，使得削薄区能够发挥作用，有利于提升电池单体的能量密度。另外，较小的间隙使得锂离子传输的路径较短，能够降低析锂的风险，提升电池单体的性能。
作为本申请实施例的一种可选技术方案，所述功能层储存电解液的能力强于所述活性物质层。
在上述技术方案中，通过使功能层储存电解液的能力强于活性物质层，使得电解液容易储存在功能层中，使得锂离子能够通过功能层储存的电解液进入隔离膜或者削薄区内，能够降低析锂的风险，提升电池单体的能量密度。
作为本申请实施例的一种可选技术方案，所述功能层包括偏二氟乙烯聚合物、六氟丙烯聚合物、偏二氟乙烯-六氟丙烯聚合物、聚丙烯酸、聚苯乙烯丁二烯共聚物、聚乙烯醇、聚烯酸酯、聚氨酯、氯化橡胶、环氧树脂中的至少一种。
在上述技术方案中，偏二氟乙烯聚合物、六氟丙烯聚合物、偏二氟乙烯-六 氟丙烯聚合物、聚丙烯酸、聚苯乙烯丁二烯共聚物、聚乙烯醇、聚烯酸酯、聚氨酯、氯化橡胶、环氧树脂均具有较好的储存电解液的能力，尤其是偏二氟乙烯聚合物、六氟丙烯聚合物、偏二氟乙烯-六氟丙烯聚合物，不但储存电解液的能力强，而且容易制造。
作为本申请实施例的一种可选技术方案，所述功能层还包括导电剂。
在上述技术方案中，通过在功能层内添加导电剂，增强功能层的导电能力，使得锂离子易于传输。
作为本申请实施例的一种可选技术方案，所述导电剂包括乙炔黑、活性炭、炭黑、导电石墨、碳纳米管中的至少一种。
在上述技术方案中，乙炔黑、活性炭、炭黑、导电石墨、碳纳米管具有较好的导电效果，尤其是乙炔黑，不但导电效果好，而且成本较低。
作为本申请实施例的一种可选技术方案，所述极片为负极片，所述功能层包括活性物质材料，所述功能层的活性物质材料体积分布中粒径大于D 1的粉末粒子占50％，所述活性物质层的活性物质材料体积分布中粒径大于D 2的粉末粒子占50％，满足：1≤D 2/D 1≤25。
在上述技术方案中，当D 2/D 1＝1时，功能层的活性物质材料可以与活性物质层的活性物质材料相同，这样，功能层不但能够有利于毛细作用的发挥，使电解液能够经过功能层快速浸润削薄区，使得削薄区能够发挥作用，而且功能层本申请也能够起到与活性物质层相同的作用，有利于提升电池单体的能量密度。当1＜D 2/D 1≤25时，功能层的活性物质材料的粉末粒子的粒径小于活性物质层的活性物质材料的粉末粒子的粒径，这样，功能层的颗粒较削薄区的颗粒小，削薄区的电解液不易排出，因而功能层能够对削薄区起到较好的保液效果，使得削薄区能够发挥作用，有利于提升电池单体的能量密度。另外，功能层的颗粒较削薄区的颗粒小，其动力学会更佳，使得该区域的功能层具有更高的析锂窗口，从而降低析锂风险，有利于保证电池单体的性能。
作为本申请实施例的一种可选技术方案，1.01≤D 2/D 1≤5。
在上述技术方案中，当1.01≤D 1/D 2≤5时，功能层具有较好的保液能力，并且动力学更好，具有更高的析锂窗口，更不易析锂，有利于保证电池单体的性能。
作为本申请实施例的一种可选技术方案，所述极片为正极片，所述功能层包括活性物质材料，所述功能层的活性物质材料体积分布中粒径大于D 1的粉末粒子占50％，所述活性物质层的活性物质材料体积分布中粒径大于D 2的粉末粒子占50％，满足：1≤D 1/D 2≤30。
在上述技术方案中，当D 1/D 2＝1时，功能层的活性物质材料可以与活性物质层的活性物质材料相同，这样，功能层不但能够有利于毛细作用的发挥，使电解液能够经过功能层快速浸润削薄区，使得削薄区能够发挥作用，而且功能层本身也能够起到与活性物质层相同的作用，有利于提升电池单体的能量密度。当1＜D 1/D 2≤30时，功能层的活性物质材料的粉末粒子的粒径大于活性物质层的活性物质材料的粉末粒子的粒径，这样，功能层的颗粒较削薄区的颗粒大，具有较大的阻抗，使得削薄区的锂 离子释放速度较慢，从而负极片单位时间需要嵌入的锂离子减少，从而更不易析锂，有利于保证电池单体的性能。
作为本申请实施例的一种可选技术方案，1.01≤D 1/D 2≤10。
在上述技术方案中，当1.01≤D 1/D 2≤10时，既能够达到不易析锂的效果，又不会使得锂离子的释放速度过慢，有利于保证放电效率。
作为本申请实施例的一种可选技术方案，所述极片为负极片，所述功能层包括活性物质材料，所述功能层的活性物质材料的克容量为M 1，所述活性物质层的活性物质材料的克容量为M 2，满足：1.01≤M 1/M 2≤5。
在上述技术方案中，1.01≤M 1/M 2≤5时，功能层的活性物质材料的克容量大于活性物质层的活性物质材料的克容量，这样，可以提升极片在功能区所在区域的CB值(Cell balance，电芯平衡率，电芯平衡率是指负极片的单位活性容量与正极片的单位活性容量之比)，负极片能够用于嵌入锂离子的空间增大，从而更不易析锂，有利于保证电池单体的性能。
作为本申请实施例的一种可选技术方案，1.01≤M 1/M 2≤1.3。
在上述技术方案中，通过使1.01≤M 1/M 2≤1.3，既能够增大负极片用于嵌入锂离子的空间，从而不易析锂，还不会使CB值过大，而造成成本大幅提升。
作为本申请实施例的一种可选技术方案，所述极片为正极片，所述功能层包括活性物质材料，所述功能层的活性物质材料的克容量为M 1，所述主体区的活性物质材料的克容量为M 2，满足：0.3≤M 1/M 2≤1.01。
在上述技术方案中，0.3≤M 1/M 2＜1时，功能层的活性物质材料的克容量小于活性物质层的活性物质材料的克容量，这样，可以提升极片在功能区所在区域的CB值，正极片能够释放的锂离子较少，从而不易析锂，有利于保证电池单体的性能。当1≤M 1/M 2≤1.01时，功能层的活性物质材料的克容量等于或者略大于活性物质层的活性物质材料的克容量，这样，功能层不但能够有利于毛细作用的发挥，使电解液能够经过功能层快速浸润削薄区，使得削薄区能够发挥作用，而且功能层本身也能够起到与活性物质层相同的作用，有利于提升电池单体的能量密度。
作为本申请实施例的一种可选技术方案，0.5≤M 1/M 2≤1.01。
在上述技术方案中，当0.5≤M 1/M 2≤1.01时，功能层的活性物质材料的克容量相对较大，功能层本身也能够起到与活性物质层相同的作用，有利于提升电池单体的能量密度。
作为本申请实施例的一种可选技术方案，沿所述集流体的厚度方向，所述功能层的最小厚度为h，满足：1μm≤h≤80μm。
在上述技术方案中，将功能层的最小厚度限制在1～80μm，这样极片卷绕或层叠形成电极组件后，功能层与隔离膜之间的间隙较小，有利于毛细作用的发挥，同时使极片不会太厚，以使电池单体具有较高的能量密度。若h＜1μm，则功能层的最小厚度较薄，对毛细作用的提升不明显。若h＞80μm，则功能层的最小厚度较厚，说明功能层整体较厚，则会使极片较厚，可能使电池单体的能量密度降低。
作为本申请实施例的一种可选技术方案，所述功能层在所述第一方向的长度 为L 1，所述削薄区在所述第一方向的长度为L 2，满足：0.8≤L 1/L 2≤1.5。
在上述技术方案中，功能层在第一方向的长度是削薄区在第一方向的长度的0.8～1.5倍。这样，功能层能够沿第一方向基本覆盖或者完全覆盖削薄区，使得极片卷绕或层叠形成电极组件后功能层与隔离膜之间的间隙较小，有利于毛细作用的发挥。
作为本申请实施例的一种可选技术方案，沿所述集流体的厚度方向，所述功能层具有背离所述集流体的第一表面，所述第一表面与所述集流体的最大距离为T 1，所述主体区的厚度为T 2，满足：0.8≤T 1/T 2≤1.1。
在上述技术方案中，沿厚度方向，第一表面与集流体的最大距离是主体区厚度的0.8～1.1倍。这样，第一表面基本与主体区背离集流体的表面相平齐，有利于毛细作用的发挥，同时使极片不会太厚，以使电池单体具有较高的能量密度。若T 1＜0.8T 2，则极片卷绕或层叠形成电池单体后，功能层与隔离膜的间隙相对较大，电解液浸润削薄区的浸润速度相对较慢。若T 1＞1.1T 2，则沿着集流体指向活性物质层的方向，功能层超出于主体区背离集流体的表面的距离较大，极片卷绕或层叠形成电池单体后，主体区与隔离膜的间距增大，使得主体区的浸润速度变慢。另外，极片占用空间增大，还存在降低电池单体能量密度的风险。
作为本申请实施例的一种可选技术方案，0.9≤T 1/T 2≤1.01。
在上述技术方案中，沿厚度方向，第一表面与集流体的最大距离是主体区厚度的0.9～1.01倍。这样，第一表面基本与主体区背离集流体的表面相平齐，主体区和削薄区均能够被快速浸润，同时使极片不会太厚，以使电池单体具有较高的能量密度。
作为本申请实施例的一种可选技术方案，所述削薄区具有第二表面，所述功能层设置于所述第二表面，沿所述主体区指向所述削薄区的方向，所述第二表面与所述集流体在所述集流体的厚度方向上的距离逐渐减小。
在上述技术方案中，沿主体区指向削薄区的方向，削薄区的厚度逐渐减小。这样，有利于减小活性物质层与极耳部交界处的应力。
作为本申请实施例的一种可选技术方案，所述第二表面为圆弧面。
在上述技术方案中，将第二表面设置为圆弧面，有利于减小应力集中。
作为本申请实施例的一种可选技术方案，所述第二表面与所述集流体相交于第一边缘，所述功能层包覆所述第一边缘。
在上述技术方案中，通过使功能层包覆第一边缘，以降低削薄区脱落掉粉的风险。
作为本申请实施例的一种可选技术方案，所述功能层覆盖所述极耳部的一部分。
在上述技术方案中，通过使功能层覆盖极耳部的一部分，可对极耳部的根部进行加固，降低极耳根部出现变形褶皱的风险。
作为本申请实施例的一种可选技术方案，沿所述第一方向，所述功能层具有背离所述主体区的第三表面，所述第三表面与所述集流体相交于第二边缘，所述第二边缘与所述第一边缘的间距为L 3，满足：0≤L 3≤5mm。
在上述技术方案中，沿第一方向，第二边缘与第一边缘的间距在0～5mm，以使得功能层能够具有足够的面积涂覆于极耳部，对极耳的根部起到加固的作用，同时，功能层又不会影响极耳的长度。若L 3＞5mm，则功能层包覆极耳部的面积较大，会影响极耳的成型。
作为本申请实施例的一种可选技术方案，1mm≤L 3≤2mm。
在上述技术方案中，沿第一方向，第二边缘与第一边缘的间距在1～2mm之间，使得功能层能够对极耳部具有较好的加固效果的同时，不易影响极耳的成型。
作为本申请实施例的一种可选技术方案，所述功能层具有第一表面、第三表面和第四表面，所述第四表面与所述第二表面贴合，所述第一表面与所述主体区沿所述集流体的厚度方向背离所述集流体的表面平行或平齐，所述第一表面与所述第四表面相交，所述第三表面连接所述第一表面和所述第四表面，所述第三表面与所述第一表面垂直。
在上述技术方案中，沿厚度方向，第三表面具有较大的长度。这样极片卷绕或层叠形成电极组件后，功能层与隔离膜之间的间隙较小，有利于毛细作用的发挥，使得电解液能够经过功能层快速浸润削薄区，使得削薄区能够发挥作用，有利于提升电池单体的能量密度。
作为本申请实施例的一种可选技术方案，所述第一表面与所述主体区沿所述集流体的厚度方向背离所述集流体的表面平齐。
在上述技术方案中，第一表面与主体区沿厚度方向背离集流体的表面平齐，则极片卷绕或层叠形成电极组件后，主体区和隔离膜之间的间隙与第一表面和隔离膜之间的间隙宽度相等，能够保证电解液快速浸润削薄区的同时，不会使极片厚度增大，能够大大提升电池单体的能量密度。这样设置功能层的效果较为理想。
作为本申请实施例的一种可选技术方案，所述第三表面与所述集流体相交。
在上述技术方案中，第三表面与集流体相交，表明功能层覆盖了削薄区从主体区指向削薄区的方向的边缘，具有较好的保液效果。
作为本申请实施例的一种可选技术方案，所述功能层具有第一表面、第三表面、第四表面和第五表面，所述第四表面与所述第二表面贴合，所述第一表面与所述主体区沿所述集流体的厚度方向背离所述集流体的表面平行或平齐，所述第五表面贴合于所述集流体，所述第三表面连接所述第五表面和所述第一表面，所述第四表面连接所述第一表面和所述第五表面。
在上述技术方案中，由于功能层可以是流体干燥后形成的，在按照较为理想的方式设置功能层时，功能层可能会流动而形成上述的形状，此时，功能层也具有较好的保液效果，能够使得削薄区被快速浸润，使得削薄区能够发挥作用。
作为本申请实施例的一种可选技术方案，所述第三表面为圆弧面。
在上述技术方案中，将第三表面设置为圆弧面，有利于减小应力集中。
作为本申请实施例的一种可选技术方案，所述集流体沿厚度方向相对的两个表面均设置有所述活性物质层，每个所述活性物质层的削薄区设置有所述功能层。
在上述技术方案中，在集流体的两侧均设置活性物质层，并在每个活性物质 层的削薄区上设置功能层，以便于将极片通过卷绕或层叠的方式形成电极组件。
第二方面，本申请实施例还提供了一种电极组件，所述电极组件包括上述的极片。
第三方面，本申请实施例还提供了一种电池单体，所述电池单体包括上述的电极组件。
第四方面，本申请实施例还提供了一种电池，所述电池包括上述的电池单体。
第五方面，本申请实施例还提供了一种用电设备，所述用电设备包括上述的电池，所述电池用于为所述用电设备提供电能。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面将对实施例中所需要使用的附图作简单地介绍，应当理解，以下附图仅示出了本申请的某些实施例，因此不应被看作是对范围的限定，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他相关的附图。
图1为本申请一些实施例提供的车辆的结构示意图；
图2为本申请一些实施例提供的电池的爆炸图；
图3为本申请一些实施例提供的电池单体的爆炸图；
图4为本申请一些实施例提供的电极组件的结构示意图；
图5为本申请一些实施例提供的极片的结构示意图；
图6为本申请另一些实施例提供的极片的结构示意图；
图7为本申请又一些实施例提供的极片的结构示意图；
图8为本申请再一些实施例提供的极片的结构示意图。
图标：10-箱体；11-第一部分；12-第二部分；20-电池单体；21-端盖；22-电极组件；221-负极片；222-正极片；223-隔离膜；23-壳体；24-极片；241-集流体；2411-极耳部；242-活性物质层；2421-主体区；2422-削薄区；24221-第二表面；243-功能层；2431-第一表面；2432-第三表面；2434-第五表面；100-电池；200-控制器；300-马达；1000-车辆。
具体实施方式
为使本申请实施例的目的、技术方案和优点更加清楚，下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚地描述，显然，所描述的实施例是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
除非另有定义，本申请所使用的所有的技术和科学术语与属于本申请的技术领域的技术人员通常理解的含义相同；本申请中在申请的说明书中所使用的术语只是 为了描述具体的实施例的目的，不是旨在于限制本申请；本申请的说明书和权利要求书及上述附图说明中的术语“包括”和“具有”以及它们的任何变形，意图在于覆盖不排他的包含。本申请的说明书和权利要求书或上述附图中的术语“第一”、“第二”等是用于区别不同对象，而不是用于描述特定顺序或主次关系。
在本申请中提及“实施例”意味着，结合实施例描述的特定特征、结构或特性可以包含在本申请的至少一个实施例中。在说明书中的各个位置出现该短语并不一定均是指相同的实施例，也不是与其它实施例互斥的独立的或备选的实施例。
在本申请的描述中，需要说明的是，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”、“附接”应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体地连接；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本申请中的具体含义。
本申请中术语“和/或”，仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，本申请中字符“/”，一般表示前后关联对象是一种“或”的关系。
在本申请的实施例中，相同的附图标记表示相同的部件，并且为了简洁，在不同实施例中，省略对相同部件的详细说明。应理解，附图示出的本申请实施例中的各种部件的厚度、长宽等尺寸，以及集成装置的整体厚度、长宽等尺寸仅为示例性说明，而不应对本申请构成任何限定。
本申请中出现的“多个”指的是两个以上(包括两个)。
本申请中，电池单体可以包括锂离子二次电池单体、锂离子一次电池单体、锂硫电池单体、钠锂离子电池单体、钠离子电池单体或镁离子电池单体等，本申请实施例对此并不限定。电池单体可呈圆柱体、扁平体、长方体或其它形状等，本申请实施例对此也不限定。电池单体一般按封装的方式分成三种：柱形电池单体、方形电池单体和软包电池单体，本申请实施例对此也不限定。
本申请的实施例所提到的电池是指包括一个或多个电池单体以提供更高的电压和容量的单一的物理模块。例如，本申请中所提到的电池可以包括电池模块或电池包等。电池一般包括用于封装一个或多个电池单体的箱体。箱体可以避免液体或其他异物影响电池单体的充电或放电。
电池单体包括电极组件和电解液，电极组件包括正极片、负极片和隔离膜。电池单体主要依靠金属离子在正极片和负极片之间移动来工作。正极片包括正极集流体和正极活性物质层，正极活性物质层涂覆于正极集流体的表面，未涂敷正极活性物质层的正极集流体凸出于已涂覆正极活性物质层的正极集流体，未涂敷正极活性物质层的正极集流体作为正极耳。以锂离子电池为例，正极集流体的材料可以为铝，正极活性物质可以为钴酸锂、磷酸铁锂、三元锂或锰酸锂等。负极片包括负极集流体和负极活性物质层，负极活性物质层涂覆于负极集流体的表面，未涂敷负极活性物质层的负极集流体凸出于已涂覆负极活性物质层的负极集流体，未涂敷负极活性物质层的负 极集流体作为负极耳。负极集流体的材料可以为铜，负极活性物质可以为碳或硅等。为了保证通过大电流而不发生熔断，正极耳的数量为多个且层叠在一起，负极耳的数量为多个且层叠在一起。隔离膜的材质可以为PP(polypropylene，聚丙烯)或PE(polyethylene，聚乙烯)等。此外，电极组件可以是卷绕式结构，也可以是叠片式结构，本申请实施例并不限于此。
目前，从市场形势的发展来看，电池的应用越加广泛。电池不仅被应用于水力、火力、风力和太阳能电站等储能电源系统，而且还被广泛应用于电动自行车、电动摩托车、电动汽车等电动交通工具，以及军事装备和航空航天等多个领域。随着电池应用领域的不断扩大，其市场的需求量也在不断地扩增。
电池技术的发展要同时考虑多方面的设计因素，例如，循环寿命、放电容量、充放电倍率等性能参数，另外，还需要考虑电池的能量密度。然而，目前，电池单体的能量密度较低。
发明人研究发现，极片包括集流体和设置于集流体表面的活性物质层，集流体上未设置活性物质层的部分为极耳部，极耳部用于成型出极耳。由于活性物质层和极耳部之间存在高度差，因此，在辊压时，应力会集中在活性物质层和极耳部的交界处，导致活性物质层脱落，集流体上产生裂纹。为了释放应力，通常会减小活性物质层靠近极耳部的一端的厚度，进而形成一个厚度较小的削薄区。
然而，在电极组件中，削薄区和隔离膜之间的间隙较大，不利于毛细作用的发挥，导致削薄区不易被浸润，削薄区内的电解液量较少或者无电解液，使得削薄区无法发挥作用(削薄区不能为电化学反应作出贡献)。具体来说，当正极片的削薄区无法发挥作用时，电池单体的能量密度降低。而当负极片的削薄区无法发挥作用时，会出现析锂，析锂会影响电池单体的性能，降低电池单体的能量密度。由此，导致电池单体的能量密度较低。
鉴于此，本申请实施例提供一种极片，极片包括集流体、活性物质层和功能层。活性物质层设置于集流体的表面。活性物质层包括主体区和削薄区，削薄区设置于主体区沿第一方向的一端，主体区的厚度大于削薄区的厚度。沿第一方向，集流体具有沿背离主体区的方向超出于削薄区的极耳部。功能层设置于削薄区背离集流体的表面，功能层被配置为允许电解液通过。
该极片在活性物质层的削薄区上设置有允许电解液通过的功能层，这样极片卷绕或层叠形成电极组件后，功能层与隔离膜之间的间隙较小，有利于毛细作用的发挥，使得电解液能够经过功能层快速浸润削薄区，使得削薄区能够发挥作用，有利于提升电池单体的能量密度。
另外，较小的间隙使得锂离子传输的路径较短，能够降低析锂的风险，提升电池单体的性能。
本申请实施例描述的技术方案适用于电池以及使用电池的用电设备。
用电设备可以是车辆、手机、便携式设备、笔记本电脑、轮船、航天器、电动玩具和电动工具等等。航天器包括飞机、火箭、航天飞机和宇宙飞船等等；电动玩具包括固定式或移动式的电动玩具，例如，游戏机、电动汽车玩具、电动轮船玩具和 电动飞机玩具等等；电动工具包括金属切削电动工具、研磨电动工具、装配电动工具和铁道用电动工具，例如，电钻、电动砂轮机、电动扳手、电动螺丝刀、电锤、冲击电钻、混凝土振动器和电刨等等。本申请实施例对上述用电设备不做特殊限制。
以下实施例为了方便说明，以用电设备为车辆1000为例进行说明。
请参照图1，图1为本申请一些实施例提供的车辆1000的结构示意图。车辆1000可以为燃油汽车、燃气汽车或新能源汽车，新能源汽车可以是纯电动汽车、混合动力汽车或增程式汽车等。车辆1000的内部设置有电池100，电池100可以设置在车辆1000的底部或头部或尾部。电池100可以用于车辆1000的供电，例如，电池100可以作为车辆1000的操作电源。车辆1000还可以包括控制器200和马达300，控制器200用来控制电池100为马达300供电，例如，用于车辆1000的启动、导航和行驶时的工作用电需求。
在本申请一些实施例中，电池100不仅可以作为车辆1000的操作电源，还可以作为车辆1000的驱动电源，代替或部分地代替燃油或天然气为车辆1000提供驱动动力。
请参照图2，图2为本申请一些实施例提供的电池100的爆炸图。电池100包括箱体10和电池单体20，电池单体20容纳于箱体10内。其中，箱体10用于为电池单体20提供容纳空间，箱体10可以采用多种结构。在一些实施例中，箱体10可以包括第一部分11和第二部分12，第一部分11与第二部分12相互盖合，第一部分11和第二部分12共同限定出用于容纳电池单体20的容纳空间。第二部分12可以为一端开口的空心结构，第一部分11可以为板状结构，第一部分11盖合于第二部分12的开口侧，以使第一部分11与第二部分12共同限定出容纳空间；第一部分11和第二部分12也可以是均为一侧开口的空心结构，第一部分11的开口侧盖合于第二部分12的开口侧。当然，第一部分11和第二部分12形成的箱体10可以是多种形状，比如，圆柱体、长方体等。
在电池100中，电池单体20可以是多个，多个电池单体20之间可串联或并联或混联，混联是指多个电池单体20中既有串联又有并联。多个电池单体20之间可直接串联或并联或混联在一起，再将多个电池单体20构成的整体容纳于箱体10内；当然，电池100也可以是多个电池单体20先串联或并联或混联组成电池模块形式，多个电池模块再串联或并联或混联形成一个整体，并容纳于箱体10内。电池100还可以包括其他结构，例如，该电池100还可以包括汇流部件，用于实现多个电池单体20之间的电连接。
其中，每个电池单体20可以为二次电池单体或一次电池单体；还可以是锂硫电池单体、钠离子电池单体或镁离子电池单体，但不局限于此。电池单体20可呈圆柱体、扁平体、长方体或其它形状等。
请参照图3，图3为本申请一些实施例提供的电池单体20的爆炸图。电池单体20是指组成电池100的最小单元。如图3，电池单体20包括有端盖21、电极组件22、壳体23以及其他的功能性部件。
端盖21是指盖合于壳体23的开口处以将电池单体20的内部环境隔绝于外 部环境的部件。不限地，端盖21的形状可以与壳体23的形状相适应以配合壳体23。可选地，端盖21可以由具有一定硬度和强度的材质(如铝合金)制成，这样，端盖21在受挤压碰撞时就不易发生形变，使电池单体20能够具备更高的结构强度，安全性能也可以有所提高。端盖21上可以设置有如电极端子(图中未示出)等的功能性部件。电极端子可以用于与电极组件22电连接，以用于输出或输入电池单体20的电能。端盖21的材质也可以是多种的，比如，铜、铁、铝、不锈钢、铝合金、塑胶等，本申请实施例对此不作特殊限制。在一些实施例中，在端盖21的内侧还可以设置有绝缘件，绝缘件可以用于隔离壳体23内的电连接部件与端盖21，以降低短路的风险。示例性的，绝缘件可以是塑料、橡胶等。
壳体23是用于配合端盖21以形成电池单体20的内部环境的组件，其中，形成的内部环境可以用于容纳电极组件22、电解液以及其他部件。壳体23和端盖21可以是独立的部件，可以于壳体23上设置开口，通过在开口处使端盖21盖合开口以形成电池单体20的内部环境。不限地，也可以使端盖21和壳体23一体化，具体地，端盖21和壳体23可以在其他部件入壳前先形成一个共同的连接面，当需要封装壳体23的内部时，再使端盖21盖合壳体23。壳体23可以是多种形状和多种尺寸的，例如长方体形、圆柱体形、六棱柱形等。具体地，壳体23的形状可以根据电极组件22的具体形状和尺寸大小来确定。壳体23的材质可以是多种，比如，铜、铁、铝、不锈钢、铝合金、塑胶等，本申请实施例对此不作特殊限制。
请参照图4，图4为本申请一些实施例提供的电极组件22的结构示意图。电极组件22是电池单体20中发生电化学反应的部件。壳体23内可以包含一个或更多个电极组件22。电极组件22主要由正极片222和负极片221卷绕或层叠放置形成，并且通常在正极片222与负极片221之间设有隔离膜223。正极片222和负极片221具有活性物质的部分构成电极组件22的主体部，正极片222和负极片221不具有活性物质的部分各自构成极耳。正极耳和负极耳可以共同位于主体部的一端或是分别位于主体部的两端。在电池100的充放电过程中，正极活性物质和负极活性物质与电解液发生反应，极耳连接电极端子以形成电流回路。
请参照图3、图4和图5，图5为本申请一些实施例提供的极片24的结构示意图。本申请实施例提供了一种极片24，极片24包括集流体241、活性物质层242和功能层243。活性物质层242设置于集流体241的表面。活性物质层242包括主体区2421和削薄区2422，削薄区2422设置于主体区2421沿第一方向的一端，主体区2421的厚度大于削薄区2422的厚度。沿第一方向，集流体241具有沿背离主体区2421的方向超出于削薄区2422的极耳部2411。功能层243设置于削薄区2422背离集流体241的表面，功能层243被配置为允许电解液通过。
极片24可以作为电极组件22的负极片221，也可以作为电极组件22的正极片222。电极组件22中可以只有负极片221采用该极片24，也可以只有正极片222采用该极片24，还可以负极片221和正极片222均采用该极片24。
主体区2421是活性物质层242的主要部分，其实现活性物质层242的主要功能。削薄区2422是活性物质层242中朝向极耳部2411的一端的减薄部分。削薄区 2422位于主体区2421沿第一方向的一端。
“主体区2421的厚度大于削薄区2422的厚度”是指主体区2421的最小厚度大于削薄区2422的最大厚度。或者说，主体区2421的任意位置的厚度均大于削薄区2422的任意位置的厚度。
请参照图5，第一方向可以是图5中所示的A方向。厚度方向可以是图5中所示的B方向。
极耳部2411是集流体241上未设置活性物质层242的部分。极耳部2411用于成型出极耳。集流体241上设置活性物质层242的部分和极耳部2411沿着第一方向排布。
功能层243具有空隙，能够允许电解液通过。功能层243可以为陶瓷层、聚合物层或者其他能够允许电解液通过的凝聚态物质层。
该极片24在活性物质层242的削薄区2422上设置有允许电解液通过的功能层243，这样极片24卷绕或层叠形成电极组件22后，功能层243与隔离膜223之间的间隙较小，有利于毛细作用的发挥，使得电解液能够经过功能层243快速浸润削薄区2422，使得削薄区2422能够发挥作用，有利于提升电池单体20的能量密度。
另外，较小的间隙使得锂离子传输的路径较短，能够降低析锂的风险，提升电池单体20的性能。
在一些实施例中，功能层243储存电解液的能力强于活性物质层242。
对于储存电解液的能力，可以通过测试浸润时间来衡量，浸润速度较快的，储存电解液的能力较强。另外，也可以通过测试挥发时间来衡量，挥发速度较慢的，储存电解液的能力较强。
功能层243储存电解液的能力强于活性物质层242储存电解液的能力，这样，在浸润时，电解液能够迅速通过功能层243流向削薄区2422，并且在浸润完成后，功能层243内的电解液更难挥发。
同时，功能层243内能够储存电解液，使得锂离子能够通过功能层243储存的电解液进入隔离膜223或者削薄区2422。
通过使功能层243储存电解液的能力强于活性物质层242，使得电解液容易储存在功能层243中，使得锂离子能够通过功能层243储存的电解液进入隔离膜223或者削薄区2422内，能够降低析锂的风险，提升电池单体20的性能。
在一些实施例中，功能层243包括偏二氟乙烯聚合物、六氟丙烯聚合物、偏二氟乙烯-六氟丙烯聚合物、聚丙烯酸、聚苯乙烯丁二烯共聚物、聚乙烯醇、聚烯酸酯、聚氨酯、氯化橡胶、环氧树脂中的至少一种。
偏二氟乙烯聚合物、六氟丙烯聚合物、偏二氟乙烯-六氟丙烯聚合物、聚丙烯酸、聚苯乙烯丁二烯共聚物、聚乙烯醇、聚烯酸酯、聚氨酯、氯化橡胶、环氧树脂均具有较好的储存电解液的能力，尤其是偏二氟乙烯聚合物、六氟丙烯聚合物、偏二氟乙烯-六氟丙烯聚合物，不但储存电解液的能力强，而且容易制造。
在一些实施例中，功能层243还包括导电剂。
导电剂能够提升功能层243的导电效果。由于上述功能层243的主要材料是 聚合物，而聚合物的导电能力较差或不具有导电能力，因此通过添加导电剂增强功能层243的导电能力，以便于锂离子通过。
通过在功能层243内添加导电剂，增强功能层243的导电能力，使得锂离子易于传输。
在一些实施例中，导电剂包括乙炔黑、活性炭、炭黑、导电石墨、碳纳米管中的至少一种。
乙炔黑、活性炭、炭黑、导电石墨、碳纳米管具有较好的导电效果，尤其是乙炔黑，不但导电效果好，而且成本较低。
在一些实施例中，极片24为负极片221。功能层243包括活性物质材料，功能层243的活性物质材料体积分布中粒径大于D 1的粉末粒子占50％。活性物质层242的活性物质材料体积分布中粒径大于D 2的粉末粒子占50％，满足：1≤D 2/D 1≤25。
D 1表示功能层243的活性物质材料体积分布中粒径大于D 1的粉末粒子占50％，也就是说，功能层243的活性物质材料体积分布中有50％的粉末粒子的粒径大于D 1。
D 2表示活性物质层242的活性物质材料体积分布中粒径大于D 2的粉末粒子占50％，也就是说，活性物质层242的活性物质材料体积分布中有50％的粉末粒子的粒径大于D 2。
D 2/D 1的取值可以为：D 2/D 1＝1、2、3、4、5、6、7、8、9、10、11、12、13、14、15、16、17、18、19、20、21、22、23、24、25等。
当D 2/D 1＝1时，功能层243的活性物质材料可以与活性物质层242的活性物质材料相同，这样，功能层243不但能够有利于毛细作用的发挥，使电解液能够经过功能层243快速浸润削薄区2422，使得削薄区2422能够发挥作用，而且功能层243本申请也能够起到与活性物质层242相同的作用，有利于提升电池单体20的能量密度。当1＜D 2/D 1≤25时，功能层243的活性物质材料的粉末粒子的粒径小于活性物质层242的活性物质材料的粉末粒子的粒径，这样，功能层243的颗粒较削薄区2422的颗粒小，削薄区2422的电解液不易排出，因而功能层243能够对削薄区2422起到较好的保液效果，使得削薄区2422能够发挥作用，有利于提升电池单体20的能量密度。另外，功能层243的颗粒较削薄区2422的颗粒小，其动力学会更佳，使得该区域的功能层具有更高的析锂窗口，从而降低析锂风险，有利于保证电池单体20的性能。
在一些实施例中，1.01≤D 2/D 1≤5。
D 1/D 2的取值可以为：D 2/D 1＝1.01、1.05、1.2、1.5、1.8、2、2.2、2.5、2.8、3、3.2、3.5、3.8、4、4.2、4.5、4.8、5等。
当1.01≤D 1/D 2≤5时，功能层243具有较好的保液能力，并且动力学更好，具有更高的析锂窗口，更不易析锂，有利于保证电池单体20的性能。
在一些实施例中，极片24为正极片222。功能层243包括活性物质材料，功能层243的活性物质材料体积分布中粒径大于D 1的粉末粒子占50％。活性物质层242的活性物质材料体积分布中粒径大于D 2的粉末粒子占50％，满足：1≤D 1/D 2≤30。
D 1/D 2的取值可以为：D 1/D 2＝1、2、3、4、5、6、7、8、9、10、11、12、13、 14、15、16、17、18、19、20、21、22、23、24、25、26、27、28、29、30等。
当D 1/D 2＝1时，功能层243的活性物质材料可以与活性物质层242的活性物质材料相同，这样，功能层243不但能够有利于毛细作用的发挥，使电解液能够经过功能层243快速浸润削薄区2422，使得削薄区2422能够发挥作用，而且功能层243本身也能够起到与活性物质层242相同的作用，有利于提升电池单体20的能量密度。当1＜D 1/D 2≤30时，功能层243的活性物质材料的粉末粒子的粒径大于活性物质层242的活性物质材料的粉末粒子的粒径，这样，功能层243的颗粒较削薄区2422的颗粒大，具有较大的阻抗，使得削薄区2422的锂离子释放速度较慢，从而负极片221单位时间需要嵌入的锂离子减少，从而更不易析锂，有利于保证电池单体20的性能。
在一些实施例中，1.01≤D 1/D 2≤10。
D 1/D 2的取值可以为：D 1/D 2＝1.01、1.05、1.2、1.5、1.8、2、2.2、2.5、2.8、3、3.2、3.5、3.8、4、4.2、4.5、4.8、5、5.2、5.5、5.8、6、6.5、7、7.5、8、8.5、9、9.5、10等。
当1.01≤D 1/D 2≤10时，既能够达到不易析锂的效果，又不会使得锂离子的释放速度过慢，有利于保证放电效率。
在一些实施例中，极片24为负极片221。功能层243包括活性物质材料，功能层243的活性物质材料的克容量为M 1。活性物质层242的活性物质材料的克容量为M 2，满足：1.01≤M 1/M 2≤5。
克容量是指活性物质材料所能释放出的电容量与活性物质材料的质量之比。
M 1表示功能层243的活性物质材料的克容量。
M 2表示活性物质层242的活性物质材料的克容量。
M 1/M 2表示功能层243的活性物质材料的克容量与活性物质层242的活性物质材料的克容量之比。
功能层243的活性物质材料的克容量与活性物质层242的活性物质材料的克容量之比的取值可以为：M 1/M 2＝1.01、1.05、1.2、1.5、1.8、2、2.2、2.5、2.8、3、3.2、3.5、3.8、4、4.2、4.5、4.8、5等。
1.01≤M 1/M 2≤5时，功能层243的活性物质材料的克容量大于活性物质层242的活性物质材料的克容量，这样，可以提升极片24在功能区所在区域的CB值(Cell balance，电芯平衡率，CB值等于负极片221的单位活性容量除以正极片222的单位活性容量)，负极片221能够用于嵌入锂离子的空间增大，从而更不易析锂，有利于保证电池单体20的性能。
在一些实施例中，1.01≤M 1/M 2≤1.3。
功能层243的活性物质材料的克容量与活性物质层242的活性物质材料的克容量之比的取值可以为：M 1/M 2＝1.01、1.05、1.08、1.1、1.12、1.15、1.18、1.2、1.22、1.25、1.28、1.3等。
通过使1.01≤M 1/M 2≤1.3，既能够增大负极片221用于嵌入锂离子的空间，从而不易析锂，还不会使CB值过大，而造成成本大幅提升。
在一些实施例中，极片24为正极片222，功能层243包括活性物质材料， 功能层243的活性物质材料的克容量为M 1，主体区2421的活性物质材料的克容量为M 2，满足：0.3≤M 1/M 2≤1.01。
功能层243的活性物质材料的克容量与活性物质层242的活性物质材料的克容量之比的取值可以为：M 1/M 2＝0.3、0.35、0.4、0.45、0.5、0.55、0.6、0.65、0.7、0.75、0.8、0.85、0.9、0.95、1、1.01等。
0.3≤M 1/M 2＜1时，功能层243的活性物质材料的克容量小于活性物质层242的活性物质材料的克容量，这样，可以提升极片24在功能区所在区域的CB值，正极片222能够释放的锂离子较少，从而不易析锂，有利于保证电池单体20的性能。当1≤M 1/M 2≤1.01时，功能层243的活性物质材料的克容量等于或者略大于活性物质层242的活性物质材料的克容量，这样，功能层243不但能够有利于毛细作用的发挥，使电解液能够经过功能层243快速浸润削薄区2422，使得削薄区2422能够发挥作用，而且功能层243本身也能够起到与活性物质层242相同的作用，有利于提升电池单体20的能量密度。
在一些实施例中，0.5≤M 1/M 2≤1.01。
功能层243的活性物质材料的克容量与活性物质层242的活性物质材料的克容量之比的取值可以为：M 1/M 2＝0.5、0.52、0.55、0.58、0.6、0.62、0.65、0.68、0.7、0.72、0.75、0.78、0.8、0.82、0.85、0.88、0.9、0.92、0.95、0.98、1、1.01等。
当0.5≤M 1/M 2≤1.01时，功能层243的活性物质材料的克容量相对较大，功能层243本身也能够起到与活性物质层242相同的作用，有利于提升电池单体20的能量密度。
请参照图5，在一些实施例中，沿集流体241的厚度方向，功能层243的最小厚度为h，满足：1μm≤h≤80μm。
功能层243的最小厚度是指功能层243在其最薄位置的厚度。请参照图5，沿第一方向，功能层243在削薄区2422指向主体区2421的方向的一端的是其最薄位置，功能层243的最小厚度也即该最薄位置的厚度。
沿集流体241的厚度方向，功能层243的最小厚度的取值可以为：h＝1μm、5μm、10μm、15μm、20μm、25μm、30μm、35μm、40μm、50μm、60μm、70μm、80μm等。
将功能层243的最小厚度限制在1～80μm，这样极片24卷绕或层叠形成电极组件22后，功能层243与隔离膜223之间的间隙较小，有利于毛细作用的发挥，同时使极片24不会太厚，以使电池单体20具有较高的能量密度。若h＜1μm，则功能层243的最小厚度较薄，对毛细作用的提升不明显。若h＞80μm，则功能层243的最小厚度较厚，说明功能层243整体较厚，则会使极片24较厚，可能使电池单体20的能量密度降低。
请参照图5，在一些实施例中，功能层243在第一方向的长度为L 1，削薄区2422在第一方向的长度为L 2，满足：0.8≤L 1/L 2≤1.5。
功能层243在第一方向的长度是指功能层243沿第一方向的两端之间的距 离。
削薄区2422在第一方向的长度是指削薄区2422沿第一方向的两端之间的距离。
L 1/L 2是指功能层243在第一方向的长度与削薄区2422在第一方向的长度之比。功能层243在第一方向的长度与削薄区2422在第一方向的长度之比的取值可以为：L 1/L 2＝0.8、0.85、0.9、0.95、1、1.05、1.1、1.15、1.2、1.25、1.3、1.35、1.4、1.45、1.5等。
功能层243在第一方向的长度是削薄区2422在第一方向的长度的0.8～1.5倍。这样，功能层243能够沿第一方向基本覆盖或者完全覆盖削薄区2422，使得极片24卷绕或层叠形成电极组件22后功能层243与隔离膜223之间的间隙较小，有利于毛细作用的发挥。
请参照图5，在一些实施例中，沿集流体241的厚度方向，功能层243具有背离集流体241的第一表面2431。第一表面2431与集流体241的最大距离为T 1，主体区2421的厚度为T 2，满足：0.8≤T 1/T 2≤1.1。
第一表面2431是功能层243沿集流体241的厚度方向背离集流体241的表面。
T1表示第一表面2431与集流体241的最大距离，也可以理解为是削薄区2422和功能层243的总厚度的最大值。
T2表示主体区2421的厚度，也可以理解为是沿厚度方向，主体区2421背离集流体241的表面到集流体241的距离。
T 1/T2表示第一表面2431与集流体241的最大距离与主体区2421的厚度的比值。第一表面2431与集流体241的最大距离与主体区2421的厚度的比值的取值可以为：T 1/T 2＝0.8、0.82、0.85、0.87、0.9、0.92、0.95、0.97、1、1.02、1.05、1.07、1.1等。
沿厚度方向，第一表面2431与集流体241的最大距离是主体区2421厚度的0.8～1.1倍。这样，第一表面2431基本与主体区2421背离集流体241的表面相平齐，有利于毛细作用的发挥，同时使极片24不会太厚，以使电池单体20具有较高的能量密度。若T 1＜0.8T 2，则极片24卷绕或层叠形成电池单体20后，功能层243与隔离膜223的间隙相对较大，电解液浸润削薄区2422的浸润速度相对较慢。若T 1＞1.1T 2，则沿着集流体241指向活性物质层242的方向，功能层243超出于主体区2421背离集流体241的表面的距离较大，极片24卷绕或层叠形成电池单体20后，主体区2421与隔离膜223的间距增大，使得主体区2421的浸润速度变慢。另外，极片24占用空间增大，还存在降低电池单体20能量密度的风险。
在一些实施例中，0.9≤T 1/T 2≤1.01。
第一表面2431与集流体241的最大距离与主体区2421的厚度的比值的取值可以为：T 1/T 2＝0.9、0.91、0.92、0.93、0.94、0.95、0.96、0.97、0.98、0.99、1、1.01等。
沿厚度方向，第一表面2431与集流体241的最大距离是主体区2421厚度的 0.9～1.01倍。这样，第一表面2431基本与主体区2421背离集流体241的表面相平齐，主体区2421和削薄区2422均能够被快速浸润，同时使极片24不会太厚，以使电池单体20具有较高的能量密度。
请参照图5，在一些实施例中，削薄区2422具有第二表面24221，功能层243设置于第二表面24221。沿主体区2421指向削薄区2422的方向，第二表面24221与集流体241在集流体241的厚度方向上的距离逐渐减小。
“沿主体区2421指向削薄区2422的方向，第二表面24221与集流体241在集流体241的厚度方向上的距离逐渐减小”也可以理解为沿主体区2421指向削薄区2422的方向，削薄区2422的厚度逐渐减小。
通过使削薄区2422沿主体区2421指向削薄区2422的方向的厚度逐渐减小，有利于减小活性物质层242与极耳部2411交界处的应力。
请参照图5，在一些实施例中，第二表面24221为圆弧面。
将第二表面24221设置为圆弧面，有利于减小应力集中。
请参照图5、图6、图7和图8，图6为本申请另一些实施例提供的极片24的结构示意图。图7为本申请又一些实施例提供的极片24的结构示意图。图8为本申请再一些实施例提供的极片24的结构示意图。在一些实施例中，第二表面24221与集流体241相交于第一边缘。功能层243包覆第一边缘。
第一边缘是第二表面24221与集流体241的设置活性物质层242的表面相交形成的。第一边缘也可以理解为是削薄区2422沿着主体区2421指向削薄区2422的方向的边缘。
功能层243包覆第一边缘也可以理解为功能层243覆盖第一边缘。
通过使功能层243包覆第一边缘，以降低削薄区2422脱落掉粉的风险。
请参照图7和图8，在一些实施例中，功能层243覆盖极耳部2411的一部分。
功能层243覆盖极耳部2411的一部分也可以理解为：功能层243的一部分设置于极耳部2411。
通过使削薄区2422覆盖极耳部2411的一部分，可对极耳部2411的根部进行加固，降低极耳根部出现变形褶皱的风险。
请参照图7和图8，在一些实施例中，沿第一方向，功能层243具有背离主体区2421的第三表面2432。第三表面2432与集流体241相交于第二边缘，第二边缘与第一边缘的间距为L 3，满足：0≤L 3≤5mm。
第二边缘是第三表面2432与集流体241的设置活性物质层242的表面相交形成的。
L 3表示第二边缘沿第一方向与第一边缘之间的距离。第二边缘沿第一方向与第一边缘之间的距离的取值可以为：L 3＝0、0.5mm、1mm、1.5mm、2mm、2.5mm、3mm、3.5mm、4mm、4.5mm、5mm等。
沿第一方向，第二边缘与第一边缘的间距在0～5mm，以使得功能层243能够具有足够的面积涂覆于极耳部2411，对极耳的根部起到加固的作用，同时，功能层 243又不会影响极耳的长度。若L 3＞5mm，则功能层243包覆极耳部2411的面积较大，会影响极耳的成型。
在一些实施例中，1mm≤L 3≤2mm。
第二边缘沿第一方向与第一边缘之间的距离的取值可以为：L 3＝1mm、1.1mm、1.2mm、1.3mm、1.4mm、1.5mm、1.6mm、1.7mm、1.8mm、1.9mm、2mm等。
沿第一方向，第二边缘与第一边缘的间距在1～2mm之间，使得功能层243能够对极耳部2411具有较好的加固效果的同时，不易影响极耳的成型。当0≤L 3＜1mm时，功能层243覆盖第一边缘的范围不够大，降低削薄区2422脱落掉粉的效果不太好。当2＜L 3≤5mm时，功能层243包覆极耳部2411的面积较大，生产成本提高。
请再次参照图5，在一些实施例中，功能层243具有第一表面2431、第三表面2432和第四表面。第四表面与第二表面24221贴合。第一表面2431与主体区2421沿集流体241的厚度方向背离集流体241的表面平行或平齐。第一表面2431与第四表面相交，第三表面2432连接第一表面2431和第四表面，第三表面2432与第一表面2431垂直。
功能层243设置于第二表面24221，其第四表面与第二表面24221相贴合，便于电解液经过功能层243后浸润削薄区2422。
第一表面2431是功能层243沿厚度方向背离集流体241的表面。第一表面2431与主体区2421沿集流体241厚度方向背离集流体241的表面平行或平齐，则使得功能层243和隔离膜223之间的间隙的宽度一致，更有利于毛细作用的发挥。
沿厚度方向，第三表面2432具有较大的长度。这样极片24卷绕或层叠形成电极组件22后，功能层243与隔离膜223之间的间隙较小，有利于毛细作用的发挥，使得电解液能够经过功能层243快速浸润削薄区2422，使得削薄区2422能够发挥作用，有利于提升电池单体20的能量密度。
请参照图6，在另一些实施例中，第一表面2431与主体区2421沿集流体241的厚度方向背离集流体241的表面平齐。
第一表面2431与主体区2421沿厚度方向背离集流体241的表面平齐，则极片24卷绕或层叠形成电极组件22后，主体区2421和隔离膜223之间的间隙与第一表面2431和隔离膜223之间的间隙宽度相等，能够保证电解液快速浸润削薄区2422的同时，不会使极片24厚度增大，能够大大提升电池单体20的能量密度。这样设置功能层243的效果较为理想。
请参照图6，在一些实施例中，第三表面2432与集流体241相交。
第三表面2432与集流体241相交，表明功能层243覆盖了削薄区2422从主体区2421指向削薄区2422的方向的边缘，具有较好的保液效果。
在另一些实施例中，第三表面2432与第二表面24221相交。此时，功能层243未覆盖削薄区2422从主体区2421指向削薄区2422的方向的边缘，但仍能够使得电解液浸润削薄区2422的大部分，使得削薄区2422能够发挥作用，提升电池单体20的能量密度。
请参照图7，在又一些实施例中，功能层243具有第一表面2431、第三表面 2432、第四表面和第五表面2434。第四表面与第二表面24221贴合。第一表面2431与主体区2421沿集流体241的厚度方向背离集流体241的表面平行或平齐。第五表面2434贴合于集流体241，第三表面2432连接第五表面2434和第一表面2431。第四表面连接第一表面2431和第五表面2434。
第五表面2434贴合于集流体241包括第五表面2434贴合于极耳部2411，这样，功能层243能够对极耳部2411的根部进行加固，降低极耳根部出现变形褶皱的风险。
由于功能层243可以是流体干燥后形成的，在按照较为理想的方式设置功能层243时，功能层243可能会流动而形成上述的形状，此时，功能层243也具有较好的保液效果，能够使得削薄区2422被快速浸润，使得削薄区2422能够发挥作用。
请参照图8，在再一些实施例中，第一表面2431与主体区2421沿集流体241的厚度方向背离集流体241的表面平齐。
第一表面2431与主体区2421沿厚度方向背离集流体241的表面平齐，则极片24卷绕或层叠形成电极组件22后，主体区2421和隔离膜223之间的间隙与第一表面2431和隔离膜223之间的间隙宽度相等，能够保证电解液快速浸润削薄区2422的同时，不会使极片24厚度增大，能够大大提升电池单体20的能量密度。
请参照图7和图8，在一些实施例中，第三表面2432为圆弧面。
将第三表面2432设置为圆弧面，有利于减小应力集中。
在另一些实施例中，第二表面24221也可以为波浪形的弧面，同样有利于减小应力集中。
在一些实施例中，集流体241沿厚度方向相对的两个表面均设置有活性物质层242，每个活性物质层242的削薄区2422设置有功能层243。
集流体241沿厚度方向包括相对设置的两个表面，两个表面上均设置有活性物质层242。每个活性物质层242均具有削薄区2422，每个削薄区2422上均设置有功能层243。
在集流体241的两侧均设置活性物质层242，并在每个活性物质层242的削薄区2422上设置功能层243，以便于将极片24通过卷绕或层叠的方式形成电极组件22。
本申请实施例还提供了一种电极组件22，电极组件22包括上述的极片24。
电极组件22包括正极片222、负极片221和隔离膜223，正极片222、隔离膜223和负极片221卷绕或层叠形成电极组件22。正极片222和负极片221中的至少一者为上述的极片24。
本申请实施例还提供了一种电池单体20，电池单体20包括上述的电极组件22。
本申请实施例还提供了一种电池100，电池100包括上述的电池单体20。
本申请实施例还提供了一种用电设备，用电设备包括上述的电池100，电池100用于为用电设备提供电能。
根据本申请的一些实施例，请参照图3～图8。
本申请实施例提供了一种极片24，极片24包括集流体241、活性物质层242和功能层243。活性物质层242设置于集流体241的表面。活性物质层242包括主体区2421和削薄区2422，削薄区2422设置于主体区2421沿第一方向的一端，主体区2421的厚度大于削薄区2422的厚度。沿第一方向，集流体241具有沿背离主体区2421的方向超出于削薄区2422的极耳部2411。功能层243设置于削薄区2422背离集流体241的表面，功能层243被配置为允许电解液通过。该极片24在活性物质层242的削薄区2422上设置有允许电解液通过的功能层243，这样极片24卷绕或层叠形成电极组件22后，功能层243与隔离膜223之间的间隙较小，有利于毛细作用的发挥，使得电解液能够经过功能层243快速浸润削薄区2422，使得削薄区2422能够发挥作用，有利于提升电池单体20的能量密度。另外，较小的间隙使得锂离子传输的路径较短，能够降低析锂的风险，提升电池单体20的性能。
削薄区2422具有第二表面24221，功能层243设置于第二表面24221，沿主体区2421指向削薄区2422的方向，第二表面24221与集流体241在集流体241的厚度方向上的距离逐渐减小。第二表面24221与集流体241相交于第一边缘，功能层243包覆第一边缘。通过使功能层243包覆第一边缘，以降低削薄区2422脱落掉粉的风险。
功能层243覆盖极耳部2411的一部分。通过使削薄区2422覆盖极耳部2411的一部分，可对极耳部2411的根部进行加固，降低极耳根部出现变形褶皱的风险。
以上所述仅为本申请的优选实施例而已，并不用于限制本申请，对于本领域的技术人员来说，本申请可以有各种更改和变化。凡在本申请的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本申请的保护范围之内。

Claims (28)

  1. 一种极片，其中，包括：
    集流体；
    活性物质层，设置于所述集流体的表面，所述活性物质层包括主体区和削薄区，所述削薄区设置于所述主体区沿第一方向的一端，所述主体区的厚度大于所述削薄区的厚度，沿所述第一方向，所述集流体具有沿背离所述主体区的方向超出于所述削薄区的极耳部；
    功能层，设置于所述削薄区背离所述集流体的表面，所述功能层被配置为允许电解液通过。
  2. 根据权利要求1所述极片，其中，所述功能层储存电解液的能力强于所述活性物质层。
  3. 根据权利要求2所述极片，其中，所述功能层包括偏二氟乙烯聚合物、六氟丙烯聚合物、偏二氟乙烯-六氟丙烯聚合物、聚丙烯酸、聚苯乙烯丁二烯共聚物、聚乙烯醇、聚烯酸酯、聚氨酯、氯化橡胶、环氧树脂中的至少一种。
  4. 根据权利要求3所述极片，其中，所述功能层还包括导电剂。
  5. 根据权利要求4所述极片，其中，所述导电剂包括乙炔黑、活性炭、炭黑、导电石墨、碳纳米管中的至少一种。
  6. 根据权利要求1所述极片，其中，所述极片为负极片，所述功能层包括活性物质材料，所述功能层的活性物质材料体积分布中粒径大于D 1的粉末粒子占50％，所述活性物质层的活性物质材料体积分布中粒径大于D 2的粉末粒子占50％，满足：1≤D 2/D 1≤25。
  7. 根据权利要求6所述极片，其中，1.01≤D 2/D 1≤5。
  8. 根据权利要求1所述极片，其中，所述极片为正极片，所述功能层包括活性物质材料，所述功能层的活性物质材料体积分布中粒径大于D 1的粉末粒子占50％，所述活性物质层的活性物质材料体积分布中粒径大于D 2的粉末粒子占50％，满足：1≤D 1/D 2≤30。
  9. 根据权利要求8所述极片，其中，1.01≤D 1/D 2≤10。
  10. 根据权利要求1所述极片，其中，所述极片为负极片，所述功能层包括活性物质材料，所述功能层的活性物质材料的克容量为M 1，所述活性物质层的活性物质材料的克容量为M 2，满足：1.01≤M 1/M 2≤5。
  11. 根据权利要求10所述极片，其中，1.01≤M 1/M 2≤1.3。
  12. 根据权利要求1所述极片，其中，所述极片为正极片，所述功能层包括活性物质材料，所述功能层的活性物质材料的克容量为M 1，所述活性物质层的活性物质材料的克容量为M 2，满足：0.3≤M 1/M 2≤1.01。
  13. 根据权利要求12所述极片，其中，0.5≤M 1/M 2≤1.01。
  14. 根据权利要求1-13任一项所述极片，其中，沿所述集流体的厚度方向，所述功能层的最小厚度为h，满足：1μm≤h≤80μm。
  15. 根据权利要求1-14任一项所述极片，其中，所述功能层在所述第一方向的长度为L 1，所述削薄区在所述第一方向的长度为L 2，满足：0.8≤L 1/L 2≤1.5。
  16. 根据权利要求1-15任一项所述极片，其中，沿所述集流体的厚度方向，所述功能层具有背离所述集流体的第一表面，所述第一表面与所述集流体的最大距离为T 1，所述主体区的厚度为T 2，满足：0.8≤T 1/T 2≤1.1。
  17. 根据权利要求16所述极片，其中，0.9≤T 1/T 2≤1.01。
  18. 根据权利要求1-17任一项所述极片，其中，所述削薄区具有第二表面，所述功能层设置于所述第二表面，沿所述主体区指向所述削薄区的方向，所述第二表面与所述集流体在所述集流体的厚度方向上的距离逐渐减小。
  19. 根据权利要求18所述极片，其中，所述第二表面为圆弧面。
  20. 根据权利要求18或19所述极片，其中，所述第二表面与所述集流体相交于第一边缘，所述功能层包覆所述第一边缘。
  21. 根据权利要求20所述极片，其中，所述功能层覆盖所述极耳部的一部分。
  22. 根据权利要求20或21所述极片，其中，沿所述第一方向，所述功能层具有背离所述主体区的第三表面，所述第三表面与所述集流体相交于第二边缘，所述第二边缘与所述第一边缘的间距为L 3，满足：0≤L 3≤5mm。
  23. 根据权利要求22所述极片，其中，1mm≤L 3≤2mm。
  24. 根据权利要求1-23任一项所述极片，其中，所述集流体沿厚度方向相对的两个表面均设置有所述活性物质层，每个所述活性物质层的削薄区设置有所述功能层。
  25. 一种电极组件，其中，包括根据权利要求1-24任一项所述的极片。
  26. 一种电池单体，其中，包括根据权利要求25所述的电极组件。
  27. 一种电池，其中，包括如权利要求26所述的电池单体。
  28. 一种用电设备，其中，包括根据权利要求27所述的电池，所述电池用于为所述用电设备提供电能。
PCT/CN2022/131740 2022-11-14 2022-11-14 极片、电极组件、电池单体、电池及用电设备 WO2024103224A1 (zh)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/CN2022/131740 WO2024103224A1 (zh) 2022-11-14 2022-11-14 极片、电极组件、电池单体、电池及用电设备

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CN2022/131740 WO2024103224A1 (zh) 2022-11-14 2022-11-14 极片、电极组件、电池单体、电池及用电设备

Publications (1)

Publication Number Publication Date
WO2024103224A1 true WO2024103224A1 (zh) 2024-05-23

Family

ID=91083587

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2022/131740 WO2024103224A1 (zh) 2022-11-14 2022-11-14 极片、电极组件、电池单体、电池及用电设备

Country Status (1)

Country Link
WO (1) WO2024103224A1 (zh)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20160329557A1 (en) * 2013-12-27 2016-11-10 Sanyo Electric Co., Ltd. Negative electrode for non-aqueous electrolyte secondary batteries
CN108258193A (zh) * 2017-12-28 2018-07-06 湖南三迅新能源科技有限公司 一种负极片及其制备方法、锂离子电池
CN109980177A (zh) * 2019-03-29 2019-07-05 宁德新能源科技有限公司 电极极片和包含所述电极极片的电化学装置
CN216563208U (zh) * 2021-12-24 2022-05-17 珠海冠宇电池股份有限公司 负极片以及电芯
CN217361642U (zh) * 2022-06-16 2022-09-02 宁德时代新能源科技股份有限公司 电极组件、电池单体、电池和用电设备
WO2022204968A1 (zh) * 2021-03-30 2022-10-06 宁德新能源科技有限公司 电化学装置和电子装置

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20160329557A1 (en) * 2013-12-27 2016-11-10 Sanyo Electric Co., Ltd. Negative electrode for non-aqueous electrolyte secondary batteries
CN108258193A (zh) * 2017-12-28 2018-07-06 湖南三迅新能源科技有限公司 一种负极片及其制备方法、锂离子电池
CN109980177A (zh) * 2019-03-29 2019-07-05 宁德新能源科技有限公司 电极极片和包含所述电极极片的电化学装置
WO2022204968A1 (zh) * 2021-03-30 2022-10-06 宁德新能源科技有限公司 电化学装置和电子装置
CN216563208U (zh) * 2021-12-24 2022-05-17 珠海冠宇电池股份有限公司 负极片以及电芯
CN217361642U (zh) * 2022-06-16 2022-09-02 宁德时代新能源科技股份有限公司 电极组件、电池单体、电池和用电设备

Similar Documents

Publication Publication Date Title
US20230170592A1 (en) Electrode assembly, battery cell, battery, and electric apparatus
EP4075563A1 (en) Electrode assembly, battery cell, battery, and method and apparatus for manufacturing electrode assembly
CN115413379B (zh) 电极组件、电池单体、电池及电极组件的制造方法和设备
WO2023246134A1 (zh) 极片、电极组件、电池单体、电池及用电设备
CN216213945U (zh) 电池单体、电池和用电装置
US20240055646A1 (en) Wound electrode assembly, battery cell, battery, and electrical device
WO2024093100A1 (zh) 电极极片、电极组件、电池单体、电池和用电设备
WO2024016911A1 (zh) 电池单体、电池及用电装置
US20230238540A1 (en) Electrode assembly, battery cell, battery, and method and device for manufacturing electrode assembly
CN217740567U (zh) 极片、电池单体、电池和用电设备
WO2023273390A1 (zh) 集流构件、电池单体、电池以及用电装置
WO2024109411A1 (zh) 电池及用电设备
CN115606020B (zh) 电极组件及其制造方法和制造系统、电池单体以及电池
CN116666774A (zh) 电极组件、电池单体、电池及用电设备
WO2024103224A1 (zh) 极片、电极组件、电池单体、电池及用电设备
WO2023236220A1 (zh) 电池单体、电池及用电设备
CN218414630U (zh) 极片、电极组件、电池单体、电池及用电装置
WO2024082138A1 (zh) 电池单体、电池及用电设备
WO2024077557A1 (zh) 电池单体、电池及用电设备
WO2023221606A1 (zh) 集流体、极片、电极组件、电池单体、电池及用电装置
CN217719658U (zh) 电极组件、电池单体、电池以及用电装置
WO2023212867A1 (zh) 正极极片、电极组件、电池单体、电池及用电装置
WO2023220885A1 (zh) 端盖、电池单体、电池及用电设备
WO2024045058A1 (zh) 电池单体、电池及用电设备
CN217788485U (zh) 电极组件、电池单体、电池及用电设备