WO2023201588A1 - 电化学装置及用电设备 - Google Patents

电化学装置及用电设备 Download PDF

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Publication number
WO2023201588A1
WO2023201588A1 PCT/CN2022/088008 CN2022088008W WO2023201588A1 WO 2023201588 A1 WO2023201588 A1 WO 2023201588A1 CN 2022088008 W CN2022088008 W CN 2022088008W WO 2023201588 A1 WO2023201588 A1 WO 2023201588A1
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WO
WIPO (PCT)
Prior art keywords
protective layer
active material
material layer
current collector
area
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PCT/CN2022/088008
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English (en)
French (fr)
Inventor
周卫源
张森
李娅洁
Original Assignee
宁德新能源科技有限公司
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Publication date
Application filed by 宁德新能源科技有限公司 filed Critical 宁德新能源科技有限公司
Priority to PCT/CN2022/088008 priority Critical patent/WO2023201588A1/zh
Priority to CN202280003727.8A priority patent/CN115552690A/zh
Publication of WO2023201588A1 publication Critical patent/WO2023201588A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • 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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • 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
    • 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 field of battery technology, specifically, to an electrochemical device and electrical equipment.
  • lithium-ion secondary batteries are mainly laminate batteries or wound batteries.
  • wound batteries the innermost pole piece at the beginning of the winding and the outermost pole piece at the end of the winding are prone to curling, resulting in reduced battery performance.
  • Embodiments of the present application provide an electrochemical device and electrical equipment that can alleviate the problem of pole piece curling in a rolled electrode assembly.
  • embodiments of the present application provide an electrochemical device, including a first pole piece, a separator, and a second pole piece.
  • the first pole piece, the separator, and the second pole piece are stacked and wound to form an electrode assembly.
  • the first pole piece includes a first current collector.
  • the first current collector includes a starting section of a single-sided winding area.
  • the initial section of the single-sided winding area is provided with a first protective layer toward the surface of the center of the electrode assembly.
  • the first current collector includes a starting section of the single-sided winding area.
  • the first active material layer is arranged on the surface of the initial section facing away from the center of the electrode assembly;
  • the second pole piece includes a second current collector, and the second current collector includes a winding single-sided area ending section, and the winding single-sided area ending section faces away from the center of the electrode assembly
  • a second protective layer is provided on the surface, and a second active material layer is provided on the surface of the ending section of the winding single-sided area toward the center of the electrode assembly;
  • the ratio of the unit area weight of the first protective layer to the unit area weight of the first active material layer is (0.03 ⁇ 0.75):1
  • the ratio of the weight per unit area of the second protective layer to the weight per unit area of the second active material layer is (0.03 ⁇ 0.75):1.
  • a first active material layer is provided on one surface of the initial section of the winding single-sided area of the first current collector, and a first protective layer is provided on the other surface, and the weight per unit area of the first protective layer is equal to
  • the ratio of the weight per unit area of the first active material layer is (0.03 ⁇ 0.75):1, which not only improves the problem of pole piece curling, but also ensures the energy density of the electrochemical device to a certain extent.
  • a second active material layer is provided on one surface of the ending section of the winding single-sided area of the second current collector, and a second protective layer is provided on the other surface, and the weight per unit area of the second protective layer is equal to that of the second active material.
  • the ratio of the weight per unit area of the layer is (0.03 ⁇ 0.75):1, which not only improves the problem of pole piece curling, but also ensures the energy density of the electrochemical device to a certain extent.
  • the electrochemical device meets at least one of the following conditions:
  • the unit area weight of the first active material layer is 0.06g/1540.25mm 2 ⁇ 0.5g/1540.25mm 2 ;
  • the weight per unit area of the second active material layer is 0.06g/1540.25mm 2 ⁇ 0.5g/1540.25mm 2 ;
  • the weight per unit area of the first protective layer is 0.01g/1540.25mm 2 ⁇ 0.13g/1540.25mm 2 ;
  • the unit area weight of the second protective layer is 0.01g/1540.25mm 2 ⁇ 0.13g/1540.25mm 2 .
  • the problem of pole piece curling can be better improved, the alignment of the electrode assembly is smaller, thereby improving the electrochemical device energy density.
  • the electrochemical device meets at least one of the following conditions:
  • the ratio of the thickness of the second protective layer to the thickness of the second active material layer is (0.1 ⁇ 0.6):1.
  • the volume occupied by the protective layer is less than the volume occupied by the active material layer, and the ratio of the thickness of the protective layer to the thickness of the active material layer and the ratio of the unit area weight of the protective layer to the unit area weight of the active material layer
  • the gap is not big, which can make the density of the protective layer more consistent with that of the active material layer, making the electrode assembly more consistent; and it can avoid the problem of the protective layer taking up too much space and causing the electrode piece to curl. is well improved, resulting in a higher volume energy density of the electrochemical device.
  • the electrochemical device meets at least one of the following conditions:
  • the thickness of the first active material layer is 15 ⁇ m ⁇ 200 ⁇ m;
  • the thickness of the second active material layer is 15 ⁇ m ⁇ 200 ⁇ m;
  • the thickness of the first protective layer is 1.5 ⁇ m ⁇ 100 ⁇ m;
  • the thickness of the second protective layer is 1.5 ⁇ m ⁇ 100 ⁇ m.
  • the specific range of the thickness of the active material layer and the thickness of the protective layer is limited, so that when the thickness of the protective layer is low, the problem of pole piece curling can be well improved, and the electrochemical device can be The volumetric energy density is higher.
  • the electrochemical device meets at least one of the following conditions:
  • the length of the initial section of the winding single-sided area accounts for 1.5% to 50% of the total length of the first current collector
  • the length of the ending section of the winding single-sided area accounts for 2% to 55% of the total length of the second current collector.
  • the length of the starting section of the winding single-sided area and the length of the ending section of the winding single-sided area are within the above range, which can improve the problem of pole piece curling of the electrode assembly and make the entire electrode assembly more stable. Alignment is reduced; and the energy density of electrochemical devices is higher.
  • the electrochemical device meets at least one of the following conditions:
  • the first protective layer covers the surface of the initial section of the partially wound single-sided area facing the center of the electrode assembly;
  • the second protective layer covers the surface of the ending section of the partially rolled single-sided area away from the center of the electrode assembly;
  • the second protective layer covers 30% to 100% of the surface area of the ending section of the winding single-sided area.
  • the protective layer covers part of the surface of the single-sided area of the current collector, which can greatly improve the curling of the pole piece, reduce the usage of the protective layer, and increase the energy density of the electrochemical device; and the protective layer
  • the minimum proportion of the surface area covering the current collector can be as low as 30%, which allows for a smaller alignment of the electrode assembly and a higher energy density of the electrochemical device.
  • the electrochemical device meets at least one of the following conditions:
  • a first active material layer is provided near the starting section of the winding single-sided area of the first current collector, and there is a gap between the first active material layer and the first protective layer located on the same side of the first current collector;
  • the second current collector is provided with a second active material layer near the ending section of the winding single-sided area, and there is a gap between the second active material layer and the second protective layer located on the same side of the second current collector.
  • the electrochemical device meets at least one of the following conditions:
  • the first protective layer is distributed in stripes or single blocks
  • the second protective layer is distributed in stripes or monoliths.
  • the protective layer is distributed in a stripe shape, and less protective layer material can be used, which can effectively solve the problem of pole piece curling, and can make the energy density of the electrochemical device higher; the protective layer is in a single piece. Shape distribution can make the protective layer easier to form and control the coating area of the protective layer.
  • both the first protective layer and the second protective layer include inorganic particles and a binder; the electrochemical device meets at least one of the following conditions:
  • the inorganic particles have Dv10 ⁇ 0.001 ⁇ m and Dv99 ⁇ 100 ⁇ m.
  • the particle size distribution of the inorganic particles is Dv10 ⁇ 0.001 ⁇ m and Dv99 ⁇ 40 ⁇ m;
  • the Dv10 of the active material particles of the first active material layer is 1 ⁇ m ⁇ 20 ⁇ m, and Dv99 ⁇ 80 ⁇ m;
  • the active material particles of the second active material layer have Dv10 of 1 ⁇ m to 20 ⁇ m and Dv99 ⁇ 80 ⁇ m.
  • inorganic particles are bonded to one surface of the current collector, and active material particles are bonded to the other surface, which can release the stress caused by the inorganic particles and greatly improve the problem of pole piece curling.
  • the particle size distribution of the inorganic particles is basically consistent with the particle size distribution of the active material.
  • the stress of the inorganic particles is basically consistent with the stress of the active material particles, which can improve the curling effect of the pole piece better.
  • the particle size of the inorganic particles is relatively small, the number of inorganic particles is relatively large, and the stress release of the inorganic particles is greater, which can make the thickness of the protective layer smaller and the weight per unit area smaller, which can well improve the curling of the pole piece. problem that can make the alignment of the electrode assembly smaller.
  • the first protective layer and the second protective layer further include a thickener, and based on the total mass of the first protective layer or the second protective layer, the mass percentage of the inorganic particles is 70% to 99%; The mass percentage of the binder is 0.3% to 30%; the mass percentage of the thickener is 0.3% to 20%.
  • the addition of thickener can make the internal stress of the protective layer larger.
  • the release stress of the inorganic particles is relatively large, and the thickness of the protective layer can be increased. In the case of small size and low weight per unit area, it solves the problem of pole piece curling and uses less protective layer.
  • the first pole piece is a negative electrode
  • the thickness of the first current collector is 4 ⁇ m to 10 ⁇ m.
  • the minimum thickness value of the negative electrode current collector can be greatly reduced, thereby increasing the energy density of the electrochemical device.
  • embodiments of the present application further provide electrical equipment, including the electrochemical device provided in any embodiment of the first aspect.
  • Figure 1 is a schematic structural diagram of a wound electrode assembly in the prior art
  • Figure 2 is a diagram of the curling mechanism of the single-sided pole piece
  • Figure 3 is a schematic structural diagram of a vehicle provided by some embodiments of the present application.
  • Figure 4 is a schematic structural diagram of an electrochemical device provided by an embodiment of the present application.
  • Figure 5 is a schematic structural diagram of a wound electrode assembly provided by some embodiments of the present application.
  • Figure 6 is a schematic diagram of the first planar and cross-sectional structure of the first pole piece shown in Figure 5;
  • Figure 7 is a schematic diagram of the first planar and cross-sectional structure of the second pole piece shown in Figure 5;
  • Figure 8 is a schematic diagram of the second planar and cross-sectional structure of the first pole piece shown in Figure 5;
  • Figure 9 is a schematic diagram of the second planar and cross-sectional structure of the second pole piece shown in Figure 5;
  • Figure 10 is a third planar and cross-sectional structural schematic diagram of the first pole piece shown in Figure 5;
  • Figure 11 is a schematic diagram of the third planar and cross-sectional structure of the second pole piece shown in Figure 5;
  • Figure 12 is a schematic diagram of the fourth planar and cross-sectional structure of the first pole piece shown in Figure 5;
  • Figure 13 is a schematic diagram of the fourth planar and cross-sectional structure of the second pole piece shown in Figure 5;
  • Figure 14 is a schematic diagram of the fifth planar and cross-sectional structure of the first pole piece shown in Figure 5;
  • Figure 15 is a schematic diagram of the sixth planar and cross-sectional structure of the first pole piece shown in Figure 5;
  • Figure 16 is a schematic diagram of the plane and cross-sectional structure of the negative electrode sheet provided in Embodiment 1 of the present application;
  • Figure 17 is a schematic diagram of the plane and cross-sectional structure of the positive electrode sheet provided in Embodiment 1 of the present application.
  • Icon 01-winding starting part; 02-winding ending part; 03-main part; 04-active material particles; 05-current collector;
  • 1000-vehicle 100-battery; 200-controller; 300-motor; 10-electrochemical device; 2-container; 21-casing; 22-end cover; 23-first electrode terminal; 24-second electrode terminal;
  • 1-electrode assembly 11-first pole piece; 111-first current collector; 1111-initial section of winding single-sided area; 112-first active material layer; 113-first protective layer; 12-second pole sheet; 121-the second current collector; 1211-the winding single-sided area finishing section; 122-the second active material layer; 123-the second protective layer; 13-separator; 131-the first separator; 132-the second separator; 171-the first pole; 172-the second pole;
  • 31-Copper foil current collector 311-A side; 312-B side; 32-negative electrode active material layer; 33-negative electrode protective layer;
  • an embodiment means that a particular feature, structure or characteristic described in connection with the embodiment may be included in at least one embodiment of the application.
  • the appearances of this phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.
  • connection should be understood in a broad sense.
  • connection can be a fixed connection, It can also be detachably connected or integrally connected; it can be directly connected or indirectly connected through an intermediate medium; it can be internal communication between two components.
  • connection can be a fixed connection
  • connection can also be detachably connected or integrally connected; it can be directly connected or indirectly connected through an intermediate medium; it can be internal communication between two components.
  • connection can also be detachably connected or integrally connected; it can be directly connected or indirectly connected through an intermediate medium; it can be internal communication between two components.
  • the core component of an electrochemical device is an electrode assembly.
  • a negative electrode sheet, a first separator, a positive electrode sheet and a second separator are usually overlapped and then rolled to form a wound electrode assembly.
  • Figure 1 is a schematic structural diagram of a winding electrode assembly in the prior art. Please refer to Figure 1.
  • the direction pointed by the arrow in Figure 1 is the winding direction.
  • the winding electrode assembly is divided into a winding starting part 01 and a winding ending part 02. and the main body part 03 located in between.
  • the innermost layer of the electrode assembly is the winding starting part 01 of the negative electrode sheet, and the outermost layer of the electrode assembly is the winding end part 02 of the positive electrode sheet.
  • the winding starting part 01 of the negative electrode sheet and the winding end part 02 of the positive electrode sheet are usually set as a single-sided area, that is, the winding of the negative electrode sheet
  • the negative active material layer is not provided in the area of the starting part 01 toward the center of the electrode assembly (the winding starting part 01 of the negative electrode sheet is a single-sided area), and the area of the winding end part 02 of the positive electrode sheet that is away from the center of the electrode assembly is also There is no positive active material layer (the winding end portion 02 of the positive electrode sheet is a single-sided area).
  • the negative electrode sheet includes a negative electrode current collector (such as copper foil) and a negative electrode active material layer (such as graphite, silicon). Both surfaces of the negative electrode current collector in the main area of the negative electrode sheet are provided with negative electrode active materials. layer (double-sided negative electrode sheet).
  • the positive electrode sheet includes a positive electrode current collector (such as aluminum foil) and a positive electrode active material layer (such as lithium cobalt type, lithium iron phosphate type, nickel cobalt manganese ternary type, etc.). Both surfaces of the positive electrode current collector in the main area of the positive electrode sheet are provided There is a positive active material layer (double-sided positive electrode sheet). The following does not differentiate between the positive electrode piece and the negative electrode piece, and directly uses the electrode piece as an example for explanation. When describing the electrode piece, the explanation is suitable for both the positive electrode piece and the negative electrode piece.
  • the active material When preparing pole pieces, the active material is usually coated on the current collector, and then rolled to increase the density of the active material layer and the bonding strength between the active material layer and the current collector to increase the energy density of the electrode assembly. and dynamic properties.
  • Figure 2 is a diagram of the curling mechanism of the single-sided pole piece. Please refer to Figure 2.
  • the inventor found that for the single-sided pole piece, before rolling, the porosity of the active material layer is relatively large, and there is no interaction between the active material particles 04 force (left panel in Figure 2). The active material particles will deform during rolling, and interaction forces will occur between particles, resulting in stored stress inside the particles (middle picture in Figure 2). After rolling, the particles are in an unstable state after storing stress and are seeking to release the stress. Since the bottom layer of particles is bonded to the current collector 05, the bottom particles cannot move. The upper particles are not bound by the current collector 05 and will move in the plane direction (parallel to the current collector 05).
  • the direction of 05 releases stress and deforms, causing the plane size of the upper coating to be larger than the plane size of the current collector 05 (R2>R1), so the pole piece curls toward the direction of the current collector 05, that is, the pole piece curls in the single-sided area ( Figure 2 right picture).
  • the size of the negative electrode sheet exceeding the positive electrode sheet is called "alignment".
  • the alignment of the negative electrode sheet and the positive electrode sheet deteriorated by 0.3mm compared to the main part 03 of the electrode assembly.
  • the curling force of the positive electrode sheet in the single-sided area will be released instantly, causing the single-sided area to be unable to spread smoothly, causing the entire strip to be The pole piece is scrapped. Even if the winding equipment (adjusting pole piece tension, adding pole piece smoothing measures, etc.) is optimized, the yield rate of the electrode assembly will be lost due to the curling of the positive electrode piece in the single-sided area.
  • the electrode assembly is formed by laminating and winding a first pole piece, a separator and a second pole piece.
  • the first pole piece includes a first current collector.
  • the first current collector includes a starting section of a single-sided winding area.
  • the initial section of the single-sided winding area is provided with a first protective layer toward the surface of the center of the electrode assembly.
  • the first current collector includes a starting section of the single-sided winding area.
  • a first active material layer is disposed on the surface of the initial section away from the center of the electrode assembly.
  • the second pole piece includes a second current collector.
  • the second current collector includes a winding single-sided area ending section.
  • a second protective layer is provided on the surface of the winding single-sided area ending section away from the center of the electrode assembly.
  • the winding single-sided area ending section faces The surface of the center of the electrode assembly is provided with a second active material layer.
  • the ratio of the unit area weight of the first protective layer to the unit area weight of the first active material layer is (0.03 ⁇ 0.75):1
  • the ratio of the unit area weight of the second protective layer to the unit area weight of the second active material layer is (0.03 ⁇ 0.75):1.
  • a first active material layer is provided on one surface of the initial section of the winding single-sided region of the first current collector, and a first protective layer is provided on the other surface, and the unit area of the first protective layer
  • the ratio of the weight to the weight per unit area of the first active material layer is (0.03 ⁇ 0.75):1, which not only improves the problem of pole piece curling, but also ensures the energy density of the electrochemical device to a certain extent.
  • a second active material layer is provided on one surface of the ending section of the winding single-sided area of the second current collector, and a second protective layer is provided on the other surface, and the weight per unit area of the second protective layer is equal to that of the second active material.
  • the ratio of the weight per unit area of the layer is (0.03 ⁇ 0.75):1, which not only improves the problem of pole piece curling, but also ensures the energy density of the electrochemical device to a certain extent.
  • the electrode assembly provided by the embodiment of the present application is suitable for electrochemical devices and electrical equipment using the electrochemical devices.
  • Embodiments of the present application provide electrical equipment.
  • the electrical equipment includes an electrochemical device, and the electrochemical device is used to provide electric energy.
  • Electrical equipment may include but is not limited to: vehicles, mobile phones, laptops, headphones, video recorders, calculators, ships, spacecraft, electric toys, etc.
  • the vehicle can be a fuel vehicle, a gas vehicle, a new energy vehicle, a motorcycle, a power-assisted bicycle, etc.
  • Spacecraft can be airplanes, rockets, space shuttles, spaceships, etc.
  • electric toys can be game consoles, electric car toys, electric ship toys, electric airplane toys, etc.
  • electric tools can be metal cutting power tools, grinding power tools, assembly power tools, etc. Tools, power tools for railways, etc. The embodiments of this application impose no special restrictions on the above electrical equipment.
  • the following embodiments take the electrical equipment as a vehicle as an example.
  • FIG 3 is a schematic structural diagram of a vehicle 1000 provided by some embodiments of the present application. Please refer to Figure 3.
  • a battery 100 is provided inside the vehicle 1000.
  • the battery 100 can be used to power the vehicle 1000.
  • the battery 100 can be provided at the bottom of the vehicle 1000 or Head or tail.
  • the vehicle 1000 may also include a controller 200 and a motor 300 .
  • the controller 200 is used to control the battery 100 to power the motor 300 .
  • Battery 100 may serve as an operating power source for vehicle 1000 . For example, it is used for the power requirements for starting, navigation and driving of the vehicle 1000 .
  • the battery 100 can also serve as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.
  • the battery 100 may include one or more electrochemical devices 10 .
  • the multiple electrochemical devices 10 can be connected in series, in parallel, or in mixed connection.
  • Mixed connection means that the multiple electrochemical devices 10 are connected in series and in parallel.
  • the battery 100 may also include a bus component, through which the multiple electrochemical devices 10 may be electrically connected to achieve series, parallel or mixed connection of the multiple electrochemical devices 10 .
  • the bus component can be a metal conductor, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.
  • FIG. 4 is a schematic structural diagram of an electrochemical device 10 provided in an embodiment of the present application. Please refer to FIG. 4 .
  • the electrochemical device 10 includes an electrode assembly.
  • the electrochemical device 10 generates chemical reaction between the electrode assembly and the electrolyte to output electrical energy.
  • the electrochemical device 10 may be a lithium-ion battery, a lithium-sulfur battery, a sodium-lithium-ion battery, a sodium-ion battery, a magnesium-ion battery, etc., and the embodiments of the present application are not limited thereto.
  • the electrochemical device 10 may be in the shape of a cylinder, a flat body, a cuboid, or other shapes, and the embodiments of the present application are not limited thereto.
  • the electrochemical device 10 is generally divided into three types according to the packaging method: cylindrical batteries, prismatic batteries and soft-pack batteries, and the embodiments of the present application are not limited thereto.
  • the electrochemical device 10 may further include a receiving member 2 , which is used to receive the electrode assembly.
  • the receiving member 2 may be a receiving shell, such as an aluminum shell, a steel shell, etc.
  • the storage member 2 may also be a storage bag, for example, a storage bag made of aluminum plastic film.
  • the receiving member 2 may include a housing 21 and an end cap 22 .
  • the housing 21 is a component used to accommodate the electrode assembly.
  • the housing 21 may be a hollow structure with an opening formed at one end.
  • the housing 21 can be in various shapes, such as cylinder, rectangular parallelepiped, etc.
  • the housing 21 can be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, etc.
  • the end cap 22 is a component that covers the opening of the housing 21 to isolate the internal environment of the electrochemical device 10 from the external environment.
  • the end cap 22 covers the opening of the housing 21 , and the end cap 22 and the housing 21 jointly define a sealed space for accommodating the electrode assembly, electrolyte and other components.
  • the shape of the end cover 22 can be adapted to the shape of the housing 21.
  • the housing 21 has a rectangular parallelepiped structure, and the end cover 22 has a rectangular plate structure matching the housing 21.
  • the housing 21 has a cylindrical shape.
  • the end cover 22 is a circular plate-shaped structure that matches the housing 21 .
  • the end cap 22 can also be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, etc.
  • a first electrode terminal 23 and a second electrode terminal 24 may be provided on the end cap 22 , and the first electrode terminal 23 and the second electrode terminal 24 are used for electrical connection with the electrode assembly to output electrical energy of the electrochemical device 10 .
  • Figure 5 is a schematic structural diagram of a wound electrode assembly provided by some embodiments of the present application.
  • the direction pointed by the arrow in Figure 5 is the winding direction
  • Figure 6 is a first plane and cross-section of the first pole piece 11 shown in Figure 5 Structural schematic diagram, in which the upper picture in Figure 6 is a schematic cross-sectional view, and the lower picture in Figure 6 is a schematic plan view
  • Figure 7 is a first planar and cross-sectional structural schematic diagram of the second pole piece 12 shown in Figure 5, wherein Figure The upper picture in Figure 7 is a schematic cross-sectional view, and the lower picture in Figure 7 is a schematic plan view.
  • an embodiment of the present application provides an electrode assembly 1.
  • the electrode assembly 1 includes a first pole piece 11, a second pole piece 12 and a diaphragm 13.
  • the first pole piece 11, the second pole piece 12 and The separators 13 are laminated and wound to form the electrode assembly 1 .
  • the stacking method may be: the first pole piece 11, the first separator 131, the second pole piece 12 and the second separator 132 are stacked and then rolled to form the electrode assembly 1.
  • the first pole piece 11 includes a first current collector 111 , and the first current collector 111 includes a rolling single-sided area starting section 1111 , and a first protective layer 113 is provided on the surface of the rolling single-sided area starting section 1111 toward the center of the electrode assembly 1 , the first active material layer 112 is disposed on the surface of the starting section 1111 of the winding single-sided area away from the center of the electrode assembly 1 .
  • the second pole piece 12 includes a second current collector 121.
  • the second current collector 121 includes a winding single-sided area ending section 1211.
  • a second protective layer 123 is provided on the surface of the winding single-sided area ending section 1211 away from the center of the electrode assembly 1.
  • the second active material layer 122 is disposed around the surface of the single-sided region ending section 1211 toward the center of the electrode assembly 1 .
  • the ratio of the unit area weight of the first protective layer 113 to the unit area weight of the first active material layer 112 is (0.03 ⁇ 0.75):1, and the ratio of the unit area weight of the second protective layer 123 to the unit area weight of the second active material layer 122 The weight ratio is (0.03 ⁇ 0.75):1.
  • the second pole piece 12 when the first pole piece 11 is a positive pole piece, the second pole piece 12 is a negative pole piece; or when the first pole piece 11 is a negative pole piece, the second pole piece 12 is a positive pole piece.
  • the corresponding first current collector 111 is a positive electrode current collector.
  • the positive electrode current collector can be aluminum foil, foamed aluminum, or aluminum composite current collector (with a polymer support layer in the middle, and two sides of the support layer.
  • a current collector with an aluminum metal layer on each surface), nickel foil, nickel foam, etc. is provided with a positive active material layer on the surface of the positive current collector.
  • the positive active material in the positive active material layer can be nickel cobalt manganese oxide. Lithium, lithium nickel cobalt aluminate, lithium cobalt oxide, lithium iron phosphate, ternary lithium, lithium manganate, etc.
  • the corresponding first current collector 111 can be a negative electrode current collector.
  • the negative electrode current collector can be copper foil, copper foam, or copper composite current collector (with a polymer support layer in the middle, and the support layer There are current collectors with copper metal layers on both surfaces), nickel foil, nickel foam, etc., and a negative active material layer is provided on the surface of the negative current collector.
  • the negative active material in the negative active material layer can be graphite. , silicon, etc.
  • the first diaphragm 131 and the second diaphragm 132 are components that separate the first pole piece 11 and the second pole piece 12 .
  • the separator can be made of a variety of materials, such as PP (polypropylene, polypropylene), PE (polyethylene, polyethylene), etc.
  • the starting section 1111 of the winding single-sided area of the first current collector 111 refers to the portion in the dotted frame near the winding center of the electrode assembly 1 shown in FIG. 5 .
  • the starting section 1111 of the winding single-sided area of the first current collector 111 refers to: at the starting end of the winding of the first current collector 111 , one surface is provided with the first active material layer 112 , and the other opposite surface is not provided with the third active material layer 112 .
  • An active material layer forms the starting section 1111 of the winding single-sided area of the first current collector 111.
  • the first current collector section of the layer When the electrode assembly 1 is formed by winding, the first current collector 111 is wound at the starting section 1111 of the single-sided area at the beginning of the winding; after the electrode assembly 1 is formed, the first current collector 111 The initial section 1111 of the winding single-sided area is located in the position of the electrode assembly 1 close to the winding center of the electrode assembly 1.
  • the initial section 1111 of the winding single-sided area of the first current collector 111 is a surface provided with the first active material.
  • the first active material layer 112 is provided on one surface of the initial section 1111 of the winding single-sided area of the first current collector 111 and the first protective layer 113 is provided on the other surface, starting from the winding single-sided area of the first current collector 111 At the beginning section 1111, after the first current collector 111 is cut with a cutter, the stress of the active material particles in the active material layer on the surface of the initial section 1111 of the winding single-sided area will be released instantly, but due to the winding of the single-sided area If the other surface of the starting section 1111 has a protective layer, the stress between the active material layer and the protective layer on both surfaces of the first current collector 111 will tend to be balanced, which can improve the performance of the first pole piece 11 to a certain extent. Curling issues can reduce alignment.
  • the first active material layer 112 is provided on one surface of the starting section 1111 of the winding single-sided area of the first current collector 111 , and the first protective layer 113 is provided on the other surface (corresponding to the first single-sided area of the first pole piece 11 ); and the ratio of the unit area weight of the first protective layer 113 to the unit area weight of the first active material layer 112 is (0.03 ⁇ 0.75):1.
  • the problem of curling of the first pole piece 11 can be improved.
  • the first protective layer 113 Compared with disposing the first active material layer 112 on both surfaces of the starting section 1111 of the winding single-sided area of the first current collector 111, the first protective layer 113 The unit area is less than the unit area weight of the first active material layer 112, and the energy density of the electrochemical device can be guaranteed to a certain extent.
  • the ratio of the unit area weight of the first protective layer 113 to the unit area weight of the first active material layer 112 is defined as X1, and the value of X1 can be 0.03:1, 0.05:1, 0.1:1, 0.15:1 , 0.2:1, 0.25:1, 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1, 0.55:1, 0.6:1, 0.65:1, 0.7:1 or 0.75:1, among which It can also be any value within the above range.
  • the first active material layer 112 can be provided on both surfaces of the main body area of the first current collector 111 to form a first double-sided area.
  • the single-surface area weights of the first active material layers 112 provided on the two surfaces of the first current collector 111 may be the same or different.
  • the ratio of the unit area weight of the first protective layer 113 to the unit area weight of the first active material layer 112 is (0.03 ⁇ 0.75):1, which can be a part of the starting section 1111 of the winding single-sided area of the first current collector 111
  • the unit area weight ratio between the first protective layer 113 provided on one surface and the first active material layer 112 provided on the other surface; it may also be the first protective layer 113 and the first active material on the same side of the first current collector 111 The basis weight ratio between layers 112.
  • the ending section 1211 of the winding single-sided area of the second current collector 121 refers to the portion in the dotted line frame of the electrode assembly 1 shown in FIG. 5 that is far away from the winding center.
  • the winding single-sided area ending section 1211 of the second current collector 121 refers to: at the winding end of the second current collector 121 , one surface is provided with the second active material layer 122 , and the other opposite surface is not provided with the second active material layer 122 .
  • the active material layer forms the ending section 1211 of the winding single-sided area of the second current collector 121.
  • a second active material layer is not provided on both surfaces at the winding end of the second current collector 121.
  • the second collector section is not provided on both surfaces at the winding end of the second current collector 121.
  • the winding end section of the second current collector 121 includes the ending section 1211 of the winding single-sided area of the second current collector 121; after the electrode assembly 1 is formed, the second current collector 121
  • the winding single-sided area ending section 1211 is located in a part of the electrode assembly 1 away from the winding center of the electrode assembly 1.
  • the winding single-sided area ending section 1211 of the second current collector 121 is a surface provided with the second active material layer 122 , after the separator 13 is separated, there is no area of the first active material layer corresponding to the second active material layer 122 on the other side of the separator.
  • the second active material layer 122 is provided on one surface of the winding single-sided area ending section 1211 of the second current collector 121 and the second protective layer 123 is provided on the other surface, the winding single-sided area ending section 1211 of the second current collector 121 At 1211, after the second current collector 121 is cut with a cutter, the stress of the active material particles in the active material layer on the surface of the winding single-sided area ending section 1211 will be released instantly, but due to the winding single-sided area ending section 1211 If the other surface of the second current collector 121 has a protective layer, the stress between the active material layer and the protective layer on the two surfaces of the second current collector 121 will tend to be balanced, which can improve the curling problem of the second pole piece 12 to a certain extent. Alignment can be reduced.
  • the second active material layer 122 is provided on one surface of the winding single-sided area ending section 1211 of the second current collector 121, and the second protective layer 123 is provided on the other surface (corresponding to the second single-sided area of the first pole piece 12). ; And the ratio of the weight per unit area of the second protective layer 123 to the weight per unit area of the second active material layer 122 is (0.03 ⁇ 0.75):1. This can improve the curling problem of the second pole piece 12.
  • the second protective layer 123 Compared with arranging the second active material layer 122 on both surfaces of the winding single-sided region ending section 1211 of the second current collector 121, the second protective layer 123 The weight per unit area is smaller than the weight per unit area of the second active material layer 122, which can ensure the energy density of the electrochemical device to a certain extent.
  • the ratio of the unit area weight of the second protective layer 123 to the unit area weight of the second active material layer 122 is defined as X2.
  • the value of X2 may be 0.03:1, 0.05:1, 0.1:1, 0.15:1 , 0.2:1, 0.25:1, 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1, 0.55:1, 0.6:1, 0.65:1, 0.7:1 or 0.75:1, among which It can also be any value within the above range.
  • both surfaces of the main body area of the second current collector 121 are the second active material layer 122, forming a second double-sided area.
  • the single-surface area weights of the second active material layers 122 provided on the two surfaces of the second current collector 121 may be the same or different.
  • the ratio of the unit area weight of the second protective layer 123 to the unit area weight of the second active material layer 122 is (0.03 ⁇ 0.75):1, which may be a surface of the winding single-sided area ending section 1211 of the second current collector 121
  • the unit area weight ratio is between 122.
  • the values of X1 and X2 may be the same or different.
  • the ratio of the unit area weight of the first protective layer 113 to the unit area weight of the first active material layer 112 is (0.1 ⁇ 0.4):1
  • the ratio of the unit area weight of the second protective layer 123 to the second active material layer The ratio of the weight per unit area of 122 is (0.1 ⁇ 0.4):1. This can make the improvement effect of the pole piece curling in the single-sided area more obvious and further reduce the alignment.
  • the weight per unit area of the first active material layer 112 is 0.06g/1540.25mm 2 to 0.5g/1540.25mm 2 .
  • the weight per unit area of the first active material layer 112 refers to: taking the first pole piece 11 with a surface area of 1540.25 mm 2 , the weight of the first active material layer 112 on one side of the first current collector 111 of the first pole piece 11 is 0.06g ⁇ 0.5g.
  • the first pole piece 11 has the first active material layer 112 with the weight per unit area. After the electrode assembly 1 is formed, the electrical performance of the electrochemical device is better.
  • the weight per unit area of the second active material layer 122 is 0.06g/1540.25mm 2 to 0.5g/1540.25mm 2 .
  • the unit area weight of the second active material layer 122 refers to: taking the second pole piece 12 with a surface area of 1540.25 mm 2 , the weight of the second active material layer 122 on the second current collector 121 side of the second pole piece 12 is 0.06g ⁇ 0.5g.
  • the second pole piece 12 has the second active material layer 122 with the weight per unit area. After the electrode assembly 1 is formed, the electrical performance of the electrochemical device is better.
  • the unit area weight of the first protective layer 113 is 0.01g/1540.25mm 2 to 0.13g/1540.25mm 2 .
  • the unit area weight of the first protective layer 113 refers to: taking the first pole piece 11 with a surface area of 1540.25 mm 2 , the first current collector 111 of the first pole piece 11 on the initial section 1111 of the winding single-sided area
  • the weight of the protective layer 113 is 0.01g ⁇ 0.13g.
  • the first pole piece 11 has the first protective layer 113 with the weight per unit area, which can better improve the curling problem of the first pole piece 11 .
  • the unit area weight of the second protective layer 123 is 0.01g/1540.25mm 2 to 0.13g/1540.25mm 2 .
  • the unit area weight of the second protective layer 123 refers to: taking the second pole piece 12 with a surface area of 1540.25 mm 2 , the second protection layer on the ending section 1211 of the winding single-sided area of the second current collector 121 of the second pole piece 12
  • the weight of layer 123 is 0.01g to 0.13g.
  • the second protective layer 123 having the weight per unit area of the second pole piece 12 can better improve the curling problem of the second pole piece 12 .
  • the problem of pole piece curling can be better improved.
  • the alignment of the electrode assembly 1 is smaller, thereby increasing the energy density of the electrochemical device.
  • limiting the unit area weight of the active material layer can make the electrical performance of the electrochemical device better.
  • the unit area weight of the first active material layer 112 is defined as M1.
  • the value of M1 may be 0.06g/1540.25mm 2 , 0.1g/1540.25mm 2 , 0.15g/1540.25mm 2 , 0.2g/1540.25mm 2 , 0.25g/ 1540.25mm 2 , 0.3g/1540.25mm 2 , 0.35g/1540.25mm 2 , 0.4g/1540.25mm 2 , 0.45g/1540.25mm 2 or 0.5g/1540.25mm 2 , which can also be any value in the above range; definition
  • the unit area weight of the second active material layer 122 is M2, and the value of M2 can be 0.06g/1540.25mm 2 , 0.1g/1540.25mm 2 , 0.15g/1540.25mm 2 , 0.2g/1540.25mm 2 , 0.25g/1540.25 mm 2 , 0.3g/1540.25mm 2 , 0.35g/1540.25mm 2 , 0.4g
  • the unit area weight of the first protective layer 113 is defined as M3.
  • the value of M3 can be 0.01g/1540.25mm 2 , 0.03g/1540.25mm 2 , 0.05g/1540.25mm 2 , 0.07g/1540.25mm 2 , 0.09g/1540.25 mm 2 , 0.1g/1540.25mm 2 or 0.13g/1540.25mm 2 , which can also be any value in the above range; define the weight per unit area of the second protective layer 123 as M4, and the value of M4 can be 0.01g/1540.25mm.
  • M3 and M4 can be the same or different.
  • the unit area weight of the first active material layer 112 and the unit area weight of the second active material layer 122 are 0.1g/1540.25mm 2 to 0.3g/1540.25mm 2 .
  • the unit area weight of the first protective layer 113 and the unit area weight of the second protective layer 123 are 0.02 to 0.08g/1540.25mm 2 . This can make the improvement effect of the pole piece curling in the single-sided area more obvious and further reduce the alignment.
  • the ratio of the unit area weight of the first protective layer 113 to the unit area weight of the first active material layer 112 is (0.3 ⁇ 0.75):1;
  • the weight per unit area of the material layer 112 is 0.06g/1540.25mm 2 ⁇ 0.3g/1540.25mm 2 ;
  • the weight per unit area of the first protective layer 113 is 0.02g/1540.25mm 2 ⁇ 0.13g/1540.25mm 2 .
  • the ratio of the unit area weight of the first protective layer 113 to the unit area weight of the first active material layer 112 is (0.03 ⁇ 0.6):1; the unit area of the first active material layer 112 The weight is 0.1g/1540.25mm 2 ⁇ 0.5g/1540.25mm 2 ; the unit area weight of the first protective layer 113 is 0.01g/1540.25mm 2 ⁇ 0.08g/1540.25mm 2 .
  • the negative electrode sheet corresponds to the negative electrode protective layer and the negative electrode active material layer
  • the positive electrode sheet corresponds to the positive electrode protective layer and the positive electrode active material layer
  • the unit area weight of the negative electrode active material layer is smaller than the unit area weight of the positive electrode active material layer, which can improve the electrical performance of the electrochemical device. Better.
  • the unit area weight of the negative electrode protective layer is greater than the unit area weight of the positive electrode protective layer, and the difference between the unit area weight of the negative electrode active material layer and the unit area weight of the negative electrode protective layer is less than the unit area weight of the positive electrode active material layer and the positive electrode protective layer.
  • the value of the difference in weight per unit area Since the inventor's research found that the curling problem in the single-sided area of the negative electrode sheet is more serious, the difference between the unit area weight of the negative electrode active material layer and the unit area weight of the negative electrode protective layer is relatively small (the unit area weight of the negative electrode protective layer The weight is relatively high), which can better improve the curling problem of the single-sided area of the negative electrode sheet.
  • the curling problem in the single-sided area of the positive electrode sheet is slightly weaker, so the difference between the unit area weight of the positive electrode active material layer and the unit area weight of the positive electrode protective layer is relatively large (the unit of the positive electrode protective layer The area weight is relatively low), which can greatly improve the curling problem of the single-sided area of the positive electrode sheet.
  • the above arrangement can not only effectively improve the curling problem of the single-sided area of the positive electrode sheet and the negative electrode sheet, but also make the electrochemical device have higher energy density and better electrical performance.
  • the ratio of the thickness of the first protective layer 113 to the thickness of the first active material layer 112 is (0.1 ⁇ 0.6):1. Please continue to refer to the schematic cross-sectional view of FIG. 6 .
  • the thickness of the first protective layer 113 is D11
  • the thickness of the first active material layer 112 is D12
  • the thickness of the first protective layer 113 is relatively thin, which not only solves the problem of curling of the single-sided area of the pole piece, but also makes the thickness of the electrode assembly 1 thinner, so that the volumetric energy density of the electrochemical device is higher.
  • the ratio of the thickness of the second protective layer 123 to the thickness of the second active material layer 122 is (0.1 ⁇ 0.6):1. Please continue to refer to the schematic cross-sectional view of FIG. 7 .
  • the thickness of the second active layer is D21
  • the thickness of the second active material layer 122 is D22
  • the thickness of the second protective layer 123 is relatively thin, which not only solves the problem of curling of the single-sided area of the pole piece, but also makes the thickness of the electrode assembly 1 thinner, so that the volumetric energy density of the electrochemical device is higher.
  • the value of Y1 may be 0.1:1, 0.15:1, 0.2:1, 0.25:1, 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1, 0.55:1 or 0.6:1, which can also be any value in the above range.
  • the value of Y2 can be 0.1:1, 0.15:1, 0.2:1, 0.25:1, 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1, 0.55:1 or 0.6:1, where It can also be any value within the above range.
  • the values of Y1 and Y2 can be the same or different.
  • the thickness D12 of the first active material layer 112 is 15 ⁇ m ⁇ 200 ⁇ m.
  • the first pole piece 11 has the first active material layer 112 of this thickness. After the electrode assembly 1 is formed, the electrical performance of the electrochemical device is better.
  • the thickness D22 of the second active material layer 122 is 15 ⁇ m ⁇ 200 ⁇ m.
  • the second pole piece 12 has the second active material layer 122 with this thickness. After the electrode assembly 1 is formed, the electrical performance of the electrochemical device is better.
  • the thickness D11 of the first protective layer 113 is 1.5 ⁇ m to 100 ⁇ m.
  • the first pole piece 11 has the first protective layer 113 with this thickness, which can better improve the curling problem of the first pole piece 11 .
  • the thickness D21 of the second protective layer 123 is 1.5 ⁇ m to 100 ⁇ m.
  • the second protective layer 123 of the second pole piece 12 having this thickness can better improve the curling problem of the second pole piece 12 .
  • Defining the thickness of the active material layer and the thickness of the protective layer respectively, in conjunction with the ratio of the thickness of the protective layer to the thickness of the active material layer, can better improve the problem of pole piece curling and make the alignment of the electrode assembly 1 smaller. , and the energy density of electrochemical devices is higher.
  • the thickness D12 of the first active material layer 112 may be 15 ⁇ m, 30 ⁇ m, 50 ⁇ m, 80 ⁇ m, 100 ⁇ m, 120 ⁇ m, 140 ⁇ m, 160 ⁇ m, 180 ⁇ m or 200 ⁇ m, or it may be any value in the above range;
  • the second active material The thickness D22 of the layer 122 can be 15 ⁇ m, 30 ⁇ m, 50 ⁇ m, 80 ⁇ m, 100 ⁇ m, 120 ⁇ m, 140 ⁇ m, 160 ⁇ m, 180 ⁇ m or 200 ⁇ m, or it can be any value in the above range; the value of D12 and the value of D22 can be the same or different. .
  • the thickness D11 of the first protective layer 113 may be 1.5 ⁇ m, 3 ⁇ m, 5 ⁇ m, 8 ⁇ m, 10 ⁇ m, 20 ⁇ m, 30 ⁇ m, 40 ⁇ m, 50 ⁇ m, 60 ⁇ m, 70 ⁇ m, 80 ⁇ m, 90 ⁇ m or 100 ⁇ m, or it may be in the above range.
  • the thickness D21 of the second protective layer 123 may be 1.5 ⁇ m, 3 ⁇ m, 5 ⁇ m, 8 ⁇ m, 10 ⁇ m, 20 ⁇ m, 30 ⁇ m, 40 ⁇ m, 50 ⁇ m, 60 ⁇ m, 70 ⁇ m, 80 ⁇ m, 90 ⁇ m or 100 ⁇ m, or it may be in the above range.
  • Any value; the value of D11 and the value of D21 can be the same or different.
  • the ratio of the thickness of the first protective layer 113 to the thickness of the first active material layer 112 is (0.15 ⁇ 0.6):1; the first active material layer 112 The thickness of the first protective layer 113 is 30 ⁇ m to 200 ⁇ m; the thickness of the first protective layer 113 is 3 ⁇ m to 100 ⁇ m. If the first electrode piece 11 is a positive electrode piece, the ratio of the thickness of the first protective layer 113 to the thickness of the first active material layer 112 is (0.1 ⁇ 0.5):1; the thickness of the first active material layer 112 is 15 ⁇ m ⁇ 180 ⁇ m. ; The thickness of the first protective layer 113 is 1.5 ⁇ m ⁇ 90 ⁇ m.
  • the negative electrode sheet corresponds to the negative electrode protective layer and the negative electrode active material layer
  • the positive electrode sheet corresponds to the positive electrode protective layer and the positive electrode active material layer
  • the thickness of the negative electrode active material layer is greater than the thickness of the positive electrode active material layer
  • the single-sided area weight of the negative electrode active material layer is smaller than the positive electrode From the unit area weight of the active material layer, it can be seen that the density of the negative active material layer is smaller than that of the positive active material layer, which is beneficial to improving the electrical performance of the electrochemical device.
  • the ratio of the thickness of the negative electrode protective layer to the thickness of the negative electrode active material layer is greater than the ratio of the thickness of the positive electrode protective layer to the thickness of the positive electrode active material layer. Since the inventor's research found that the curling problem in the single-sided area of the negative electrode sheet is more serious, the ratio of the thickness of the negative active material layer to the thickness of the negative electrode protective layer is relatively large, which can solve the curling problem in the single-sided area of the negative electrode sheet. Better improvements. For the positive electrode sheet, the curling problem in the single-sided area of the positive electrode sheet is slightly less severe. Therefore, the ratio of the thickness of the positive active material layer to the thickness of the positive electrode protective layer is relatively small, which can prevent the curling of the single-sided area of the positive electrode sheet. The problem has been greatly improved. The above arrangement can not only effectively improve the curling problem of the single-sided area of the positive electrode sheet and the negative electrode sheet, but also make the electrochemical device have higher energy density and better electrical performance.
  • the length of the initial section 1111 of the winding single-sided area accounts for 1.5% to 50% of the total length of the first current collector 111 .
  • the direction pointed by the arrow in Figure 5 is the winding direction of the electrode assembly 1.
  • the first pole piece 11 shown in the cross-sectional schematic diagram in Figure 6 starts to wind in the clockwise direction from the right end.
  • the length of the starting section 1111 of the winding single-sided area in Figure 6 is L11
  • the length of the first current collector 111 in Figure 6 is L12
  • L11/L12 1.5% to 50%.
  • the length of the winding single-sided area ending section 1211 accounts for 2% to 55% of the total length of the second current collector 121 .
  • the value of L22 is greater than the value of L12. This is because the starting section 1111 of the winding single-sided area is located on the inner ring of the electrode assembly 1, and the ending section 1211 of the winding single-sided area is located on the outer ring of the electrode assembly 1. The length of the ending section 1211 of the single-sided area is greater than the length of the starting section 1111 of the winding single-sided area.
  • the length of the initial section 1111 of the winding single-sided area accounts for 1.5%, 3%, 5%, 10%, 15%, 20%, 25%, 30%, 35% of the total length of the first current collector 111 , 40%, 45% or 50%, which can also be any value in the above range;
  • the length of the winding single-sided area ending section 1211 accounts for 2%, 4%, 8%, 12% of the total length of the second current collector 121 , 16%, 20%, 25%, 30%, 35%, 40%, 45%, 50% or 55%, which can also be any value in the above range.
  • the length of the starting section 1111 of the winding single-sided area accounts for 1.5% to 10% of the total length of the first current collector 111; along the winding direction of the electrode assembly 1, the length of the winding single-sided area
  • the length of the surface area ending section 1211 accounts for 2% to 15% of the total length of the second current collector 121 .
  • the starting section 1111 of the single-sided winding area can be basically located on the inner ring of the electrode assembly 1
  • the ending section 1211 of the single-sided winding area can be basically located on the outer ring of the electrode assembly 1.
  • the problem of pole piece curling of the electrode assembly 1 can be well solved. Solved, and the energy density of electrochemical devices is higher.
  • the first protective layer 113 does not completely cover the right end of the first current collector 111 .
  • the first protective layer 113 is on the first current collector 111 .
  • the orthographic projection basically coincides with the orthographic projection of the first active material layer 112 on the first current collector 111. Therefore, it can be seen that the first protective layer 113 completely covers the starting section 1111 of the winding single-sided area toward the center of the electrode assembly 1 s surface.
  • the first protective layer 113 completely covering the surface of the starting section 1111 of the winding single-sided area of the first current collector 111 toward the center of the electrode assembly 1 may refer to: the coating area of the first protective layer 113 and the first The coating areas of the first active material layer 112 opposite to the protective layer 113 substantially overlap.
  • the second protective layer 123 does not completely cover the left end of the second current collector 121 .
  • the second protective layer 123 is on the second current collector 121 .
  • the orthographic projection basically coincides with the orthographic projection of the second active material layer 122 on the second current collector 121. Therefore, it can be seen that the second protective layer 123 completely covers the winding single-sided area ending section 1211 away from the center of the electrode assembly 1 surface.
  • the second protective layer 123 completely covering the surface of the winding single-sided area ending section 1211 of the second current collector 121 away from the center of the electrode assembly 1 may refer to: the coating area of the second protective layer 123 and the second protective layer.
  • the coating areas of the second active material layer 122 opposite the layer 123 substantially overlap.
  • FIG. 8 is a schematic diagram of the second planar and cross-sectional structure of the first pole piece 11 shown in FIG. 5 .
  • the orthographic projection of the first protective layer 113 on the first current collector 111 can be Beyond the orthographic projection of the first active material layer 112 on the first current collector 111 , please continue to refer to the cross-sectional schematic diagram in FIG. 8 , in which the first protective layer 113 extends to the right beyond the first active material layer 112 , or/and , the first protective layer 113 in this figure is recoated with part of the first active material layer 112 to the left.
  • the first protective layer 113 completely covers the surface of the initial section 1111 of the winding single-sided area of the first current collector 111 facing the center of the electrode assembly 1. It may also mean that the coating area of the first protective layer 113 exceeds the A protective layer 113 faces the coated area of the first active material layer 112 .
  • the length of the first protective layer 113 beyond the first active material layer 112 to the right accounts for 0.1% to 0.5% of the total length of the first fluid
  • the length of the first protective layer 113 to the left The overlap length with the first active material layer 112 accounts for 0.1% to 0.5% of the total length of the first fluid, which can still achieve the purpose of improving the pole piece curling problem.
  • FIG. 9 is a schematic diagram of the second planar and cross-sectional structure of the second pole piece 12 shown in FIG. 5 .
  • the orthographic projection of the second protective layer 123 on the second current collector 121 can be Beyond the orthographic projection of the second active material layer 122 on the second current collector 121 , please continue to refer to the cross-sectional schematic diagram in FIG. 9 , in which the second protective layer 123 extends to the left beyond the second active material layer 122 , or/and , the second protective layer 123 in this figure is overcoated with part of the second active material layer 122 to the right.
  • the second protective layer 123 completely covers the surface of the winding single-sided area ending section 1211 of the second current collector 121 away from the center of the electrode assembly 1. It may also mean that the coating area of the second protective layer 123 exceeds the area between the second current collector 121 and the second current collector 121.
  • the two protective layers 123 are opposite to the coating area of the second active material layer 122 .
  • the length of the second protective layer 123 beyond the second active material layer 122 accounts for 0.1% to 0.5% of the total length of the second current collector 121 , and the second protective layer 123 is directed to the left.
  • the overlap length with the second active material layer 122 accounts for 0.1% to 0.5% of the total length of the second fluid, which can still achieve the purpose of improving the problem of pole piece curling.
  • the first protective layer 113 covers the surface of the starting section 1111 of the partially rolled single-sided area facing the center of the electrode assembly 1; the second protective layer 123 covers the ending section 1211 of the partially rolled single-sided area facing away from the center of the electrode assembly 1 s surface.
  • Figure 10 is a third planar and cross-sectional structural schematic view of the first pole piece 11 shown in Figure 5.
  • Figure 11 is a third planar and cross-sectional structural schematic view of the second pole piece 12 shown in Figure 5.
  • Figure 12 is a diagram 5 is a schematic diagram of the fourth planar and cross-sectional structure of the first pole piece 11
  • FIG. 13 is a schematic diagram of the fourth planar and cross-sectional structure of the second pole piece 12 shown in FIG. 5 .
  • the surface of the first protective layer 113 covering part of the starting section 1111 of the winding single-sided area towards the center of the electrode assembly 1 refers to: the orthogonal projection area of the first protective layer 113 on the first current collector 111.
  • the orthographic projection of the first protective layer 113 on the first current collector 111 does not exceed the area of the first active material layer 112 on the first current collector 111
  • the edge of the orthographic projection on the first current collector 111 that is to say, at the initial section 1111 of the winding single-sided area of the first current collector 111 , the orthographic projection of the first protective layer 113 on the first current collector 111 does not completely cover the first active Orthographic projection of the layer on the first current collector 111.
  • the second protective layer 123 covering the surface of the partially wound single-sided area ending section 1211 away from the center of the electrode assembly 1 means that the orthogonal projected area of the second protective layer 123 on the second current collector 121 is less than The orthographic projection area of the second active material layer 122 on the second current collector 121 , and the orthographic projection of the second protective layer 123 on the second current collector 121 does not exceed the area of the second active material layer 122 on the second current collector 121 At the edge of the orthographic projection on the second current collector 121 , that is, at the ending section 1211 of the winding single-sided area of the second current collector 121 , the orthographic projection of the second protective layer 123 on the second current collector 121 does not completely cover the second active layer. Orthographic projection on the second current collector 121 .
  • the protective layer covers part of the surface of the single-sided area of the current collector, the curling of the pole piece can be greatly improved, the usage of the protective layer can be reduced, and the energy density of the electrochemical device can be increased.
  • the first protective layer 113 covers 30% to 100% of the surface area of the initial section 1111 of the single-sided winding area. Please continue to refer to Figure 10.
  • the surface area of the initial section 1111 of the single-sided winding area is length L31 times the width D31.
  • the surface area of the first protective layer 113 covering the initial section 1111 of the single-sided winding area is length L41 times the width.
  • the surface area of the second protective layer 123 covering the ending section 1211 of the single-sided winding area accounts for 30% to 100%. Please continue to refer to Figure 12.
  • the surface area of the initial section 1111 of the single-sided winding area is length L51 times the width D51.
  • the surface area of the first protective layer 113 covering the starting section 1111 of the single-sided winding area accounts for 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100%. , it can also be any value in the above range; the surface area of the second protective layer 123 covering the ending section 1211 of the winding single-sided area accounts for 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100%, it can also be any value in the above range.
  • the first protective layer 113 covers 50% to 80% of the surface area of the starting section 1111 of the single-sided winding area; or/and, the second protective layer 123 covers the ending section of the single-sided winding area.
  • the surface area of 1211 accounts for 50% to 80%.
  • a first active material layer 112 is provided at a position of the first current collector 111 close to the initial section 1111 of the winding single-sided region, and the first active material layer 112 located on the same side of the first current collector 111 and There is a gap between the first protective layers 113; a second active material layer 122 is provided on the second current collector 121 close to the ending section 1211 of the winding single-sided area, and the second active material layer 122 is located on the same side of the second current collector 121. There is a gap between the active material layer 122 and the second protective layer 123 .
  • Figures 10 and 12 As shown in the schematic cross-sectional views in Figures 10 and 12, there is a gap between the first protective layer 113 on the upper surface of the first current collector 111 and the first active material layer 112. Figures 10 and 12 As shown in the plan view in FIG. 12 , there is a gap between the first protective layer 113 and the first active material layer 112 on the surface of the first current collector 111 . Please continue to refer to FIGS. 11 and 13 . As shown in the schematic cross-sectional views in FIGS. 11 and 13 , there is a gap between the second protective layer 123 and the second active material layer 122 on the lower surface of the second current collector 121 .
  • the first protective layer 113 is distributed in a stripe shape or a single piece; the second protective layer 123 is distributed in a stripe shape or a single piece.
  • the protective layer is distributed in a single block, which makes it easier to form the protective layer and control the coating area of the protective layer.
  • the protective layer is distributed in a stripe shape. Less protective layer material can be used, which can effectively solve the problem of pole piece curling and make the energy density of the electrochemical device higher.
  • Figure 14 is a schematic diagram of the fifth planar and cross-sectional structure of the first pole piece 11 shown in Figure 5.
  • the first protective layer 113 can also be in the shape of vertical stripes (a in Figure 14 Figure)
  • the second protective layer 123 can also be in the shape of vertical stripes
  • the first protective layer 113 can also be in the shape of horizontal stripes (figure b in Figure 14);
  • the second protective layer 123 can also be in the shape of horizontal stripes
  • the first protective layer 113 can also be in the shape of horizontal stripes.
  • the 113 can also be in the shape of diagonal stripes (picture c in Figure 14); the second protective layer 123 can also be in the shape of diagonal stripes, and the first protective layer 113 can also be in an irregular shape (picture d in Figure 14); the second protective layer 123 can also be in the shape of diagonal stripes (picture d in Figure 14); 123 can also be of irregular shape.
  • the first protective layer 113 and the second protective layer 123 include inorganic particles and a binder. After the inorganic particles and the binder are mixed, a slurry can be formed, and the slurry can be coated on the starting section 1111 of the rolling single-sided area and the ending section 1211 of the rolling single-sided area, thereby forming the first protective layer 113 and the second protective layer 113. Second protective layer 123. There are active material particles in the active material layer, so that one surface of the current collector can be bonded with inorganic particles, and the other surface can be bonded with active material particles, which can release the stress through the inorganic particles and greatly improve the single-sided curling of the pole piece. The problem.
  • the protective layer formed by the adhesion between the inorganic particles and the insulating protective layer can be formed in the starting section 1111 of the single-sided winding area or the ending section of the single-sided winding area formed in the current collector. 1211, it can also improve the safety of electrochemical devices.
  • the inorganic particles can be boehmite, aluminum oxide, titanium oxide, silicon oxide, magnesium oxide, hafnium oxide, tin oxide, cerium oxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, aluminum hydroxide, At least one of magnesium hydride, calcium hydroxide, barium sulfate, calcium sulfate, calcium silicate, and silicon carbide.
  • the inorganic particles are insulating particles, and the protective layer formed by the inorganic particles and the adhesiveness is an insulating protective layer. When formed in the starting section 1111 of the winding single-sided area of the current collector or the ending section 1211 of the winding single-sided area, it can also be Improve the safety of electrochemical devices.
  • the binder may be polyacrylic acid, polyacrylate, polyacrylate, polyacrylonitrile, carboxymethylcellulose salt, nitrile rubber, styrene-butadiene rubber, polypropylene, polyethylene, polytetrafluoroethylene, At least one of polyvinylidene fluoride and polyetherimide can form a protective layer on the current collector, and improve the bonding force between the current collector and the protective layer.
  • the Dv10 of the inorganic particles is ⁇ 0.001 ⁇ m, and the Dv99 is ⁇ 100 ⁇ m; the Dv10 of the first active material layer 112 is 1 ⁇ m to 20 ⁇ m, and the Dv99 is ⁇ 80 ⁇ m; and the Dv10 of the active material particles of the second active material layer 122 is 1 ⁇ m to 100 ⁇ m. 20 ⁇ m, Dv99 ⁇ 80 ⁇ m.
  • the particle size distribution state of the inorganic particles in the first protective layer 113 may be the same as or different from the particle size distribution state of the inorganic particles in the second protective layer 123; similarly, the particle size distribution state of the active material particles in the first active material layer 112
  • the particle size distribution state may be the same as or different from the particle size distribution state of the active material particles in the second active material layer 122 .
  • the Dv10 ⁇ 0.001 ⁇ m of inorganic particles means: the inorganic particles in the protective layer are accumulated from small to large. When they add up to 10% of the total volume, the particle size of the inorganic particles is ⁇ 0.001 ⁇ m; the Dv99 of the inorganic particles ⁇ 100 ⁇ m means: the inorganic particles in the protective layer are accumulated from small to large. When they are added up to account for 99% of the total volume, the particle size of the inorganic particles is ⁇ 100 ⁇ m.
  • the Dv10 of the active material particles is 1 ⁇ m to 20 ⁇ m. This means that the active material particles in the active material layer are accumulated from small to large. When they are added up to account for 10% of the total volume, the particle size of the active material particles is between 1 ⁇ m and 20 ⁇ m. between; Dv99 ⁇ 80 ⁇ m of active material particles means: the active material particles in the active material layer are accumulated from small to large. When the active material particles are accumulated to account for 99% of the total volume, the particle size of the active material particles is ⁇ 80 ⁇ m.
  • the particle size distribution of the inorganic particles is basically consistent with the particle size distribution of the active material.
  • the stress of the inorganic particles is basically consistent with the stress of the active material particles, which can improve the curling effect of the pole piece better.
  • the inorganic particles have Dv10 ⁇ 0.001 ⁇ m and Dv99 ⁇ 40 ⁇ m.
  • the particle size of inorganic particles is relatively small, the number of inorganic particles is relatively large, and the stress release of inorganic particles is greater.
  • the thickness of the protective layer and the weight per unit area are small, which can effectively improve the problem of pole piece curling. , the alignment of the electrode assembly 1 can be made smaller.
  • the materials in the protective layer may also have thickeners. That is to say, the first protective layer 113 and the second protective layer 123 include inorganic particles, binders and thickeners. Based on the first protective layer 113 or The total mass of the second protective layer 123 includes a mass percentage of inorganic particles ranging from 70% to 99%; a mass percentage of the adhesive ranging from 0.3% to 30%; and a thickening agent ranging from 0.3% to 30%. 20%.
  • the thickener can be carboxymethylcellulose, propylene glycol alginate, methylcellulose, sodium starch phosphate, sodium carboxymethylcellulose, sodium alginate, casein, sodium polyacrylate, polyoxyethylene , at least one of polyvinylpyrrolidone.
  • the ingredients of the slurry forming the first protective layer 113 and the slurry forming the second protective layer 123 may be the same or different; if the ingredients of the slurry forming the first protective layer 113 and the slurry forming the second protective layer 123
  • the components of the slurry are the same, and the mass percentage of each cost can also be the same or different, which is not limited in this application.
  • the mass percentage of inorganic particles is 70%, 75%, 80%, 85%, 90%, 95% or 99%, which can also be any value in the above range;
  • the mass of the adhesive The content is 0.3%, 0.5%, 1%, 3%, 5%, 10%, 15%, 20%, 25% or 30%, which can also be any value in the above range;
  • the mass percentage of the thickener The content is 0.3%, 0.5%, 1%, 3%, 5%, 10%, 15% or 20%, and it can also be any value in the above range.
  • the addition of thickener can make the internal stress of the protective layer larger. After the protective layer is placed on one surface of the current collector, the release stress of the inorganic particles is relatively large. The thickness of the protective layer can be small and the weight per unit area can be reduced. In smaller cases, the problem of pole piece curling is solved and the amount of protective layer used is reduced.
  • the first pole piece 11 is a negative electrode
  • the thickness of the first current collector 111 is 4-10 ⁇ m.
  • the thickness of the first current collector 111 is 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, 9 ⁇ m or 10 ⁇ m, which may also be any value within the above range.
  • the setting of the protective layer can reduce the thickness of the negative electrode current collector to 4 ⁇ m, which can greatly reduce the thickness of the negative electrode current collector, thereby increasing the energy density of the electrochemical device.
  • Figure 15 is a schematic diagram of the sixth planar and cross-sectional structure of the first pole piece 11 shown in Figure 5.
  • the electrode assembly 1 also includes a first pole tab 171 and a second pole tab 172.
  • the pole tab 171 is disposed on one side of the first pole piece 11 and is electrically connected to the first current collector 111.
  • (e), (f) and (g) in Figure 15 are respectively the first pole tab 171.
  • the second tab 172 is disposed on one side of the second pole piece 12 and is electrically connected to the second current collector 121 .
  • the first tab 171 is connected to the first electrode terminal 23, and the second tab 172 is connected to the second electrode terminal 24, so as to output current.
  • the stacked first pole piece 11, first separator 131, second pole piece 12 and second separator 132 are rolled to form the electrode assembly 1.
  • the component 1 has a stacked first pole piece 11, a first diaphragm 131, a second pole piece 12 and a second diaphragm 132.
  • the first pole piece 11 includes a first current collector 111, and the first current collector 111 is wound on one side.
  • the first active material layer 112 is provided on the surface of the region starting section 1111 away from the center of the electrode assembly 1 , and the first protective layer 113 is provided on the surface of the wound single-sided region starting section 1111 of the first current collector 111 facing the center of the electrode assembly 1 , the ratio of the unit area weight of the first protective layer 113 to the unit area weight of the first active material layer 112 is (0.03 ⁇ 0.75):1, and the unit area weight of the first active material layer 112 is 0.06g/1540.25mm 2 ⁇ 0.5g/1540.25mm 2 ; the unit area weight of the first protective layer 113 is 0.01g/1540.25mm 2 ⁇ 0.13g/1540.25mm 2 ; the ratio of the thickness of the first protective layer 113 to the thickness of the first active material layer 112 is (0.1 ⁇ 0.6):1; the thickness of the first active material layer 112 is 15 ⁇ m ⁇ 200 ⁇ m; the thickness of the first protective layer 113 is 1.5 ⁇ m ⁇ 100 ⁇ m; along the winding direction
  • the second pole piece 12 includes a second current collector.
  • the second active material layer 122 is disposed on the surface of the ending section 1211 of the winding single-sided area of the second current collector 121 toward the center of the electrode assembly 1.
  • the second current collector 121 has a winding single-sided surface.
  • a second protective layer 123 is provided on the surface of the surface region ending section 1211 away from the center of the electrode assembly 1.
  • the ratio of the unit area weight of the second protective layer 123 to the unit area weight of the second active material layer 122 is (0.03-0.75): 1 , the unit area weight of the second active material layer 122 is 0.06g/1540.25mm 2 ⁇ 0.5g/1540.25mm 2 ; the unit area weight of the second protective layer 123 is 0.01g/1540.25mm 2 ⁇ 0.13g/1540.25mm 2 ; The ratio of the thickness of the second protective layer 123 to the thickness of the second active material layer 122 is (0.1 ⁇ 0.6):1; the thickness of the second active material layer 122 is 15 ⁇ m ⁇ 200 ⁇ m; the thickness of the second protective layer 123 is 1.5 ⁇ m.
  • the length of the winding single-sided area ending section 1211 accounts for 2% to 55% of the total length of the second current collector 121;
  • the second protective layer 123 covers part of the winding single-sided area ending section 1211 is the surface away from the center of the electrode assembly 1;
  • the surface area of the second protective layer 123 covering the ending section 1211 of the single-sided winding area accounts for 30% to 100%;
  • the second protective layer 123 is distributed in a stripe shape or a single block.
  • the arrangement of the electrode assembly 1 can significantly improve the curling problem of the pole pieces of the electrode assembly 1, reduce the alignment, and ensure the energy density of the electrochemical device.
  • Step 1 Configure the negative electrode material.
  • the negative electrode material includes 80wt% negative active material particle graphite, 15wt% conductive agent Super P, 3wt% thickener sodium carboxymethyl cellulose and 2wt% binder D
  • the second step configure the negative electrode protective layer 33 material, wherein the protective layer material includes 80wt% inorganic particle zirconia, 15wt% binder polyvinylidene fluoride and 5wt% thickener sodium carboxymethyl cellulose,
  • Step 3 Figure 16 is a schematic diagram of the planar and cross-sectional structure of the negative electrode sheet provided in Embodiment 1 of the present application. Please refer to Figure 16.
  • the negative active material layer 32 is obtained by coating on one side of the copper foil current collector 31, which is called side A 311.
  • the film length is 1140 mm
  • the film width is 98 mm
  • the gap is 15 mm.
  • Step 4 Please continue to refer to 16. After the coating of side A 311 is completed, collect it into a roll, and then use the same method to apply the negative active material in the first step on the symmetrical side B 312 of side A 311 to obtain the negative active material layer. 32.
  • the film length is 1012mm, the film width is 98mm, and the gap length is 143mm;
  • Step 5 After the coating of the active material on the B side 312 is completed, collect it into a roll, and then apply the negative electrode protective layer 33 material to the opposite side of the negative electrode single-sided area (the blank area of the B side 312) to obtain the negative electrode protective layer 33.
  • Step 6 Roll the negative electrode sheet, set the rolling parameters and then collect it into rolls by cold pressing.
  • Step 7 Divide the strips according to the dotted line shown in Figure 16, set the width of the strips, measure the burr level, and turn on the machine after the setting is completed to collect into rolls.
  • Step 1 Configure the cathode material.
  • the cathode material includes 80wt% cathode active material particles LiCoO 2 , 10wt% conductive agent Super P and 10wt% binder polyvinylidene fluoride.
  • the second step configure the positive electrode protective layer 43 material, wherein the protective layer material includes 80wt% inorganic particle zirconia, 15wt% binder polyvinylidene fluoride and 5wt% thickener sodium carboxymethylcellulose,
  • Step 3 Figure 17 is a schematic diagram of the planar and cross-sectional structure of the positive electrode sheet provided in Embodiment 1 of the present application. Please refer to Figure 17.
  • the negative active material layer 32 was obtained by covering one side of the aluminum foil current collector 41, which is called the C side 411.
  • the film length is 1130 mm
  • the film width is 96.8 mm
  • the gap is 35 mm.
  • Step 4 Please continue to refer to 17. After the C surface 411 is coated, collect it into a roll, and then use the same method to apply the positive active material in the first step on the symmetrical surface D surface 412 of the C surface 411 to obtain the positive active material layer. 42.
  • the film length is 1010mm, the film width is 96.8mm, and the gap length is 155mm;
  • Step 5 After the coating of the active material on the D side 412 is completed, collect it into a roll, and then apply the positive electrode protective layer 43 material to the opposite side of the positive electrode single-sided area (the blank area of the D side 412) to obtain the positive electrode protective layer 43.
  • Step 6 Roll the positive electrode sheet, set the rolling parameters, and then collect it into rolls by cold pressing.
  • Step 7 Divide the strips according to the dotted line shown in Figure 17, set the width of the strips, measure the burr level, and turn on the machine after the setting is completed to collect into rolls.
  • the isolation film is made of PP (polypropylene, polypropylene), and the thickness of the isolation film is 20 ⁇ m.
  • the negative electrode sheet, the first separator film, the positive electrode sheet and the second separator film are stacked and then rolled up to form an electrode assembly as shown in Figure 5.
  • the negative electrode sheet is close to the center of the electrode assembly, the positive electrode sheet is away from the center of the electrode assembly, and the positive electrode sheet is formed
  • One side of the electrode assembly is provided with positive electrode tabs and negative electrode tabs.
  • the method for detecting the curling ratio of each of the above-mentioned electrode assemblies is to take pictures with CCD and check the status of the pole pieces at the starting section of the winding single-sided area and the ending section of the winding single-sided area of the electrode assembly.
  • the method for detecting the alignment of the non-tab sides of each of the above electrode assemblies is (in Figure 5, the average of the alignment of the upper and lower parts of the inner and outer rings of the electrode assembly, that is, the first fold and the second fold)
  • the average alignment of the folds; the non-tab side refers to the lower side in Figure 15 (the side without tabs)): Take X-ray photos to detect the length of the negative electrode piece at the end of the electrode assembly beyond the positive electrode piece.
  • the method to detect the energy density (Wh/L) of an electrochemical device containing each of the above electrode assemblies is: after the battery is fully charged, then discharge to test the actual energy of the battery.
  • the energy/cell volume is the energy density.
  • the electrode assembly provided by the embodiment of the present application has a lower curl ratio and a smaller alignment; at the same time, its energy density can be basically guaranteed.
  • the negative electrode protective layer 33 is not provided in the single-sided area at the beginning of the winding single-sided area of the negative electrode sheet, and the positive electrode protective layer 43 is not provided at the single-sided area at the end of the winding single-sided area of the positive electrode sheet; for D2
  • the negative electrode protective layer 33 is not provided in the single-sided area at the beginning of the winding single-sided area of the negative electrode sheet, and the positive electrode protective layer 43 is provided in the single-sided area at the end of the winding single-sided area of the positive electrode sheet;
  • the single-sided area of the initial section of the winding single-sided area of the negative electrode sheet is provided with a negative electrode protective layer 33, and the single-sided area of the ending section of the wound single-sided area of the positive electrode sheet is not provided with a positive electrode protective layer 43; the final electrochemical Although the energy density of the components is high, the curling ratio of the negative electrode sheet or/and the positive electrode sheet is high, and the alignment of the inner ring or/and the
  • the ratio of the unit area coating amount of the negative electrode active material layer 32 to the unit area coating amount of the negative electrode protective layer 33 is too small (0.02), and the positive electrode
  • the ratio of the coating amount per unit area of the cathode active material layer 42 to the coating amount per unit area of the cathode protective layer 43 is too small (0.01), and the energy of the electrochemical device finally obtained
  • the density is relatively high, the curling problem and the alignment problem have basically not been improved.
  • the ratio of the coating amount per unit area of the negative active material layer 32 to the coating amount per unit area of the negative electrode protective layer 33 is too large (0.85)
  • the positive electrode At the end of the winding single-sided area of the sheet, the ratio of the coating amount per unit area of the cathode active material layer 42 to the coating amount per unit area of the cathode protective layer 43 is too large (0.87), and the resulting curled electrochemical device It will be more serious. This is because the protective layer is too much, the pole piece is rewinded, and the energy density of the electrochemical device is significantly reduced.
  • R7 and R8 are basically the same as R2.
  • the difference is that the thickness of the copper foil current collector 31 of R7 is 5 ⁇ m, and the thickness of the copper foil current collector 31 of R8 is 4 ⁇ m.
  • R9 is basically the same as R2.
  • the difference is that the protective layer of R9 It is striped.
  • the film length is 120mm and the TD gap is 10mm.
  • the negative electrode protective layer 33 is divided into three pieces, the film width of each piece is 28mm, and the TD gap of the two adjacent pieces is 2mm; for the positive electrode As for the protective layer 43, its film length is 112mm, and the TD gap is 10mm.
  • the positive electrode protective layer 43 is divided into three pieces, the film width of each piece is 27mm, and the TD gap of the two adjacent pieces is 2.9mm.
  • R10 to R14 are basically the same as R2.
  • the difference is that the particle size distributions of zirconium oxide, graphite and LiCoO 2 are different, as shown in Table 4.
  • the particle size distribution is detected by using a laser particle size analyzer for testing.
  • the particle size of the inorganic particles is basically smaller than the particle size of the active material particles, or when it is basically equivalent to the particle size of the active material particles, the electrode assembly can be The curl ratio is reduced and the alignment is reduced.

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Abstract

本申请实施例提供了一种电化学装置及用电设备，属于电池技术领域。其中，电化学装置的第一极片的第一集流体的卷绕单面区起始段朝向电极组件中心的表面设置第一保护层，背离电极组件中心的表面设置第一活性材料层；第二极片的第二集流体的卷绕单面区收尾段背离电极组件中心的表面设置第二保护层，朝向电极组件中心的表面设置第二活性材料层；第一保护层的单位面积重量与第一活性材料层的单位面积重量的比为（0.03～0.75）:1，第二保护层的单位面积重量与第二活性材料层的单位面积重量的比为（0.03～0.75）:1。其能够改善卷绕单面区起始段和收尾段的卷曲问题，使其对齐度减小，并能够在一定程度上保证电化学装置的能量密度。

Description

电化学装置及用电设备 技术领域
本申请涉及电池技术领域，具体而言，涉及一种电化学装置及用电设备。
背景技术
目前，锂离子二次电池主要是叠片电池或卷绕电池。对于卷绕电池来说，卷绕起始部的最内层极片和卷绕收尾部的最外层极片容易出现卷曲，导致电池的性能下降。
发明内容
本申请实施例提供一种电化学装置及用电设备，能够缓解卷绕形成的电极组件的极片卷曲问题。
第一方面，本申请实施例提供一种电化学装置，包括第一极片、隔膜和第二极片，第一极片、隔膜和第二极片层叠并卷绕形成电极组件。第一极片包括第一集流体，第一集流体包括卷绕单面区起始段，卷绕单面区起始段朝向电极组件中心的表面设置第一保护层，卷绕单面区起始段背离电极组件中心的表面设置第一活性材料层；第二极片包括第二集流体，第二集流体包括卷绕单面区收尾段，卷绕单面区收尾段背离电极组件中心的表面设置第二保护层，卷绕单面区收尾段朝向电极组件中心的表面设置第二活性材料层；第一保护层的单位面积重量与第一活性材料层的单位面积重量的比为(0.03～0.75):1，第二保护层的单位面积重量与第二活性材料层的单位面积重量的比为(0.03～0.75):1。
上述技术方案中，在第一集流体的卷绕单面区起始段的一表面设置有第一活性材料层，另一表面设置有第一保护层，且第一保护层的单位面积重量与第一活性材料层的单位面积重量的比为(0.03～0.75):1，在改善极片卷曲问题的同时，还可以在一定程度上保证电化学装置的能量密度。同样，在第二集流体的卷绕单面区收尾段的一表面设置有第二活性材料层，另一表面设置有第二保护层，且第二保护层的单位面积重量与第二活性材料层的单位面积重量的比为(0.03～0.75):1，在改善极片卷曲问题的同时，还可以在一定程度上保证电化学装置的能量密度。
在一些实施例中，电化学装置满足以下条件中的至少一者：
a)第一活性材料层的单位面积重量为0.06g/1540.25mm 2～0.5g/1540.25mm 2；
b)第二活性材料层的单位面积重量为0.06g/1540.25mm 2～0.5g/1540.25mm 2；
c)第一保护层的单位面积重量为0.01g/1540.25mm 2～0.13g/1540.25mm 2；
d)第二保护层的单位面积重量为0.01g/1540.25mm 2～0.13g/1540.25mm 2。
上述技术方案中，限定活性材料层的单位面积重量以及保护层的单位面积重量的具体范围，可以使极片卷曲的问题得到更好地改善，电极组件的对齐度更小，从而提升电化学装置的能量密度。
在一些实施例中，电化学装置满足以下条件中的至少一者：
e)第一保护层的厚度与第一活性材料层的厚度的比为(0.1～0.6):1；
f)第二保护层的厚度与第二活性材料层的厚度的比为(0.1～0.6):1。
上述技术方案中，保护层所占用的体积小于活性材料层所占用的体积，且保护层的厚度与活性材料层的厚度的比值以及保护层的单位面积重量与活性材料层的单位面积重量的比值差距不大，可以使保护层的密实度与活性材料层的密实度较为一致，可以使电极组件的一致性较好；且可以避免保护层占用过多的空间的同时，使极片卷曲的问题得到很好的改善，从而使电化学装置的体积能量密度较高。
在一些实施例中，电化学装置满足以下条件中的至少一者：
g)第一活性材料层的厚度为15μm～200μm；
h)第二活性材料层的厚度为15μm～200μm；
i)第一保护层的厚度为1.5μm～100μm；
j)第二保护层的厚度为1.5μm～100μm。
上述技术方案中，限定活性材料层的厚度以及保护层的厚度的具体范围，可以使保护层的厚度较低的情况下，就能够使极片卷曲的问题得到很好的改善，使电化学装置的体积能量密度较高。
在一些实施例中，电化学装置满足以下条件中的至少一者：
k)沿电极组件的卷绕方向，卷绕单面区起始段长度占第一集流体总长度的1.5％～50％；
l)沿电极组件的卷绕方向，卷绕单面区收尾段长度占第二集流体的总长度的2％～55％。
上述技术方案中，卷绕单面区起始段的长度和卷绕单面区收尾段的长度占比在上述范围内，可以对电极组件的极片卷曲问题进行改善，并且使整个电极组件的对齐度减小；且电化学装置的能量密度更高。
在一些实施例中，电化学装置满足以下条件中的至少一者：
m)第一保护层覆盖部分卷绕单面区起始段朝向电极组件中心的表面；
n)第二保护层覆盖部分卷绕单面区收尾段背离电极组件中心的表面；
o)第一保护层覆盖在卷绕单面区起始段的表面面积占比为30％～100％；
p)第二保护层覆盖在卷绕单面区收尾段的表面面积占比为30％～100％。
上述技术方案中，保护层覆盖集流体的单面区的部分表面，就可以对极片卷曲进行很好的改善，可以降低保护层的使用量，提高电化学装置的能量密度；且保护层的覆盖集流体的表面面积的最低占比可以到30％，可以在电极组件的对齐度较小的同时，电化学装置的能量密度也更高。
在一些实施例中，电化学装置满足以下条件中的至少一者：
q)第一集流体的靠近卷绕单面区起始段的位置设置有第一活性材料层，位于第一集流体的同一侧的第一活性材料层与第一保护层之间具有间隔；
r)第二集流体的靠近卷绕单面区收尾段的位置设置有第二活性材料层，位于第二集流体的同一侧的第二活性材料层与第二保护层之间具有间隔。
上述技术方案中，集流体的同一侧，活性材料层与保护层之间具有一定的距离，可以避免活性材料层和保护层之间出现重涂，使活性材料层的使用率更高。
在一些实施例中，电化学装置满足以下条件中的至少一者：
s)第一保护层呈条纹状或单块状分布；
t)第二保护层呈条纹状或单块状分布。
上述技术方案中，保护层呈条纹状分布，可以使用较少的保护层材料，就能够很好地解决极片卷曲的问题，且可以使电化学装置的能量密度较高；保护层呈单块状分布，可以使保护层更加容易形成，容易控制保护层的涂覆区域。
在一些实施例中，第一保护层和第二保护层均包括无机颗粒和粘结剂；电化学装置满足以下条件中的至少一者：
u)无机颗粒的Dv10≥0.001μm，Dv99≤100μm，优选地，无机颗粒的粒径分布为Dv10≥0.001μm，Dv99≤40μm；
v)第一活性材料层的活性材料颗粒的Dv10为1μm～20μm，Dv99≤80μm；
w)第二活性材料层的活性材料颗粒的Dv10为1μm～20μm，Dv99≤80μm。
上述技术方案中，集流体的一表面粘接有无机颗粒，另一表面粘接有活性材料颗粒，可以使通过无机颗粒的应力释放，很好地改善极片卷曲的问题。同时，无机颗粒的粒径分布基本与活性材料的粒径分布一致，对于集流体的两个表面来说，无机颗粒的应力与活性材料颗粒的应力基本一致，可以极片卷曲的改善效果更好。
此外，无机颗粒的粒径相对较小，无机颗粒的数量相对较多，无机颗粒的应力释放更大，可以使保护层的厚度较小、单位面积重量较小就能够很好地改善极片卷曲的问题，可以使电极组件的对齐度更小。
在一些实施例中，第一保护层和第二保护层还包括增稠剂，基于第一保护层或第二保护层的总质量，无机颗粒的质量百分含量为70％～99％；粘接剂的质量百分含量为0.3％～30％；增稠剂的质量百分含量为0.3％～20％。
上述技术方案中，增稠剂的添加，可以使保护层的内应力较大，在将保护层设置在集流体的一表面以后，无机颗粒的释放应力相对较大，可以在保护层的厚度较小、单位面积重量较小的情况下，解决极片卷曲的问题，使保护层的使用量更少。
在一些实施例中，第一极片为负极，第一集流体的厚度为4μm～10μm。
上述技术方案中，可以大大降低负极集流体的最小厚度值，从而增加电化学装置的能量密度。
第二方面，本申请实施例还提供一种用电设备，包括上述第一方面任意一个实施例提供的电化学装置。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面将对实施例中所需要使用的附图作简单地介绍，应当理解，以下附图仅示出了本申请的某些实施例，因此不应被看作是对范围的限定，对于本领域普通技术人员来讲，还可以根据这些附图获得其他相关的附图。
图1为现有技术的卷绕电极组件的结构示意图；
图2为单面区极片的卷曲机理图；
图3为本申请一些实施例提供的车辆的结构示意图；
图4为本申请实施例提供的电化学装置的结构示意图；
图5为本申请一些实施例提供的卷绕电极组件的结构示意图；
图6为图5所示的第一极片的第一种平面和截面结构示意图；
图7为图5所示的第二极片的第一种平面和截面结构示意图；
图8为图5所示的第一极片的第二种平面和截面结构示意图；
图9为图5所示的第二极片的第二种平面和截面结构示意图；
图10为图5所示的第一极片的第三种平面和截面结构示意图；
图11为图5所示的第二极片的第三种平面和截面结构示意图；
图12为图5所示的第一极片的第四种平面和截面结构示意图；
图13为图5所示的第二极片的第四种平面和截面结构示意图；
图14为图5所示的第一极片的第五种平面和截面结构示意图；
图15为图5所示的第一极片的第六种平面和截面结构示意图；
图16为本申请实施例1提供的负极片的种平面和截面结构示意图；
图17为本申请实施例1提供的正极片的种平面和截面结构示意图。
图标：01-卷绕起始部；02-卷绕收尾部；03-主体部；04-活性材料颗粒；05-集流体；
1000-车辆；100-电池；200-控制器；300-马达；10-电化学装置；2-收容件；21-壳体；22-端盖；23-第一电极端子；24-第二电极端子；
1-电极组件；11-第一极片；111-第一集流体；1111-卷绕单面区起始段；112-第一活性材料层；113-第一保护层；12-第二极片；121-第二集流体；1211-卷绕单面区收尾段；122-第二活性材料层；123-第二保护层；13-隔膜；131-第一隔膜；132-第二隔膜；171-第一极耳；172-第二极耳；
31-铜箔集流体；311-A面；312-B面；32-负极活性材料层；33-负极保护层；
41-铝箔集流体；411-C面；412-D面；42-正极活性材料层；43-正极保护层。
具体实施方式
为使本申请实施例的目的、技术方案和优点更加清楚，下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚地描述，显然，所描述的实施例是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员所获得的所有其他实施例，都属于本申请保护的范围。
除非另有定义，本申请所使用的所有的技术和科学术语与属于本申请的技术领域的技术人员通常理解的含义相同；本申请中在申请的说明书中所使用的术语只是为了描述具体的实施例的目的，不是旨在于限制本申请；本申请的说明书和权利要求书及上述附图说明中的术语“包括”和“具有”以及它们的任何变形，意图在于覆盖不排他的包含。本申请的说明书和权利要求书或上述附图中的术语“第一”、“第二”等是用于区别不同对象，而不是用于描述特定顺序或主次关系。
在本申请中提及“实施例”意味着，结合实施例描述的特定特征、结构或特性可以包含在本申请的至少一个实施例中。在说明书中的各个位置出现该短语并不一定均是指相同的实施例，也不是与其它实施例互斥的独立的或备选的实施例。
在本申请的描述中，需要说明的是，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”、“附接”应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体地连接；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本申请中的具体含义。
本申请中术语“和/或”，仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，本申请中字符“/”，一般表示前后关联对象是一种“或”的关系。
在本申请的实施例中，相同的附图标记表示相同的部件，并且为了简洁，在不同实施例中，省略对相同部件的详细说明。应理解，附图示出的本申请实施例中的各种部件的厚度、长宽等尺寸，以及集成装置的整体厚度、长宽等尺寸仅为示例性说明，而不应对本申请构成任何限定。
随着储能技术的不断发展，电化学装置应用越来越广泛，同时对电化学装置的能量密度也提出了更高的要求。
电化学装置的核心部件为电极组件，对于卷绕电极组件来说，其通常是将负极片、第一隔膜、正极片和第二隔膜重叠起来，然后通过卷绕以后形成卷绕电极组件。图1为现有技术的卷绕电极组件的结构示意图，请参阅图1，图1中箭头所指方向为卷绕方向，卷绕电极组件分为卷绕起始部01、卷绕收尾部02和位于之间的主体部03，电极组件的最内层为负极片的卷绕起始部01，电极组件的最外层为正极片的卷绕收尾部02，由于负极片的卷绕起始部01的朝向电极组件中心的负极活性材料层没有与之对应的正极活性材料层，正极片的卷绕收尾部02的背离电极组件中心的正极活性材料层没有与之对应的负极活性材料层，所以，为了降低电极组件的厚度并避免能量密度损失，通常将负极片的卷绕起始部01和正极片的卷绕收尾部02设置成单面区，也就是说，负极片的卷绕起始部01的朝向电极组件的中心的区域没有设置负极活性材料层(负极片的卷绕起始部01为单面区)，正极片的卷绕收尾部02的背离电极组件的中心的区域也没有设置正极活性材料层(正极片的卷绕收尾部02为单面区)。
请继续参阅图1，负极片包括负极集流体(例如铜箔)和负极活性材料层(例如石墨类、硅类)，负极片的主体区域的负极集流体的两个表面均设置有负极活性材料层(双面区负极片)。正极片包括正极集流体(例如铝箔)和正极活性材料层(例如锂钴类、磷酸铁锂类、镍钴锰三元类等)，正极片的主体区域的正极集流体的两个表面均设置有正极活性材料层(双面区正极片)。下面不对正极片和负极片进行区分，直接以极片为例进行说明，其对极片进行说明时，该说明既适合正极片，也适合负极片。
在制备极片的时候，通常是将活性物质涂覆在集流体上，然后通过辊压的方式提高活性材料层的密实度以及活性材料层与集流体的结合强度，以提高电极组件的能量密度和动力学性能。
图2为单面区极片的卷曲机理图，请参阅图2，发明人发现，对于单面区极片，辊压前，活性材料层的孔隙率较大，活性材料颗粒04间没有相互作用力(图2左图)。辊压时活性物质颗粒会发生形变，颗粒与颗粒间会产生相互作用力，导致颗粒内部存储应力(图2中图)。辊压后，存储应力后颗粒处于不稳定状态寻求释放应力，由于颗粒底层与集流体05粘接导致底层颗粒无法移动，上层的颗粒不受集流体05束缚，会向平面方向(平行于集流体05的方向)释放应力产生形变，导致上层涂层的平面尺寸比集流体05的平面尺寸大(R2＞R1)，因此极片向集流体05方向卷曲，即单面区极片卷曲(图2右图)。
发明人继续研究发现，对于双面区极片，由于集流体05的两个表面都有活性材料颗粒04，集流体05两个表面的活性材料颗粒04之间的应力会相互平衡，双面区极片不发生卷曲。
请继续参阅图1，对于单面区负极片来说，在负极片的卷绕起始部01处，切刀将负极片裁断以后，单面区负极片的卷曲力会瞬间释放，导致单面区无法平整铺展，使整条极片报废。即使对卷绕设备(调整极片张力，增加极片抚平措施等)进行了优化，也会由于单面区负极片的卷曲，而导致电极组件的优率损失。
对于卷绕电极组件来说，在极片的宽度方向上，负极片超过正极片的尺寸称为“对齐度”，在电极组件的卷绕起始部01处，由于卷绕时负极片单面区无法平整铺展，会导致负极片和正极片的对齐度恶化，收集量产数据发现，负极片和正极片的对齐度相比电极组件的主体部03恶化0.3mm。
对于单面区正极片来说，在正极片的卷绕首尾段处，切刀将正极片裁断后，单面区正极片的卷曲力会瞬间释放，导致单面区无法平整铺展，使整条极片报废。即使对卷绕设备(调整极片张力，增加极片抚平措施等)进行了优化，也会由于单面区正极片的卷曲，而导致电极组件的优率损失。
此外，在电极组件的卷绕收尾部02处，由于卷绕时正极片单面区无法平整铺展，会导致负极片和正极片的对齐度恶化，收集量产数据发现，负极片和正极片的对齐度相比电极组件的主体部03恶化0.2mm。
鉴于此，为有效避免电极组件的出现卷曲的问题，发明人经过深入研究，设计了一种电极组件，该电极组件通过第一极片、隔膜和第二极片层叠并卷绕形成。第一极片包括第一集流体，第一集流体包括卷绕单面区起始段，卷绕单面区起始段朝向电极组件中心的表面设置第一保护层，卷绕单面区起始段背离电极组件中心的表面设置第一活性材料层。第二极片包括第二集流体，第二集流体包括卷绕单面区收尾段，卷绕单面区收尾段背离电极组件中心的表面设置第二保护层，卷绕单面区收尾段朝向电极组件中心 的表面设置第二活性材料层。第一保护层的单位面积重量与第一活性材料层的单位面积重量的比为(0.03～0.75):1，第二保护层的单位面积重量与第二活性材料层的单位面积重量的比为(0.03～0.75):1。
在这样的电极组件中，在第一集流体的卷绕单面区起始段的一表面设置有第一活性材料层，另一表面设置有第一保护层，且第一保护层的单位面积重量与第一活性材料层的单位面积重量的比为(0.03～0.75):1，在改善极片卷曲问题的同时，还可以在一定程度上保证电化学装置的能量密度。同样，在第二集流体的卷绕单面区收尾段的一表面设置有第二活性材料层，另一表面设置有第二保护层，且第二保护层的单位面积重量与第二活性材料层的单位面积重量的比为(0.03～0.75):1，在改善极片卷曲问题的同时，还可以在一定程度上保证电化学装置的能量密度。
本申请实施例提供的电极组件适用于电化学装置以及使用该电化学装置的用电设备。
本申请实施例提供一种用电设备，用电设备包括电化学装置，电化学装置用于提供电能。
用电设备可以包括但不限于：车辆、手机、笔记本电脑、耳机、录像机、计算器、轮船、航天器、电动玩具等等。车辆可以是燃油汽车、燃气汽车、新能源汽车、摩托车、助力自行车等。航天器可以是飞机、火箭、航天飞机、宇宙飞船等；电动玩具可以是游戏机、电动汽车玩具、电动轮船玩具和电动飞机玩具等；电动工具可以是金属切削电动工具、研磨电动工具、装配电动工具、铁道用电动工具等。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。
图3为本申请一些实施例提供的车辆1000的结构示意图，请参照图3，车辆1000的内部设置有电池100，电池100可以用于车辆1000的供电，电池100可以设置在车辆1000的底部或头部或尾部。
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。电池100可以作为车辆1000的操作电源。例如，用于车辆1000的启动、导航和行驶时的工作用电需求。电池100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。
在本申请实施例中，电池100可以包括一个或多个电化学装置10。在电池100中，若电化学装置10为多个，多个电化学装置10之间可串联或并联或混联，混联是指多个电化学装置10中既有串联又有并联。
电池100还可以包括汇流部件，多个电化学装置10之间可通过汇流部件实现电连接，以实现多个电化学装置10的串联或并联或混联。汇流部件可以是金属导体，比如，铜、铁、铝、不锈钢、铝合金等。
图4为本申请实施例提供的电化学装置10的结构示意图，请参照图4，电化学装置10包括电极组件，电化学装置10通过电极组件和电解液发生化学反应，以输出电能。
电化学装置10可以是锂离子电池、锂硫电池、钠锂离子电池、钠离子电池或镁离子电池等，本申请实施例对此并不限定。电化学装置10可呈圆柱体、扁平体、长方体或其它形状等，本申请实施例对此也不限定。电化学装置10一般按封装的方式分成三种：柱形电池、方形电池和软包电池，本申请实施例对此也不限定。
在一些实施例中，请继续参照图4，电化学装置10还可以包括收容件2，收容件2用于收容电极组件，收容件2可以是收容外壳，例如，铝壳、钢壳等。收容件2也可以是收容袋，例如，由铝塑膜制成的收容袋。
在一些实施例中，收容件2可以包括壳体21和端盖22。壳体21是用于收容电极组件的部件，壳体21可以是一端形成开口的空心结构。壳体21可以是多种形状，比如，圆柱体、长方体等。壳体21的材质可以是多种，比如，铜、铁、铝、钢、铝合金等。端盖22是盖合于壳体21的开口以将电化学装置10的内部环境与外部环境隔绝的部件。端盖22盖合于壳体21的开口，端盖22与壳体21共同限定出用于容纳电极组件、电解液以及其他部件的密封空间。端盖22的形状可以与壳体21的形状相适配，比如，壳体21为长方体结构，端盖22为与壳体21相适配的矩形板状结构，再如，壳体21为圆柱体结构，端盖22为与壳体21相适配的圆形板状结构。端盖22的材质也可以是多种，比如，铜、铁、铝、钢、铝合金等。
此外，端盖22上可以设置第一电极端子23和第二电极端子24，第一电极端子23和第二电极端子24用于与电极组件电连接，以输出电化学装置10的电能。
图5为本申请一些实施例提供的卷绕电极组件的结构示意图，图5箭头所指的方向为卷绕方向；图6为图5所示的第一极片11的第一种平面和截面结构示意图，其中图6中的上方的图片为截面示意图，图6中下方的图片为平面示意图；图7为图5所示的第二极片12的第一种平面和截面结构示意 图，其中图7中的上方的图片为截面示意图，图7中下方的图片为平面示意图。请参照图5～图7，本申请实施例提供一种电极组件1，电极组件1包括第一极片11、第二极片12和隔膜13，第一极片11、第二极片12和隔膜13层叠并卷绕形成电极组件1。其中，层叠的方式可以是：第一极片11、第一隔膜131、第二极片12和第二隔膜132层叠以后进行卷绕形成电极组件1。
第一极片11包括第一集流体111，第一集流体111包括卷绕单面区起始段1111，卷绕单面区起始段1111朝向电极组件1中心的表面设置第一保护层113，卷绕单面区起始段1111背离电极组件1中心的表面设置第一活性材料层112。第二极片12包括第二集流体121，第二集流体121包括卷绕单面区收尾段1211，卷绕单面区收尾段1211背离电极组件1中心的表面设置第二保护层123，卷绕单面区收尾段1211朝向电极组件1中心的表面设置第二活性材料层122。第一保护层113的单位面积重量与第一活性材料层112的单位面积重量的比为(0.03～0.75):1，第二保护层123的单位面积重量与第二活性材料层122的单位面积重量的比为(0.03～0.75):1。
本实施例中，第一极片11是正极片时，第二极片12是负极片；或第一极片11是负极片时，第二极片12是正极片。
若第一极片11为正极片，对应第一集流体111为正极集流体，例如：正极集流体可以是铝箔、泡沫铝、铝复合集流体(中间为高分子支撑层，该支撑层的两个表面均有铝金属层的集流体)、镍箔、泡沫镍等，在正极集流体的表面上设置有正极活性材料层，例如：正极活性材料层中的正极活性材料可以是镍钴锰酸锂、镍钴铝酸锂、钴酸锂、磷酸铁锂、三元锂、锰酸锂等。
若第一极片11可以是负极片，对应第一集流体111为负极集流体，例如：负极集流体可以是铜箔、泡沫铜、铜复合集流体(中间为高分子支撑层，该支撑层的两个表面均有铜金属层的集流体)、镍箔、泡沫镍等，在负极集流体的表面上设置有负极活性材料层，例如：负极活性材料层中的负极活性材料可以是石墨类、硅类等。
第一隔膜131和第二隔膜132是分隔第一极片11和第二极片12的部件。隔膜可以是多种材质，比如，PP(polypropylene，聚丙烯)、PE(polyethylene，聚乙烯)等。
请继续参阅图5，第一集流体111的卷绕单面区起始段1111是指图5所示的电极组件1的靠近卷绕中心的部位的虚线框中的部分。第一集流体111的卷绕单面区起始段1111是指：在第一集流体111的卷绕起始端，其中一个表面设置有第一活性材料层112，相对的另一个表面未设置第一活性材料层，形成了第一集流体111的卷绕单面区起始段1111，特别的，在第一集流体111的卷绕起始端还可设置两个表面均未设置第一活性材料层的第一集流体段。在卷绕形成电极组件1时，第一集流体111的卷绕开始的一段，有第一集流体111卷绕单面区起始段1111；在形成了电极组件1以后，第一集流体111的卷绕单面区起始段1111位于电极组件1的靠近电极组件1的卷绕中心的部位，第一集流体111的卷绕单面区起始段1111为一个表面设置有第一活性材料层112，间隔隔膜13以后，隔膜13的另一侧没有与第一活性材料层112对应的第二活性材料层的区域。
由于第一集流体111的卷绕单面区起始段1111的一表面设置第一活性材料层112，另一表面设置第一保护层113，在第一集流体111的卷绕单面区起始段1111处，采用切刀将第一集流体111裁断以后，卷绕单面区起始段1111一表面的活性材料层中的活性材料颗粒的应力会瞬间释放，但由于卷绕单面区起始段1111的另一表面具有保护层，则会使第一集流体111两个表面的活性材料层和保护层之间的应力趋于平衡，可以在一定程度上改善第一极片11的卷曲的问题，可以使其对齐度减小。
此外，第一集流体111的卷绕单面区起始段1111的一表面设置第一活性材料层112，另一表面设置第一保护层113(对应第一极片11的第一单面区)；且第一保护层113的单位面积重量与第一活性材料层112的单位面积重量的比为(0.03～0.75):1。既可以改善第一极片11的卷曲的问题，相较于在第一集流体111的卷绕单面区起始段1111的两个表面都设置第一活性材料层112，第一保护层113的单位面积小于第一活性材料层112的单位面积重量，又可以在一定程度上保证电化学装置的能量密度。
可选地，定义第一保护层113的单位面积重量与第一活性材料层112的单位面积重量的比为X1，X1的值可以为0.03:1、0.05:1、0.1:1、0.15:1、0.2:1、0.25:1、0.3:1、0.35:1、0.4:1、0.45:1、0.5:1、0.55:1、0.6:1、0.65:1、0.7:1或0.75:1，其也可以是上述范围的任意值。
本实施例中，第一集流体111的主体区域可以两个表面均设置第一活性材料层112，形成了第一双面区。第一集流体111的两个表面上设置的第一活性材料层112的单面面积重量可以相同，也可以不同。第一保护层113的单位面积重量与第一活性材料层112的单位面积重量的比为(0.03～0.75):1，可以是第一集流体111的卷绕单面区起始段1111的一表面设置的第一保护层113与另一表面设置的第一活性材 料层112之间的单位面积重量比；也可以是第一集流体111的同一侧的第一保护层113与第一活性材料层112之间的单位面积重量比。
请继续参阅图5，第二集流体121的卷绕单面区收尾段1211是指图5所示的电极组件1的远离卷绕中心的部位的虚线框中的部分。第二集流体121的卷绕单面区收尾段1211是指：在第二集流体121的卷绕收尾端，其中一个表面设置有第二活性材料层122，相对的另一个表面未设置第二活性材料层，形成了第二集流体121的卷绕单面区收尾段1211，特别的，在第二集流体121的卷绕收尾端还可设置两个表面均未设置第二活性材料层的第二集流体段。在卷绕形成电极组件1时，第二集流体121的卷绕结束的一段，有第二集流体121的卷绕单面区收尾段1211；在形成了电极组件1以后，第二集流体121的卷绕单面区收尾段1211位于电极组件1的远离电极组件1的卷绕中心的部位，第二集流体121的卷绕单面区收尾段1211为一个表面设置有第二活性材料层122，间隔隔膜13以后，隔膜的另一侧没有与第二活性材料层122对应的第一活性材料层的区域。
由于第二集流体121的卷绕单面区收尾段1211的一表面设置第二活性材料层122，另一表面设置第二保护层123，在第二集流体121的卷绕单面区收尾段1211处，采用切刀将第二集流体121裁断以后，卷绕单面区收尾段1211一表面的活性材料层中的活性材料颗粒的应力会瞬间释放，但由于卷绕单面区收尾段1211的另一表面具有保护层，则会使第二集流体121两个表面的活性材料层和保护层之间的应力趋于平衡，可以在一定程度上改善第二极片12的卷曲的问题，可以使其对齐度减小。
此外，第二集流体121的卷绕单面区收尾段1211的一表面设置第二活性材料层122，另一表面设置第二保护层123(对应第一极片12的第二单面区)；且第二保护层123的单位面积重量与第二活性材料层122的单位面积重量的比为(0.03～0.75):1。既可以改善第二极片12的卷曲的问题，相较于在第二集流体121的卷绕单面区收尾段1211的两个表面都设置第二活性材料层122，第二保护层123的单位面积重量小于第二活性材料层122的单位面积重量，又可以在一定程度上保证电化学装置的能量密度。
可选地，定义第二保护层123的单位面积重量与第二活性材料层122的单位面积重量的比为X2，X2的值可以为0.03:1、0.05:1、0.1:1、0.15:1、0.2:1、0.25:1、0.3:1、0.35:1、0.4:1、0.45:1、0.5:1、0.55:1、0.6:1、0.65:1、0.7:1或0.75:1，其也可以是上述范围的任意值。
本实施例中，第二集流体121的主体区域的两个表面均为第二活性材料层122，形成了第二双面区。第二集流体121的两个表面上设置的第二活性材料层122的单面面积重量可以相同，也可以不同。第二保护层123的单位面积重量与第二活性材料层122的单位面积重量的比为(0.03～0.75):1，可以是第二集流体121的卷绕单面区收尾段1211的一表面设置的第二保护层123与另一表面设置的第二活性材料层122之间的单位面积重量比；也可以是第二集流体121的同一侧的第二保护层123与第二活性材料层122之间的单位面积重量比。
本实施例中，X1与X2的值可以相同，也可以不同。可选地，第一保护层113的单位面积重量与第一活性材料层112的单位面积重量的比为(0.1～0.4):1，第二保护层123的单位面积重量与第二活性材料层122的单位面积重量的比为(0.1～0.4):1。可以使单面区的极片卷曲改善效果更好明显，对齐度进一步减小。
在一些实施例中，第一活性材料层112的单位面积重量为0.06g/1540.25mm 2～0.5g/1540.25mm 2。第一活性材料层112的单位面积重量是指：取表面积为1540.25mm 2的第一极片11，第一极片11的第一集流体111的一侧的第一活性材料层112的重量为0.06g～0.5g。
第一极片11具有该单位面积重量的第一活性材料层112，形成电极组件1以后，其电化学装置的电学性能较佳。
第二活性材料层122的单位面积重量为0.06g/1540.25mm 2～0.5g/1540.25mm 2。第二活性材料层122的单位面积重量是指：取表面积为1540.25mm 2的第二极片12，第二极片12的第二集流体121的一侧的第二活性材料层122的重量为0.06g～0.5g。
第二极片12具有该单位面积重量的第二活性材料层122，形成电极组件1以后，其电化学装置的电学性能较佳。
第一保护层113的单位面积重量为0.01g/1540.25mm 2～0.13g/1540.25mm 2。第一保护层113的单位面积重量是指：取表面积为1540.25mm 2的第一极片11，第一极片11的第一集流体111的卷绕单面区起始段1111上的第一保护层113的重量为0.01g～0.13g。
第一极片11具有该单位面积重量的第一保护层113，可以更好地改善第一极片11的卷曲问题。
第二保护层123的单位面积重量为0.01g/1540.25mm 2～0.13g/1540.25mm 2。第二保护层123的单位面积重量是指：取表面积为1540.25mm 2的第二极片12，第二极片12的第二集流体121的卷绕单面区收尾段1211上的第二保护层123的重量为0.01g～0.13g。
第二极片12具有该单位面积重量的第二保护层123，可以更好地改善第二极片12的卷曲问题。
分别限定活性材料层的单位面积重量和保护层的单位面积重量，与保护层的单位面积重量和活性材料层的单位面积重量的比相配合，可以使极片卷曲的问题得到更好地改善，电极组件1的对齐度更小，从而提升电化学装置的能量密度。同时，限定了活性材料层的单位面积重量，可以使电化学装置的电学性能较佳。
定义第一活性材料层112的单位面积重量为M1，M1的值可以是0.06g/1540.25mm 2、0.1g/1540.25mm 2、0.15g/1540.25mm 2、0.2g/1540.25mm 2、0.25g/1540.25mm 2、0.3g/1540.25mm 2、0.35g/1540.25mm 2、0.4g/1540.25mm 2、0.45g/1540.25mm 2或0.5g/1540.25mm 2，其也可以是上述范围的任意值；定义第二活性材料层122的单位面积重量为M2，M2的值可以是0.06g/1540.25mm 2、0.1g/1540.25mm 2、0.15g/1540.25mm 2、0.2g/1540.25mm 2、0.25g/1540.25mm 2、0.3g/1540.25mm 2、0.35g/1540.25mm 2、0.4g/1540.25mm 2、0.45g/1540.25mm 2或0.5g/1540.25mm 2，其也可以是上述范围的任意值。M1与M2的值可以相同，也可以不同。
定义第一保护层113的单位面积重量为M3，M3的值可以是0.01g/1540.25mm 2、0.03g/1540.25mm 2、0.05g/1540.25mm 2、0.07g/1540.25mm 2、0.09g/1540.25mm 2、0.1g/1540.25mm 2或0.13g/1540.25mm 2，其也可以是上述范围的任意值；定义第二保护层123的单位面积重量为M4，M4的值可以是0.01g/1540.25mm 2、0.03g/1540.25mm 2、0.05g/1540.25mm 2、0.07g/1540.25mm 2、0.09g/1540.25mm 2、0.1g/1540.25mm 2或0.13g/1540.25mm 2，其也可以是上述范围的任意值。M3与M4的值可以相同，也可以不同。
可选地，第一活性材料层112的单位面积重量和第二活性材料层122的单位面积重量为0.1g/1540.25mm 2～0.3g/1540.25mm 2。第一保护层113的单位面积重量和所述第二保护层123的单位面积重量为0.02～0.08g/1540.25mm 2。可以使单面区的极片卷曲改善效果更好明显，对齐度进一步减小。
在一些实施例中，如果第一极片11为负极片，则第一保护层113单位面积重量与第一活性材料层112的单位面积重量的比为(0.3～0.75):1；第一活性材料层112的单位面积重量为0.06g/1540.25mm 2～0.3g/1540.25mm 2；第一保护层113的单位面积重量为0.02g/1540.25mm 2～0.13g/1540.25mm 2。如果第一极片11为正极片，则第一保护层113单位面积重量与第一活性材料层112的单位面积重量的比为(0.03～0.6):1；第一活性材料层112的单位面积重量为0.1g/1540.25mm 2～0.5g/1540.25mm 2；第一保护层113的单位面积重量为0.01g/1540.25mm 2～0.08g/1540.25mm 2。
负极片对应负极保护层和负极活性材料层，正极片对应正极保护层和正极活性材料层；负极活性材料层的单位面积重量小于正极活性材料层的单位面积重量，可以使电化学装置的电学性能更佳。
负极保护层的单位面积重量大于正极保护层的单位面积重量，负极活性材料层的单位面积重量与负极保护层的单位面积重量之差的值小于正极活性材料层的单位面积重量与正极保护层的单位面积重量之差的值。由于发明人研究发现，负极片的单面区的卷曲问题更加严重，所以，负极活性材料层的单位面积重量与负极保护层的单位面积重量之差的值相对较小(负极保护层的单位面积重量相对较高)，能够对负极片的单面区的卷曲问题进行较好的改善。而对于正极片来说，正极片的单面区的卷曲问题稍弱，所以，正极活性材料层的单位面积重量与正极保护层的单位面积重量之差的值相对较大(正极保护层的单位面积重量相对较低)，就能够对正极片的单面区的卷曲问题进行很好的改善。上述设置方式，可以使正极片和负极片的单面区卷曲问题都能够得到很好地改善的同时，还可以使电化学装置的能量密度较高，电学性能较好。
在一些实施例中，第一保护层113的厚度与第一活性材料层112的厚度的比为(0.1～0.6):1。请继续参阅图6的截面示意图，第一保护层113的厚度为D11，第一活性材料层112的厚度为D12，第一保护层113的厚度与第一活性材料层112的厚度的比Y1＝D11/D12＝(0.1～0.6):1。
第一保护层113的厚度相对较薄，其在解决极片的单面区卷曲问题的同时，还可以使电极组件1的厚度较薄，使电化学装置的体积能量密度较高。
第二保护层123的厚度与第二活性材料层122的厚度的比为(0.1～0.6):1。请继续参阅图7的截面示意图，第二活性层的厚度为D21，第二活性材料层122的厚度为D22，第二保护层123的厚度与第二活性材料层122的厚度的比Y2＝D21/D22＝(0.1～0.6):1。
第二保护层123的厚度相对较薄，其在解决极片的单面区卷曲问题的同时，还可以使电极组件1的厚度较薄，使电化学装置的体积能量密度较高。
作为示例性地，Y1的值可以是0.1:1、0.15:1、0.2:1、0.25:1、0.3:1、0.35:1、0.4:1、0.45:1、0.5:1、0.55:1或0.6:1，其也可以是上述范围的任意值。Y2的值可以是0.1:1、0.15:1、0.2:1、0.25:1、0.3:1、0.35:1、0.4:1、0.45:1、0.5:1、0.55:1或0.6:1，其也可以是上述范围的任意值。Y1与Y2的值可以相同，也可以不同。
在一些实施例中，第一活性材料层112的厚度D12为15μm～200μm。第一极片11具有该厚度的第一活性材料层112，形成电极组件1以后，其电化学装置的电学性能较佳。
第二活性材料层122的厚度D22为15μm～200μm。第二极片12具有该厚度的第二活性材料层122，形成电极组件1以后，其电化学装置的电学性能较佳。
第一保护层113的厚度D11为1.5μm～100μm。第一极片11具有该厚度的第一保护层113，可以更好地改善第一极片11的卷曲问题。
第二保护层123的厚度D21为1.5μm～100μm。第二极片12具有该厚度的第二保护层123，可以更好地改善第二极片12的卷曲问题。
分别限定活性材料层的厚度和保护层的厚度，与保护层的厚度和活性材料层的厚度的比相配合，可以使极片卷曲的问题得到更好地改善，电极组件1的对齐度更小，且电化学装置的能量密度更高。
作为示例性地，第一活性材料层112的厚度D12可以是15μm、30μm、50μm、80μm、100μm、120μm、140μm、160μm、180μm或200μm，其也可以是上述范围的任意值；第二活性材料层122的厚度D22可以是15μm、30μm、50μm、80μm、100μm、120μm、140μm、160μm、180μm或200μm，其也可以是上述范围的任意值；D12的值与D22的值可以相同，也可以不同。
作为示例性地，第一保护层113的厚度D11可以是1.5μm、3μm、5μm、8μm、10μm、20μm、30μm、40μm、50μm、60μm、70μm、80μm、90μm或100μm，其也可以是上述范围的任意值；第二保护层123的厚度D21可以是1.5μm、3μm、5μm、8μm、10μm、20μm、30μm、40μm、50μm、60μm、70μm、80μm、90μm或100μm，其也可以是上述范围的任意值；D11的值与D21的值可以相同，也可以不同。
在一些实施例中，如果第一极片11为负极片，则第一保护层113的厚度与第一活性材料层112的厚度的比为(0.15～0.6):1；第一活性材料层112的厚度为30μm～200μm；第一保护层113的厚度为3μm～100μm。如果第一极片11为正极片，则第一保护层113的厚度与第一活性材料层112的厚度的比为(0.1～0.5):1；第一活性材料层112的厚度为15μm～180μm；第一保护层113的厚度为1.5μm～90μm。
负极片对应负极保护层和负极活性材料层，正极片对应正极保护层和正极活性材料层；负极活性材料层的厚度大于正极活性材料层的厚度，且负极活性材料层的单面面积重量小于正极活性材料层的单位面积重量，可知，负极活性材料层的密实度小于正极活性材料层的密实度，有利于提高电化学装置的电学性能更佳。
负极保护层的厚度与负极活性材料层的厚度的比值大于正极保护层的厚度与正极活性材料层的厚度的比值。由于发明人研究发现，负极片的单面区的卷曲问题更加严重，所以，负极活性材料层的厚度与负极保护层的厚度的比值相对较大，能够对负极片的单面区的卷曲问题进行较好的改善。而对于正极片来说，正极片的单面区的卷曲问题稍弱，所以，正极活性材料层的厚度与正极保护层的厚度的比值相对较小，就能够对正极片的单面区的卷曲问题进行很好的改善。上述设置方式，可以使正极片和负极片的单面区卷曲问题都能够得到很好地改善的同时，还可以使电化学装置的能量密度较高，电学性能较好。
在一些实施例中，沿电极组件1的卷绕方向，卷绕单面区起始段1111长度占第一集流体111总长度的1.5％～50％。请继续参阅图5～图7，图5中箭头所指的方向为电极组件1的卷绕方向，图6中截面示意图所示的第一极片11沿顺时针的方向从右端开始卷绕，图6中卷绕单面区起始段1111的长度为L11，图6中第一集流体111的长度为L12，L11/L12＝1.5％～50％。
沿电极组件1的卷绕方向，卷绕单面区收尾段1211长度占第二集流体121的总长度的2％～55％。图7中截面示意图所示的第二极片12沿顺时针的方向从右端开始卷绕，则图7中卷绕单面区收尾段1211的长度为L21，图7中第二集流体121的长度为L22，L21/L22＝2％～55％。
可选地，L22的值大于L12的值，这是因为卷绕单面区起始段1111位于电极组件1的内圈，卷绕单面区收尾段1211位于电极组件1的外圈，卷绕单面区收尾段1211的长度大于卷绕单面区起始段1111的长度。
作为示例性地，卷绕单面区起始段1111长度占第一集流体111总长度的1.5％、3％、5％、10％、15％、20％、25％、30％、35％、40％、45％或50％，其也可以是上述范围的任意值；卷绕单面区收尾段1211长度占第二集流体121的总长度的2％、4％、8％、12％、16％、20％、25％、30％、35％、40％、45％、50％或55％，其也可以是上述范围的任意值。
可选地，沿电极组件1的卷绕方向，卷绕单面区起始段1111长度占第一集流体111总长度的1.5％～10％；沿电极组件1的卷绕方向，卷绕单面区收尾段1211长度占第二集流体121的总长度的2％～15％。可以使卷绕单面区起始段1111基本全部位于电极组件1的内圈，卷绕单面区收尾段1211基本全部位于电极组件1的外圈，电极组件1的极片卷曲问题得到良好的解决，且电化学装置的能量密度更高。
请继续参阅图6，从图6中的平面示意图和截面示意图可知，第一保护层113没有完全覆盖第一集流体111的右端部，但是，第一保护层113在第一集流体111上的正投影基本和第一活性材料层112在第一集流体111上的正投影重合，所以，可以看成是第一保护层113完全覆盖卷绕单面区起始段1111的朝向电极组件1中心的表面。也就是说，第一保护层113完全覆盖第一集流体111的卷绕单面区起始段1111的朝向电极组件1中心的表面可以是指：第一保护层113的涂覆区域与第一保护层113相对的第一活性材料层112的涂覆区域基本重合。
请继续参阅图7，从图7中的平面示意图和截面示意图可知，第二保护层123没有完全覆盖第二集流体121的左端部，但是，第二保护层123在第二集流体121上的正投影基本和第二活性材料层122在第二集流体121上的正投影重合，所以，可以看成是第二保护层123完全覆盖卷绕单面区收尾段1211的背离电极组件1中心的表面。也就是说，第二保护层123完全覆盖第二集流体121的卷绕单面区收尾段1211的背离电极组件1中心的表面可以是指：第二保护层123的涂覆区域与第二保护层123相对的第二活性材料层122的涂覆区域基本重合。
在其他实施例中，图8为图5所示的第一极片11的第二种平面和截面结构示意图，请参阅图8，第一保护层113在第一集流体111上的正投影可以超出第一活性材料层112在第一集流体111上的正投影，请继续参阅图8中的截面示意图，该图中的第一保护层113向右超出第一活性材料层112，或/和，该图中的第一保护层113向左与部分第一活性材料层112重涂。也就是说，第一保护层113完全覆盖第一集流体111的卷绕单面区起始段1111的朝向电极组件1中心的表面还可以是指：第一保护层113的涂覆区域超出第一保护层113相对的第一活性材料层112的涂覆区域。
可选地，沿电极组件1的卷绕方向，第一保护层113向右超出第一活性材料层112的长度占第一流体的总长度的0.1％～0.5％，第一保护层113向左与第一活性材料层112重叠的长度占第一流体的总长度的0.1％～0.5％，其依然能够起到改善极片卷曲问题的目的。
在其他实施例中，图9为图5所示的第二极片12的第二种平面和截面结构示意图，请参阅图9，第二保护层123在第二集流体121上的正投影可以超出第二活性材料层122在第二集流体121上的正投影，请继续参阅图9中的截面示意图，该图中的第二保护层123向左超出第二活性材料层122，或/和，该图中的第二保护层123向右与部分第二活性材料层122重涂。也就是说，第二保护层123完全覆盖第二集流体121的卷绕单面区收尾段1211的背离电极组件1中心的表面还可以是指：第二保护层123的涂覆区域超出与第二保护层123相对的第二活性材料层122的涂覆区域。
可选地，沿电极组件1的卷绕方向，第二保护层123超出第二活性材料层122的长度占第二集流体121的总长度的0.1％～0.5％，第二保护层123向左与第二活性材料层122重叠的长度占第二流体的总长度的0.1％～0.5％，其依然能够起到改善极片卷曲问题的目的。
在一些实施例中，第一保护层113覆盖部分卷绕单面区起始段1111朝向电极组件1中心的表面；第二保护层123覆盖部分卷绕单面区收尾段1211背离电极组件1中心的表面。
图10为图5所示的第一极片11的第三种平面和截面结构示意图，图11为图5所示的第二极片12的第三种平面和截面结构示意图，图12为图5所示的第一极片11的第四种平面和截面结构示意图，图13为图5所示的第二极片12的第四种平面和截面结构示意图。
请参阅图10和图12，第一保护层113覆盖部分卷绕单面区起始段1111朝向电极组件1中心的表面是指：第一保护层113在第一集流体111上的正投影面积小于第一活性材料层112在第一集流体111上的正投影面积，且第一保护层113在第一集流体111上的正投影全部没有超出第一活性材料层112在第一集流体111上的正投影的边缘，也就是说，在第一集流体111的卷绕单面区起始段1111处，第一保护层113在第一集流体111上的正投影未完全覆盖第一活性层在第一集流体111上的正投影。
请参阅图11和图13，第二保护层123覆盖部分卷绕单面区收尾段1211背离电极组件1中心的表面是指：第二保护层123在第二集流体121上的正投影面积小于第二活性材料层122在第二集流体121上的正投影面积，且第二保护层123在在第二集流体121上的正投影全部没有超出第二活性材料层122在第二集流体121上的正投影的边缘，也就是说，在第二集流体121的卷绕单面区收尾段1211处，第二保护层123在第二集流体121上的正投影未完全覆盖第二活性层在第二集流体121上的正投影。
保护层覆盖集流体的单面区的部分表面，就可以对极片卷曲进行很好的改善，可以降低保护层的使用量，提高电化学装置的能量密度。
在一些实施例中，第一保护层113覆盖在卷绕单面区起始段1111的表面面积占比为30％～100％。请继续参阅图10，卷绕单面区起始段1111的表面面积为长L31乘以宽D31，第一保护层113覆盖在卷绕单面区起始段1111的表面面积为长L41乘以宽D41，则第一保护层113覆盖在卷绕单面区起始段1111的表面面积占比为(L31×D31)/(L41×D41)＝30％～100％。
第二保护层123覆盖在卷绕单面区收尾段1211的表面面积占比为30％～100％。请继续参阅图12，卷绕单面区起始段1111的表面面积为长L51乘以宽D51，第一保护层113覆盖在卷绕单面区起始段1111的表面面积为长L61乘以宽D61乘以3，则第一保护层113覆盖在卷绕单面区起始段1111的表面面积占比为(L51×D51)/(L61×D61×3)＝30％～100％。
作为示例性地，第一保护层113覆盖在卷绕单面区起始段1111的表面面积占比为30％、40％、50％、60％、70％、80％、90％或100％，其也可以是上述范围的任意值；第二保护层123覆盖在卷绕单面区收尾段1211的表面面积占比为30％、40％、50％、60％、70％、80％、90％或100％，其也可以是上述范围的任意值。
可选地，第一保护层113覆盖在卷绕单面区起始段1111的表面面积占比为50％～80％；或/和，第二保护层123覆盖在卷绕单面区收尾段1211的表面面积占比为50％～80％。可以使电极组件1的极片卷曲问题得到良好的解决，且在电极组件1的对齐度较小的同时，电化学装置的能量密度也更高。
在一些实施例中，第一集流体111的靠近卷绕单面区起始段1111的位置设置有第一活性材料层112，位于第一集流体111的同一侧的第一活性材料层112与所述第一保护层113之间具有间隔；第二集流体121的靠近卷绕单面区收尾段1211的位置设置有第二活性材料层122，位于第二集流体121的同一侧的第二活性材料层122与第二保护层123之间具有间隔。
请继续参阅图10和图12，图10和图12中的截面示意图所示，第一集流体111的上表面的第一保护层113与第一活性材料层112之间具有间隙，图10和图12中的平面示意图所示，第一集流体111的表面上的第一保护层113与第一活性材料层112之间具有间隙。请继续参阅图11和图13，图11和图13中截面示意图所示，第二集流体121的下表面的第二保护层123与第二活性材料层122之间具有间隙。
在集流体的同一侧，活性材料层与保护层之间具有一定的距离，可以避免活性材料层和保护层之间出现重涂，使活性材料层的使用率更高。
在一些实施例中，第一保护层113呈条纹状或单块状分布；第二保护层123呈条纹状或单块状分布。
请继续参阅图10和图11，保护层呈单块状分布，可以使保护层更加容易形成，容易控制保护层的涂覆区域。请继续参阅图12和图13，保护层呈条纹状分布，可以使用较少的保护层材料，就能够很好地解决极片卷曲的问题，且可以使电化学装置的能量密度较高。
图14为图5所示的第一极片11的第五种平面和截面结构示意图，请参阅图14，在其他实施例中，第一保护层113还可以呈竖条纹形状(图14中a图)，第二保护层123也可以呈竖条纹形状，第一保护层113还可以呈横条纹形状(图14中b图)；第二保护层123也可以呈横条纹形状，第一保护层113还可以呈斜条纹形状(图14中c图)；第二保护层123也可以呈斜条纹形状，第一保护层113还可以呈不规则形状(图14中d图)；第二保护层123也可以呈不规则形状。
在一些实施例中，第一保护层113和第二保护层123包括无机颗粒和粘结剂。通过无机颗粒和粘结剂混合以后，可以形成浆料，该浆料可以涂覆在卷绕单面区起始段1111和卷绕单面区收尾段1211，从而形成第一保护层113和第二保护层123。活性材料层中有活性材料颗粒，可以使集流体的一表面粘接有无机颗粒，另一表面粘接有活性材料颗粒，可以使通过无机颗粒的应力释放，很好地改善极片单面卷曲的问题。由于浆料中的颗粒为无机颗粒，可以使无机颗粒与粘接性形成的保护层为绝缘保护层，在形成在集流体的卷绕单面区起始段1111或卷绕单面区收尾段1211时，还可以提高电化学装置的安全性。
其中，无机颗粒可以为勃姆石、氧化铝、氧化钛、氧化硅、氧化镁、氧化铪、氧化锡、氧化 铈、氧化镍、氧化锌、氧化钙、氧化锆、氧化钇、氢氧化铝、氢氢化镁、氢氧化钙、硫酸钡、硫酸钙、硅酸钙、碳化硅中的至少一种。该无机颗粒为绝缘颗粒，无机颗粒与粘接性形成的保护层为绝缘保护层，在形成在集流体的卷绕单面区起始段1111或卷绕单面区收尾段1211时，还可以提高电化学装置的安全性。
可选地，粘结剂可以为聚丙烯酸、聚丙烯酸盐、聚丙烯酸酯、聚丙烯腈、羧甲基纤维素盐、丁腈橡胶、丁苯橡胶、聚丙烯、聚乙烯、聚四氟乙烯、聚偏氟乙烯、聚醚酰亚胺中的至少一种，可以在集流体上形成保护层，且使集流体与保护层之间的结合力较佳。
在一些实施例中，无机颗粒的Dv10≥0.001μm，Dv99≤100μm；第一活性材料层112的Dv10为1μm～20μm，Dv99≤80μm；第二活性材料层122的活性材料颗粒的Dv10为1μm～20μm，Dv99≤80μm。
第一保护层113中的无机颗粒的粒径分布状态可以与第二保护层123中的无机颗粒的粒径分布状态相同，也可以不同；同样，第一活性材料层112中的活性材料颗粒的粒径分布状态可以与第二活性材料层122中的活性材料颗粒的粒径分布状态相同，也可以不同。
无机颗粒的Dv10≥0.001μm是指：将保护层中的无机颗粒按照从小到大累加，当累加到占总体积的10％时，这时无机颗粒的粒径≥0.001μm；无机颗粒的Dv99≤100μm是指：将保护层中的无机颗粒按照从小到大累加，当累加到占总体积的99％时，这时无机颗粒的粒径≤100μm。
活性材料颗粒的Dv10为1μm～20μm是指：将活性材料层中的活性材料颗粒按照从小到大累加，当累加到占总体积的10％时，这时活性材料颗粒的粒径在1μm～20μm之间；活性材料颗粒的Dv99≤80μm是指：将活性材料层中的活性材料颗粒按照从小到大累加，当累加到占总体积的99％时，这时活性材料颗粒的粒径≤80μm。
无机颗粒的粒径分布基本与活性材料的粒径分布一致，对于集流体的两个表面来说，无机颗粒的应力与活性材料颗粒的应力基本一致，可以使极片卷曲的改善效果更好。
在一些实施例中，无机颗粒的Dv10≥0.001μm，Dv99≤40μm。无机颗粒的粒径相对较小，无机颗粒的数量相对较多，无机颗粒的应力释放更大，可以使保护层的厚度较小、单位面积重量较小就能够很好地改善极片卷曲的问题，可以使电极组件1的对齐度更小。
本申请中，保护层中的材料还可以有增稠剂，也就是说，第一保护层113和第二保护层123包括无机颗粒、粘结剂和增稠剂，基于第一保护层113或第二保护层123的总质量，无机颗粒的质量百分含量为70％～99％；粘接剂的质量百分含量为0.3％～30％；增稠剂的质量百分含量为0.3％～20％。
其中，增稠剂可以是羧甲基纤维素、丙二醇藻蛋白酸酯、甲基纤维素、淀粉磷酸钠、羧甲基纤维素钠、藻蛋白酸钠、酪蛋白、聚丙烯酸钠、聚氧乙烯、聚乙烯吡咯烷酮中的至少一种。
本申请中，形成第一保护层113的浆料和形成第二保护层123的浆料的成分可以相同，也可以不同；如果形成第一保护层113的浆料和形成第二保护层123的浆料的成分相同，对于每种成本的质量百分含量，也可以相同或不同，本申请不做限定。
作为示例性地，无机颗粒的质量百分含量为70％、75％、80％、85％、90％、95％或99％，其也可以是上述范围的任意值；粘接剂的质量百分含量为0.3％、0.5％、1％、3％、5％、10％、15％、20％、25％或30％，其也可以是上述范围的任意值；增稠剂的质量百分含量为0.3％、0.5％、1％、3％、5％、10％、15％或20％，其也可以是上述范围的任意值。
增稠剂的添加，可以使保护层的内应力较大，在将保护层设置在集流体的一表面以后，无机颗粒的释放应力相对较大，可以在保护层的厚度较小、单位面积重量较小的情况下，解决极片卷曲的问题，使保护层的使用量更少。
在一些实施例中，第一极片11为负极，第一集流体111的厚度为4～10μm。可选地，第一集流体111的厚度为4μm、5μm、6μm、7μm、8μm、9μm或10μm，其也可以是上述范围的任意值。对于负极片来说，保护层的设置，可以使负极集流体的厚度降低至4μm，可以大大缩小负极集流体的厚度，从而增加电化学装置的能量密度。
图15为图5所示的第一极片11的第六种平面和截面结构示意图，请参阅图5和图15，电极组件1还包括第一极耳171和第二极耳172，第一极耳171设置于第一极片11的一侧，且与第一集流体111电性连接，其中，图15中的(e)、(f)和(g)分别是第一极耳171设置的三种示意图，第二极耳172设置于第二极片12的一侧，且与第二集流体121电性连接。通过第一极耳171和第二极耳172的设置，第一极耳171与第一电极端子23连接，第二极耳172与第二电极端子24连接，以便将电流输出。
在一些实施例中，请参照图5、图6和图7，层叠的第一极片11、第一隔膜131、第二极片12和第二隔膜132卷绕以后形成电极组件1，该电极组件1的具有层叠的第一极片11、第一隔膜131、第二 极片12和第二隔膜132，第一极片11包括第一集流体111，第一集流体111的卷绕单面区起始段1111的背离电极组件1中心的表面设置第一活性材料层112，第一集流体111的卷绕单面区起始段1111的朝向电极组件1中心的表面设置第一保护层113，第一保护层113的单位面积重量与第一活性材料层112的单位面积重量的比为(0.03～0.75):1，第一活性材料层112的单位面积重量为0.06g/1540.25mm 2～0.5g/1540.25mm 2；第一保护层113的单位面积重量为0.01g/1540.25mm 2～0.13g/1540.25mm 2；第一保护层113的厚度与第一活性材料层112的厚度的比为(0.1～0.6):1；第一活性材料层112的厚度为15μm～200μm；第一保护层113的厚度为1.5μm～100μm；沿电极组件1的卷绕方向，卷绕单面区起始段1111长度占第一集流体111总长度的1.5％～50％；第一保护层113覆盖部分卷绕单面区起始段1111朝向电极组件1中心的表面；第一保护层113覆盖在卷绕单面区起始段1111的表面面积占比为30％～100％；第一保护层113呈条纹状或单块状分布。
第二极片12包括第二集流体，第二集流体121的卷绕单面区收尾段1211的朝向电极组件1中心的表面设置第二活性材料层122，第二集流体121的卷绕单面区收尾段1211的背离电极组件1中心的表面设置第二保护层123，第二保护层123的单位面积重量与第二活性材料层122的单位面积重量的比为(0.03～0.75):1，第二活性材料层122的单位面积重量为0.06g/1540.25mm 2～0.5g/1540.25mm 2；第二保护层123的单位面积重量为0.01g/1540.25mm 2～0.13g/1540.25mm 2；第二保护层123的厚度与第二活性材料层122的厚度的比为(0.1～0.6):1；第二活性材料层122的厚度为15μm～200μm；第二保护层123的厚度为1.5μm～100μm；沿电极组件1的卷绕方向，卷绕单面区收尾段1211长度占第二集流体121总长度的2％～55％；第二保护层123覆盖部分卷绕单面区收尾段1211背离电极组件1中心的表面；第二保护层123覆盖在卷绕单面区收尾段1211的表面面积占比为30％～100％；第二保护层123呈条纹状或单块状分布。
在本实施例中，该电极组件1的设置，可以使电极组件1的极片卷曲问题得到明显改善，对齐度减小，并且能够使电化学装置的能量密度得到保证。
接下来参照下面的示例更详细地描述一个或多个实施例。当然，这些示例并不限制一个或多个实施例的范围。
实施例1
制备负极片：
第一步：配置负极材料，其中，负极材料包括80wt％的负极活性材料颗粒石墨、15wt％的导电剂Super P、3wt％的增稠剂羧甲基纤维素钠和2wt％的粘结剂丁苯橡胶，石墨的粒径分布为Dv10＝2μm，Dv99＝67.32μm；
第二步：配置负极保护层33材料，其中，保护层材料包括80wt％的无机颗粒氧化锆、15wt％的粘结剂聚偏二氟乙烯和5wt％的增稠剂羧甲基纤维素钠，氧化锆的粒径分布为Dv10＝0.01μm，Dv99＝39.56μm；
第三步：图16为本申请实施例1提供的负极片的种平面和截面结构示意图，请参阅图16，使用4μm铜箔集流体31，按照图16所示将第一步的负极活性材料涂布在铜箔集流体31的一面得到负极活性材料层32，称为A面311，膜长1140mm，膜宽98mm，间隙15mm。
第四步：请继续参阅16，A面311涂布完成后收集成卷，然后同样的方法在A面311的对称面B面312进行第一步的负极活性材料的涂布得到负极活性材料层32，膜长1012mm，膜宽98mm，间隙长度143mm；
第五步：B面312活性材料涂布完成后收集成卷，然后将负极保护层33材料涂布到负极单面区的对立面位置(B面312的空白区)得到负极保护层33，膜长120mm，膜宽88mm，TD间隙10mm，MD间隙8mm。
第六步：负极片辊压，设置辊压参数然后冷压收集成卷。
第七步：按照图16所示的虚线处分条，设置分条宽度，测量毛刺水平，设置完成后开机收集成卷。
制备正极片：
第一步：配置正极材料，其中，正极材料包括80wt％的正极活性材料颗粒LiCoO 2、10wt％的导电剂Super P和10wt％的粘结剂聚偏二氟乙烯，LiCoO 2的粒径分布为Dv10＝2μm，Dv99＝67.32μm；
第二步：配置正极保护层43材料，其中，保护层材料包括80wt％的无机颗粒氧化锆、15wt％的粘结剂聚偏二氟乙烯和5wt％的增稠剂羧甲基纤维素钠，氧化锆的粒径分布为Dv10＝0.01μm，Dv99＝39.56μm；
第三步：图17为本申请实施例1提供的正极片的种平面和截面结构示意图，请参阅图17，使用9μm铝箔集流体41，按照图17所示将第一步的正极活性材料涂布在铝箔集流体41的一面得到负极活性材料层32，称为C面411，膜长1130mm，膜宽96.8mm，间隙35mm。
第四步：请继续参阅17，C面411涂布完成后收集成卷，然后同样的方法在C面411的对称面D面412进行第一步的正极活性材料的涂布得到正极活性材料层42，膜长1010mm，膜宽96.8mm，间隙长度155mm；
第五步：D面412活性材料涂布完成后收集成卷，然后将正极保护层43材料涂布到正极单面区的对立面位置(D面412的空白区)得到正极保护层43，膜长112mm，膜宽86mm，TD间隙10mm，MD间隙8mm。
第六步：正极片辊压，设置辊压参数，然后冷压收集成卷。
第七步：按照图17所示的虚线处分条，设置分条宽度，测量毛刺水平，设置完成后开机收集成卷。
制备电极组件：
隔离膜为PP(polypropylene，聚丙烯)材质，隔离膜厚度为20μm。
将负极片、第一隔离膜、正极片和第二隔离膜层叠以后按照图5的方式进行卷绕形成电极组件，负极片靠近电极组件的中心，正极片背离电极组件的中心，且正形成的电极组件的一侧设置有正极极耳和负极极耳。
下面对电极组件的参数进行具体介绍如表1
表1电极组件的参数
Figure PCTCN2022088008-appb-000001
检测上述各电极组件的卷曲比例的方法是：通过CCD拍照，检查电极组件的卷绕单面区起始段和卷绕单面区收尾段的极片状态。
检测上述各电极组件的非极耳侧的对齐度的方法是(图5电极组件的内圈和外圈中，两条上下两个部分的对齐度的平均值，也就是第一折和第二折的平均对齐度；非极耳侧是指图15中的下侧(没有设置极耳的一侧))：通过X-ray拍照，检测电极组件尾部负极片超出正极片的长度。
检测含有上述各电极组件的电化学装置的能量密度(Wh/L)的方法是：将电池充满电后，再放电测试电池实际能量，能量/电芯体积即为能量密度。
其中，电极组件及电化学装置的性能如表2。
表2电极组件及电化学装置的性能
Figure PCTCN2022088008-appb-000002
从表1和表2可以看出，本申请实施例提供的电极组件的卷曲比例较低，对齐度较小；同时，其能量密度基本能够得到保证。
对于D1来说，负极片的卷绕单面区起始段的单面区未设置负极保护层33，正极片的卷绕单面区收尾段的单面区未设置正极保护层43；对于D2来说，负极片的卷绕单面区起始段的单面区未设置负极保护层33，正极片的卷绕单面区收尾段的单面区设置有正极保护层43；对于D3来说，负极片的卷绕单面区起始段的单面区设置有负极保护层33，正极片的卷绕单面区收尾段的单面区未设置有正极保护层43；最终得到的电化学组件的能量密度虽然都较高，但是，其负极片或/和正极片的卷曲比例较高，内圈对齐度或/和外圈对齐度较大，使最终得到的产品的性能不佳。
对于D4来说，负极片的卷绕单面区起始段处，负极活性材料层32的单位面积涂覆量与负极保护层33的单位面积涂覆量的比值过小(为0.02)，正极片的卷绕单面区收尾段处，正极活性材料层42的单位面积涂覆量与正极保护层43的单位面积涂覆量的比值过小(为0.01)，最终得到的电化学装置的能量密度虽然比较高，但是，其卷曲问题和对齐度较大的问题基本没有得到改善。
对于D5来说，负极片的卷绕单面区起始段处，负极活性材料层32的单位面积涂覆量与负极保护层33的单位面积涂覆量的比值过大(为0.85)，正极片的卷绕单面区收尾段处，正极活性材料层42的单位面积涂覆量与正极保护层43的单位面积涂覆量的比值过大(为0.87)，最终得到的电化学装置的卷曲会更加严重，这是由于保护层涂覆量过多，出现极片反卷的现象，且电化学装置的能量密度明显下降。
实施例2
R7和R8与R2基本相同，其不同在于：R7的铜箔集流体31的厚度为5μm，R8的铜箔集流体31的厚度为4μm；R9与R2基本相同，其不同在于：R9的保护层为条纹状，对于负极保护层33来说，其膜长为120mm，TD间隙10mm，负极保护层33分成三块，每块的膜宽为28mm，相邻的两块的TD间隙2mm；对于正极保护层43来说，其膜长为112mm，TD间隙10mm，正极保护层43分成三块，每块的膜宽为27mm，相邻的两块的TD间隙2.9mm。
使用实施例1提供的方法检测R7～R9的性能如表3。
表3电极组件及电化学装置的性能
Figure PCTCN2022088008-appb-000003
Figure PCTCN2022088008-appb-000004
从表3可以看出，R2和R7、R8比较可知，虽然R7和R8中铜箔集流体31的厚度减小，但是，其卷曲问题依然能够得到很好的改善，对齐度较小；同时，其能量密度可以有一定程度的提高。D1与R2和R9比较可知，如果负极保护层33和正极保护层43是条纹状(R9)，其虽然依然能够对卷曲问题进行改善，并且使对齐度减小(相较于D1)；但是，相较于负极保护层33和正极保护层43是单块状(R2)，其卷曲问题的改善效果稍差，对齐度稍大。
实施例3
R10～R14与R2基本相同，其不同在于：氧化锆、石墨和LiCoO 2的粒径分布不同，具体如表4。
其中，粒径分布的检测方式为：使用激光粒度分析仪进行测试。
表4氧化锆、石墨和钴锂类的粒径分布
Figure PCTCN2022088008-appb-000005
使用实施例1提供的方法检测R10～R14的性能如表5。
表5电极组件及电化学装置的性能
Figure PCTCN2022088008-appb-000006
从表4和表5可以看出，R2、R10、R12～R14中，无机颗粒的粒径基本小于活性材料颗粒的粒径，或者与活性材料颗粒的粒径基本相当时，可以使电极组件的卷曲比例下降，且对齐度降低。
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。
以上实施例仅用以说明本申请的技术方案，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 (10)

  1. 一种电化学装置，包括第一极片、隔膜和第二极片，所述第一极片、所述隔膜和所述第二极片层叠并卷绕形成电极组件；
    其中，所述第一极片包括第一集流体，所述第一集流体包括卷绕单面区起始段，所述卷绕单面区起始段朝向所述电极组件中心的表面设置第一保护层，所述卷绕单面区起始段背离所述电极组件中心的表面设置第一活性材料层；
    所述第二极片包括第二集流体，所述第二集流体包括卷绕单面区收尾段，所述卷绕单面区收尾段背离所述电极组件中心的表面设置第二保护层，所述卷绕单面区收尾段朝向所述电极组件中心的表面设置第二活性材料层；
    所述第一保护层的单位面积重量与所述第一活性材料层的单位面积重量的比为(0.03～0.75):1，所述第二保护层的单位面积重量与所述第二活性材料层的单位面积重量的比为(0.03～0.75):1。
  2. 根据权利要求1所述的电化学装置，其中，所述电化学装置满足以下条件中的至少一者：
    a)所述第一活性材料层的单位面积重量为0.06g/1540.25mm 2～0.5g/1540.25mm 2；
    b)所述第二活性材料层的单位面积重量为0.06g/1540.25mm 2～0.5g/1540.25mm 2；
    c)所述第一保护层的单位面积重量为0.01g/1540.25mm 2～0.13g/1540.25mm 2；
    d)所述第二保护层的单位面积重量为0.01g/1540.25mm 2～0.13g/1540.25mm 2。
  3. 根据权利要求1所述的电化学装置，其中，所述电化学装置满足以下条件中的至少一者：
    e)所述第一保护层的厚度与所述第一活性材料层的厚度的比为(0.1～0.6):1；
    f)所述第二保护层的厚度与所述第二活性材料层的厚度的比为(0.1～0.6):1。
  4. 根据权利要求3所述的电化学装置，其中，所述电化学装置满足以下条件中的至少一者：
    g)所述第一活性材料层的厚度为15μm～200μm；
    h)所述第二活性材料层的厚度为15μm～200μm；
    i)所述第一保护层的厚度为1.5μm～100μm；
    j)所述第二保护层的厚度为1.5μm～100μm。
  5. 根据权利要求1～4任一项所述的电化学装置，其中，所述电化学装置满足以下条件中的至少一者：
    k)沿所述电极组件的卷绕方向，所述卷绕单面区起始段长度占所述第一集流体总长度的1.5％～50％；
    l)沿所述电极组件的卷绕方向，所述卷绕单面区收尾段长度占所述第二集流体的总长度的2％～55％；
    m)所述第一保护层覆盖部分所述卷绕单面区起始段朝向所述电极组件中心的表面；
    n)所述第二保护层覆盖部分所述卷绕单面区收尾段背离所述电极组件中心的表面；
    o)所述第一保护层覆盖在所述卷绕单面区起始段的表面面积占比为30％～100％；
    p)所述第二保护层覆盖在所述卷绕单面区收尾段的表面面积占比为30％～100％。
  6. 根据权利要求1所述的电化学装置，其中，所述电化学装置满足以下条件中的至少一者：
    q)所述第一集流体的靠近所述卷绕单面区起始段的位置设置有第一活性材料层，位于所述第一集流体的同一侧的所述第一活性材料层与所述第一保护层之间具有间隔；
    r)所述第二集流体的靠近所述卷绕单面区收尾段的位置设置有第二活性材料层，位于所述第二集流体的同一侧的所述第二活性材料层与所述第二保护层之间具有间隔；
    s)所述第一保护层呈条纹状或单块状分布；
    t)所述第二保护层呈条纹状或单块状分布。
  7. 根据权利要求1所述的电化学装置，其中，所述第一保护层和所述第二保护层均包括无机颗粒和粘结剂；所述电化学装置满足以下条件中的至少一者：
    u)所述无机颗粒的Dv10≥0.001μm，Dv99≤100μm；
    v)所述第一活性材料层的活性材料颗粒的Dv10为1μm～20μm，Dv99≤80μm；
    w)所述第二活性材料层的活性材料颗粒的Dv10为1μm～20μm，Dv99≤80μm。
  8. 根据权利要求7所述的电化学装置，其中，所述第一保护层和所述第二保护层还包括增稠剂，基于所述第一保护层或所述第二保护层的总质量，所述无机颗粒的质量百分含量为70％～99％；所述粘接剂的质量百分含量为0.3％～30％；所述增稠剂的质量百分含量为0.3％～20％。
  9. 根据权利要求1所述的电化学装置，其中，所述第一极片为负极，所述第一集流体的厚度为4μm～10μm。
  10. 一种用电设备，其中，包括根据权利要求1～9任一项所述的电化学装置。
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117638254A (zh) * 2024-01-26 2024-03-01 宁德新能源科技有限公司 一种电极组件及电池
CN117790684A (zh) * 2024-02-27 2024-03-29 武汉星纪魅族科技有限公司 锂离子电池及其制备方法、电极片的制备方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013048027A (ja) * 2011-08-29 2013-03-07 Panasonic Corp 二次電池用電極群およびこれを用いた二次電池
CN107039685A (zh) * 2016-02-04 2017-08-11 泰州新超锂离子科技有限公司 锂离子电池
CN113557625A (zh) * 2020-03-31 2021-10-26 宁德新能源科技有限公司 电芯、电池及电子装置
CN114270578A (zh) * 2021-03-30 2022-04-01 宁德新能源科技有限公司 电化学装置和电子装置

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013048027A (ja) * 2011-08-29 2013-03-07 Panasonic Corp 二次電池用電極群およびこれを用いた二次電池
CN107039685A (zh) * 2016-02-04 2017-08-11 泰州新超锂离子科技有限公司 锂离子电池
CN113557625A (zh) * 2020-03-31 2021-10-26 宁德新能源科技有限公司 电芯、电池及电子装置
CN114270578A (zh) * 2021-03-30 2022-04-01 宁德新能源科技有限公司 电化学装置和电子装置

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117638254A (zh) * 2024-01-26 2024-03-01 宁德新能源科技有限公司 一种电极组件及电池
CN117638254B (zh) * 2024-01-26 2024-04-26 宁德新能源科技有限公司 一种电极组件及电池
CN117790684A (zh) * 2024-02-27 2024-03-29 武汉星纪魅族科技有限公司 锂离子电池及其制备方法、电极片的制备方法

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