WO2024087190A1 - 极片、电极组件、二次电池及用电装置 - Google Patents

极片、电极组件、二次电池及用电装置 Download PDF

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Publication number
WO2024087190A1
WO2024087190A1 PCT/CN2022/128342 CN2022128342W WO2024087190A1 WO 2024087190 A1 WO2024087190 A1 WO 2024087190A1 CN 2022128342 W CN2022128342 W CN 2022128342W WO 2024087190 A1 WO2024087190 A1 WO 2024087190A1
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WIPO (PCT)
Prior art keywords
buffer space
pole piece
active material
material layer
electrode sheet
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PCT/CN2022/128342
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English (en)
French (fr)
Inventor
刘智
陈宁
邓亚茜
吕瑞景
史东洋
金海族
李白清
Original Assignee
宁德时代新能源科技股份有限公司
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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/CN2022/128342 priority Critical patent/WO2024087190A1/zh
Publication of WO2024087190A1 publication Critical patent/WO2024087190A1/zh

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    • 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
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • 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

Definitions

  • the present application relates to the field of battery technology, and in particular to pole pieces, electrode assemblies, secondary batteries and electrical devices.
  • Electrode components can be divided into laminated structures and wound structures due to different preparation processes.
  • the present application provides a pole piece having a plurality of corner regions spaced apart along a first direction, wherein when the pole piece is wound along the first direction, the corner regions form a bending layer of the electrode assembly;
  • the pole piece comprises: a current collector; an active material layer disposed on two opposite surfaces of the current collector; wherein, in at least one corner region, a buffer space is provided on the active material layer for forming a concave surface of the bending layer, and the buffer space is recessed along the thickness direction of the pole piece but does not penetrate the current collector.
  • the above-mentioned pole piece is recessed inwardly on the active material layer used to form the concave surface of the bending layer to open a buffer space, and the buffer space is controlled not to penetrate the current collector.
  • the pole piece designed in this way uses the buffer space to at least partially replace the redundancy of active materials that occurs when the active material layer is bent into a concave surface. In this way, when the active material layer on the pole piece is bent at the corner area, a buffer is formed in the buffer space, avoiding the pole piece from being broken due to the mutual squeezing of the redundancy of active materials, thereby effectively improving the stability of the performance of the secondary battery.
  • the buffer space in the corner area with the buffer space, is extended along the second direction, and the second direction is defined as being perpendicular to the plane formed by the first direction and the thickness direction of the pole piece.
  • the buffer space is designed to extend along the second direction, so that the active materials on both sides and in the second direction can better act on the buffer space, further reducing the probability of the current collector being broken due to mutual squeezing of the active materials.
  • the length of the buffer space along the second direction is recorded as L1
  • the length of the active material layer where the buffer space is located along the second direction is recorded as L2
  • the condition satisfied by L1 and L2 is: 0.3 ⁇ L1/L2 ⁇ 1.
  • the thickness of the active material layer used to form the concave surface of the bending layer is recorded as D, and the buffer space is formed with openings on the surface of the active material layer.
  • the sum of the widths of the openings along the first direction is recorded as W, and the condition satisfied by W and D is: 0.6 ⁇ D ⁇ W ⁇ 1.4 ⁇ D.
  • the sum of the widths W of the openings is designed to be between 0.6 ⁇ D and 1.4 ⁇ D, which can satisfy the width collapse caused by the bending of the active material layer surface and avoid the active materials from being squeezed against each other due to the bending.
  • the sum of the widths W also satisfies the condition: 50 micrometers ( ⁇ m) ⁇ W ⁇
  • the range of the sum of the widths of the openings can be reasonably controlled to meet the bending requirements of active material layers of different thicknesses.
  • the width of the buffer space along the first direction is recorded as A, and the width A starts from the surface of the active material layer and gradually decreases along the thickness direction of the pole piece and toward the current collector.
  • the width of the buffer space is designed to be smaller as it is closer to the current collector, so as to keep it consistent with the change of the redundancy of the active material in the thickness direction of the pole piece, and avoid the buffer space being too wide to affect the performance of the secondary battery while satisfying the effective buffering effect.
  • the corner area with buffer space there are multiple buffer spaces, and all buffer spaces are arranged at intervals along the first direction.
  • multiple buffer spaces are arranged in the first direction, increasing the space for deformable buffer in the first direction, further preventing the active materials from being squeezed against each other during bending, resulting in the current collector being broken.
  • the gap between two adjacent buffer spaces is denoted as H, and the condition that H satisfies is: 25 ⁇ m ⁇ H ⁇ 2500 ⁇ m.
  • the gap between the buffer spaces is controlled between 25 ⁇ m and 2500 ⁇ m, which facilitates the design of the buffer space on the active material layer.
  • the sum of the widths W also satisfies the condition: 80 ⁇ m ⁇ H ⁇ 1000 ⁇ m. In this way, the gap between two adjacent buffer spaces is reasonably controlled to avoid large extrusion internal stress caused by bending of the pole piece, and to avoid excessive concentration of buffer spaces resulting in excessively wide pole piece gaps.
  • the buffer space does not penetrate the active material layer where it is located along the thickness direction of the electrode sheet. In this way, the active material layer is not penetrated, so that the active material layer is prevented from falling off due to disconnection, and the structure of the electrode assembly is stable.
  • the present application provides an electrode assembly, which is formed by winding a positive electrode sheet, a negative electrode sheet and a separator interposed between the positive electrode sheet and the negative electrode sheet, and the electrode assembly includes a bending portion, and the bending portion includes a plurality of stacked bending layers; wherein the positive electrode sheet and/or the negative electrode sheet is any one of the above electrode sheets.
  • the electrode assembly further includes a straight portion and two bent portions, which are respectively arranged on opposite sides of the straight portion. This design forms an electrode assembly with a flat structure having bent ends and a straight middle.
  • the present application provides a secondary battery comprising the above electrode assembly.
  • the present application provides an electrical device, comprising the above secondary battery.
  • FIG1 is a schematic diagram of the structure of an electrode assembly provided in some embodiments of the present application.
  • FIG2 is a schematic diagram of the structure of the bending layer in FIG1 ;
  • FIG3 is a schematic diagram of the structure of a vehicle provided in some embodiments of the present application.
  • FIG4 is a schematic diagram of an exploded structure of a secondary battery provided in some embodiments of the present application.
  • FIG5 is a top view of the structure of a pole piece provided in some embodiments of the present application.
  • FIG6 is a cross-sectional view 1 of a pole piece in the same corner region provided by some embodiments of the present application.
  • FIG. 7 is a second cross-sectional view of a pole piece in the same corner region provided in some embodiments of the present application.
  • 1000 electrical device; 100, secondary battery; 200, motor; 300, controller; 10, electrode assembly; 20, end cap; 30, electrode terminal; 40, shell; 1, pole piece; 11, current collector; 12, buffer space; 121, first inner wall; 122, second inner wall; 123, opening; 13, corner area; 14, straight area; 15, active material layer; 2, positive pole piece; 3, negative pole piece; 4, diaphragm; 5, straight portion; 6, bending portion; 61, bending layer; 611, concave surface; 612, convex surface; X, first direction; Y, second direction; Z, thickness direction.
  • the term "and/or" is only a description of the association relationship of associated objects, indicating that three relationships may exist.
  • 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 article generally indicates that the associated objects before and after are in an "or" relationship.
  • multiple refers to more than two (including two).
  • multiple groups refers to more than two groups (including two groups), and “multiple pieces” refers to more than two pieces (including two pieces).
  • Power 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 the application field of power batteries, the market demand is also constantly expanding.
  • each bent layer 61 has a concave surface 611 and a convex surface 612 opposite to each other, and the concave surface 611 and the convex surface 612 of the bent layer 61 are respectively formed by bending the active material layer 15 on both sides of the electrode sheet 1.
  • the curvature radius of the concave surface 611 of the bending layer 61 is smaller than the curvature radius of the convex surface 612 of the bending layer 61, when the active material layer 15 is bent to form the concave surface 611, some active materials will be redundant, resulting in the mutual squeezing of the active materials on the concave surface 611, which generates a large tensile stress on the current collector 1111. In this way, after the hot pressing process or cyclic expansion in production, the current collector 1111 on the bending layer 61 is easily broken, affecting the stability of the performance of the secondary battery 100.
  • a pole piece 1 after in-depth research.
  • a buffer space 12 is provided on the active material layer 15 used to form the concave surface 611 of the bending layer 61, and the buffer space 12 is recessed along the thickness direction Z of the pole piece 1 but does not penetrate the current collector 1111.
  • the active material layer 15 used to form the concave surface 611 of the bending layer 61 is recessed inward to form a buffer space 12, and the buffer space 12 is controlled not to penetrate the current collector 1111.
  • the buffer space 12 is used to at least partially replace the redundancy of active materials that occurs when the active material layer 15 is bent into the concave surface 611, so that when the active material layer 15 on the pole piece 1 is bent at the corner area 13, a buffer is formed in the buffer space 12, avoiding the pole piece 1 from being broken due to the mutual squeezing of the redundancy of active materials, thereby effectively improving the stability of the performance of the secondary battery 100.
  • the secondary battery 100 disclosed in the embodiment of the present application can be used in, but not limited to, an electric device 1000 such as a vehicle, a ship, or an aircraft.
  • a power supply system including the secondary battery 100 disclosed in the present application and the like can be used to form the electric device 1000.
  • the embodiment of the present application provides an electric device 1000 using a battery as a power source
  • the electric device 1000 may be, but is not limited to, a mobile phone, a tablet, a laptop, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, etc.
  • the electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc.
  • the spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.
  • FIG. 3 is a schematic diagram of the structure of a vehicle provided in some embodiments of the present application.
  • the vehicle can be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc.
  • a secondary battery 100 is arranged inside the vehicle, and the secondary battery 100 can be arranged at the bottom, head or tail of the vehicle.
  • the secondary battery 100 can be used to power the vehicle, for example, the secondary battery 100 can be used as an operating power source for the vehicle.
  • the vehicle may also include a controller 300 and a motor 200, and the controller 300 is used to control the secondary battery 100 to power the motor 200, for example, for the starting, navigation and working power requirements of the vehicle during driving.
  • the secondary battery 100 can be used not only as an operating power source for the vehicle, but also as a driving power source for the vehicle, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle.
  • the secondary battery 100 may also include other structures.
  • the secondary battery 100 may also include a confluence component for realizing electrical connection between the multiple secondary batteries 100.
  • the secondary battery 100 may be cylindrical, flat, rectangular, or in other shapes.
  • FIG. 4 is a schematic diagram of the exploded structure of a secondary battery 100 provided in some embodiments of the present application.
  • the secondary battery 100 refers to the smallest unit of a battery.
  • the secondary battery 100 includes an end cap 20, a housing 40, an electrode assembly 10, and other functional components.
  • the end cap 20 refers to a component that covers the opening of the shell 40 to isolate the internal environment of the secondary battery 100 from the external environment.
  • the shape of the end cap 20 can be adapted to the shape of the shell 40 to match the shell 40.
  • the end cap 20 can be made of a material with a certain hardness and strength (such as an aluminum alloy), so that the end cap 20 is not easily deformed when it is squeezed and collided, so that the secondary battery 100 can have a higher structural strength and the safety performance can also be improved.
  • Functional components such as electrode terminals 30 can be provided on the end cap 20. The electrode terminal 30 can be used to electrically connect to the electrode assembly 10 for outputting or inputting electrical energy of the secondary battery 100.
  • the end cap 20 can also be provided with a pressure relief mechanism for releasing the internal pressure when the internal pressure or temperature of the secondary battery 100 reaches a threshold.
  • the material of the end cap 20 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 any special restrictions on this.
  • an insulating member may be provided inside the end cap 20, and the insulating member may be used to isolate the electrical connection components in the housing 40 from the end cap 20 to reduce the risk of short circuit.
  • the insulating member may be plastic, rubber, or the like.
  • the shell 40 is a component used to cooperate with the end cap 20 to form the internal environment of the secondary battery 100, wherein the formed internal environment can be used to accommodate the electrode assembly 10, the electrolyte and other components.
  • the shell 40 and the end cap 20 can be independent components, and an opening can be set on the shell 40, and the internal environment of the secondary battery 100 is formed by covering the opening with the end cap 20 at the opening.
  • the end cap 20 and the shell 40 can also be integrated.
  • the end cap 20 and the shell 40 can form a common connection surface before other components enter the shell, and when the interior of the shell 40 needs to be encapsulated, the end cap 20 covers the shell 40.
  • the shell 40 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 40 can be determined according to the specific shape and size of the electrode assembly 10.
  • the material of the shell 40 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.
  • the electrode assembly 10 is a component in the secondary battery 100 where electrochemical reactions occur.
  • One or more electrode assemblies 10 may be included in the housing 40.
  • the electrode assembly 10 is mainly formed by winding or stacking a positive electrode sheet 2 and a negative electrode sheet 3, and a separator 4 is usually provided between the positive electrode sheet 2 and the negative electrode sheet 3.
  • the parts of the positive electrode sheet 2 and the negative electrode sheet 3 with active materials constitute the main body of the electrode assembly 10, and the parts of the positive electrode sheet 2 and the negative electrode sheet 3 without active materials each constitute a tab.
  • the positive electrode tab and the negative electrode tab 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 tabs connect the electrode terminals 30 to form a current loop.
  • the present application provides a pole piece 1.
  • the pole piece 1 has a plurality of corner regions 13 spaced apart along a first direction X. When the pole piece 1 is wound along the first direction X, the corner regions 13 form a bending layer 61 of the electrode assembly 10.
  • the pole piece 1 includes a current collector 11 and an active material layer 15, and the active material layer 15 is disposed on two opposite surfaces of the current collector 11. Among them, in at least one corner region 13, a buffer space 12 is provided on the active material layer 15 for forming a concave surface of the bending layer 61, and the buffer space 12 is recessed along the thickness direction Z of the pole piece 1 but does not penetrate the current collector 11.
  • the current collector 11 refers to a component that can not only carry active materials, but also collect and output the current generated by the electrode active materials.
  • the material of the current collector 11 can be selected differently according to the polarity of the electrode sheet 1.
  • the material of the current collector 11 in the positive electrode sheet 2, can be but not limited to metal materials such as aluminum and nickel, and can also be composite materials such as conductive resin, titanium-nickel shape memory alloy, and carbon-coated aluminum foil.
  • the material of the current collector 11 can be but not limited to metal materials such as copper, and of course it can also be a composite material such as conductive resin, titanium-nickel shape memory alloy, etc.
  • the active material layer 15 refers to the active material coated on the current collector 11, and its material can be selected according to the polarity of the electrode 1.
  • the material of the active material layer 15 can be but not limited to lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, lithium iron phosphate, ternary materials, etc.
  • the material of the active material layer 15 can be but not limited to graphite, silicon oxide, etc.
  • the corner area 13 refers to the bending layer 61 formed on several sections when the electrode sheet 1 is wound along the first direction X in the preparation of the electrode assembly 10, and the bending layer 61 in the area corresponding to the electrode sheet 1 is the corner area 13.
  • the electrode assembly 10 formed by winding includes a bending portion 6, and the bending portion 6 includes a plurality of stacked bending layers 61.
  • corner regions 13 are arranged at intervals along the first direction X on the current collector 11, and a straight region 14 is left between two adjacent corner regions 13, which is opposite to the straight portion 5 of the electrode assembly 10.
  • the two adjacent corner regions 13 are respectively located on different bending portions 6 of the electrode assembly 10.
  • the two bending portions 6 of the electrode assembly 10 can be defined as the left bending portion 6 and the right bending portion 6, respectively.
  • the first corner region 13 is wound on the left bending portion 6, and the second corner region 13 is wound on the right bending portion 6; then, the third corner region 13 is wound on the left bending portion 6, and the fourth corner region 13 is wound on the right bending portion 6, and so on.
  • the remaining corner regions 13 are respectively wound on different bending portions 6.
  • corner areas 13 on the current collecting body 11 only some of the corner areas 13 may be provided with the buffer space 12 , or all of the corner areas 13 may be provided with the buffer space 12 .
  • the buffer space 12 refers to the inwardly concave space on the surface of the active material layer 15, which can reduce the content of active materials on the active material layer 15, for example, the volume in the buffer space 12 is just the redundancy of the active material when bending.
  • the buffer space 12 plays a role in buffering the deformation of the active material layer 15 when bending. For example, when bending, the active materials located on both sides of the buffer space 12 are deformed toward the inside of the buffer space 12 due to the bending, so that the extrusion internal stress is released in the buffer space 12, avoiding the mutual extrusion of the active materials.
  • the shape of the buffer space 12 formed on the active material layer 15 can be square, circular, elliptical, etc.
  • the distribution state of the buffer space 12 in the same turning area can be set only on the active material layer 15 that can form a concave surface; or it can be set on the active material layer 15 on both sides at the same time.
  • the number of buffer spaces 12 can be one or more.
  • the buffer space 12 extends along the thickness direction Z of the electrode 1 but does not penetrate the current collector 11. It should be understood that: the buffer space 12 extends inward on the active material layer 15, but cannot extend through the current collector 11, for example: the buffer space 12 extends inside the active material layer 15; or, the buffer space 12 penetrates the active material layer 15 and just extends to the surface of the current collector 11; or, the buffer space 12 penetrates the active material layer 15 and extends to the inside of the current collector 11, etc.
  • the buffer space 12 is utilized to at least partially replace the redundancy of active materials that occurs when the active material layer 15 is bent into a concave surface.
  • a buffer is formed in the buffer space 12, thereby preventing the pole piece 1 from being broken due to mutual squeezing of the redundant active materials, thereby effectively improving the stability of the performance of the secondary battery 100.
  • the buffer space 12 is extended along the second direction Y, and the second direction Y is defined as being perpendicular to the plane formed by the first direction X and the thickness direction Z of the pole piece 1 .
  • the first direction X refers to the direction in which the pole piece 1 is wound, and can also be understood as the length direction of the pole piece 1 ; meanwhile, the second direction Y can also be understood as the width direction of the pole piece 1 .
  • the buffer space 12 is designed to extend along the second direction Y to ensure that the active material on both sides and in the second direction Y can better act on the buffer space 12.
  • the opposite ends of the buffer space 12 extend to the opposite sides of the active material layer 15 along the second direction Y, that is, the buffer space 12 penetrates the active material layer 15 along the second direction Y; or, one end of the buffer space 12 extends along the second direction Y to a side surface of the active material layer 15 along the second direction Y; or, neither end of the buffer space 12 extends to the opposite sides of the active material layer 15 along the second direction Y, etc.
  • the number of the buffer space 12 may be one or more in the second direction Y.
  • a single buffer space 12 may be arranged along the second direction Y, or multiple buffer spaces 12 may be arranged in the second direction Y at intervals.
  • the buffer space 12 is designed to extend along the second direction Y, so that the active materials on both sides and in the second direction Y can better act on the buffer space 12, further reducing the probability of the current collector 11 being broken due to mutual squeezing of the active materials.
  • the length of the buffer space 12 along the second direction Y is recorded as L1
  • the length of the active material layer 15 where the buffer space 12 is located along the second direction Y is recorded as L2
  • the condition satisfied by L1 and L2 is: 0.3 ⁇ L1/L2 ⁇ 1.
  • L1/L2 When L1/L2 is equal to 1, it means that the buffer space 12 penetrates the opposite sides of the active material layer 15 in the second direction Y, which facilitates better bending of the active material layer 15.
  • L1/L2 When L1/L2 is equal to 0.3, it means that the minimum extension of the buffer space 12 along the second direction Y can effectively reduce the probability of cracking of the current collector 11 due to the extrusion of the active material.
  • Reasonable control of the ratio L1/L2 can achieve effective bending deformation buffering, reduce the probability of cracking of the current collector 11 due to squeezing of active materials, and improve the stability of the performance of the secondary battery 100.
  • the thickness of the active material layer 15 used to form the concave surface of the bending layer 61 is recorded as D
  • the buffer space 12 is formed with an opening 123 on the surface of the active material layer 15, and the sum of the widths of each opening 123 along the first direction X is recorded as W, and the condition satisfied by W and D is: 0.6 ⁇ D ⁇ W ⁇ 1.4 ⁇ D.
  • the opening 123 refers to a structure formed by the buffer space 12 on a surface of the active material layer 15 facing away from the current collector 11, and its shape may be square, oval, etc.
  • the width of the opening 123 has a certain change in the second direction Y
  • different positions (such as more than two different positions, etc.) of the opening 123 along the second direction Y can be taken for measurement and value taking, and the different width values obtained are averaged, and the average value obtained can be used as the width value of the opening 123 along the first direction X.
  • the pole piece 1 in the corner area 13 is bent to form a bending layer 61.
  • the radius of the concave surface of the bending layer 61 is recorded as R0
  • the radius of the middle surface of the bending layer 61 (recorded as the surface of the active material layer 15 facing away from the concave surface after bending) is recorded as R1.
  • the arc length of the concave surface of the bending layer 61 (half of the circle) is: ⁇ R0
  • the middle surface of the bending layer 61 (half of the circle) is: ⁇ R1.
  • the sum W of the widths of the openings 123 is designed to be between 0.6 ⁇ D and 1.4 ⁇ D. On the one hand, it can satisfy the width collapse caused by the bending of the surface of the active material layer 15, and avoid the mutual squeezing of the active materials due to bending (for example, a coefficient of 0.6 means that a small amount of squeezing is allowed, etc.); on the other hand, in the case of setting a buffer space on the active material layer 15 of the negative electrode sheet 3, lithium precipitation due to excessive loss of active materials can be avoided.
  • Such a design can satisfy the width collapse caused by bending of the surface of the active material layer 15 and avoid mutual squeezing of the active materials due to bending; meanwhile, it can also avoid lithium deposition due to excessive loss of active materials.
  • the sum of the widths W also satisfies the condition: 50 ⁇ m ⁇ W ⁇ 5000 ⁇ m.
  • the sum of the widths W is related to the thickness of the active material layer 15 where the buffer space 12 is located. If the thickness of the active material layer 15 is thin, the amount of active material collapse on the surface of the active material layer 15 is not large. In this case, W can be designed to be 50 ⁇ m; if the thickness of the active material layer 15 is thick, the amount of active material collapse on the surface of the active material layer 15 is large. In this case, W can be designed to be 5000 ⁇ m.
  • the range of the sum of the widths of the openings 123 is reasonably controlled, which is helpful to satisfy the curvature of the thickness of the active material layer 15 with different thicknesses.
  • the width of the buffer space 12 along the first direction X is denoted as A, and the width A starts from the surface of the active material layer 15 and gradually decreases along the thickness direction Z of the electrode 1 and toward the current collector 11 side.
  • the width of the buffer space 12 is designed to be smaller as it is closer to the current collector 11, so as to keep it consistent with the change of redundancy of the active material, so as to avoid the buffer space 12 being too wide and affecting the performance of the secondary battery 100, such as causing the gap on the negative electrode 3 to be too large and lithium deposition; or causing the active material of the positive electrode 2 to be reduced and affect the capacity of the secondary battery 100, etc.
  • the inner wall of the buffer space 12 includes a first inner wall 121 and a second inner wall 122 that are spaced apart from each other in the first direction X, and the distance between the first inner wall 121 and the second inner wall 122 is the width of the buffer space 12.
  • the first inner wall 121 and the second inner wall 122 can be designed as a plane or a curved surface.
  • the width of the buffer space 12 is designed to be smaller as it is closer to the current collector 11 , so as to be consistent with the change of the active material redundancy in the thickness direction Z of the electrode 1 , while satisfying the effective buffering effect, and preventing the buffer space 12 from being too wide to affect the performance of the secondary battery 100 .
  • the corner area 13 having the buffer space 12 there are a plurality of buffer spaces 12 , and all the buffer spaces 12 are arranged along the first direction X at intervals.
  • Arranging a plurality of buffer spaces 12 in the first direction X can increase the space for deformable buffering in the first direction X, and prevent the active material layers 15 from being squeezed against each other due to width collapse when being bent.
  • each buffer space 12 on the surface of the active material layer 15 may be kept equal or unequal.
  • a plurality of buffer spaces 12 are arranged in the first direction X, so as to increase the deformable buffer space in the first direction X, and further prevent the current collector 11 from being broken due to mutual squeezing of active materials during bending.
  • a gap between two adjacent buffer spaces 12 is denoted as H, and the condition satisfied by H is: 25 ⁇ m ⁇ H ⁇ 2500 ⁇ m.
  • the gap between two adjacent buffer spaces 12 may be, but is not limited to, 25 ⁇ m, 2500 ⁇ m, etc.
  • the number of buffer spaces 12 may be appropriately reduced when designing the buffer spaces 12 to ensure that the sum of the widths of the buffer spaces 12 on the active material layer 15 is constant; similarly, when the gap between the buffer spaces 12 is 2500 ⁇ m, the number of buffer spaces 12 may be appropriately increased when designing the buffer spaces 12.
  • the gaps between the buffer spaces 12 are controlled to be between 25 ⁇ m and 2500 ⁇ m, which facilitates the design of the buffer spaces 12 on the active material layer 15 .
  • the sum of the widths W also satisfies the condition: 80 ⁇ m ⁇ H ⁇ 1000 ⁇ m.
  • the gap between two adjacent buffer spaces 12 should not be too large or too small. If the gap between the buffer spaces 12 is too large, there will be a wide active material between the two adjacent buffer spaces 12. When bending, it cannot be effectively bent and deformed, and internal extrusion stress is prone to occur. If the gap between the buffer spaces 12 is too small, the buffer spaces 12 are concentrated, which will cause the gap in a certain area on the pole piece 1 to be too wide, and the risk of lithium deposition is prone to occur.
  • the gap of the buffer space 12 is controlled to be 80 ⁇ m to 1000 ⁇ m.
  • the gap between two adjacent buffer spaces 12 may be but not limited to 80 ⁇ m or 1000 ⁇ m. This can facilitate the bending of the electrode 1 and reduce the extrusion internal stress; it can also avoid the problem of uneven distribution of lithium ions caused by the buffer space 12 being arranged too concentratedly.
  • Reasonable control of the gap between two adjacent buffer spaces 12 can avoid large extrusion internal stress caused by bending of the pole piece 1, and can also prevent the buffer spaces 12 from being too concentrated, resulting in too wide gaps in the pole piece 1.
  • the buffer space 12 does not penetrate the active material layer 15 where the buffer space 12 is located along the thickness direction Z of the electrode sheet 1 .
  • the buffer space 12 does not penetrate the active material layer 15 in which it is located along the thickness direction Z of the electrode 1 should be understood as follows: the buffer space 12 is opened on one surface of the active material layer 15 and extends along the thickness direction Z of the electrode 1, but one end of the buffer space 12 does not extend to the other surface of the active material layer 15 (i.e., a surface of the active material layer 15 that is in contact with the current collector 11).
  • the active material layer 15 is not penetrated, so that the active material layer 15 is prevented from falling off due to disconnection, thereby ensuring the structural stability of the electrode assembly 10.
  • the present application provides an electrode assembly 10, which is formed by winding a positive electrode sheet 2, a negative electrode sheet 3 and a separator 4 separated from the positive electrode sheet 2 and the negative electrode sheet 3, and the electrode assembly 10 includes a bending portion 6, and the bending portion 6 includes a plurality of stacked bending layers 61; wherein the positive electrode sheet 2 and/or the negative electrode sheet 3 is any one of the electrode sheets 1 above.
  • At least one of the positive electrode sheet 2 and the negative electrode sheet 3 is the electrode sheet 1 in any of the above solutions, for example: the positive electrode sheet 2 is the electrode sheet 1 in any of the above solutions; or, the positive electrode sheet 2 and the negative electrode sheet 3 are both the electrode sheet 1 in any of the above solutions, etc.
  • the electrode assembly 10 is formed by winding a positive electrode sheet 2 , a negative electrode sheet 3 and a separator 4 , and its shape is a flat winding structure. Therefore, the structure of the electrode assembly 10 includes a straight portion 5 and bent portions 6 arranged on both sides of the straight portion 5 .
  • the bending layer 61 refers to a structure formed by bending a portion of the pole piece 1 in the corner area 13 .
  • a plurality of bending layers 61 stacked on top of each other can form a bending portion 6 .
  • the above-mentioned electrode assembly 10 adopts the pole piece 1 in the above scheme.
  • the buffer space 12 is used to at least partially replace the redundancy of active material that occurs when the active material layer 15 is bent into a concave surface.
  • a buffer will be formed in the buffer space 12, thereby avoiding the pole piece 1 from being broken due to the mutual squeezing of the redundant active materials, thereby effectively improving the stability of the performance of the secondary battery 100.
  • the electrode assembly 10 further includes a straight portion 5 , and two bent portions 6 , which are respectively disposed on opposite sides of the straight portion 5 .
  • the straight portion 5 refers to a component corresponding to the large surface area of the flat electrode assembly 10 , and the straight portion 5 is formed by stacking the straight areas 14 of the multiple electrode sheets 1 .
  • an electrode assembly 10 with a flat structure having curved ends and a straight middle is formed.
  • the present application provides a secondary battery 100 including the above electrode assembly 10 .
  • the present application provides an electric device 1000 including the above secondary battery 100 .
  • the present application provides a pole piece 1.
  • the position of the corner area 13 of the pole piece 1 is determined according to the winding size of the electrode assembly 10, and then a stripe-like structure arranged at intervals is etched in the corner area 13 by laser or mechanical methods, such as a buffer space 12, and the cross-sectional shape of the buffer space 12 includes but is not limited to a triangle, a trapezoid or an arc.
  • the buffer space 12 has a certain width and depth, but the current collector 11 cannot leak out.
  • the positive electrode active material ternary material nickel cobalt manganese (NCM811), the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) are mixed evenly in a mass ratio of 97:2:1 and added into the solvent NMP to prepare a positive electrode slurry; the positive electrode slurry is evenly coated on an aluminum foil, dried at 85°C and then cold pressed, and then die-cut and slit to prepare a lithium-ion battery positive electrode sheet 2.
  • the coating weight of the active material of the positive electrode sheet 2 is 17.6 mg/cm 2 , and the thickness of the active material layer 15 of the positive electrode sheet 2 is 50 ⁇ m.
  • the negative electrode active material graphite, the conductive agent acetylene black, the thickener sodium carboxymethyl cellulose (CMC), and the binder styrene butadiene rubber (SBR) were added into the solvent water in a mass ratio of 96:2:1:1, mixed evenly and made into a negative electrode slurry; the negative electrode slurry was evenly coated on the copper foil, dried at 85°C and then cold pressed to make a negative electrode sheet 3.
  • the coating weight of the negative electrode sheet 3 is 10 mg/cm 2 , and the thickness of the active material layer 15 of the negative electrode sheet 3 is 61 ⁇ m. In addition, no buffer space 12 is provided in the corner area 13 of the negative electrode sheet 3 .
  • a polyethylene microporous film is used as a porous isolation membrane substrate, and inorganic alumina powder, polyvinylpyrrolidone and acetone solvent are evenly mixed in a weight ratio of 3:1.5:5.5 to form a slurry, which is then coated on one side of the substrate and dried to obtain an isolation membrane.
  • Lithium hexafluorophosphate is dissolved in a mixed solvent of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate (the volume ratio of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate is 1:2:1) to obtain a lithium ion battery electrolyte.
  • the positive electrode sheet 2, the negative electrode sheet 3 and the isolation film are wound to obtain a bare cell, and then a lithium-ion battery is obtained through packaging, liquid injection, formation, exhaust and other processes.
  • the designed charging N/P of the battery is 1.03, and the designed capacity of the cell is 160Ah.
  • the buffer space 12 is evenly arranged in the corner area 13 of the negative electrode sheet 3 (note that the depth of a single buffer space 12 can be close to the thickness of the active material layer 15), the width of a single buffer space 12 is 19 ⁇ m, and the sum of the widths of the buffer spaces 12 is 192 ⁇ m.
  • the buffer spaces 12 are evenly arranged in the corner areas 13 of the negative electrode sheets 3, the width of a single buffer space 12 is 96 ⁇ m, and the total width of the buffer spaces 12 is 192 ⁇ m.
  • the buffer spaces 12 are evenly arranged in the corner area 13 of the negative electrode sheet 3, the width of a single buffer space 12 is 100 ⁇ m, and the total width of the buffer spaces 12 is 1000 ⁇ m.
  • the buffer spaces 12 are evenly arranged in the corner areas 13 of the negative electrode sheets 3, the width of a single buffer space 12 is 1000 ⁇ m, and the sum of the widths of the buffer spaces 12 is 1000 ⁇ m.
  • the buffer spaces 12 are evenly arranged in the corner areas 13 of the negative electrode sheets 3, the width of a single buffer space 12 is 300 ⁇ m, and the total width of the buffer spaces 12 is 3000 ⁇ m.
  • the secondary battery 100 prepared in the above comparative example and embodiment was used to record the fracture frequency of the corner area 13 during the hot pressing shaping process of the winding structure. At the same time, after the secondary battery 100 was manufactured, it was charged to 4.2V at 0.33C, and then discharged to 2.8V at 0.33C. After 2000 cycles, it was disassembled to observe whether the corner was fractured and lithium was deposited.
  • Table 1 The specific results can be referred to Table 1.

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Abstract

本申请提供了一种极片、电极组件、二次电池及用电装置，在用于形成弯折层凹面的活性物质层上向内凹陷开设缓冲空间，并控制缓冲空间不贯穿集流体设置。如此设计的极片在卷绕过程中，利用缓冲空间，至少部分取代活性物质层弯曲成凹面时出现的活性物质冗余，这样极片上的活性物质层在拐角区处弯曲时，会在缓冲空间中形成缓冲，避免因活性物质冗余相互挤压而导致极片发生断裂，从而有效提升二次电池性能的稳定性。

Description

极片、电极组件、二次电池及用电装置 技术领域
本申请涉及电池技术领域，特别是涉及极片、电极组件、二次电池及用电装置。
背景技术
随着二次电池被广泛应用，对其性能稳定性的要求越来越高，尤其作为二次电池中发生电化学反应的电极组件，需保证其结构在循环充放电中保持稳定。电极组件因制备工艺的不同，可分为叠片式结构和卷绕式结构等。
对于卷绕式结构，因受限于传统极片结构设计缺陷，在电池生产的热压整形工序及循环充放电过程中，易在弯折层处发生断裂，导致二次电池的性能降低。
发明内容
基于此，有必要提供一种极片、电极组件、二次电池及用电装置，降低因活性物质相互挤压而导致极片断裂的几率，提升二次电池性能的稳定性。
第一方面，本申请提供了一种极片，沿第一方向间隔具有若干拐角区，当极片沿第一方向进行卷绕时，拐角区形成电极组件的弯折层；极片包括：集流体；活性物质层，设于集流体的相对两表面上；其中，在至少一个拐角区内，用于形成弯折层凹面的活性物质层上设有缓冲空间，缓冲空间沿极片的厚度方向凹陷但不贯穿集流体。
上述的极片，在用于形成弯折层凹面的活性物质层上向内凹陷开设缓冲 空间，并控制缓冲空间不贯穿集流体设置。如此设计的极片在卷绕过程中，利用缓冲空间，至少部分取代活性物质层弯曲成凹面时出现的活性物质冗余，这样极片上的活性物质层在拐角区处弯曲时，会在缓冲空间中形成缓冲，避免因活性物质冗余相互挤压而导致极片发生断裂，从而有效提升二次电池性能的稳定性。
在一些实施例中，在具有缓冲空间的拐角区内，缓冲空间沿第二方向延伸设置，第二方向被定义为与第一方向和极片的厚度方向构成的平面垂直。如此，将缓冲空间设计为沿第二方向延伸，使得两侧且在第二方向上的活性物质能更好地作用在缓冲空间上，进一步降低因活性物质相互挤压导致集流体断裂的几率。
在一些实施例中，缓冲空间沿第二方向上的长度记为L1，缓冲空间所在的活性物质层沿第二方向上的长度记为L2，L1与L2满足的条件为：0.3≤L1/L2≤1。如此，合理控制L1/L2的比值，能实现有效的弯曲形变缓冲，降低集流体因活性物质挤压而开裂的几率，提升二次电池性能的稳定性。
在一些实施例中，用于形成弯折层凹面的活性物质层的厚度记为D，缓冲空间在活性物质层表面上形成有开口，各开口沿第一方向上的宽度之和记为W，W与D满足的条件为：0.6×π×D≤W≤1.4×π×D。如此设计，将开口的宽度之和W设计为0.6×π×D～1.4×π×D之间，能满足活性物质层表面因弯曲而导致的宽度溃缩，避免活性物质因弯曲而相互挤压。
在一些实施例中，宽度之和W还满足的条件为：50微米(μm)≤W≤
5000μm。如此，合理控制开口的宽度之和的范围值，有利于满足不同厚度的活性物质层厚度的弯曲。
在一些实施例中，缓冲空间沿第一方向上的宽度记为A，宽度A自活性 物质层表面开始，沿极片的厚度方向并朝向集流体一侧逐渐减小。如此，将缓冲空间的宽度设计为越靠近集流体，宽度越小，使之与活性物质冗余的在极片的厚度方向上的变化保持一致，在满足有效缓冲作用下，避免缓冲空间过宽而影响二次电池的性能。
在一些实施例中，在具有缓冲空间的拐角区内，缓冲空间为多个，全部缓冲空间沿第一方向间隔排布。如此设计，在第一方向上排列多个缓冲空间，增加第一方向上可变形缓冲的空间，进一步避免弯曲时活性物质因相互挤压而导致集流体断裂。
在一些实施例中，在具有缓冲空间的拐角区内，相邻两个缓冲空间之间间隙记为H，H满足的条件为：25μm≤H≤2500μm。如此，将缓冲空间之间的间隙控制25μm～2500μm之间，方便活性物质层上缓冲空间的设计。
在一些实施例中，宽度之和W还满足的条件为：80μm≤H≤1000μm。如此，合理控制相邻两个缓冲空间之间间隙，避免极片弯折出现较大挤压内应力，又能避免缓冲空间过于集中而导致极片缝隙过宽。
在一些实施例中，在具有缓冲空间的拐角区内，缓冲空间沿极片的厚度方向不贯穿自身所在的活性物质层。如此，不贯穿活性物质层，避免活性物质层因断开而易发生脱落的现象，保证电极组件的结构稳定。
第二方面，本申请提供了一种电极组件，由正极片、负极片及隔设于正极片和负极片之间的隔膜卷绕形成，电极组件包括弯折部，弯折部包括若干层叠的弯折层；其中，正极片和/或负极片为以上任一项的极片。
在一些实施例中，电极组件还包括平直部，弯折部为两个，两个弯折部分别设于平直部的相对两侧。如此设计，形成两端弯曲、中间平直的扁状结构的电极组件。
第三方面，本申请提供了一种二次电池，包括以上的电极组件。
第四方面，本申请提供了一种用电装置，包括以上的二次电池。
上述说明仅是本申请技术方案的概述，为了能够更清楚了解本申请的技术手段，而可依照说明书的内容予以实施，并且为了让本申请的上述和其它目的、特征和优点能够更明显易懂，以下特举本申请的具体实施方式。
附图说明
通过阅读对下文优选实施方式的详细描述，各种其他的优点和益处对于本领域普通技术人员将变得清楚明了。附图仅用于示出优选实施方式的目的，而并不认为是对本申请的限制。而且在全部附图中，用相同的附图标号表示相同的部件。在附图中：
图1为本申请一些实施例提供的电极组件的结构示意图；
图2为图1中的弯折层的结构示意图；
图3为本申请一些实施例提供的车辆的结构示意图；
图4为本申请一些实施例提供的二次电池的分解结构示意图；
图5为本申请一些实施例提供的极片的结构俯视图；
图6为本申请一些实施例提供的同一拐角区内极片的剖视图一；
图7为本申请一些实施例提供的同一拐角区内极片的剖视图二。
1000、用电装置；100、二次电池；200、马达；300、控制器；10、电极组件；20、端盖；30、电极端子；40、壳体；1、极片；11、集流体；12、缓冲空间；121、第一内壁；122、第二内壁；123、开口；13、拐角区；14、平直区；15、活性物质层；2、正极片；3、负极片；4、隔膜；5、平直部；6、弯折部；61、弯折层；611、凹面；612、凸面；X、第一方向；Y、第二方向；Z、厚度 方向。
具体实施方式
下面将结合附图对本申请技术方案的实施例进行详细的描述。以下实施例仅用于更加清楚地说明本申请的技术方案，因此只作为示例，而不能以此来限制本申请的保护范围。
除非另有定义，本文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；本文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。
在本申请实施例的描述中，技术术语“第一”“第二”等仅用于区别不同对象，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量、特定顺序或主次关系。在本申请实施例的描述中，“多个”的含义是两个以上，除非另有明确具体的限定。
在本文中提及“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。本领域技术人员显式地和隐式地理解的是，本文所描述的实施例可以与其它实施例相结合。
在本申请实施例的描述中，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，本文中字符“/”，一般表示前后关 联对象是一种“或”的关系。
在本申请实施例的描述中，术语“多个”指的是两个以上(包括两个)，同理，“多组”指的是两组以上(包括两组)，“多片”指的是两片以上(包括两片)。
在本申请实施例的描述中，技术术语“中心”“纵向”“横向”“长度”“宽度”“厚度”“上”“下”“前”“后”“左”“右”“竖直”“水平”“顶”“底”“内”“外”“顺时针”“逆时针”“轴向”“径向”“周向”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本申请实施例和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请实施例的限制。
在本申请实施例的描述中，除非另有明确的规定和限定，技术术语“安装”“相连”“连接”“固定”等术语应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或成一体；也可以是机械连接，也可以是电连接；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或两个元件的相互作用关系。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实施例中的具体含义。
目前，从市场形势的发展来看，动力电池的应用越加广泛。动力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。随着动力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。
本申请人注意到，请参照图1，当电极组件10被构造成卷绕式结构时，其包括平直部5及设于平直部5两侧的弯折部6。在弯折部6中，有交替多层不同曲率半径的弯折层61。请参照图2，各弯折层61具有相对的凹面611和凸面 612，且弯折层61的凹面611和凸面612则分别对应由极片1两侧的活性物质层15弯曲形成。
由于弯折层61的凹面611的曲率半径小于弯折层61的凸面612曲率半径，因此，活性物质层15弯曲形成凹面611时，会有部分活性物质出现冗余，导致凹面611上的活性物质相互挤压，对集流体1111产生很大的拉应力。这样在生产的热压工序或循环膨胀以后，弯折层61上的集流体1111很容易发生断裂，影响二次电池100性能的稳定。
基于此，为了解决弯折层61凹面611因活性物质相互挤压而导致极片1易断裂，影响二次电池100性能的稳定性的问题，本申请人经过深入研究，设计了一种极片1。在至少一个拐角区13内，用于形成弯折层61凹面611的活性物质层15上设有缓冲空间12，缓冲空间12沿极片1的厚度方向Z凹陷但不贯穿集流体1111。
在用于形成弯折层61凹面611的活性物质层15上向内凹陷开设缓冲空间12，并控制缓冲空间12不贯穿集流体1111设置。如此设计的极片1在卷绕过程中，利用缓冲空间12，至少部分取代活性物质层15弯曲成凹面611时出现的活性物质冗余，这样极片1上的活性物质层15在拐角区13处弯曲时，会在缓冲空间12中形成缓冲，避免因活性物质冗余相互挤压而导致极片1发生断裂，从而有效提升二次电池100性能的稳定性。
本申请实施例公开的二次电池100可以但不限用于车辆、船舶或飞行器等用电装置1000中。可以使用具备本申请公开的二次电池100等组成该用电装置1000的电源系统。
本申请实施例提供一种使用电池作为电源的用电装置1000，用电装置1000可以为但不限于手机、平板、笔记本电脑、电动玩具、电动工具、电瓶车、 电动汽车、轮船、航天器等等。其中，电动玩具可以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，航天器可以包括飞机、火箭、航天飞机和宇宙飞船等等。
以下实施例为了方便说明，以本申请一实施例的一种用电装置1000为车辆为例进行说明。
请参照图3，图3为本申请一些实施例提供的车辆的结构示意图。车辆可以为燃油汽车、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。车辆的内部设置有二次电池100，二次电池100可以设置在车辆的底部或头部或尾部。二次电池100可以用于车辆的供电，例如，二次电池100可以作为车辆的操作电源。车辆还可以包括控制器300和马达200，控制器300用来控制二次电池100为马达200供电，例如，用于车辆的启动、导航和行驶时的工作用电需求。
在本申请一些实施例中，二次电池100不仅可以作为车辆的操作电源，还可以作为车辆的驱动电源，代替或部分地代替燃油或天然气为车辆提供驱动动力。
二次电池100可以是多个，多个二次电池100之间可串联或并联或混联，混联是指多个二次电池100中既有串联又有并联。多个二次电池100之间可直接串联或并联或混联在一起，再将多个二次电池100构成的整体容纳于箱体内；当然，二次电池100也可以是多个二次电池100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，并容纳于箱体内。二次电池100还可以包括其他结构，例如，该二次电池100还可以包括汇流部件，用于实现多个二次电池100之间的电连接。二次电池100可呈圆柱体、扁平体、长方体或其它形状等。
请参照图4，图4为本申请一些实施例提供的二次电池100的分解结构示意图。二次电池100是指组成电池的最小单元。如图4，二次电池100包括有端盖20、壳体40、电极组件10以及其他的功能性部件。
端盖20是指盖合于壳体40的开口处以将二次电池100的内部环境隔绝于外部环境的部件。不限地，端盖20的形状可以与壳体40的形状相适应以配合壳体40。可选地，端盖20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20在受挤压碰撞时就不易发生形变，使二次电池100能够具备更高的结构强度，安全性能也可以有所提高。端盖20上可以设置有如电极端子30等的功能性部件。电极端子30可以用于与电极组件10电连接，以用于输出或输入二次电池100的电能。在一些实施例中，端盖20上还可以设置有用于在二次电池100的内部压力或温度达到阈值时泄放内部压力的泄压机构。端盖20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20的内侧还可以设置有绝缘件，绝缘件可以用于隔离壳体40内的电连接部件与端盖20，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40是用于配合端盖20以形成二次电池100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10、电解液以及其他部件。壳体40和端盖20可以是独立的部件，可以于壳体40上设置开口，通过在开口处使端盖20盖合开口以形成二次电池100的内部环境。不限地，也可以使端盖20和壳体40一体化，具体地，端盖20和壳体40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40的内部时，再使端盖20盖合壳体40。壳体40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40的形状可以根据电极组件10的具体形状和尺寸大小来确定。壳 体40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。
电极组件10是二次电池100中发生电化学反应的部件。壳体40内可以包含一个或更多个电极组件10。电极组件10主要由正极片2和负极片3卷绕或层叠放置形成，并且通常在正极片2与负极片3之间设有隔膜4。正极片2和负极片3具有活性物质的部分构成电极组件10的主体部，正极片2和负极片3不具有活性物质的部分各自构成极耳。正极极耳和负极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。在二次电池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30以形成电流回路。
根据本申请的一些实施例，请参照图2、图5及图6，本申请提供了一种极片1。极片1沿第一方向X间隔具有若干拐角区13，当极片1沿第一方向X进行卷绕时，拐角区13形成电极组件10的弯折层61。极片1包括集流体11和活性物质层15，活性物质层15设于集流体11的相对两表面上。其中，在至少一个拐角区13内，用于形成弯折层61凹面的活性物质层15上设有缓冲空间12，缓冲空间12沿极片1的厚度方向Z凹陷但不贯穿集流体11。
集流体11是指不仅能承载活性物质，而且还能将电极活性物质产生的电流汇集并输出的部件。集流体11的材料可根据极片1的极性不同有不同的选择，比如：在正极片2中，集流体11的材料可为但不限于铝、镍等金属材料，也可为导电树脂、钛镍形状记忆合金、覆碳铝箔等复合材料。在负极片3中，集流体11的材料可为但不限于铜等金属材料，当然也可为导电树脂、钛镍形状记忆合金等复合材料。
活性物质层15是指涂覆在集流体11上的活性物质，其材料可根据极片1 的极性进行选择。比如：在正极片2中，活性物质层15的材料可为但不限于钴酸锂、锰酸锂、镍酸锂、磷酸铁锂、三元材料等。在负极片3中，活性物质层15的材料可为但不限于石墨、硅氧化物等。
拐角区13是指在制备电极组件10中，极片1沿第一方向X进行卷绕时会在若干部分段上形成弯折层61，该弯折层61在极片1所对应的区域为拐角区13。同时，卷绕形成的电极组件10包括弯折部6，该弯折部6包括层叠的多个弯折层61。
若干拐角区13在集流体11沿第一方向X间隔排布，相邻两个拐角区13之间留有平直区14，与电极组件10的平直部5相对。同时，相邻两个拐角区13在卷绕后，则分别位于电极组件10的不同弯折部6上，为便于理解，可将电极组件10的两个弯折部6分别定义为左弯折部6和右弯折部6，在卷绕时，第一个拐角区13绕在左弯折部6上，第二个拐角区13绕在右弯折部6上；接着，第三个拐角区13绕在左弯折部6上，第四个拐角区13又绕在右弯折部6上等，按如此逻辑，其余拐角区13分别对应绕在不同的弯折部6上。
集流本体11上所有的拐角区13中，可仅有部分拐角区13设置缓冲空间12，也可全部拐角区13均设置缓冲空间12等。
缓冲空间12是指活性物质层15表面上向内凹陷的空间，能减少该活性物质层15上的活性物质含量，比如：缓冲空间12内的体积正好与弯曲时活性物质的冗余量等。同时，缓冲空间12对活性物质层15弯曲时起到缓冲形变的作用，例如：弯曲时，位于缓冲空间12两侧的活性物质因弯曲向缓冲空间12内部形变，使得挤压内应力在缓冲空间12内得到释放，避免出现活性物质相互挤压。
缓冲空间12在活性物质层15上形成的形状有多种设计，比如：缓冲空 间12在活性物质层15上形成的形状可为方形、圆形、椭圆形等。同时，缓冲空间12在同一拐弯区内的分布状态，可仅设置在可形成凹面的活性物质层15上；也可同时设置两侧的活性物质层15上。另外，缓冲空间12的数量可为一个，也可为多个。
缓冲空间12沿极片1的厚度方向Z延伸但不贯穿集流体11应理解为：缓冲空间12在活性物质层15上内凹延伸，但不能延伸透过集流体11，比如：缓冲空间12延伸在活性物质层15内部；或者，缓冲空间12贯穿活性物质层15并刚好延伸至集流体11表面；又或者，缓冲空间12贯穿活性物质层15并延伸至集流体11的内部等。
利用缓冲空间12，至少部分取代活性物质层15弯曲成凹面时出现的活性物质冗余，这样极片1上的活性物质层15在拐角区13处弯曲时，会在缓冲空间12中形成缓冲，避免因活性物质冗余相互挤压而导致极片1发生断裂，从而有效提升二次电池100性能的稳定性。
根据本申请的一些实施例，请参照图5，在具有缓冲空间12的拐角区13内，缓冲空间12沿第二方向Y延伸设置，第二方向Y被定义为与第一方向X和极片1的厚度方向Z构成的平面垂直。
第一方向X是指极片1进行卷绕的方向，也可理解为极片1的长度方向；同时，第二方向Y也可理解为极片1的宽度方向。
当活性物质层15在第一方向X上进行卷绕时，位于缓冲空间12两侧并在第二方向Y上的活性物质会朝向缓冲空间12一侧挤压变形，为此，将缓冲空间12设计为沿第二方向Y延伸，保证两侧且在第二方向Y上的活性物质能更好地作用在缓冲空间12上。
缓冲空间12沿第二方向Y的延伸状态有多种，比如：缓冲空间12的相 对两端分别延伸至活性物质层15沿第二方向Y上的相对两侧，即缓冲空间12沿第二方向Y贯穿活性物质层15；或者，缓冲空间12的一端沿第二方向Y延伸至活性物质层15沿第二方向Y上的一侧面；又或者，缓冲空间12的两端均未延伸至活性物质层15沿第二方向Y上的相对两侧上等。
另外，在第二方向Y上，缓冲空间12的数量可为一个或者多个。当缓冲空间12为多个时，单个缓冲空间12沿第二方向Y延伸设置外，多个缓冲空间12也可在第二方向Y上间隔排列。
将缓冲空间12设计为沿第二方向Y延伸，使得两侧且在第二方向Y上的活性物质能更好地作用在缓冲空间12上，进一步降低因活性物质相互挤压导致集流体11断裂的几率。
根据本申请的一些实施例，请参照图5，缓冲空间12沿第二方向Y上的长度记为L1，缓冲空间12所在的活性物质层15沿第二方向Y上的长度记为L2，L1与L2满足的条件为：0.3≤L1/L2≤1。
当L1/L2等于1时，说明缓冲空间12在第二方向Y上贯穿了活性物质层15的相对两侧，这样便于活性物质层15实现更好弯曲。当L1/L2等于0.3时，则说明缓冲空间12沿第二方向Y上的最低延伸量，能实现有效降低集流体11因活性物质挤压而开裂的几率。
合理控制L1/L2的比值，能实现有效的弯曲形变缓冲，降低集流体11因活性物质挤压而开裂的几率，提升二次电池100性能的稳定性。
根据本申请的一些实施例，请参照图6，用于形成弯折层61凹面的活性物质层15的厚度记为D，缓冲空间12在活性物质层15表面上形成有开口123，各开口123沿第一方向X上的宽度之和记为W，W与D满足的条件为：0.6×π×D≤W≤1.4×π×D。
开口123是指缓冲空间12在活性物质层15背向集流体11的一表面上形成的结构，其形状可为方形、椭圆形等。在反向确定开口123沿第一方向X上的宽度时，应在开口123沿第二方向Y的中间部分上取值，而不应在开口123沿第二方向Y上的两端测量取值。若开口123的宽度在第二方向Y上具有一定变化时，可在开口123沿第二方向Y上取不同的位置(如两个以上的不同位置等)进行测量取值，所得不同的宽度值进行平均计算，获取的平均值可作为开口123沿第一方向X上的宽度值。
将拐角区13内的极片1进行弯曲以形成一层弯折层61，请参照图2，弯折层61的凹面半径记为R0，弯折层61的中间面(记为弯曲后活性物质层15背向凹面的一表面)半径记为R1。此时，弯折层61的凹面弧长(圆的一半)为：π×R0；弯折层61的中间面(圆的一半)为：π×R1。由于活性物质层15上下两表面在弯曲之前，两者长度保持相等，因此，弯曲后，活性物质层15两表面的长度之差为：π×(R1-R0)＝π×(D)，即弯曲后，活性物质层15一表面的活性物质的宽度比另一表面的活性物质的宽度少了π×D。
将开口123的宽度之和W设计为0.6×π×D～1.4×π×D之间，一方面，能满足活性物质层15表面因弯曲而导致的宽度溃缩，避免活性物质因弯曲而相互挤压(比如：系数0.6表示允许有少量挤压等)；另一方面，对于在负极片3的活性物质层15上设置缓冲空间的情况，避免因活性物质损失过多而导致析锂。
如此设计，能满足活性物质层15表面因弯曲而导致的宽度溃缩，避免活性物质因弯曲而相互挤压；同时也能避免因活性物质损失过多而导致析锂。
根据本申请的一些实施例，宽度之和W还满足的条件为：50μm≤W≤5000μm。
宽度之和W与缓冲空间12所在活性物质层15的厚度有关，若活性物质 层15的厚度较薄，活性物质层15一表面的活性物质溃缩量不大，此时W可设计为50μm；若活性物质层15的厚度较厚，活性物质层15一表面的活性物质溃缩量较大，此时W可设计为5000μm。
如此，合理控制开口123的宽度之和的范围值，有利于满足不同厚度的活性物质层15厚度的弯曲。
根据本申请的一些实施例，请参照图6，缓冲空间12沿第一方向X上的宽度记为A，宽度A自活性物质层15表面开始，沿极片1的厚度方向Z并朝向集流体11一侧逐渐减小。
极片1在弯曲成弯折部6时，内侧的活性物质层15上越远离集流体11的部分，其弯曲度越大，活性物质的冗余则越多；相反，越接近集流体11的部分，弯曲度越小，活性物质的冗余越小。因此，将缓冲空间12的宽度设计为：越靠近集流体11，宽度越小，使之与活性物质冗余的变化保持一致，避免缓冲空间12过宽而影响二次电池100的性能，比如：导致负极片3上间隙过大而析锂；或者，导致正极片2活性物质减少影响二次电池100的容量等。
在一些实施例中，请参照图6，缓冲空间12的内壁包括在第一方向X上相对间隔的第一内壁121与第二内壁122，第一内壁121与第二内壁122之间间距为缓冲空间12的宽度。第一内壁121和第二内壁122均可设计为平面，也可设计为曲面。
另外，请参照图6与图7，以第一方向X和极片1的厚度方向Z构成的平面截取缓冲空间12，所获取的形状有多种，比如：抛物线状、倒梯形状、三角状等。
将缓冲空间12的宽度设计为越靠近集流体11，宽度越小，使之与活性物质冗余的在极片1的厚度方向Z上的变化保持一致，在满足有效缓冲作用下， 避免缓冲空间12过宽而影响二次电池100的性能。
根据本申请的一些实施例，请参照图5，在具有缓冲空间12的拐角区13内，缓冲空间12为多个，全部缓冲空间12沿第一方向X间隔排布。
在第一方向X上排列多个缓冲空间12，可增加第一方向X上可变形缓冲的空间，避免弯曲时活性物质层15因宽度溃缩而相互挤压。
每个缓冲空间12在活性物质层15表面上的宽度可保持相等，也可不相等。当每个缓冲空间12的宽度均相等时，将单个缓冲空间12在活性物质层15表面上的宽度记为A，缓冲空间12在活性物质层15表面的宽度之和记为W(宽度之和可根据活性物质层15厚度进行计算，具体可参考上文描述，在此不再赘述)，缓冲空间12在第一方向X上的数量记为m，如此，各个参数之间满足如下公式：A＝W/m。
如此设计，在第一方向X上排列多个缓冲空间12，增加第一方向X上可变形缓冲的空间，进一步避免弯曲时活性物质因相互挤压而导致集流体11断裂。
根据本申请的一些实施例，请参照图7，在具有缓冲空间12的拐角区13内，相邻两个缓冲空间12之间间隙记为H，H满足的条件为：25μm≤H≤2500μm。
相邻两个缓冲空间12之间间隙可为但不限于25μm、2500μm等。当缓冲空间12之间间隙为25μm时，在设计缓冲空间12时可适当减少缓冲空间12的数量，以保证缓冲空间12在活性物质层15上的宽度之和一定；同样，当缓冲空间12之间间隙为2500μm时，在设计缓冲空间12时可适当增加缓冲空间12的数量等。
将缓冲空间12之间的间隙控制25μm～2500μm之间，方便活性物质层15上缓冲空间12的设计。
根据本申请的一些实施例，宽度之和W还满足的条件为：80μm≤H≤ 1000μm。
相邻两个缓冲空间12之间间隙设计时不宜过大，也不宜过小。若缓冲空间12之间间隙过大，导致相邻两个缓冲空间12之间具有较宽的活性物质，在弯曲时，无法有效弯折变形，易出现内部挤压应力。若缓冲空间12之间间隙过小，缓冲空间12分布集中，会导致极片1上某一区域的缝隙过宽，易出现析锂风险。
将缓冲空间12的间隙控制在80μm～1000μm，比如：相邻两个缓冲空间12之间间隙可为但不限于80μm或1000μm等，这样既能方便极片1以弯折，减少挤压内应力；又能避免缓冲空间12过于集中布置而导致锂离子分布不均的问题。
合理控制相邻两个缓冲空间12之间间隙，避免极片1弯折出现较大挤压内应力，又能避免缓冲空间12过于集中而导致极片1缝隙过宽。
根据本申请的一些实施例，在具有缓冲空间12的拐角区13内，缓冲空间12沿极片1的厚度方向Z不贯穿自身所在的活性物质层15。
缓冲空间12沿极片1的厚度方向Z不贯穿自身所在活性物质层15应理解为：缓冲空间12开设在活性物质层15的一表面，并沿着极片1的厚度方向Z延伸，但缓冲空间12的一端没有延伸至活性物质层15的另一表面(即活性物质层15与集流体11贴合的一表面)。
不贯穿活性物质层15，避免活性物质层15因断开而易发生脱落的现象，保证电极组件10的结构稳定。
根据本申请的一些实施例，请参照图1，本申请提供了一种电极组件10，由正极片2、负极片3及隔设于正极片2和负极片3之间的隔膜4卷绕形成，电极组件10包括弯折部6，弯折部6包括若干层叠的弯折层61；其中，正极片2 和/或负极片3为以上任一项的极片1。
正极片2和负极片3中至少一者为以上任一方案中的极片1，比如：正极片2为以上任一方案中的极片1；或者，正极片2和负极片3同时为以上任一方案中的极片1等。
电极组件10由正极片2、负极片3和隔膜4卷绕形成，其形状成扁状的卷绕式结构，因此，电极组件10的结构包括平直部5和设于平直部5两侧的弯折部6。
弯折层61是指拐角区13内极片1的部分弯曲形成的结构，多个弯折层61相互层叠可构成弯折部6。
上述的电极组件10，采用以上方案中的极片1，在卷绕过程中，利用缓冲空间12，至少部分取代活性物质层15弯曲成凹面时出现的活性物质冗余，这样极片1上的活性物质层15在拐角区13处弯曲时，会在缓冲空间12中形成缓冲，避免因活性物质冗余相互挤压而导致极片1发生断裂，从而有效提升二次电池100性能的稳定性。
根据本申请的一些实施例，请参照图1，电极组件10还包括平直部5，弯折部6为两个，两个弯折部6分别设于平直部5的相对两侧。
平直部5是指扁状的电极组件10大面区域所对应的部件，平直部5由多层极片1的平直区14层叠形成。
如此设计，形成两端弯曲、中间平直的扁状结构的电极组件10。
根据本申请的一些实施例，本申请提供了一种二次电池100，包括以上的电极组件10。
根据本申请的一些实施例，本申请提供了一种用电装置1000，包括以上的二次电池100。
根据本申请的一些实施例，本申请提供了一种极片1。根据电极组件10的卷绕尺寸确认出极片1的拐角区13位置，然后在该拐角区13通过激光或机械等方法刻蚀出间隔排列的条纹状结构，如缓冲空间12，缓冲空间12的横截面形状包括但不限于三角形、梯形或圆弧形。同时，该缓冲空间12具有一定的宽度和深度，但不能漏出集流体11。
为了使本申请的目的、技术方案及优点更加简洁明了，本申请用以下具体实施例进行说明，但本申请绝非仅限于这些实施例。以下所描述的实施例仅为本申请较好的实施例，可用于描述本申请，不能理解为对本申请的范围的限制。应当指出的是，凡在本申请的精神和原则之内所做的任何修改、等同替换和改进等，均应包含在本申请的保护范围之内。
为了更好地说明本申请，下面结合实施例对本申请内容作进一步说明。以下为具体实施例。
对比例1
正极片2：
将正极活性物质三元材料镍钴锰(NCM811)、导电剂乙炔黑、粘结剂聚偏氟乙烯(PVDF)按质量比97：2：1混合均匀并加入到溶剂NMP中，制成正极浆料；将正极浆料均匀涂布在铝箔上，在85℃下烘干后冷压，再进行模切、分条，制成锂离子电池正极片2。
其中，正极片2的活性物质的涂布重量为17.6毫克每平方厘米(mg/cm 2)，正极片2的活性物质层15厚度为50μm。
负极片3：
将负极活性物质石墨、导电剂乙炔黑、增稠剂羟甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比96：2：1：1加入溶剂水中混合均匀并制成负极浆 料；将负极浆料均匀涂布在铜箔上，在85℃下烘干后进行冷压，制成负极片3。
其中，负极片3的涂布重量为10mg/cm 2，负极片3的活性物质层15厚度61μm。另外，负极片3的拐角区13内不设置缓冲空间12。
隔膜4：
采用聚乙烯微孔薄膜作为多孔隔离膜基材，将无机三氧化铝粉末、聚乙烯呲咯烷酮、丙酮溶剂按重量比3：1.5：5.5混合均匀制成浆料并涂布于基材的一面并烘干，得到隔离膜。
电解液：
将六氟磷酸锂溶解于碳酸乙烯酯、碳酸二甲酯和碳酸甲乙酯的混合溶剂中(碳酸乙烯酯、碳酸二甲酯、碳酸甲乙酯的体积比为1：2：1)，得到锂离子电池电解液。
二次电池100的制备：
将上述正极片2、负极片3以及隔离膜进行卷绕，得到裸电芯，之后经过封装、注液、化成、排气等工序，制得锂离子电池，该电池的设计充电N/P＝1.03，电芯设计容量为160Ah。
实施例1
与对比例1基本相同，区别仅在于：负极片3的拐角区13内均匀设置缓冲空间12(注单个缓冲空间12的深度可接近活性物质层15的厚度)，单个缓冲空间12的宽度为19μm，缓冲空间12的宽度之和为192μm。
实施例2
与对比例1基本相同，区别仅在于：负极片3的拐角区13内均匀设置缓冲空间12，单个缓冲空间12的宽度为96μm，缓冲空间12的宽度之和为192μm。
实施例3
与对比例1基本相同，区别仅在于：负极片3的拐角区13内均匀设置缓冲空间12，单个缓冲空间12的宽度为100μm，缓冲空间12的宽度之和为1000μm。
实施例4
与对比例1基本相同，区别仅在于：负极片3的拐角区13内均匀设置缓冲空间12，单个缓冲空间12的宽度为1000μm，缓冲空间12的宽度之和为1000μm。
实施例5
与对比例1基本相同，区别仅在于：负极片3的拐角区13内均匀设置缓冲空间12，单个缓冲空间12的宽度为300μm，缓冲空间12的宽度之和为3000μm。
采用以上对比例和实施例中制备的二次电池100，记录在卷绕结构的热压整形过程中拐角区13的断裂频次。同时，二次电池100制作完成后以0.33C充电到4.2V，然后以0.33C放电到2.8V，循环2000圈之后，拆解观察拐角处是否断裂和析锂，具体结果可参考表1。
从表1可知，将实施例1至实施例5分别与对比例1比较得出：在拐角区13内设置缓冲空间12，能有效解决电极组件10的弯折层61开裂的问题。
表1
Figure PCTCN2022128342-appb-000001
将实施例3至实施例5相互比较可得出：缓冲空间12的总宽度或单个缓冲空间12的宽度过大时，会导致负极片3的弯折层61的缝隙过大而产生析锂 问题。
最后应说明的是：以上各实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述各实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的范围，其均应涵盖在本申请的权利要求和说明书的范围当中。尤其是，只要不存在结构冲突，各个实施例中所提到的各项技术特征均可以任意方式组合起来。本申请并不局限于文中公开的特定实施例，而是包括落入权利要求的范围内的所有技术方案。

Claims (14)

  1. 一种极片(1)，沿第一方向(X)间隔具有若干拐角区(13)，当所述极片(1)沿所述第一方向(X)进行卷绕时，所述拐角区(13)形成电极组件(10)的弯折层(61)；
    所述极片(1)包括：
    集流体(11)；
    活性物质层(15)，设于所述集流体(11)的相对两表面上；
    其中，在至少一个所述拐角区(13)内，用于形成所述弯折层(61)凹面(611)的所述活性物质层(15)上设有缓冲空间(12)，所述缓冲空间(12)沿所述极片(1)的厚度方向(Z)凹陷但不贯穿所述集流体(11)。
  2. 根据权利要求1所述的极片(1)，其中，在具有所述缓冲空间(12)的拐角区(13)内，所述缓冲空间(12)沿第二方向(Y)延伸设置，所述第二方向(Y)被定义为与所述第一方向(X)和所述极片(1)的厚度方向(Z)构成的平面垂直。
  3. 根据权利要求2所述的极片(1)，其中，所述缓冲空间(12)沿所述第二方向(Y)上的长度记为L1，所述缓冲空间(12)所在的活性物质层(15)沿所述第二方向(Y)上的长度记为L2，L1与L2满足的条件为：0.3≤L1/L2≤1。
  4. 根据权利要求1-3任一项所述的极片(1)，其中，用于形成所述弯折层(61)凹面(611)的所述活性物质层(15)的厚度记为D，所述缓冲空间(12)在所述活性物质层(15)表面上形成有开口(123)，各所述开口(123)沿所述第一方向(X)上的宽度之和记为W，W与D满足的条件为：0.6×π×D≤W≤1.4×π×D。
  5. 根据权利要求4所述的极片(1)，其中，所述宽度之和W还满足的条件为：50μm≤W≤5000μm。
  6. 根据权利要求1-5任一项所述的极片(1)，其中，所述缓冲空间(12)沿所述第一方向(X)上的宽度记为A，所述宽度A自所述活性物质层(15)表面开始， 沿所述极片(1)的厚度方向(Z)并朝向所述集流体(11)一侧逐渐减小。
  7. 根据权利要求1-6任一项所述的极片(1)，其中，在具有所述缓冲空间(12)的拐角区(13)内，所述缓冲空间(12)为多个，全部所述缓冲空间(12)沿所述第一方向(X)间隔排布。
  8. 根据权利要求7所述的极片(1)，其中，在具有所述缓冲空间(12)的拐角区(13)内，相邻两个所述缓冲空间(12)之间间隙记为H，H满足的条件为：25μm≤H≤2500μm。
  9. 根据权利要求8所述的极片(1)，其中，所述宽度之和W还满足的条件为：80μm≤H≤1000μm。
  10. 根据权利要求1-9任一项所述的极片(1)，其中，在具有所述缓冲空间(12)的拐角区(13)内，所述缓冲空间(12)沿所述极片(1)的厚度方向(Z)不贯穿自身所在的所述活性物质层(15)。
  11. 一种电极组件(10)，由正极片(2)、负极片(3)及隔设于所述正极片(2)和所述负极片(3)之间的隔膜(4)卷绕形成，所述电极组件(10)包括弯折部(6)，所述弯折部(6)包括若干层叠的弯折层(61)；
    其中，所述正极片(2)和/或所述负极片(3)为权利要求1-10任一项所述的极片(1)。
  12. 根据权利要求11所述的电极组件(10)，其中，所述电极组件(10)还包括平直部(5)，所述弯折部(6)为两个，两个所述弯折部(6)分别设于所述平直部(5)的相对两侧。
  13. 一种二次电池(100)，包括权利要求11或12所述的电极组件(10)。
  14. 一种用电装置(1000)，包括权利要求13所述的二次电池(100)。
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012174579A (ja) * 2011-02-23 2012-09-10 Denso Corp 捲回型電池、その製造方法および製造装置
CN103151553A (zh) * 2011-12-06 2013-06-12 株式会社半导体能源研究所 方形锂二次电池
CN109565033A (zh) * 2016-08-31 2019-04-02 株式会社村田制作所 电池、电池组、电子设备、电动车辆、蓄电装置以及电力系统
CN216872019U (zh) * 2022-01-18 2022-07-01 宁德时代新能源科技股份有限公司 正极片、卷绕式电芯、电池单体、电池及用电装置

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012174579A (ja) * 2011-02-23 2012-09-10 Denso Corp 捲回型電池、その製造方法および製造装置
CN103151553A (zh) * 2011-12-06 2013-06-12 株式会社半导体能源研究所 方形锂二次电池
CN109565033A (zh) * 2016-08-31 2019-04-02 株式会社村田制作所 电池、电池组、电子设备、电动车辆、蓄电装置以及电力系统
CN216872019U (zh) * 2022-01-18 2022-07-01 宁德时代新能源科技股份有限公司 正极片、卷绕式电芯、电池单体、电池及用电装置

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