WO2023130902A1 - 卷绕式电极组件、电池单体、电池及用电设备 - Google Patents

卷绕式电极组件、电池单体、电池及用电设备 Download PDF

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Publication number
WO2023130902A1
WO2023130902A1 PCT/CN2022/138049 CN2022138049W WO2023130902A1 WO 2023130902 A1 WO2023130902 A1 WO 2023130902A1 CN 2022138049 W CN2022138049 W CN 2022138049W WO 2023130902 A1 WO2023130902 A1 WO 2023130902A1
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WIPO (PCT)
Prior art keywords
positive electrode
active material
electrode assembly
electrode active
positive
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
PCT/CN2022/138049
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English (en)
French (fr)
Inventor
罗威
杨龙飞
杨丽美
叶思敏
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Contemporary Amperex Technology Co Ltd
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Contemporary Amperex Technology Co Ltd
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
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Application filed by Contemporary Amperex Technology Co Ltd filed Critical Contemporary Amperex Technology Co Ltd
Priority to CN202290000304.6U priority Critical patent/CN221928200U/zh
Priority to EP22918352.0A priority patent/EP4386929A4/en
Publication of WO2023130902A1 publication Critical patent/WO2023130902A1/zh
Priority to US18/599,922 priority patent/US20240213544A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/04—Construction or manufacture in general
    • 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
    • H01M10/04—Construction or manufacture in general
    • H01M10/0404—Machines for assembling batteries
    • H01M10/0409—Machines for assembling batteries for cells with wound electrodes
    • 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
    • H01M10/04—Construction or manufacture in general
    • H01M10/0431—Cells with wound or folded electrodes
    • 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
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • 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
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/204—Racks, modules or packs for multiple batteries or multiple cells
    • H01M50/207—Racks, modules or packs for multiple batteries or multiple cells characterised by their shape
    • H01M50/209—Racks, modules or packs for multiple batteries or multiple cells characterised by their shape adapted for prismatic or rectangular cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present application relates to the technical field of batteries, in particular, to a wound electrode assembly, a battery cell, a battery, electrical equipment, and a manufacturing method and equipment for the wound electrode assembly.
  • the lithium deposition is one of the main factors affecting the electrical performance and safety performance of the battery. Once the lithium deposition occurs in the battery, it will not only reduce the electrical performance of the battery, but also easily form dendrites and dendrites as the amount of lithium deposition accumulates. It is possible to puncture the diaphragm, causing a short circuit in the battery, causing a safety hazard.
  • the embodiment of the present application provides a wound electrode assembly, a battery cell, a battery, electrical equipment, and a manufacturing method and equipment for the wound electrode assembly, so as to reduce the risk of lithium deposition in the electrode assembly.
  • an embodiment of the present application provides a wound electrode assembly, the wound electrode assembly has a bending area, includes a positive electrode sheet, and the positive electrode sheet includes a positive electrode collector and is disposed on the positive electrode collector.
  • the positive electrode sheet includes a Multi-layer bending parts arranged in sequence;
  • the first positive electrode active material layer includes a plurality of first positive electrode active material parts located in the multi-layer bending parts, at least one of the first positive electrode active material parts is provided with a plurality of first groove.
  • the first positive electrode active material layer on the inner surface of the positive electrode current collector is located in at least one layer of the bending area and is provided with a plurality of first grooves, which can reduce the capacity of the positive electrode active material in the bending area, thereby increasing the bending area.
  • the CB (Cell Balance, battery balance) value of the folding area where the CB value is the ratio of the capacity of the negative active material to the capacity of the positive active material; it can also reserve expansion space for the wound electrode assembly, reducing the bending area of the pole piece (Positive pole piece and/or negative pole piece) are subject to stress, reduce the resistance of ions embedded in the negative pole piece; the setting of multiple first grooves can also make the inside of the wound electrode assembly able to accommodate more electrolyte , can be used as a supplementary electrolyte when the wound electrode assembly is subjected to expansion and extrusion, and the internal electrolyte is reduced, reducing the risk of lithium precipitation caused by insufficient electrolyte infiltration affecting ion transfer, reducing concentration polarization, and improving battery cell performance.
  • the internal cycle performance reduces the risk of lithium separation in the bending area, thereby improving the safety performance of the battery cell with the wound electrode assembly.
  • a plurality of the first grooves are arranged at intervals along the extending direction of the positive electrode sheet.
  • a plurality of first grooves are arranged at intervals along the extending direction of the positive electrode sheet, so as to reduce the risk of lithium precipitation at any part of the bending region along the extending direction of the positive electrode sheet.
  • a plurality of the first grooves are disposed on an inner surface of the first positive electrode active material part away from the positive electrode current collector.
  • a plurality of first grooves are arranged on the inner surface of the first positive electrode active material part away from the positive electrode current collector, which can reduce the capacity of the positive electrode active material in the bending area, thereby increasing the CB value of the bending area, and The risk of lithium precipitation of the wound electrode assembly is reduced, and the safety performance of the battery cell with the wound electrode assembly is improved.
  • the first groove provided on the inner surface of the first positive electrode active material part can also reserve expansion space for the wound electrode assembly, reducing the impact on the pole piece (positive pole piece and/or negative pole piece) in the bending area.
  • the stress reduces the resistance of ions embedded in the negative electrode sheet; the first groove is arranged on the inner surface of the first positive electrode active material part away from the positive electrode current collector, which can also increase the distance between the first positive electrode active material part and the negative electrode sheet inside the first positive electrode active material part.
  • Space to accommodate more electrolyte further reducing the risk of lithium precipitation caused by the impact of ion transfer after the electrolyte in the wound electrode assembly is squeezed out, and can also improve the risk of internal cycle performance of the battery cell and reduce bending
  • the risk of lithium is analyzed, thereby improving the safety performance of the battery cell with the wound electrode assembly.
  • the first groove runs through the first positive electrode active material portion and is located at both ends of the winding axis in the extending direction.
  • the first groove runs through both ends of the first positive electrode active material part, providing a channel for the electrolyte to infiltrate the wound electrode assembly, which is conducive to the flow of the electrolyte in the wound electrode assembly.
  • Internal flow reduces the risk of insufficient infiltration of the wound electrode assembly due to high stress in the bending area, reduces concentration polarization, and improves lithium analysis in the bending area.
  • the extension direction of the first groove is parallel to the extension direction of the winding axis.
  • the extension direction of the first groove is parallel to the extension direction of the winding axis, which facilitates the formation of the first groove on the first positive electrode active material part and reduces the difficulty of production.
  • At least two of the first positive electrode active material parts are provided with a plurality of the first grooves; In the active material part, the density of the first grooves of the first positive electrode active material part located on the inner side is greater than the density of the first grooves of the first positive electrode active material part located on the outer side .
  • the closer to the electrode assembly the easier it is to deposit lithium.
  • the density of the first grooves of the first positive electrode active material part located on the inside is greater than the density of the first grooves of the first positive electrode active material part located on the outside, so that the first positive electrode active material part located on the inside and the first positive electrode active material part on the inside.
  • the first positive electrode active material parts are provided with a plurality of the first grooves; Among the active material parts, the width of the first groove of the first positive electrode active material part located on the inner side is greater than the width of the first groove of the first positive electrode active material part located on the outer side.
  • the closer to the electrode assembly the easier it is to deposit lithium.
  • the width of the first groove of the first positive electrode active material part located on the inside is greater than the width of the first groove of the first positive electrode active material part located on the outside, so that the first positive electrode active material part located on the inside and the negative electrode on the inside.
  • There is a larger space between the sheets which can reserve more expansion space for the wound electrode assembly, reduce the stress on the electrode sheet (positive electrode sheet and/or negative electrode sheet) in the bending area, and reduce the ion insertion into the negative electrode
  • the resistance of the pole piece it can also accommodate more electrolyte, reduce the risk of lithium precipitation caused by the influence of ion transfer after the electrolyte near the winding axis is squeezed out, and improve the risk of internal cycle performance of the battery cell .
  • At least one of the first positive electrode active material parts located on the innermost side is provided with a plurality of the first grooves.
  • the innermost layer of the positive electrode sheet is first squeezed, and the degree of extrusion is more severe, and the innermost first positive electrode active material part is provided with a plurality of first grooves , so that more electrolyte can be accommodated between the innermost first positive electrode active material part and its inner negative electrode sheet, and can be used as Replenish the electrolyte to reduce the risk of lithium precipitation caused by the extrusion of the electrolyte inside the wound electrode assembly and affect the ion transfer, and it can also improve the risk of the internal cycle performance of the battery cell.
  • the positive electrode sheet includes a winding end section, and in the bending region, at least part of the first positive electrode active material part of the winding end section is arranged There are a plurality of said first grooves.
  • the pole piece closer to the inner wall of the casing is subject to a greater pressing force.
  • At least part of the first positive electrode active material part of the winding end section is provided with a plurality of first grooves, which can reserve expansion space in the area of the wound electrode assembly close to the inner wall of the shell, and reduce the bending area near the inner wall of the shell.
  • the stress on the pole piece reduces the resistance of ions embedded in the negative pole piece; it also enables the inside of the wound electrode assembly to accommodate more electrolyte, which can be used in the wound type
  • the internal electrolyte is squeezed out as a supplementary electrolyte, which reduces the risk of lithium precipitation caused by the impact of ion transfer caused by the extrusion of the internal electrolyte of the wound electrode assembly, and improves the battery life.
  • the internal cycle performance of the monomer reduces the internal cycle performance of the monomer reduces the
  • the plurality of first grooves are arranged in a grid.
  • the plurality of first grooves are arranged in a grid, which can guide the electrolyte to flow in different directions, facilitate the circulation of the electrolyte inside the wound electrode assembly, and reduce the Insufficient infiltration due to high stress reduces concentration polarization and improves corner lithium separation.
  • the positive electrode sheet further includes a second positive active material layer disposed on the outer surface of the positive current collector, and the second positive active material layer includes The bent portion has a plurality of second positive electrode active material portions; at least one of the second positive electrode active material portions is provided with a plurality of second grooves.
  • the second positive electrode active material layer on the outer surface of the positive electrode current collector is located in the bending area, and at least one layer is provided with a plurality of second grooves, which can reserve expansion space for the wound electrode assembly and reduce bending
  • the stress on the regional pole piece (positive pole piece and/or negative pole piece) reduces the resistance of ions embedded in the negative pole piece; the setting of multiple second grooves can also allow the inside of the wound electrode assembly to accommodate more
  • the electrolyte can be used as a supplementary electrolyte when the internal electrolyte of the wound electrode assembly is reduced due to expansion and extrusion, reducing the risk of lithium precipitation caused by the impact of ion transfer due to the extrusion of the internal electrolyte of the wound electrode assembly , improve the internal cycle performance of the battery cell, reduce the risk of bending and decomposing lithium, thereby improving the safety performance of the battery cell with the wound electrode assembly.
  • the wound electrode assembly includes a straight region and two bent regions, and the two bent regions are respectively connected to two ends of the straight region
  • the weight W0 of the positive electrode active material layer per unit area of the positive electrode sheet located in the flat area and the weight Wn of the positive electrode active material per unit area of the positive electrode sheet located in the bending area meet: 30%W0 ⁇ Wn ⁇ 95%W0.
  • the weight W0 of the positive electrode active material layer per unit area of the positive electrode sheet located in the straight region and the weight Wn of the positive electrode active material per unit area of the positive electrode sheet located in the bent region satisfy 30% W0 ⁇ Wn ⁇ 95%W0, not only reduces the risk of lithium deposition in the bending area of the wound electrode assembly, but also ensures the energy density of the wound electrode assembly.
  • the wound electrode assembly further includes a negative pole piece and a separator
  • the thickness of the positive pole piece is M1
  • the thickness of the negative pole piece is M2
  • the The thickness of the separator is M3, the first first groove and the last first groove of the nth layer of the bent part along the winding direction of the wound electrode assembly from the inside to the outside
  • the distance between the slots is Cn, which satisfies: 0.1mm ⁇ Cn ⁇ pi*(M1+M2+M3)*a+50mm
  • n is a natural number greater than or equal to 2
  • a is the positive electrode of layer a from the inside to the outside slice
  • pi is the circumference ratio.
  • the thickness of the positive electrode sheet is M1
  • the thickness of the negative electrode sheet is M2
  • the thickness of the separator is M3
  • the thickness of the nth bending part from the inside to the outside along the winding direction of the wound electrode assembly The distance between the first first groove and the last first groove is Cn, satisfying 0.1mm ⁇ Cn ⁇ pi*(M1+M2+2M3)*a+50mm, the farther the layer is from the winding axis
  • the greater the span of the plurality of first grooves on the bending portion along the winding direction the greater the span of the plurality of first grooves on each layer of the bending portion matches the length of the corresponding bending portion, effectively improving the bending process.
  • Part of the problem of lithium precipitation is caused by the decay of active lithium.
  • an embodiment of the present application provides a battery cell, including a casing and the wound electrode assembly provided in the embodiment of the first aspect; the casing has an opening; the wound electrode assembly is accommodated in the casing .
  • the battery cell includes the wound electrode assembly provided in the embodiment of the first aspect, so that the cycle performance of the battery cell is better, and the risk of lithium precipitation in the battery cell is smaller, thereby improving the safety performance of the battery cell better.
  • the embodiment of the present application provides a battery, including the battery cell provided in the embodiment of the second aspect.
  • the battery includes the battery cell provided by the embodiment of the second aspect, so that the cycle performance of the battery is better, and the risk of lithium precipitation in the battery is smaller, so that the safety performance of the battery is better.
  • the embodiment of the present application provides an electric device, including the battery cell provided in the embodiment of the second aspect.
  • the embodiment of the present application provides a method for manufacturing a wound electrode assembly, including:
  • the positive electrode sheet includes a positive electrode current collector and a first positive electrode active material layer disposed on one side of the positive electrode current collector, the first positive electrode active material layer is provided with a plurality of first grooves;
  • the first positive electrode active material layer is located on the inner surface of the positive electrode current collector, and the inner surface faces the winding axis of the wound electrode assembly after winding, and the wound electrode assembly has a curved In the bending area, the positive electrode sheet includes multi-layer bending parts arranged in sequence from the inside to the outside in the bending area, and at least part of the first grooves in the plurality of first grooves are located in at least one of the first grooves. layer the bent portion.
  • an embodiment of the present application provides a manufacturing equipment for a wound electrode assembly, including a supply device and an assembly device; the supply device is configured to provide a positive electrode sheet; the positive electrode sheet includes a positive electrode current collector and a device On the first positive electrode active material layer on one side of the positive electrode current collector, the first positive electrode active material layer is provided with a plurality of first grooves; the assembly device is configured to wind the positive electrode sheet, To form a wound electrode assembly; wherein, the first positive electrode active material layer is located on the inner surface of the positive electrode current collector, and the inner surface faces the winding axis of the wound electrode assembly after winding, so
  • the wound electrode assembly has a bending area, and the positive pole piece includes multi-layer bending parts located in the bending area and arranged sequentially from inside to outside, at least part of the plurality of first grooves are The first groove is located on at least one layer of the bent portion.
  • Fig. 1 is a schematic structural diagram of a vehicle provided by some embodiments of the present application.
  • Fig. 2 is a schematic structural diagram of a battery provided by some embodiments of the present application.
  • Fig. 3 is a schematic structural diagram of a battery cell provided by some embodiments of the present application.
  • Fig. 4 is an exploded view of a battery cell provided by some embodiments of the present application.
  • Fig. 5 is a schematic structural diagram of an electrode assembly provided by some embodiments of the present application.
  • Fig. 6 is a schematic structural diagram of an electrode assembly provided by another embodiment of the present application.
  • Figure 7 is a partial enlarged view of an electrode assembly provided by some embodiments of the present application.
  • Fig. 8 is a partial enlarged view of an electrode assembly provided by another embodiment of the present application.
  • Fig. 9 is a partial enlarged view of an electrode assembly provided in some further embodiments of the present application.
  • Fig. 10 is a partial enlarged view of an electrode assembly provided in some other embodiments of the present application.
  • Fig. 11 is a partial schematic diagram of electrode assemblies provided by other embodiments of the present application.
  • Fig. 12 is a partial schematic diagram of an electrode assembly provided by some other embodiments of the present application.
  • Fig. 13 is a schematic diagram of an unfolded state of a positive electrode sheet with a plurality of first grooves arranged in a grid pattern provided by some embodiments of the present application;
  • Fig. 14 is a partial schematic diagram of a wound electrode assembly provided in some further embodiments of the present application.
  • Fig. 15 is a schematic diagram of the expanded state of the positive electrode sheet provided by other embodiments of the present application.
  • Fig. 16 is a flowchart of a manufacturing method of a wound electrode assembly provided by some embodiments of the present application.
  • Fig. 17 is a schematic structural diagram of a manufacturing equipment for a wound electrode assembly provided by some embodiments of the present application.
  • Icons 1000-vehicle; 100-battery; 10-box; 11-accommodating space; 12-first part; 13-second part; 20-battery unit; 21-shell; 211-opening; 22-end cover assembly 221-end cover; 222-electrode terminal; 23-electrode assembly; 231-positive pole piece; 2311-positive current collector; 2312-first positive active material layer; 2314-first groove; 2315-second positive active material layer; 2315a-second positive active material part; 2316-second groove; 232-negative pole piece; 24-current collecting member; 25-insulation protection member; 200-controller; 300-motor; 2000-manufacturing equipment of wound electrode assembly; 2100-providing device;
  • the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship that is usually placed when the product of the application is used, or the orientation or positional relationship of this application.
  • Orientations or positional relationships commonly understood by those skilled in the art are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood For the limitation of this application.
  • the terms “first”, “second”, “third”, etc. are only used for distinguishing descriptions, and should not be construed as indicating or implying relative importance.
  • Power batteries are not only used in energy storage power systems such as hydraulic, thermal, wind and solar power plants, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric vehicles, as well as military equipment and aerospace and other fields . With the continuous expansion of power battery application fields, its market demand is also constantly expanding.
  • the wound electrode assembly expands, the electrolyte in the bending area is squeezed out severely, resulting in insufficient electrolyte infiltration in the bending area, increasing concentration polarization, and serious lithium analysis in the bending area.
  • the inventors have conducted in-depth research and designed a wound electrode assembly.
  • the first positive electrode active material layer on the inner surface of the inner surface is located at least one layer of the bending area is provided with a plurality of first grooves, which can reduce the capacity of the positive electrode active material in the bending area, thereby increasing the CB value of the bending area; Reserve expansion space for the wound electrode assembly, reduce the stress on the pole piece (positive pole piece and/or negative pole piece) in the bending area, and reduce the resistance of ions embedded in the negative pole piece; the multiple first grooves
  • the setting can also enable the inside of the wound electrode assembly to accommodate more electrolyte, which can be used as a supplementary electrolyte when the wound electrode assembly is expanded and squeezed to reduce the internal electrolyte, reducing the impact of insufficient electrolyte infiltration.
  • the wound electrode assembly disclosed in the embodiments of the present application can be used, but not limited, in electrical equipment such as vehicles, ships, or aircraft.
  • a power supply system comprising the battery cells and batteries disclosed in the present application can be used to form the power consumption device, which is beneficial to the slow decomposition of lithium and improves the safety of power consumption.
  • An embodiment of the present application provides an electric device using a battery as a power source.
  • the electric device may be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, an electric tool, and the like.
  • Vehicles can be fuel vehicles, gas vehicles or new energy vehicles, and new energy vehicles can be pure electric vehicles, hybrid vehicles or extended-range vehicles; spacecraft include airplanes, rockets, space shuttles and spacecraft, etc.; electric toys include fixed Type or mobile electric toys, such as game consoles, electric car toys, electric boat toys and electric airplane toys, etc.; electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools and railway electric tools, for example, Electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, electric planers, and more.
  • the embodiment of the present application does not impose special limitations on the above electric equipment.
  • FIG. 1 is a schematic structural diagram of a vehicle 1000 provided by some embodiments of the present application.
  • the interior of the vehicle 1000 is provided with a battery 100 , and the battery 100 may be provided at the bottom, head or tail of the vehicle 1000 .
  • the battery 100 can be used for power supply of the vehicle 1000 , for example, the battery 100 can be used as an operating power source of the vehicle 1000 .
  • the vehicle 1000 may further include a controller 200 and a motor 300 , the controller 200 is used to control the battery 100 to supply power to the motor 300 , for example, for starting, navigating and running the vehicle 1000 .
  • the battery 100 can not only be used as an operating power source for the vehicle 1000 , but can also be used as a driving power source for the vehicle 1000 to provide driving power for the vehicle 1000 instead of or partially replacing fuel oil or natural gas.
  • FIG. 2 is a schematic structural diagram of a battery 100 provided by some embodiments of the present application.
  • the battery 100 includes a case 10 and battery cells 20 , and the battery cells 20 are accommodated in the case 10 .
  • the box body 10 is used to provide an accommodating space 11 for the battery cells 20 .
  • the box body 10 may include a first part 12 and a second part 13 , and the first part 12 and the second part 13 cover each other to define an accommodating space 11 for accommodating the battery cells 20 .
  • the connection between the first part 12 and the second part 13 can be sealed by a sealing member (not shown in the figure), and the sealing member can be a sealing ring, a sealant, or the like.
  • the first part 12 and the second part 13 can be in various shapes, such as cuboid, cylinder and so on.
  • the first part 12 may be a hollow structure with an opening on one side to form a cavity for accommodating the battery cell 20
  • the second part 13 may also be a hollow structure with an opening on one side to form a cavity for accommodating the battery cell 20 .
  • the opening side of the part 13 is covered with the opening side of the first part 12 to form a box body 10 with a receiving space 11 .
  • the first part 12 may also be a hollow structure with one side opening
  • the second part 13 may be a plate-like structure
  • the second part 13 covers the opening side of the first part 12 to form an accommodating space. 11 of the box 10 .
  • the battery 100 there may be one or a plurality of battery cells 20 . If there are multiple battery cells 20 , the multiple battery cells 20 may be connected in series, in parallel or in parallel.
  • the mixed connection means that the multiple battery cells 20 are both in series and in parallel.
  • a plurality of battery cells 20 can be directly connected in series, in parallel or mixed together, and then the whole composed of a plurality of battery cells 20 is housed in the box 10; of course, a plurality of battery cells 20 can also be connected in series first
  • a battery module is formed by connecting in parallel or in series, and a plurality of battery modules are connected in series or in parallel or in series to form a whole, and are accommodated in the box 10 .
  • the battery cell 20 may be in the form of a cylinder, a flat body, a cuboid or other shapes.
  • FIG. 2 exemplarily shows the case where the battery cell 20 is in a square shape.
  • the battery 100 may further include a confluence component (not shown in the figure), and multiple battery cells 20 may be electrically connected through the confluence component, so as to realize series connection, parallel connection or mixed connection of multiple battery cells 20 . couplet.
  • FIG. 4 is a schematic structural diagram of a battery cell 20 provided in some embodiments of the application
  • FIG. 4 is an exploded view of a battery cell 20 provided in some embodiments of the application.
  • the battery cell 20 may include a case 21 , an end cap assembly 22 and an electrode assembly 23 .
  • the casing 21 has an opening 211
  • the electrode assembly 23 is accommodated in the casing 21
  • the end cap assembly 22 is used to cover the opening 211 .
  • the shell 21 can be in various shapes, such as cylinder, cuboid and so on.
  • the shape of the casing 21 can be determined according to the specific shape of the electrode assembly 23 .
  • the shell 21 can be a cylindrical structure; if the electrode assembly 23 is a rectangular parallelepiped, the shell 21 can be a rectangular parallelepiped.
  • FIG. 3 and FIG. 4 exemplarily show the case that the casing 21 and the electrode assembly 23 are square.
  • the housing 21 may also be made of various materials, for example, copper, iron, aluminum, stainless steel, aluminum alloy, etc., which are not particularly limited in this embodiment of the present application.
  • the end cap assembly 22 includes an end cap 221 and an electrode terminal 222 .
  • the end cap assembly 22 is used to cover the opening 211 of the casing 21 to form a closed installation space (not shown in the figure), and the installation space is used to accommodate the electrode assembly 23 .
  • the installation space is also used to accommodate electrolyte, such as electrolytic solution.
  • the end cover assembly 22 is used as a component for outputting the electric energy of the electrode assembly 23, and the electrode terminal 222 in the end cover assembly 22 is used to be electrically connected to the electrode assembly 23, that is, the electrode terminal 222 is electrically connected to the tab of the electrode assembly 23, for example, the electrode terminal 222 and the tab are connected through the current collecting member 24 to realize the electrical connection between the electrode terminal 222 and the tab.
  • the end cover assembly 22 can also be one, and then two electrode terminals 222 can be arranged in the end cover assembly 22, and the two electrode terminals 222 are respectively used for connecting with the positive pole lug and the negative pole of the electrode assembly 23.
  • the two electrode terminals 222 in the end cap assembly 22 are respectively a positive electrode terminal and a negative electrode terminal. If there are two openings 211 of the housing 21, for example, the two openings 211 are arranged on opposite sides of the housing 21, the end cover assembly 22 may also be two, and the two end cover assemblies 22 cover the two sides of the housing 21 respectively. at the opening 211 .
  • the electrode terminal 222 in one end cap assembly 22 may be a positive electrode terminal for electrical connection with the positive electrode lug of the electrode assembly 23; the electrode terminal 222 in the other end cap assembly 22 may be a negative electrode The terminal is used for electrical connection with the negative electrode sheet of the electrode assembly 23 .
  • the battery cell 20 may further include an insulating protection member 25 fixed on the outer periphery of the electrode assembly 23 , and the insulating protection member 25 is used to insulate and isolate the electrode assembly 23 from the casing 21 .
  • the insulating protection member 25 is an adhesive tape bonded to the outer periphery of the electrode assembly 23 .
  • the number of electrode assemblies 23 is multiple, and the insulating protection member 25 surrounds the outer circumference of the plurality of electrode assemblies 23 and forms the plurality of electrode assemblies 23 into an integral structure to keep the structure of the electrode assemblies 23 stable.
  • FIG. 5 is a schematic structural diagram of an electrode assembly 23 provided in some embodiments of the present application
  • FIG. 6 is a schematic structural diagram of an electrode assembly 23 provided in other embodiments of the present application.
  • the electrode assembly 23 may include a positive pole piece 231 , a negative pole piece 232 and a separator (not shown in the figure).
  • the electrode assembly 23 is a winding structure formed by winding the positive pole piece 231 , the separator and the negative pole piece 232 .
  • the positive electrode sheet 231 includes a positive electrode current collector 2311 (shown in FIG. 7 ) and a positive electrode active material layer, the positive electrode active material layer is coated on the surface of the positive electrode current collector 2311, and the positive electrode current collector 2311 that is not coated with the positive electrode active material layer protrudes
  • the positive electrode current collector 2311 coated with the positive electrode active material layer and the positive electrode current collector 2311 not coated with the positive electrode active material layer serve as positive electrode tabs.
  • the positive electrode active material layer includes a first positive electrode active material layer 2312 and a second positive electrode active material layer. Along the thickness direction of the positive electrode current collector 2311, the first positive electrode active material layer 2312 and the second positive electrode active material layer are respectively arranged on the positive electrode current collector 2311 of the two surfaces.
  • the material of the positive electrode current collector 2311 may be aluminum, and the positive electrode active material may be lithium cobaltate, lithium iron phosphate, ternary lithium, or lithium manganate.
  • the negative electrode sheet 232 includes a negative electrode current collector (not shown in the figure) and a negative electrode active material layer, the negative electrode active material layer is coated on the surface of the negative electrode current collector, and the negative electrode current collector that is not coated with the negative electrode active material layer protrudes beyond the coated surface.
  • the negative electrode current collector covered with the negative electrode active material layer, and the negative electrode current collector not coated with the negative electrode active material layer are used as negative electrode tabs.
  • the negative electrode active material layer includes a first negative electrode active material layer and a second negative electrode active material layer. Along the thickness direction of the negative electrode current collector, the first negative electrode active material layer and the second negative electrode active material layer are respectively arranged on both surfaces of the negative electrode current collector. .
  • the material of the negative electrode current collector may be copper, and the negative electrode active material may be carbon or silicon.
  • the number of positive pole tabs is multiple and stacked together, and the number of negative pole tabs is multiple and stacked together.
  • the material of the isolation film may be PP (polypropylene, polypropylene) or PE (polyethylene, polyethylene).
  • the wound electrode assembly 23 has a bending area 233, the wound electrode assembly 23 includes a positive electrode sheet 231, and the positive electrode sheet 231 includes a positive electrode current collector 2311 and an electrode set on the positive electrode current collector 2311.
  • the first positive electrode active material layer 2312 on the inner surface, the inner surface faces the winding axis of the wound electrode assembly 23 after winding;
  • the positive electrode sheet 231 includes multi-layer bends located in the bend region 233 and arranged in sequence from the inside to the outside.
  • the first positive electrode active material layer 2312 includes multiple first positive electrode active material portions 2312 a located in the multilayer folded portion 2313 , and at least one first positive electrode active material portion 2312 a is provided with multiple first grooves 2314 .
  • one of the two surfaces in the thickness direction of the positive electrode current collector 2311 is closer to the winding axis and arranged facing the winding axis, and this surface is the positive electrode current collector 2311.
  • the inner surface and the other surface are farther away from the winding axis and set away from the winding axis, which is the outer surface of the positive current collector 2311 .
  • the wound electrode assembly 23 can also be a cylindrical electrode assembly, and any range along the circumferential direction of the wound electrode assembly 23 can be defined as the bending area 233 , then any bending area 233 can be provided with a plurality of first grooves 2314 .
  • the wound electrode assembly 23 can be square, as shown in Figure 6 and Figure 7,
  • Figure 6 is a schematic structural diagram of an electrode assembly 23 provided in another embodiment of the present application
  • Figure 7 is a schematic diagram of some implementations of the present application
  • the wound electrode assembly 23 includes a straight area 234 and two bent areas 233 , and the two bent areas 233 are connected to two ends of the straight area 234 .
  • a part of the positive pole piece 231 is located in the straight area 234
  • the other part of the positive pole piece 231 is located in the bent area 233 to form a multi-layered bent portion 2313 arranged sequentially from inside to outside.
  • Each layer of bending portion 2313 includes a portion of the first positive electrode active material layer 2312, therefore, the positive electrode sheet 231 includes a plurality of first positive electrode active material portions 2312a located in the multilayer bending portion 2313, and the plurality of first positive electrode active material The parts 2312a are arranged sequentially from the inside to the outside.
  • At least one first positive electrode active material part 2312a is provided with a plurality of first grooves 2314, each first positive electrode active material part 2312a is provided with a first groove 2314, or a plurality of first positive electrode active material parts Part of the first positive electrode active material part 2312a in 2312a is provided with a first groove 2314 .
  • the first groove 2314 can be formed by laser etching.
  • the first positive electrode active material layer 2312 on the inner surface of the positive electrode current collector 2311 is located at least one layer of the bending area 233 and is provided with a plurality of first grooves 2314, which can reduce the capacity of the positive electrode active material in the bending area 233, thereby increasing the bending area.
  • the CB value of the folding area 233, the CB value is the ratio of the negative electrode active material capacity to the positive electrode active material capacity, and the CB value can be greater than 1; it can also reserve expansion space for the wound electrode assembly 23, reducing the bending area 233 pole piece (Positive pole piece 231 and/or negative pole piece 232) suffered stress reduces the resistance of ions embedded in negative pole piece 232 and/or the resistance of ions from positive pole piece 231; the arrangement of multiple first grooves 2314 also It can make the inside of the wound electrode assembly 23 accommodate more electrolyte, and can be used as a supplementary electrolyte when the wound electrode assembly 23 is expanded and squeezed to reduce the internal electrolyte, reducing the impact of insufficient electrolyte infiltration on ions. transfer to cause the risk of lithium precipitation, reduce concentration polarization, improve the internal cycle performance of the battery cell 20, reduce the risk of lithium precipitation in the bending area 233, thereby improving the safety of the battery cell 20 with the wound electrode assembly 23 performance.
  • a plurality of first grooves 2314 are arranged at intervals along the extending direction of the positive pole piece 231 .
  • the extension direction of the positive pole piece 231 is consistent with the winding direction, and when the positive pole piece 231 is in the unfolded state, the extension direction of the positive pole piece 231 is consistent with the length direction of the positive pole piece 231 .
  • the plurality of first grooves 2314 may also be arranged in the first positive electrode active material part 2312a in other ways, for example, the plurality of first grooves 2314 are arranged along the extending direction of the winding axis or the plurality of first grooves 2314 A groove 2314 is circularly arranged in the plurality of first grooves 2314 .
  • a plurality of first grooves 2314 are arranged at intervals along the extending direction of the positive electrode sheet 231 to reduce the risk of lithium deposition at any part of the bending region 233 along the extending direction of the positive electrode sheet 231 .
  • a plurality of first grooves 2314 are disposed on the inner surface of the first positive electrode active material portion 2312 a away from the positive electrode current collector 2311 .
  • the inner surface of the first positive electrode active material part 2312a away from the positive electrode current collector 2311 refers to the surface of the first positive electrode active material part 2312a that is farther away from the inner surface of the positive electrode current collector 2311 along the thickness direction of the positive electrode sheet 231. After the winding of the positive electrode sheet 231 is completed, the surface of the first positive electrode active material portion 2312 a farther from the inner surface of the positive electrode current collector 2311 faces the winding axis.
  • a plurality of first grooves 2314 may also be disposed at opposite ends of the first positive electrode active material portion 2312a along the direction of the winding axis.
  • a plurality of first grooves 2314 are provided on the inner surface of the first positive electrode active material part 2312a away from the positive electrode current collector 2311, which can reduce the capacity of the positive electrode active material in the bending area 233, thereby increasing the CB value of the bending area 233, so as to The risk of lithium deposition in the wound electrode assembly 23 is reduced, and the safety performance of the battery cell 20 with the wound electrode assembly 23 is improved.
  • the first groove 2314 provided on the inner surface of the first positive electrode active material part 2312a can also reserve expansion space for the wound electrode assembly 23, reducing the bending area 233 pole piece (positive pole piece 231 and/or negative pole piece 231) sheet 232) to reduce the resistance of ions inserted into the negative electrode sheet 232 and/or the resistance of ions to escape from the positive electrode sheet 231; the first groove 2314 is arranged on the first positive electrode active material part 2312a away from the positive electrode current collector 2311
  • the inner surface of the inner surface can also increase the space between the first positive electrode active material part 2312a and the negative electrode sheet 232 inside to accommodate more electrolyte, so that the electrode assembly 23 can be fully wetted, further reducing the The electrolytic solution inside the electrode assembly 23 is squeezed out to affect the ion transfer and lead to the risk of lithium precipitation. It can also improve the risk of internal cycle performance of the battery cell 20 and reduce the risk of lithium precipitation in the bending area 233, thereby increasing the risk of lithium deposition in the winding
  • the first groove 2314 runs through the first positive electrode active material portion 2312 a and is located at both ends of the winding axis in the extending direction.
  • the first groove 2314 is formed from the inner surface of the first positive electrode active material part 2312a far away from the positive electrode current collector 2311.
  • the surface is recessed toward the inner surface close to the positive electrode sheet 231 , and extends along the winding axis until it penetrates both ends of the first positive electrode active material portion 2312 a.
  • the first groove 2314 is recessed from the inner surface of the first positive electrode active material part 2312a away from the positive electrode current collector 2311 to the inner surface close to the positive electrode sheet 231.
  • the depth is smaller than the thickness of the first positive electrode active material part 2312a, so that the first concave
  • the distance between the bottom wall of the groove 2314 and the inner surface of the positive electrode collector 2311 is greater than zero.
  • the first groove 2314 is formed on the first positive active material portion 2312a channel, wherein the first groove 2314 in the form of a channel can be defined by the first positive electrode active material part 2312a; as shown in FIG. Commonly defined.
  • the first groove 2314 may not pass through the two ends of the first positive electrode active material part 2312a along the winding axis direction, for example, the first groove 2314 is provided on the inner surface of the first positive electrode active material part 2312a And/or the pits at both ends of the first positive electrode active material portion 2312a along the extending direction of the winding axis.
  • the first groove 2314 runs through both ends of the first positive electrode active material part 2312a, providing a channel for the electrolyte to infiltrate the wound electrode assembly 23, which is beneficial for the electrolyte to flow inside the wound electrode assembly 23. flow, reduce the risk of insufficient infiltration of the wound electrode assembly 23 in the bending area 233 due to high stress, reduce concentration polarization, and improve lithium separation in the bending area 233 .
  • the extension direction of the first groove 2314 is parallel to the extension direction of the winding axis.
  • the first groove 2314 can also be arranged in other forms, for example, the first groove 2314 is arranged at an included angle with the extension direction of the winding axis, or the first groove 2314 is in a wave shape.
  • the extension direction of the first groove 2314 is parallel to the extension direction of the winding axis, which facilitates the formation of the first groove 2314 on the first positive electrode active material part 2312a and reduces production difficulty.
  • the coil layers closer to the winding axis are easier to precipitate lithium.
  • the electrode assembly 23 expands, the coil layers closer to the winding axis are squeezed more severely. Therefore, as shown in FIG. 10 , in some embodiments, in the bending region 233, at least two first positive electrode active material parts 2312a are provided with a plurality of first grooves 2314; among the two first positive electrode active material parts 2312a, the inner one The density of the first grooves 2314 of the first positive electrode active material portion 2312a is greater than the density of the first grooves 2314 of the outer first positive electrode active material portion 2312a.
  • the density of the first grooves 2314 can be defined as the number of the first grooves 2314 provided in the first positive electrode active material part 2312a per unit area.
  • a first positive electrode active material part 2312a located on the inner side refers to a first positive electrode active material part 2312a that is closer to the winding axis among the two first positive electrode active material parts 2312a; "a first positive electrode active material part 2312a located on the outer side The positive electrode active material part 2312a” refers to the first positive electrode active material part 2312a that is farther from the winding axis among the two first positive electrode active material parts 2312a.
  • the at least two first positive electrode active material parts 2312a provided with the first groove 2314 may be the first positive electrode active material parts 2312a that are sequentially adjacent from the inside to the outside; as shown in FIG. At least one first positive active material portion 2312a not provided with the first groove 2314 may be provided between two first positive electrode active material portions 2312a, that is, two first positive electrode active material portions 2312a provided with the first groove 2314 . Wherein, the comparison of the density of the first grooves 2314 is performed between the two first positive electrode active material parts 2312a provided with the first grooves 2314 .
  • the density of the first grooves 2314 of the first positive electrode active material part 2312a located on the inside is greater than the density of the first grooves 2314 of the first positive electrode active material part 2312a located on the outside, so that the first positive electrode active material part located on the inside
  • At least two first positive electrode active material parts 2312a are provided with a plurality of first grooves 2314; In the material part 2312a, the width of the first groove 2314 of the inner first positive electrode active material part 2312a is greater than the width of the first groove 2314 of the outer first positive electrode active material part 2312a.
  • first positive electrode active material parts 2312a are provided with a plurality of first grooves 2314;
  • the width of the first groove 2314 of a positive electrode active material part 2312a is greater than the width of the first groove 2314 of a first positive electrode active material part 2312a located on the outside, and the first groove 2314 of a first positive electrode active material part 2312a located on the inside
  • the density of the grooves 2314 is greater than the density of the first grooves 2314 of the outer first positive electrode active material portion 2312a.
  • the width of the first groove 2314 on each first positive electrode active material part 2312a may also be the same.
  • the width of the first groove 2314 of the first positive electrode active material part 2312a located on the inner side is greater than the width of the first groove 2314 of the first positive electrode active material part 2312a located on the outer side, so that the first positive electrode active material part 2312a located on the inner side
  • the received stress reduces the resistance of ions embedded in the negative pole piece 232 and/or the resistance of ions from the positive pole piece 231; it can also accommodate more electrolyte and reduce the extrusion of the electrolyte near the winding axis Afterwards, the ion transfer is affected to cause the risk of lithium precipitation, and the risk of improving the internal cycle performance of the battery cell 20 can also be improved.
  • the innermost layer of the bent portion 2313 is squeezed first, and the squeeze is more serious. Therefore, as shown in FIG. 11 , in some embodiments Among them, in the bending region 233 , at least one of the first positive active material parts located on the innermost side is provided with a plurality of first grooves 2314 .
  • the innermost first positive electrode active material part 2312a refers to the first positive electrode active material part 2312a closest to the winding axis in the same bending region 233 .
  • other first positive electrode active material layers 2312 may be provided with first grooves 2314 or may not be provided with first grooves 2314 .
  • the innermost first positive electrode active part is provided with a plurality of first grooves 2314, so that more electrolyte can be accommodated between the innermost first positive electrode active part and the inner negative electrode sheet 232, and the innermost
  • the internal electrolyte is reduced as a supplementary electrolyte, which reduces the risk of lithium precipitation caused by the impact of ion transfer due to the impact of ion transfer on the internal electrolyte of the wound electrode assembly 23, and can also The risk of improving the internal cycle performance of the battery cell 20 .
  • the positive electrode sheet 231 includes a winding end section, and in the bending area 233, at least part of the first positive electrode active material part 2312a of the winding end section is provided with a plurality of first groove 2314 .
  • the winding end section is a portion defined by extending a certain distance from the winding end end in a direction opposite to the winding direction.
  • the winding end section may be a part extending one turn from the winding end in the opposite direction of the winding direction, or a part of multiple turns, and the winding end section passes at least one turn from the winding end in the opposite direction of the winding direction. Folding area 233.
  • At least part of the first positive electrode active material part 2312a of the winding end section is provided with a plurality of first grooves 2314, which can reserve expansion space in the area of the wound electrode assembly 23 close to the inner wall of the casing 21, reducing the size of the electrode assembly 23 near the casing 21.
  • the inner wall bending area 233 of the pole piece (positive pole piece 231 and/or negative pole piece 232) is subject to stress, which reduces the resistance of ions embedded in the negative pole piece 232; it can also make the inside of the wound electrode assembly 23 accommodate more
  • a large amount of electrolyte can be used as a supplementary electrolyte when the internal electrolyte is squeezed out when the wound electrode assembly 23 expands to the inner wall of the casing 21, reducing the pressure caused by the internal electrolyte of the wound electrode assembly 23 Afterwards, it will affect the ion transfer and lead to the risk of lithium deposition, improve the internal cycle performance of the battery cell 20, reduce the risk of lithium deposition in the bending area 233, thereby improving the safety performance of the battery cell 20 with the wound electrode assembly 23.
  • a plurality of first grooves 2314 are arranged in a grid.
  • the plurality of first grooves 2314 are arranged in a grid, which means that in one bent portion 2313, at least two first grooves 2314 are alternately arranged and connected. For example, two of the plurality of first grooves 2314 are connected, in other words, the plurality of first grooves 2314 are connected to each other.
  • the plurality of first grooves 2314 are arranged in a grid, which can guide the electrolyte to flow in different directions, facilitate the circulation of the electrolyte in the wound electrode assembly 23, and reduce the Insufficient infiltration caused by high stress reduces concentration polarization and improves lithium separation at corners.
  • the positive electrode sheet 231 further includes a second positive electrode active material layer 2315 disposed on the outer surface of the positive electrode current collector 2311 , and the second positive electrode active material layer includes a multi-layer bent portion 2313 A plurality of second positive active material parts 2315a; at least one second positive active material part 2315a is provided with a plurality of second grooves 2316.
  • the second active material part 2315 may not be provided with the second groove 2316 , and only the first active material part 2312a is provided with the first groove 2314 .
  • the second positive electrode active material layer 2315 on the outer surface of the positive electrode current collector 2311 is located in the bending area 233, and at least one layer is provided with a plurality of second grooves 2316, which can reserve expansion space for the wound electrode assembly 23 and reduce bending.
  • the interior of the coiled electrode assembly 23 can accommodate more electrolyte, and can be used as a supplementary electrolyte when the internal electrolyte of the coiled electrode assembly 23 is reduced due to expansion and extrusion, reducing the impact caused by the extrusion of the internal electrolyte of the coiled electrode assembly 23
  • the ion transfer causes the risk of lithium deposition, improves the internal cycle performance of the battery cell 20, reduces the risk of lithium deposition in the bending area 233, thereby improving the safety performance of the battery cell 20 with the wound electrode assembly 23.
  • the wound electrode assembly 23 includes a straight region 234 and two bent regions 233, and the two bent regions 233 are respectively connected to two ends of the straight region 234;
  • the weight W0 of the positive electrode active material layer per unit area of the sheet 231 and the weight Wn of the positive electrode active material per unit area of the positive electrode sheet 231 located in the bending region 233 satisfy: 30%W0 ⁇ Wn ⁇ 95%W0.
  • the weight W0 of the positive electrode active material layer per unit area of the positive electrode sheet 231 in the flat region 234 refers to the average weight of the positive electrode active material layer per unit area of the positive electrode sheet 231 in the flat region 234;
  • the weight Wn of the positive active material per unit area of the pole piece 231 refers to the average weight of the positive active material per unit area of the positive pole piece 231 in the bending region 233 .
  • W0 and Wn satisfy 30%W0 ⁇ Wn ⁇ 95%W0, which not only reduces the risk of lithium deposition in the bending region 233 of the wound electrode assembly 23, but also ensures the energy density of the wound electrode assembly 23.
  • the wound electrode assembly 23 further includes a negative pole piece 232 and a separator
  • the thickness of the positive pole piece 231 is M1
  • the thickness of the negative pole piece 232 is M2
  • the thickness of the separator is is M3
  • the distance between the first first groove 2314 and the last first groove 2314 along the winding direction of the wound electrode assembly 23 of the nth layer of bent portion 2313 from the inner to the outer is Cn
  • n is a natural number greater than or equal to 2
  • a is the positive pole piece 231 representing the a-th layer from outside to inside
  • pi is the circumference ratio.
  • the length of the bent portion 2313 along the winding direction gradually increases from the inside to the outside, so the multiple first grooves 2314 on the bent portion 2313 need to have a larger span range, So that along the winding direction, the plurality of first grooves 2314 cover the corresponding bending portion 2313 as much as possible.
  • the first first groove 2314 and the last first groove 2314 in the first-layer bending part 2313 from the inside to the outside satisfy: 0.1mm ⁇ C1 ⁇ pi*(M1+M2+M3)*1 +50mm; the first first groove 2314 and the last first groove 2314 in the second-layer bending part 2313 from the inner to the outer, satisfy: 0.1mm ⁇ C2 ⁇ pi*(M1+M2+M3)* 2+50mm, and so on.
  • the thickness of the positive pole piece 231 is M1
  • the thickness of the negative pole piece 232 is M2
  • the thickness of the separator is M3.
  • the distance between a first groove 2314 and the last first groove 2314 is Cn, satisfying 0.1mm ⁇ Cn ⁇ pi*(M1+M2+2M3)*a+50mm, the farther away from the winding axis
  • the span of the plurality of first grooves 2314 on the layer bending portion 2313 along the winding direction is larger, so that the span of the plurality of first grooves 2314 of each layer bending portion 2313 matches the length of the corresponding bending portion 2313 , effectively improving the problem of lithium precipitation at the bent portion 2313 due to attenuation of active lithium.
  • the first first groove 2314 of one of the bent parts 2313 of the two adjacent bent parts 2313 is connected to the other of the two adjacent bent parts 2313
  • the distance Ln between the last first groove 2314 of the bent portion 2313 is greater than or equal to 0 and less than the total length of the positive pole piece 231 .
  • the embodiment of the present application provides a square wound electrode assembly 23.
  • the wound electrode assembly 23 includes a positive electrode sheet 231.
  • the positive electrode sheet 231 includes a positive electrode current collector 2311, and a first electrode disposed on the inner surface of the positive electrode current collector 2311.
  • the positive electrode active material layer 2312 and the second positive electrode active material layer 2315 disposed on the outer surface of the positive electrode current collector 2311 .
  • the positive electrode sheet 231 includes a multi-layer bent portion 2313 located in the bent region 233 and arranged sequentially from the inside to the outside; the first positive active material layer 2312 includes a plurality of first positive active material portions 2312a located in the multi-layer bent portion 2313 , at least one first positive electrode active material portion 2312a is provided with a plurality of first grooves 2314 .
  • a plurality of first grooves 2314 are arranged at intervals along the extending direction of the positive electrode sheet 231.
  • the first grooves 2314 are arranged on the inner surface of the first positive electrode active material part 2312a away from the positive electrode current collector 2311, and the first grooves 2314 run through the first positive electrode active material part 2312a.
  • the two ends of a positive electrode active material part 2312a are along the winding axial direction, and the extending direction of the first groove 2314 is parallel to the winding axial direction.
  • At least two first positive electrode active material portions 2312a are provided with a plurality of first grooves 2314; among the two first positive electrode active material portions 2312a provided with first grooves 2314, the inner The density of the first grooves 2314 of a first positive electrode active material part 2312a is greater than the density of the first grooves 2314 of a first positive electrode active material part 2312a located on the outside; a first positive electrode located on the inside The width of the first groove 2314 of the active material part 2312a is greater than the width of the first groove 2314 of the first positive electrode active material part 2312a located outside.
  • Some embodiments of the present application also provide a battery cell 20, the battery cell 20 includes a casing 21 and a wound electrode assembly 23 provided in any of the above embodiments; the casing 21 has an opening 211; the wound electrode assembly 23 is accommodated in the casing Within 21.
  • the battery cell 20 includes the wound electrode assembly 23 provided in any of the above embodiments, so that the cycle performance of the battery cell 20 is better, and the risk of lithium deposition in the battery cell 20 is smaller, so that the safety performance of the battery cell 20 is improved. good.
  • the embodiment of the present application also provides a battery 100.
  • the battery 100 includes the battery cell 20 provided in the above embodiment, so that the cycle performance of the battery 100 is better, and the risk of lithium deposition in the battery 100 is smaller, so that the safety performance of the battery 100 is improved. good.
  • the embodiment of the present application also provides an electric device, which includes the battery cell 20 provided in the above embodiment.
  • the embodiment of the present application also provides a manufacturing method of the wound electrode assembly 23, the manufacturing method includes:
  • a positive electrode sheet 231 is provided.
  • the positive electrode sheet 231 includes a positive electrode current collector 2311 and a first positive electrode active material layer 2312 disposed on one side of the positive electrode current collector 2311.
  • the first positive electrode active material layer 2312 is provided with a plurality of first groove 2314;
  • Step S200 winding the positive pole piece 231 to form a wound electrode assembly 23;
  • the first positive electrode active material layer 2312 is located on the inner surface of the positive electrode current collector 2311, and the inner surface faces the winding axis of the wound electrode assembly 23 after winding.
  • the wound electrode assembly 23 has a bending area 233, and the positive electrode
  • the sheet 231 includes multiple layers of bent parts 2313 located in the bent area 233 and arranged sequentially from the inside to the outside, and at least part of the first grooves 2314 in the plurality of first grooves 2314 are located in at least one layer of the bent parts 2313 .
  • the embodiment of the present application also provides a winding electrode assembly manufacturing equipment 2000, the manufacturing equipment includes a providing device 2100 and an assembly device 2200; the providing device 2100 is configured to provide a positive pole piece 231; a positive pole piece 231 includes a positive electrode current collector 2311 and a first positive electrode active material layer 2312 disposed on one side of the positive electrode current collector 2311, the first positive electrode active material layer 2312 is provided with a plurality of first grooves 2314; the assembly device 2200 is configured to be wound The positive electrode sheet 231 is to form a wound electrode assembly 23; wherein, the first positive electrode active material layer 2312 is located on the inner surface of the positive electrode current collector 2311, and the inner surface faces the winding of the wound electrode assembly 23 after winding axis, the wound electrode assembly 23 has a bending area 233, the positive pole piece 231 includes a multi-layer bending portion 2313 located in the bending area 233 and arranged in sequence from the inside to the outside, and at least part of the

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Abstract

本申请提供了一种卷绕式电极组件、电池单体、电池、用电设备、卷绕式电极组件的制造方法及设备，涉及电池技术领域。卷绕式电极组件包括正极极片，正极极片包括正极集流体和设置于正极集流体的内表面的第一正极活性物质层；正极极片包括位于弯折区且从内至外依次布置的多层弯折部；第一正极活性物质层包括位于多层弯折部的多个第一正极活性物质部，至少一个第一正极活性物质部设有多个第一凹槽，以减少弯折区的正极活性物质容量，增大弯折区的CB值；还能预留膨胀空间，减小弯折区极片所受到的应力；以及使得电极组件的内部能够容纳更多的电解液，降低因电解液浸润不足影响离子转移而导致析锂的风险，降低浓差极化，降低弯折区析锂的风险。

Description

卷绕式电极组件、电池单体、电池及用电设备
相关申请的交叉引用
本申请要求享有于2022年01月05日提交的名称为“卷绕式电极组件、电池单体、电池及用电设备”的中国专利申请202210010096.4的优先权，该申请的全部内容通过引用并入本文中。
技术领域
本申请涉及电池技术领域，具体而言，涉及一种卷绕式电极组件、电池单体、电池、用电设备、卷绕式电极组件的制造方法及设备。
背景技术
目前，智能手机、平板电脑和电动汽车等的迅猛发展，锂离子电池的应用也日益广泛，因此对锂离子电池也提出了更高的要求。
人们在注重电池安全性能的同时还要求锂电池具有更好的电性能表现。而析锂是影响电池的电性能和安全性能的主要因素的之一，电芯一旦发生析锂，不但会降低电池的电性能，而且随着析锂量的累加，容易形成枝晶，枝晶有可能会刺破隔膜，而引发电池内短路，造成安全隐患。
发明内容
本申本申请实施例提供一种卷绕式电极组件、电池单体、电池、用电设备、卷绕式电极组件的制造方法及设备，以降低电极组件析锂的风险。
第一方面，本申请实施例提供一种卷绕式电极组件，所述卷绕式电极组件具有弯折区，包括正极极片，所述正极极片包括正极集流体和设置于所述正极集流体的内表面的第一正极活性物质层，所述内表面在卷绕后面向所述卷绕式电极组件的卷绕轴线；所述正极极片包括位于所述弯折区且从内至外依次布置的多层弯折部；所述第一正极活性物质层包括位于多层所述弯折部的多个第一正极活性物质部，至少一个所述第一正极活性物质部设有多个第一凹槽。
上述技术方案中，正极集流体的内表面的第一正极活性物质层位于弯折区的至少一层设置有多个第一凹槽，能够减少弯折区的正极活性物质容量，从而增大弯折区的CB(Cell Balance，电池平衡)值，其中，CB值为负极活性物质容量与正极活性物质容量的比值；还能为卷绕式电极组件预留膨胀空间，减小弯折区极片(正极极片和/或负极极片)所受到的应力，降低离子嵌入负极极片的阻力；多个第一凹槽的设置还能使得卷绕式电极组件的内部能够容纳更多的电解液，能够在卷绕式电极组件受到膨胀挤压内部电解液减少的情况下作为补充电解液，降低因电解液浸润不足影响离子转移而导致析锂的风险，降低浓差极化，提高电池单体内部循环性能，降低弯折区析锂的风险，从而提高具有该卷绕式电极组件的电池单体的安全性能。
在本申请第一方面的一些实施例中，多个所述第一凹槽沿所述正极极片的延伸方向间隔排布。
上述技术方案中，多个第一凹槽沿正极极片的延伸方向间隔排布，以降低弯折区沿正极极片的延伸方向的任意部位出现析锂的风险。
在本申请第一方面的一些实施例中，多个所述第一凹槽设置于所述第一正极活性物质部的远离所述正极集流体的内表面。
上述技术方案中，多个第一凹槽设置于第一正极活性物质部的远离正极集流体的内表面，能够减少弯折区的正极活性物质容量，从而增大弯折区的CB值，以降低卷绕式电极组件析锂的风险，提高具有该卷绕式电极组件的电池单体的安全性能。设置于第一正极活性物质部的内表面的第一凹槽还能为卷绕式电极组件预留膨胀空间，减小弯折区极片(正极极片和/或负极极片)所受到的应力，降低离子嵌入负极极片的阻力；第一凹槽设置于第一正极活性物质部的远离正极集流体的内表面还能够增大第一正极活性物质部与其内侧的负极极片之间的空间，以容纳更多的电解液，进一步降低因卷绕式电极组件内部电解液被挤出后影响离子转移而导致析锂的风险，还能提高电池单体内部循环性能的风险，降低弯折区析锂的风险，从而提高具有该卷绕式电极组件的电池单体的安全性能。
在本申请第一方面的一些实施例中，所述第一凹槽贯穿所述第一正极活性物质部位于所述卷绕轴线的延伸方向的两端。
上述技术方案中，沿卷绕轴线的延伸方向，第一凹槽贯穿第一正极活性物质部的两端，为电解液浸润卷绕式电极组件提供通道，有利于电解液在卷绕式电极组件内部流动，降低卷绕式电极组件在弯折区因应力大导致的浸润不足的风险，降低浓差极化，改善弯折区析锂。
在本申请第一方面的一些实施例中，所述第一凹槽的延伸方向与所述卷绕轴线的延伸方向平行。
上述技术方案中，第一凹槽的延伸方向与卷绕轴线的延伸方向平行，方便第一凹槽在第一正极活性物质 部上成型，降低生产难度。
在本申请第一方面的一些实施例中，在所述弯折区中，至少两个所述第一正极活性物质部设有多个所述第一凹槽；在两个所述第一正极活性物质部中，位于内侧的一个所述第一正极活性物质部的所述第一凹槽的密集程度大于位于外侧的一个所述第一正极活性物质部的所述第一凹槽的密集程度。
上述技术方案中，卷绕式电极组件中，越靠近电极组件的部分越容易析锂，在电极组件膨胀时，越靠近卷绕式电极组件的卷绕轴线的圈层被挤压越严重，因此，位于内侧的第一正极活性物质部的第一凹槽的密集程度大于位于外侧的第一正极活性物质部的第一凹槽的密集程度，使得位于内侧的第一正极活性物质部与其内侧的负极极片之间具有更大的空间，能为卷绕式电极组件预留更大膨胀空间，减小弯折区极片(正极极片和/或负极极片)所受到的应力，降低离子嵌入负极极片的阻力；还能以容纳更多的电解液，降低靠近卷绕轴线的部分的电解液被挤出后影响离子转移而导致析锂的风险，还能提高电池单体内部循环性能的风险。
在本申请第一方面的一些实施例中，在所述弯折区中，至少两个所述第一正极活性物质部设有多个所述第一凹槽；在两个所述第一正极活性物质部中，位于内侧的一个所述第一正极活性物质部的所述第一凹槽的宽度大于位于外侧的一个所述第一正极活性物质部的所述第一凹槽的宽度。
上述技术方案中，卷绕式电极组件中，越靠近电极组件的部分越容易析锂，在电极组件膨胀时，越靠近卷绕式电极组件的卷绕轴线的圈层被挤压越严重，因此，位于内侧的第一正极活性物质部的第一凹槽的宽度大于位于外侧的第一正极活性物质部的第一凹槽的宽度，使得位于内侧的第一正极活性物质部与其内侧的负极极片之间具有更大的空间，能为卷绕式电极组件预留更大膨胀空间，减小弯折区极片(正极极片和/或负极极片)所受到的应力，降低离子嵌入负极极片的阻力；还能以容纳更多的电解液，降低靠近卷绕轴线的部分的电解液被挤出后影响离子转移而导致析锂的风险，还能提高电池单体内部循环性能的风险。
在本申请第一方面的一些实施例中，在所述弯折区中，至少位于最内侧的一个所述第一正极活性物部设有多个所述第一凹槽。
上述技术方案中，卷绕式电极组件中，最内侧一层正极极片最先受到挤压，且挤压程度更为严重，最内侧的第一正极活性物部设有多个第一凹槽，使得最内侧的第一正极活性物部与其内侧的负极极片之间能够容纳更多的电解液，能够在最内侧的第一正极活性物部受到膨胀挤压内部电解液减少的情况下作为补充电解液，降低因卷绕式电极组件内部电解液被挤出后影响离子转移而导致析锂的风险，还能提高电池单体内部循环性能的风险。
在本申请第一方面的一些实施例中，所述正极极片包括卷绕收尾段，在所述弯折区中，所述卷绕收尾段的至少部分的所述第一正极活性物质部设有多个所述第一凹槽。
上述技术方案中，当卷绕式电极组件膨胀至与电池单体的外壳相抵时，较为靠近外壳的内壁的极片受到较大的挤压力。卷绕收尾段的至少部分的第一正极活性物质部设有多个第一凹槽，能在卷绕式电极组件靠近外壳的内壁的区域预留膨胀空间，减小近外壳的内壁弯折区极片(正极极片和/或负极极片)所受到的应力，降低离子嵌入负极极片的阻力；还能使得卷绕式电极组件的内部能够容纳更多的电解液，能够在卷绕式电极组件膨胀至与外壳的内壁相抵时内部电解液被挤出的情况下作为补充电解液，降低因卷绕式电极组件内部电解液被挤出后影响离子转移而导致析锂的风险，提高电池单体内部循环性能，降低弯折区析锂的风险，从而提高具有该卷绕式电极组件的电池单体的安全性能。
在本申请第一方面的一些实施例中，所述多个第一凹槽呈网格排布。
上述技术方案中，多个第一凹槽呈网格排布，能够引导电解液沿不同的方向流动，有利于电解液在卷绕式电极组件内部流通，降低卷绕式电极组件弯折区处因应力大导致的浸润不足，降低浓差极化，改善拐角析锂。
在本申请第一方面的一些实施例中，所述正极极片还包括设置于所述正极集流体的外表面的第二正极活性物质层，所述第二正极活性物质层包括位于多层所述弯折部多个第二正极活性物质部；至少一个所述第二正极活性物质部设有多个第二凹槽。
上述技术方案中，正极集流体的外表面的第二正极活性物质层位于弯折区至少一层设置有多个第二凹槽，能为卷绕式电极组件预留膨胀空间，减小弯折区极片(正极极片和/或负极极片)所受到的应力，降低离子嵌入负极极片的阻力；多个第二凹槽的设置还能使得卷绕式电极组件的内部能够容纳更多的电解液，能够在卷绕式电极组件受到膨胀挤压内部电解液减少的情况下作为补充电解液，降低因卷绕式电极组件内部电解液被挤出后影响离子转移而导致析锂的风险，提高电池单体内部循环性能，降低弯折区析锂的风险，从而提高具有该卷绕式电极组件的电池单体的安全性能。
在本申请第一方面的一些实施例中，所述卷绕式电极组件包括平直区和两个所述弯折区，两个所述弯折区分别连接于所述平直区的两端；位于所述平直区的所述正极极片的单位面积的正极活性物质层的重量W0与位于所述弯折区的所述正极极片的单位面积的正极活性物质的重量Wn，满足：30％W0≤Wn≤95％W0。
上述技术方案中，位于平直区的正极极片的单位面积的正极活性物质层的重量W0与位于弯折区的正极极片的单位面积的正极活性物质的重量Wn，满足30％W0≤Wn≤95％W0，既降低卷绕式电极组件的弯折区的析锂 的风险，还能够保证卷绕式电极组件的能量密度。
在本申请第一方面的一些实施例中，所述卷绕式电极组件还包括负极极片和隔离膜，所述正极极片的厚度为M1，所述负极极片的厚度为M2，所述隔离膜的厚度为M3，从内至外第n层所述弯折部的沿所述卷绕式电极组件的卷绕方向的第一个所述第一凹槽和最后一个所述第一凹槽之间的距离为Cn，满足：0.1mm≤Cn≤pi*(M1+M2+M3)*a+50mm，n为大于或等于2的自然数，a为表示从内至外第a层正极极片，pi为圆周率。
上述技术方案中，正极极片的厚度为M1，负极极片的厚度为M2，隔离膜的厚度为M3，从内至外第n层弯折部的沿卷绕式电极组件的卷绕方向的第一个第一凹槽和最后一个第一凹槽之间的距离为Cn，满足0.1mm≤Cn≤pi*(M1+M2+2M3)*a+50mm，则越远离卷绕轴线的一层弯折部上的多个第一凹槽沿卷绕方向的跨度越大，使得每层弯折部的多个第一凹槽的跨度与对应的弯折部的长度匹配，有效改善在弯折部因活性锂衰减导致析锂的问题。
第二方面，本申请实施例提供一种电池单体，包括外壳和第一方面实施例提供的卷绕式电极组件；所述外壳具有开口；所述卷绕式电极组件容纳于所述外壳内。
上述技术方案中，电池单体包括第一方面实施例提供的卷绕式电极组件，使得电池单体的循环性能更好，电池单体析锂的风险更小，从而使得电池单体的安全性能更好。
第三方面，本申请实施例提供一种电池，包括第二方面实施例提供的电池单体。
上述技术方案中，电池包括第二方面实施例提供的电池单体，使得电池的循环性能更好，电池析锂的风险更小，从而使得电池的安全性能更好。
第四方面，本申请实施例提供一种用电设备，包括第二方面实施例提供的电池单体。
第五方面，本申请实施例提供一种卷绕式电极组件的制造方法，包括：
提供正极极片，所述正极极片包括正极集流体和设置于所述正极集流体的一侧的第一正极活性物质层，所述第一正极活性物质层设有多个第一凹槽；
卷绕所述正极极片，以形成卷绕式电极组件；
其中，所述第一正极活性物质层位于所述正极集流体的内表面，所述内表面在卷绕后面向所述卷绕式电极组件的卷绕轴线，所述卷绕式电极组件具有弯折区，所述正极极片包括位于所述弯折区且从内至外依次布置的多层弯折部，多个所述第一凹槽中的至少部分所述第一凹槽位于至少一层所述弯折部。
第六方面，本申请实施例提供一种卷绕式电极组件的制造设备，包括提供装置和组装装置；所述提供装置被配置为提供正极极片；所述正极极片包括正极集流体和设置于所述正极集流体的一侧的第一正极活性物质层，所述第一正极活性物质层设有多个第一凹槽；所述组装装置，被配置为卷绕所述正极极片，以形成卷绕式电极组件；其中，所述第一正极活性物质层位于所述正极集流体的内表面，所述内表面在卷绕后面向所述卷绕式电极组件的卷绕轴线，所述卷绕式电极组件具有弯折区，所述正极极片包括位于所述弯折区且从内至外依次布置的多层弯折部，多个所述第一凹槽中的至少部分所述第一凹槽位于至少一层所述弯折部。
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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结构示意图；
图3为本申请一些实施例提供的电池单体的结构示意图；
图4为本申请一些实施例提供的电池单体的爆炸图；
图5为本申请一些实施例提供的电极组件的结构示意图；
图6为本申请另一些实施例提供的电极组件的结构示意图；
图7为本申请一些实施例提供的电极组件的局部放大图；
图8为本申请另一些实施例提供的电极组件的局部放大图；
图9为本申请再一些实施例提供的电极组件的局部放大图；
图10为本申请又一些实施例提供的电极组件的局部放大图；
图11为本申请另一些实施例提供的电极组件的局部示意图；
图12为本申请又一些实施例提供的电极组件的局部示意图；
图13为本申请一些实施例提供的多个第一凹槽呈网格状布置的正极极片的展开状态示意图；
图14为本申请再一些实施例提供的卷绕式电极组件的局部示意图；
图15为本申请另一些实施例提供的正极极片的展开状态示意图；
图16为本申请一些实施例提供的卷绕式电极组件的制造方法的流程图；
图17为本申请一些实施例提供的卷绕式电极组件的制造设备的结构示意图。
图标：1000-车辆；100-电池；10-箱体；11-容纳空间；12-第一部分；13-第二部分；20-电池单体；21-外壳；211-开口；22-端盖组件；221-端盖；222-电极端子；23-电极组件；231-正极极片；2311-正极集流体；2312-第一正极活性物质层；2312a-第一正极活性物质部；2313-弯折部；2314-第一凹槽；2315-第二正极活性物质层；2315a-第二正极活性物质部；2316-第二凹槽；232-负极极片；233-弯折区；234-平直区；24-集流构件；25-绝缘保护件；200-控制器；300-马达；2000-卷绕式电极组件的制造设备；2100-提供装置；2200-组装装置。
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、完整地描述，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。通常在此处附图中描述和示出的本申请实施例的组件可以以各种不同的配置来布置和设计。
因此，以下对在附图中提供的本申请的实施例的详细描述并非旨在限制要求保护的本申请的范围，而是仅仅表示本申请的选定实施例。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。
需要说明的是，在不冲突的情况下，本申请中的实施例及实施例中的特征可以相互组合。
应注意到：相似的标号和字母在下面的附图中表示类似项，因此，一旦某一项在一个附图中被定义，则在随后的附图中不需要对其进行进一步定义和解释。
在本申请实施例的描述中，需要说明的是，指示方位或位置关系为基于附图所示的方位或位置关系，或者是该申请产品使用时惯常摆放的方位或位置关系，或者是本领域技术人员惯常理解的方位或位置关系，仅是为了便于描述本申请和简化描述，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的限制。此外，术语“第一”、“第二”、“第三”等仅用于区分描述，而不能理解为指示或暗示相对重要性。
在本申请实施例的描述中，还需要说明的是，除非另有明确的规定和限定，术语“设置”、“安装”、“连接”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；可以是直接连接，也可以通过中间媒介间接连接。对于本领域的普通技术人员而言，可以具体情况理解上述术语在本申请中的具体含义。
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。
发明人注意到，随着锂电池不断的充放电，锂电池的活性锂不断被消耗，导致CB值减小，从而导致析锂，而析锂现象在卷绕式电极组件的弯折区更为显著；此外，在卷绕式电极组件膨胀时，弯折区的电解液被挤出严重，导致弯折区电解液浸润不足，增大浓差极化，弯折区析锂严重。
基于以上考虑，为了缓解卷绕式电极组件因活性锂消耗和膨胀后电解液浸润不足而导致析锂的问题，发明人经过深入研究，设计了一种卷绕式电极组件，通过在正极集流体的内表面的第一正极活性物质层位于弯折区的至少一层设置有多个第一凹槽，能够减少弯折区的正极活性物质容量，从而增大弯折区的CB值；还能为卷绕式电极组件预留膨胀空间，减小弯折区极片(正极极片和/或负极极片)所受到的应力，降低离子嵌入负极极片的阻力；多个第一凹槽的设置还能使得卷绕式电极组件的内部能够容纳更多的电解液，能够在卷绕式电极组件受到膨胀挤压内部电解液减少的情况下作为补充电解液，降低因电解液浸润不足影响离子转移而导致析锂的风险，降低浓差极化，提高电池单体内部循环性能，降低弯折区析锂的风险，从而提高具有该卷绕式电极组件的电池单体的安全性能。
本申请实施例公开的卷绕式电极组件可以但不限用于车辆、船舶或飞行器等用电设备中。可以使用具备本申请公开的电池单体、电池等组成该用电装置的电源系统，这样，有利于缓解析锂，提高用电安全。
本申请实施例提供一种使用电池作为电源的用电设备，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。车辆可以是燃油汽车、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；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的结构示意图。电池100包括箱体10和电池单体20，电池单体20收容于箱体10内。
箱体10用于为电池单体20提供容纳空间11。在一些实施例中，箱体10可以包括第一部分12和第二部分13，第一部分12与第二部分13相互盖合，以限定出用于容纳电池单体20的容纳空间11。当然，第一部分12与第二部分13的连接处可通过密封件(图未示出)来实现密封，密封件可以是密封圈、密封胶等。
第一部分12和第二部分13可以是多种形状，比如，长方体、圆柱体等。第一部分12可以是一侧开口以形成有容纳电池单体20的容纳腔的空心结构，第二部分13也可以是一侧开口以形成有容纳电池单体20的容纳腔的空心结构，第二部分13的开口侧盖合于第一部分12的开口侧，则形成具有容纳空间11的箱体10。当然，如图2所示，也可以是第一部分12为一侧开口的空心结构，第二部分13为板状结构，第二部分13盖合于第一部分12的开口侧，则形成具有容纳空间11的箱体10。
在电池100中，电池单体20可以是一个、也可以是多个。若电池单体20为多个，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，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，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。电池单体20可呈圆柱体、扁平体、长方体或其它形状等。图2示例性的示出了电池单体20呈方形的情况。
在一些实施例中，电池100还可以包括汇流部件(图未示出)，多个电池单体20之间可通过汇流部件实现电连接，以实现多个电池单体20的串联或并联或混联。
请参照图3、图4，图4为申请一些实施例提供的电池单体20的结构示意图，图4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可以包括外壳21、端盖组件22和电极组件23。外壳21具有开口211，电极组件23容纳于外壳21内，端盖组件22用于封盖于开口211。
外壳21可以是多种形状，比如，圆柱体、长方体等。外壳21的形状可根据电极组件23的具体形状来确定。比如，若电极组件23为圆柱体结构，外壳21则可选用为圆柱体结构；若电极组件23为长方体结构，外壳21则可选用长方体结构。图3和图4示例性的示出了外壳21和电极组件23为方形的情况。
外壳21的材质也可以是多种，比如，铜、铁、铝、不锈钢、铝合金等，本申请实施例对此不作特殊限制。
端盖组件22包括端盖221和电极端子222。端盖组件22用于封盖外壳21的开口211，以形成一密闭的安装空间(图未示出)，安装空间用于容纳电极组件23。安装空间还用于容纳电解质，例如电解液。端盖组件22作为输出电极组件23的电能的部件，端盖组件22中的电极端子222用于与电极组件23电连接，即电极端子222与电极组件23的极耳电连接，比如，电极端子222与极耳通过集流构件24连接，以实现电极端子222与极耳的电连接。
需要说明的，外壳21的开口211可以是一个，也可以是两个。若外壳21的开口211为一个，端盖组件22也可以为一个，端盖组件22中则可设置两个电极端子222，两个电极端子222分别用于与电极组件23正极极耳和负极极耳电连接，端盖组件22中的两个电极端子222分别为正极电极端子和负极电极端子。若外壳21的开口211为两个，比如，两个开口211设置在外壳21相对的两侧，端盖组件22也可以为两个，两个端盖组件22分别盖合于外壳21的两个开口211处。在这种情况下，可以是一个端盖组件22中的电极端子222为正极电极端子，用于与电极组件23的正极极耳电连接；另一个端盖组件22中的电极端子222为负极电极端子，用于与电极组件23的负极片电连接。
在一些实施例中，如图4所示，电池单体20还可以包括固定于电极组件23外周的绝缘保护件25，绝缘保护件25用于绝缘隔离电极组件23与外壳21。示例性的，绝缘保护件25为粘接于电极组件23的外周的胶带。在 一些实施例中，电极组件23的数量为多个，绝缘保护件25围设于多个电极组件23的外周，并将多个电极组件23形成一个整体结构，以保持电极组件23结构稳定。
请参照图5、图6，图5为本申请一些实施例提供的电极组件23的结构示意图，图6为本申请另一些实施例提供的电极组件23的结构示意图。电极组件23可以包括正极极片231、负极极片232和隔离膜(图中未示出)。电极组件23是由正极极片231、隔离膜和负极极片232通过卷绕形成的卷绕式结构。
正极极片231包括正极集流体2311(图7中示出)和正极活性物质层，正极活性物质层涂覆于正极集流体2311的表面，未涂敷正极活性物质层的正极集流体2311凸出于已涂覆正极活性物质层的正极集流体2311，未涂敷正极活性物质层的正极集流体2311作为正极极耳。正极活性物质层包括第一正极活性物质层2312和第二正极活性物质层，沿正极集流体2311的厚度方向，第一正极活性物质层2312和第二正极活性物质层分别设置于正极集流体2311的两个表面。以锂离子电池100为例，正极集流体2311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。
负极极片232包括负极集流体(图中未示出)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极耳。负极活性物质层包括第一负极活性物质层和第二负极活性物质层，沿负极集流体的厚度方向，第一负极活性物质层和第二负极活性物质层分别设置于负极集流体的两个表面。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，正极极耳的数量为多个且层叠在一起，负极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。
请继续参照图5、图6，卷绕式电极组件23具有弯折区233，卷绕式电极组件23包括正极极片231，正极极片231包括正极集流体2311和设置于正极集流体2311的内表面的第一正极活性物质层2312，内表面在卷绕后面向卷绕式电极组件23的卷绕轴线；正极极片231包括位于弯折区233且从内至外依次布置的多层弯折部2313；第一正极活性物质层2312包括位于多层弯折部2313的多个第一正极活性物质部2312a，至少一个第一正极活性物质部2312a设有多个第一凹槽2314。
当正极极片231绕卷绕轴线卷绕后，正极集流体2311的厚度方向上的两个表面中的一个表面距离卷绕轴线较近并面向卷绕轴线设置，该表面为正极集流体2311的内表面，另一个表面距离卷绕轴线较远并背离卷绕轴线设置，该表面为正极集流体2311的外表面。
在一些实施例中，如图5所示，卷绕式电极组件23也可以是圆柱式的电极组件，则沿卷绕式电极组件23的周向，任意范围均可以被定义为弯折区233，则任意弯折区233均可以设置多个第一凹槽2314。
在一些实施例中，卷绕式电极组件23可以是方形，如图6、图7所示，图6为本申请另一些实施例提供的电极组件23的结构示意图，图7为本申请一些实施例提供的电极组件23的局部示意图。卷绕式电极组件23包括平直区234和两个弯折区233，两个弯折区233连接于平直区234的两端。正极极片231卷绕完成后，正极极片231的一部分位于平直区234，正极极片231的另一部分位于弯折区233并形成从内至外依次布置的多层弯折部2313。每层弯折部2313包括第一正极活性物质层2312的部分，因此，则正极极片231包括位于多层弯折部2313的多个第一正极活性物质部2312a，多个第一正极活性物质部2312a从内至外依次布置。
至少一个第一正极活性物质部2312a设有多个第一凹槽2314，可以是每个第一正极活性物质部2312a均设有第一凹槽2314，也可以是多个第一正极活性物质部2312a中的部分第一正极活性物质部2312a设置有第一凹槽2314。
第一凹槽2314可以通过激光刻蚀的方式形成。
正极集流体2311的内表面的第一正极活性物质层2312位于弯折区233的至少一层设置有多个第一凹槽2314，能够减少弯折区233的正极活性物质容量，从而增大弯折区233的CB值，CB值为负极活性物质容量与正极活性物质容量的比值，CB值可以大于1；还能为卷绕式电极组件23预留膨胀空间，减小弯折区233极片(正极极片231和/或负极极片232)所受到的应力，降低离子嵌入负极极片232的阻力和/或离子从正极极片231脱离的阻力；多个第一凹槽2314的设置还能使得卷绕式电极组件23的内部能够容纳更多的电解液，能够在卷绕式电极组件23受到膨胀挤压内部电解液减少的情况下作为补充电解液，降低因电解液浸润不足影响离子转移而导致析锂的风险，降低浓差极化，提高电池单体20内部循环性能，降低弯折区233析锂的风险，从而提高具有该卷绕式电极组件23的电池单体20的安全性能。
请继续参见图7，在一些实施例中，多个第一凹槽2314沿正极极片231的延伸方向间隔排布。
在正极极片231处于卷绕状态时，正极极片231的延伸方向与卷绕方向一致，在正极极片231处于展开状态时，正极极片231的延伸方向与正极极片231的长度方向一致。
在其他实施例中，多个第一凹槽2314也可以以其他方式排布于第一正极活性物质部2312a，比如多个第一凹槽2314沿卷绕轴线的延伸方向排布或者多个第一凹槽2314环形排布于多个第一凹槽2314。
多个第一凹槽2314沿正极极片231的延伸方向间隔排布，以降低弯折区233沿正极极片231的延伸方向的任意部位出现析锂的风险。
请继续参见图7，在一些实施例中，多个第一凹槽2314设置于第一正极活性物质部2312a的远离正极集流体2311的内表面。
第一正极活性物质部2312a的远离正极集流体2311的内表面，是指沿正极极片231的厚度方向，第一正极活性物质部2312a的距离正极集流体2311的内表面更远的表面，在正极极片231卷绕完成后，第一正极活性物质部2312a距离正极集流体2311的内表面更远的表面面向卷绕轴线。
在其他实施例中，多个第一凹槽2314也可以设置于第一正极活性物质部2312a沿卷绕轴线方向的相对的两端。
多个第一凹槽2314设置于第一正极活性物质部2312a的远离正极集流体2311的内表面，能够减少弯折区233的正极活性物质容量，从而增大弯折区233的CB值，以降低卷绕式电极组件23析锂的风险，提高具有该卷绕式电极组件23的电池单体20的安全性能。设置于第一正极活性物质部2312a的内表面的第一凹槽2314还能为卷绕式电极组件23预留膨胀空间，减小弯折区233极片(正极极片231和/或负极极片232)所受到的应力，降低离子嵌入负极极片232的阻力和/或离子从正极极片231脱离的阻力；第一凹槽2314设置于第一正极活性物质部2312a的远离正极集流体2311的内表面还能够增大第一正极活性物质部2312a与其内侧的负极极片232之间的空间，以容纳更多的电解液，以使电极组件23能够被充分浸润，进一步降低因卷绕式电极组件23内部电解液被挤出后影响离子转移而导致析锂的风险，还能提高电池单体20内部循环性能的风险，降低弯折区233析锂的风险，从而提高具有该卷绕式电极组件23的电池单体20的安全性能。
请参照图7，在一些实施例中，第一凹槽2314贯穿第一正极活性物质部2312a位于卷绕轴线的延伸方向的两端。
在第一凹槽2314设置于第一正极活性物质部2312a的远离正极集流体2311的内表面的实施例中，第一凹槽2314从第一正极活性物质部2312a的远离正极集流体2311的内表面向靠近正极极片231的内表面凹陷，并沿卷绕轴线方向延伸直至贯穿第一正极活性物质部2312a的两端。第一凹槽2314从第一正极活性物质部2312a的远离正极集流体2311的内表面向靠近正极极片231的内表面凹陷的深度小于第一正极活性物质部2312a的厚度，以使第一凹槽2314的底壁与正极集流体2311的内表面之间的距离大于零。
请参照图8，在第一凹槽2314设置于第一正极活性物质部2312a的位于卷绕轴线的延伸方向的两端的实施例中，第一凹槽2314为形成在第一正极活性物质部2312a的通道，其中通道形式的第一凹槽2314可以是由第一正极活性物质部2312a限定出；如图9所示，也可以是由第一正极活性物质部2312a和正极集流体2311的内表面共同限定出。
在其他实施例中，第一凹槽2314也可以未贯穿第一正极活性物质部2312a沿卷绕轴线方向的两端，比如第一凹槽2314为设置在第一正极活性物质部2312a的内表面和/或第一正极活性物质部2312a沿卷绕轴线的延伸方向两端的凹坑。
沿卷绕轴线的延伸方向，第一凹槽2314贯穿第一正极活性物质部2312a的两端，为电解液浸润卷绕式电极组件23提供通道，有利于电解液在卷绕式电极组件23内部流动，降低卷绕式电极组件23在弯折区233因应力大导致的浸润不足的风险，降低浓差极化，改善弯折区233析锂。
在一些实施例中，第一凹槽2314的延伸方向与卷绕轴线的延伸方向平行。
在其他实施例中，第一凹槽2314也可以是其他形式布置，比如第一凹槽2314与卷绕轴线的延伸方向呈夹角布置，或者第一凹槽2314呈波浪形。
第一凹槽2314的延伸方向与卷绕轴线的延伸方向平行，方便第一凹槽2314在第一正极活性物质部2312a上成型，降低生产难度。
在卷绕式电极组件23中，越靠近卷绕轴线的圈层越容易析锂，在电极组件23膨胀时，越靠近卷绕轴线的圈层被挤压越严重，因此，如图10所示，在一些实施例中，在弯折区233中，至少两个第一正极活性物质部2312a设有多个第一凹槽2314；在两个第一正极活性物质部2312a中，位于内侧的一个第一正极活性物质部2312a的第一凹槽2314的密集程度大于位于外侧的一个第一正极活性物质部2312a的第一凹槽2314的密集程度。
第一凹槽2314的密集程度可以定义为，单位面积的第一正极活性物质部2312a内设有的第一凹槽2314的数量。
“位于内侧的一个第一正极活性物质部2312a”是指，两个第一正极活性物质部2312a中，距离卷绕轴线较近的一个第一正极活性物质部2312a；“位于外侧的一个第一正极活性物质部2312a”是指，两个第一正极活性物质部2312a中，距离卷绕轴线较远的一个第一正极活性物质部2312a。
设有第一凹槽2314的至少两个第一正极活性物质部2312a，可以是从内至外依次相邻的第一正极活性物 质部2312a；如图11所示，也可以是间隔布置的至少两个第一正极活性物质部2312a，即两个设有第一凹槽2314的第一正极活性物质部2312a之间可以设有至少一个未设置第一凹槽2314的第一正极活性物质部2312a。其中，第一凹槽2314的密集程度的比较是在设有第一凹槽2314的两个第一正极活性物质部2312a之间进行。
位于内侧的第一正极活性物质部2312a的第一凹槽2314的密集程度大于位于外侧的第一正极活性物质部2312a的第一凹槽2314的密集程度，使得位于内侧的第一正极活性物质部2312a与其内侧的负极极片232之间具有更大的空间，能为卷绕式电极组件23预留更大膨胀空间，减小弯折区233极片(正极极片231和/或负极极片232)所受到的应力，降低离子嵌入负极极片232的阻力和/或离子从正极极片231脱离的阻力；还能以容纳更多的电解液，降低靠近卷绕轴线的部分的电解液被挤出后影响离子转移而导致析锂的风险，还能提高电池单体20内部循环性能的风险。
请参照图7、图8所示，在一些实施例中，在弯折区233中，至少两个第一正极活性物质部2312a设有多个第一凹槽2314；在两个第一正极活性物质部2312a中，位于内侧的一个第一正极活性物质部2312a的第一凹槽2314的宽度大于位于外侧的一个第一正极活性物质部2312a的第一凹槽2314的宽度。
在其他实施例中，在弯折区233中，至少两个第一正极活性物质部2312a设有多个第一凹槽2314；在两个第一正极活性物质部2312a中，位于内侧的一个第一正极活性物质部2312a的第一凹槽2314的宽度大于位于外侧的一个第一正极活性物质部2312a的第一凹槽2314的宽度，且位于内侧的一个第一正极活性物质部2312a的第一凹槽2314的密集程度大于位于外侧的一个第一正极活性物质部2312a的第一凹槽2314的密集程度。
在其他实施例中，每一个第一正极活性物质部2312a上的第一凹槽2314的宽度也可以相同。
位于内侧的第一正极活性物质部2312a的第一凹槽2314的宽度大于位于外侧的第一正极活性物质部2312a的第一凹槽2314的宽度，使得位于内侧的第一正极活性物质部2312a与其内侧的负极极片232之间具有更大的空间，能为卷绕式电极组件23预留更大膨胀空间，减小弯折区233极片(正极极片231和/或负极极片232)所受到的应力，降低离子嵌入负极极片232的阻力和/或离子从正极极片231脱离的阻力；还能以容纳更多的电解液，降低靠近卷绕轴线的部分的电解液被挤出后影响离子转移而导致析锂的风险，还能提高电池单体20内部循环性能的风险。
在卷绕式电极组件23中，在电极组件23膨胀时，最内侧一层弯折部2313最先受到挤压，且挤压程度更为严重，因此，如图11所示，在一些实施例中，在弯折区233中，至少位于最内侧的一个第一正极活性物部设有多个第一凹槽2314。
最内侧的第一正极活性物质部2312a是指，在同一个弯折区233中，距离卷绕轴线最近的第一正极活性物质部2312a。在最内侧的第一正极活性物质部2312a设有多个第一凹槽2314的情况下，其他的第一正极活性物质层2312可以设置第一凹槽2314，也可以不设置第一凹槽2314。
最内侧的第一正极活性物部设有多个第一凹槽2314，使得最内侧的第一正极活性物部与其内侧的负极极片232之间能够容纳更多的电解液，能够在最内侧的第一正极活性物部受到膨胀挤压内部电解液减少的情况下作为补充电解液，降低因卷绕式电极组件23内部电解液被挤出后影响离子转移而导致析锂的风险，还能提高电池单体20内部循环性能的风险。
当卷绕式电极组件23膨胀较为严重时，卷绕式电极组件23的外周会与外壳21的内壁相抵，使得卷绕式电极组件23与外壳21(图3、图4中示出)的相互挤压，卷绕式电极组件23较为靠近外壳21的部分的电解液被挤出严重，导致为靠近外壳21的部分的极片浸润不足。
如图12所示，在一些实施例中，正极极片231包括卷绕收尾段，在弯折区233中，卷绕收尾段的至少部分的第一正极活性物质部2312a设有多个第一凹槽2314。
卷绕收尾段为从卷绕收尾端沿卷绕方向的反方向延伸一段距离所限定的部分。卷绕收尾段可以是从卷绕收尾端沿卷绕方向的反方向延伸一圈的部分，或者多圈的部分，卷绕收尾段从卷绕收尾端沿卷绕方向的反方向至少经过一次弯折区233。
当卷绕式电极组件23膨胀至与电池单体20的外壳21相抵时，较为靠近外壳21的内壁的极片受到较大的挤压力。卷绕收尾段的至少部分的第一正极活性物质部2312a设有多个第一凹槽2314，能在卷绕式电极组件23靠近外壳21的内壁的区域预留膨胀空间，减小近外壳21的内壁弯折区233极片(正极极片231和/或负极极片232)所受到的应力，降低离子嵌入负极极片232的阻力；还能使得卷绕式电极组件23的内部能够容纳更多的电解液，能够在卷绕式电极组件23膨胀至与外壳21的内壁相抵时内部电解液被挤出的情况下作为补充电解液，降低因卷绕式电极组件23内部电解液被挤出后影响离子转移而导致析锂的风险，提高电池单体20内部循环性能，降低弯折区233析锂的风险，从而提高具有该卷绕式电极组件23的电池单体20的安全性能。
如图13所示，在一些实施例中，多个第一凹槽2314呈网格排布。
多个第一凹槽2314呈网格排布，是指在一个弯折部2313中，至少两个第一凹槽2314部交错布置并连通。比如，多个第一凹槽2314中，两两连通，换句话说，多个第一凹槽2314相互连通。
多个第一凹槽2314呈网格排布，能够引导电解液沿不同的方向流动，有利于电解液在卷绕式电极组件23内部流通，降低卷绕式电极组件23弯折区233处因应力大导致的浸润不足，降低浓差极化，改善拐角析锂。
如图14所示，在一些实施例中，正极极片231还包括设置于正极集流体2311的外表面的第二正极活性物质层2315，第二正极活性物质层包括位于多层弯折部2313的多个第二正极活性物质部2315a；至少一个第二正极活性物质部2315a设有多个第二凹槽2316。
第二凹槽的相关可以参照第一凹槽2314，在此不再赘述。
在其他实施例中，第二活性物质部2315也可以不设置第二凹槽2316，仅仅第一活性物质部2312a设置第一凹槽2314。
正极集流体2311的外表面的第二正极活性物质层2315位于弯折区233至少一层设置有多个第二凹槽2316，能为卷绕式电极组件23预留膨胀空间，减小弯折区233极片(正极极片231和/或负极极片232)所受到的应力，降低离子嵌入负极极片232的阻力；多个第二凹槽2316的设置还能使得卷绕式电极组件23的内部能够容纳更多的电解液，能够在卷绕式电极组件23受到膨胀挤压内部电解液减少的情况下作为补充电解液，降低因卷绕式电极组件23内部电解液被挤出后影响离子转移而导致析锂的风险，提高电池单体20内部循环性能，降低弯折区233析锂的风险，从而提高具有该卷绕式电极组件23的电池单体20的安全性能。
在一些实施例中，卷绕式电极组件23包括平直区234和两个弯折区233，两个弯折区233分别连接于平直区234的两端；位于平直区234的正极极片231的单位面积的正极活性物质层的重量W0与位于弯折区233的正极极片231的单位面积的正极活性物质的重量Wn，满足：30％W0≤Wn≤95％W0。
平直区234的正极极片231的单位面积的正极活性物质层的重量W0，是指平直区234的正极极片231的单位面积的正极活性物质层的平均重量；弯折区233的正极极片231的单位面积的正极活性物质的重量Wn，是指弯折区233的正极极片231的单位面积的正极活性物质的平均重量。
W0和Wn满足30％W0≤Wn≤95％W0，既降低卷绕式电极组件23的弯折区233的析锂的风险，还能够保证卷绕式电极组件23的能量密度。
如图15所示，在一些实施例中，卷绕式电极组件23还包括负极极片232和隔离膜，正极极片231的厚度为M1，负极极片232的厚度为M2，隔离膜的厚度为M3，从内至外第n层弯折部2313的沿卷绕式电极组件23的卷绕方向的第一个第一凹槽2314和最后一个第一凹槽2314之间的距离为Cn，满足：0.1mm≤Cn≤pi*(M1+M2+M3)*a+50mm，n为大于或等于2的自然数，a为表示从外至内第a层正极极片231，pi为圆周率。
随着卷绕半径逐渐增大，从内至外，弯折部2313沿卷绕方向的长度逐渐增大，因此需要弯折部2313上的多个第一凹槽2314具有较大的跨度范围，以使沿卷绕方向，多个第一凹槽2314尽可能大范围地覆盖对应的弯折部2313。比如，从内至外第一层弯折部2313中的第一个第一凹槽2314和最后一个第一凹槽2314，满足：0.1mm≤C1≤pi*(M1+M2+M3)*1+50mm；从内至外第二层弯折部2313中的第一个第一凹槽2314和最后一个第一凹槽2314，满足：0.1mm≤C2≤pi*(M1+M2+M3)*2+50mm，依次类推。
正极极片231的厚度为M1，负极极片232的厚度为M2，隔离膜的厚度为M3，从内至外第n层弯折部2313的沿卷绕式电极组件23的卷绕方向的第一个第一凹槽2314和最后一个第一凹槽2314之间的距离为Cn，满足0.1mm≤Cn≤pi*(M1+M2+2M3)*a+50mm，则越远离卷绕轴线的一层弯折部2313上的多个第一凹槽2314沿卷绕方向的跨度越大，使得每层弯折部2313的多个第一凹槽2314的跨度与对应的弯折部2313的长度匹配，有效改善在弯折部2313因活性锂衰减导致析锂的问题。
在一些实施例中，沿卷绕方向，相邻的两个弯折部2313中的一个弯折部2313的第一个第一凹槽2314与相邻的两个弯折部2313中的另一个弯折部2313的最后一个第一凹槽2314之间的距离Ln大于或者等于0，且小于正极极片231的总长。
本申请实施例提供一种方形的卷绕式电极组件23，卷绕式电极组件23包括正极极片231，正极极片231包括正极集流体2311、设置于正极集流体2311的内表面的第一正极活性物质层2312和设置于正极集流体2311的外表面的第二正极活性物质层2315。正极极片231包括位于弯折区233且从内至外依次布置的多层弯折部2313；第一正极活性物质层2312包括位于多层弯折部2313的多个第一正极活性物质部2312a，至少一个第一正极活性物质部2312a设有多个第一凹槽2314。多个第一凹槽2314沿正极极片231的延伸方向间隔排布，第一凹槽2314设置于第一正极活性物质部2312a的远离正极集流体2311的内表面，第一凹槽2314贯穿第一正极活性物质部2312a沿卷绕轴向方向的两端，第一凹槽2314的延伸方向平行卷绕轴线方向。
在弯折区233中，至少两个第一正极活性物质部2312a设有多个第一凹槽2314；在设有第一凹槽2314的两个第一正极活性物质部2312a中，位于内侧的一个所述第一正极活性物质部2312a的所述第一凹槽2314的密集程度大于位于外侧的一个第一正极活性物质部2312a的第一凹槽2314的密集程度；位于内侧的一个第一正极活性物质部2312a的第一凹槽2314的宽度大于位于外侧的一个第一正极活性物质部2312a的第一凹槽2314的宽度。
本申请一些实施例还提供一种电池单体20，电池单体20包括外壳21和上述任意实施例提供的卷绕式电 极组件23；外壳21具有开口211；卷绕式电极组件23容纳于外壳21内。
电池单体20包括上述任意实施例提供的卷绕式电极组件23，使得电池单体20的循环性能更好，电池单体20析锂的风险更小，从而使得电池单体20的安全性能更好。
本申请实施例还提供一种电池100，电池100包括上述施例提供的电池单体20，使得电池100的循环性能更好，电池100析锂的风险更小，从而使得电池100的安全性能更好。
本申请实施例还提供一种用电设备，用电设备包括上述实施例提供的电池单体20。
请参照图16，本申请实施例还提供一种卷绕式电极组件23的制造方法，该制造方法包括：
步骤S100，提供正极极片231，正极极片231包括正极集流体2311和设置于正极集流体2311的一侧的第一正极活性物质层2312，第一正极活性物质层2312设有多个第一凹槽2314；
步骤S200，卷绕所正极极片231，以形成卷绕式电极组件23；
其中，第一正极活性物质层2312位于正极集流体2311的内表面，内表面在卷绕后面向卷绕式电极组件23的卷绕轴线，卷绕式电极组件23具有弯折区233，正极极片231包括位于弯折区233且从内至外依次布置的多层弯折部2313，多个第一凹槽2314中的至少部分第一凹槽2314位于至少一层弯折部2313。
请参照图17，本申请实施例还提供一种卷绕式电极组件的制造设备2000，该制造设备包括提供装置2100和组装装置2200；提供装置2100被配置为提供正极极片231；正极极片231包括正极集流体2311和设置于正极集流体2311的一侧的第一正极活性物质层2312，第一正极活性物质层2312设有多个第一凹槽2314；组装装置2200被配置为卷绕所述正极极片231，以形成卷绕式电极组件23；其中，第一正极活性物质层2312位于正极集流体2311的内表面，内表面在卷绕后面向卷绕式电极组件23的卷绕轴线，卷绕式电极组件23具有弯折区233，正极极片231包括位于弯折区233且从内至外依次布置的多层弯折部2313，多个第一凹槽2314中的至少部分第一凹槽2314位于至少一层弯折部2313。
以上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 (18)

  1. 一种卷绕式电极组件，所述卷绕式电极组件具有弯折区，包括：
    正极极片，包括正极集流体和设置于所述正极集流体的内表面的第一正极活性物质层，所述内表面在卷绕后面向所述卷绕式电极组件的卷绕轴线；所述正极极片包括位于所述弯折区且从内至外依次布置的多层弯折部；所述第一正极活性物质层包括位于多层所述弯折部的多个第一正极活性物质部，至少一个所述第一正极活性物质部设有多个第一凹槽。
  2. 根据权利要求1所述的卷绕式电极组件，其中，多个所述第一凹槽沿所述正极极片的延伸方向间隔排布。
  3. 根据权利要求1或2所述的卷绕式电极组件，其中，多个所述第一凹槽设置于所述第一正极活性物质部的远离所述正极集流体的内表面。
  4. 根据权利要求1-3任一项所述的卷绕式电极组件，其中，所述第一凹槽贯穿所述第一正极活性物质部位于所述卷绕轴线的延伸方向的两端。
  5. 根据权利要求4所述的卷绕式电极组件，其中，所述第一凹槽的延伸方向与所述卷绕轴线的延伸方向平行。
  6. 根据权利要求1-5任一项所述的卷绕式电极组件，其中，在所述弯折区中，至少两个所述第一正极活性物质部设有多个所述第一凹槽；
    在两个所述第一正极活性物质部中，位于内侧的一个所述第一正极活性物质部的所述第一凹槽的密集程度大于位于外侧的一个所述第一正极活性物质部的所述第一凹槽的密集程度。
  7. 根据权利要求1-6任一项所述的卷绕式电极组件，其中，在所述弯折区中，至少两个所述第一正极活性物质部设有多个所述第一凹槽；
    在两个所述第一正极活性物质部中，位于内侧的一个所述第一正极活性物质部的所述第一凹槽的宽度大于位于外侧的一个所述第一正极活性物质部的所述第一凹槽的宽度。
  8. 根据权利要求1-7任一项所述的卷绕式电极组件，其中，在所述弯折区中，至少位于最内侧的一个所述第一正极活性物部设有多个所述第一凹槽。
  9. 根据权利要求1-8任一项所述的卷绕式电极组件，其中，所述正极极片包括卷绕收尾段，在所述弯折区中，所述卷绕收尾段的至少部分的所述第一正极活性物质部设有多个所述第一凹槽。
  10. 根据权利要求1-9任一项所述的卷绕式电极组件，其中，所述多个第一凹槽呈网格排布。
  11. 根据权利要求1-10任一项所述的卷绕式电极组件，其中，所述正极极片还包括设置于所述正极集流体的外表面的第二正极活性物质层，所述第二正极活性物质层包括位于多层所述弯折部多个第二正极活性物质部；
    至少一个所述第二正极活性物质部设有多个第二凹槽。
  12. 根据权利要求1-11任一项所述的卷绕式电极组件，其中，所述卷绕式电极组件包括平直区和两个所述弯折区，两个所述弯折区分别连接于所述平直区的两端；
    位于所述平直区的所述正极极片的单位面积的正极活性物质层的重量W0与位于所述弯折区的所述正极极片的单位面积的正极活性物质的重量Wn，满足：30％W0≤Wn≤95％W0。
  13. 根据权利要求1-12任一项所述的卷绕式电极组件，其中，所述卷绕式电极组件还包括负极极片和隔离膜，所述正极极片的厚度为M1，所述负极极片的厚度为M2，所述隔离膜的厚度为M3，从内至外第n层所述弯折部的沿所述卷绕式电极组件的卷绕方向的第一个所述第一凹槽和最后一个所述第一凹槽之间的距离为Cn，满足：0.1mm≤Cn≤pi*(M1+M2+2M3)*a+50mm，n为大于或等于2的自然数，a为表示从内至外第a层正极极片，pi为圆周率。
  14. 一种电池单体，包括：
    外壳，具有开口；
    根据权利要求1-13任一项所述的卷绕式电极组件，容纳于所述外壳内。
  15. 一种电池，包括根据权利要求14所述的电池单体。
  16. 一种用电设备，包括根据权利要求14所述的电池单体。
  17. 一种卷绕式电极组件的制造方法，包括：
    提供正极极片，所述正极极片包括正极集流体和设置于所述正极集流体的一侧的第一正极活性物质层，所述第一正极活性物质层设有多个第一凹槽；
    卷绕所述正极极片，以形成卷绕式电极组件；
    其中，所述第一正极活性物质层位于所述正极集流体的内表面，所述内表面在卷绕后面向所述卷绕式电极组件的卷绕轴线，所述卷绕式电极组件具有弯折区，所述正极极片包括位于所述弯折区且从内至外依次布置的多层弯折部，多个所述第一凹槽中的至少部分所述第一凹槽位于至少一层所述弯折部。
  18. 一种卷绕式电极组件的制造设备，包括：
    提供装置，被配置为提供正极极片；
    所述正极极片包括正极集流体和设置于所述正极集流体的一侧的第一正极活性物质层，所述第一正极活性物质层设有多个第一凹槽；
    组装装置，被配置为卷绕所述正极极片，以形成卷绕式电极组件；
    其中，所述第一正极活性物质层位于所述正极集流体的内表面，所述内表面在卷绕后面向所述卷绕式电极组件的卷绕轴线，所述卷绕式电极组件具有弯折区，所述正极极片包括位于所述弯折区且从内至外依次布置的多层弯折部，多个所述第一凹槽中的至少部分所述第一凹槽位于至少一层所述弯折部。
PCT/CN2022/138049 2022-01-05 2022-12-09 卷绕式电极组件、电池单体、电池及用电设备 Ceased WO2023130902A1 (zh)

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