WO2024099397A1 - 电极片、卷芯和电池 - Google Patents

电极片、卷芯和电池 Download PDF

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Publication number
WO2024099397A1
WO2024099397A1 PCT/CN2023/130790 CN2023130790W WO2024099397A1 WO 2024099397 A1 WO2024099397 A1 WO 2024099397A1 CN 2023130790 W CN2023130790 W CN 2023130790W WO 2024099397 A1 WO2024099397 A1 WO 2024099397A1
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WO
WIPO (PCT)
Prior art keywords
coating
coated
electrode sheet
active material
whitening
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/CN2023/130790
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English (en)
French (fr)
Inventor
张健
何娜
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Zhuhai Cosmx Battery Co Ltd
Original Assignee
Zhuhai Cosmx Battery Co Ltd
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Filing date
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Application filed by Zhuhai Cosmx Battery Co Ltd filed Critical Zhuhai Cosmx Battery Co Ltd
Publication of WO2024099397A1 publication Critical patent/WO2024099397A1/zh
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • 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
    • 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
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • 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 disclosure relates to the technical field of lithium-ion batteries, and in particular to an electrode sheet, a winding core and a battery.
  • Lithium-ion batteries are widely used in various electronic devices due to their advantages such as high platform voltage, high energy density, no memory effect, and long life.
  • the positive electrode, negative electrode, and separator are in a partially broken state.
  • the present disclosure provides an electrode sheet, a winding core and a battery to solve the problems of difficulty in identifying the finishing glue in lithium-ion batteries and easy inflation of lithium-ion batteries at high temperatures.
  • an electrode sheet applied to a winding core comprising:
  • a current collector comprising a first side surface and a second side surface disposed opposite to each other;
  • the protective coating comprising a target side, the target side being disposed away from the current collector;
  • an active material coating comprising an active material
  • the active material coating is coated on the target side and the second side;
  • the active material coating is coated on the target side
  • a whitening coating is applied on the target side, and the area not coated with the active material coating is provided with the whitening coating, and the difference A between the gray value of the whitening coating and the finishing glue of the winding core is 40 to 80.
  • the difference B between the grayscale values of the protective coating and the finishing adhesive of the core is 10 to 30, then A>B;
  • the target side is provided with a first region and a second region, the second region is provided close to an end of the current collector, the active material coating is coated on the first region, and the whitening coating is coated on the second region.
  • the length of the second region ranges from 50 mm to 200 mm, and the length direction of the second region is parallel to the length direction of the current collector.
  • the whitening coating has a thickness of 2 ⁇ m to 20 ⁇ m, preferably 5 ⁇ m to 10 ⁇ m.
  • A is 50 to 80;
  • B is 10 to 20;
  • A-B is 30 to 70.
  • the coating area of the whitening coating is smaller than the coating area of the active material coating
  • the sum of the coating area of the whitening coating and the coating area of the active material coating is not less than the area of the target side of the protective coating.
  • the present disclosure further provides a winding core, comprising the electrode sheet as described in the first aspect.
  • the second regions of the protective coating on both sides are coated with a whitening coating.
  • a second region of the protective coating on one side is coated with a whitening coating, and the whitening coating is located in the second region away from the center of the winding core.
  • the present disclosure further provides a battery, comprising the winding core as described in the second aspect.
  • an electrode sheet is applied to a winding core, and includes: a current collector, a protective coating and an active material coating, wherein the current collector includes a first side surface and a second side surface disposed opposite to each other; and the protective coating is coated on the first side surface and/or the second side surface.
  • the difference A in the grayscale value between the whitening coating and the finishing glue of the winding core is limited to 40 to 80, thereby increasing the grayscale value of the whitening coating and the finishing glue of the winding core, and can be more accurate when positioning the finishing glue using a CCD device.
  • the whitening coating and the finishing glue are clearly and conveniently distinguished to increase recognition, thereby improving the accuracy and convenience of locating the finishing glue; and the whitening coating is coated on the side of the target, and the area not coated with the active material coating is provided with the whitening coating to avoid contact between the protective coating and the electrolyte, thereby reducing the side reaction between the protective coating and the electrolyte, improving high-temperature inflation, and reducing the expansion rate of the battery.
  • FIG1 is a schematic cross-sectional view of an electrode sheet according to an embodiment of the present disclosure.
  • FIG2 is a second cross-sectional schematic diagram of an electrode sheet provided in an embodiment of the present disclosure.
  • FIG3 is a third cross-sectional schematic diagram of an electrode sheet provided in an embodiment of the present disclosure.
  • FIG4 is a fourth cross-sectional schematic diagram of an electrode sheet provided in an embodiment of the present disclosure.
  • FIG5 is a fifth cross-sectional schematic diagram of an electrode sheet provided in an embodiment of the present disclosure.
  • FIG6 is a sixth cross-sectional schematic diagram of an electrode sheet provided in an embodiment of the present disclosure.
  • FIG. 7 is one of the structural schematic diagrams of the winding core provided in an embodiment of the present disclosure.
  • FIG. 8 is a second schematic diagram of the structure of the winding core provided in an embodiment of the present disclosure.
  • an electrode sheet which is applied to a winding core, comprising:
  • a current collector 10 wherein the current collector 10 comprises a first side surface and a second side surface disposed opposite to each other;
  • the active material coating 30 is coated on the target side and the second side;
  • the active material coating 30 is coated on the target side
  • a whitening coating 40 is coated on the target side, and the area not coated with the active material coating is provided with the whitening coating, and the difference A between the grayscale value of the whitening coating (40) and the finishing glue of the winding core is 40 to 80 (for example, 40, 45, 50, 55, 60, 65, 70, 75, 80).
  • the grayscale value can be obtained by a CCD visual detection system.
  • A is 50-80.
  • the protective coating 20 is coated on the first side and the second side of the current collector 10, and the active material coating 30 is coated on the target side (the side of the protective coating 20 facing away from the current collector 10). Specifically, the active material coating 30 is coated on the target side of the protective coating 20 on both sides.
  • the protective coating 20 is only coated on the first side of the current collector 10
  • the active material coating 30 is coated on the target side of the protective coating 20 and the second side of the current collector 10 .
  • first side and the second side are only used to distinguish the two opposite sides of the current collector 10.
  • the case where the protective coating 20 is only coated on the second side of the current collector 10 can be referred to the case where the protective coating 20 is only coated on the first side of the current collector 10. In order to avoid repetition, it will not be repeated here.
  • the specific structure of the current collector 10 is not limited herein.
  • the current collector 10 is an aluminum foil.
  • the active material included in the active material coating 30 is not limited here.
  • the active material coating 30 can adopt active materials commonly used in related technologies.
  • the active material coating 30 includes lithium cobalt oxide, acetylene black and polyvinylidene fluoride.
  • the protective coating 20 includes conductive powder, conductive agent and adhesive, wherein the specific ratio of the conductive powder, conductive agent and adhesive is not limited here. Since the protective coating includes conductive powder and conductive agent, the protective coating has good conductivity, and thus the electrode sheet has good electrical properties. At the same time, since the protective coating includes adhesive, the bonding performance between the protective coating and the current collector is improved, and the probability of the protective coating falling off during mechanical abuse is reduced.
  • the specific structure of the conductive powder is not limited here, and the conductive powder can be understood as a powder with conductivity.
  • the protective coating 20 uses conductive powder as the main material, which can make the protective coating 20 have better conductivity, thereby making the lithium-ion battery have better electrical properties.
  • the conductive powder includes inorganic particles and a conductive coating layer, and the conductive coating layer wraps the inorganic particles.
  • the conductor powder can be understood as a composite conductive material with inorganic particles as the core and a conductive coating layer as the shell.
  • the conductive coating layer is a metal oxide, or a metal oxide doped with an impurity element.
  • the metal oxide may be any metal oxide, and the impurity element doped in the metal oxide may also be any element.
  • the conductive coating layer is tin oxide (SnO 2 ) doped with antimony (Sb) element, or antimony doped tin oxide (ATO).
  • the conductive coating layer is SnO 2 doped with fluorine (F), or TCO conductive glass (FTO).
  • the conductive coating layer is indium oxide (In 2 O 3 ) doped with tin (Sn) element, or indium tin oxide. (Indium tin oxide, ITO).
  • the inorganic particles included in the conductive powder may also be any inorganic particles.
  • the inorganic particles included in the conductive powder include at least one of the following: titanium dioxide, zinc oxide, mica powder, quartz powder, barite, aluminum oxide, boehmite, magnesium oxide, and silicon oxide.
  • the Dv50 of the conductive powder is less than 5 ⁇ m (e.g., 5 ⁇ m, 4.5 ⁇ m, 4 ⁇ m, 3.5 ⁇ m, 3 ⁇ m, 2.5 ⁇ m, 2 ⁇ m, 1.5 ⁇ m, 1 ⁇ m, 0.5 ⁇ m, 0.1 ⁇ m). Furthermore, in one embodiment, the Dv50 of the conductive powder is less than 4 ⁇ m. Optionally, in another embodiment, the Dv50 of the conductive powder is less than 1 ⁇ m.
  • Dv50 can be understood as the particle size corresponding to when the cumulative volume particle size distribution percentage of a sample reaches 50%. Its physical meaning is that particles with a particle size larger than it account for 50%, and particles with a particle size smaller than it also account for 50%, so Dv50 is also called the median diameter or median particle size.
  • the Dv50 of the active material included in the active material coating 30 is generally 15 ⁇ m.
  • the Dv50 of the conductive powder is much smaller than the Dv50 of the active material included in the active material coating 30. It can be seen that the D50 of the material included in the protective coating 20 is smaller, so when the active material coating 30 is broken due to mechanical abuse, the probability of the protective coating 20 breaking is small, thereby reducing the probability of the current collector 10 being exposed and improving the safety of the battery.
  • the difference B between the grayscale values of the protective coating 20 and the finishing adhesive of the core is 10 to 30 (eg, 10, 12, 15, 17, 20, 22, 25, 27, 30), then A>B.
  • B is 10-20.
  • A-B is 30 to 70 (e.g., 30, 35, 40, 45, 50, 55, 60, 65, 70).
  • the target side is provided with a first region and a second region, the second region is arranged close to the end of the current collector 10, and in the core, the end is the tail of the core away from the center of the core, the active material coating 30 is coated on the first region, and the whitening coating 40 is coated on the second region.
  • the electrode sheet further comprises a whitening coating 40.
  • the whitening coating 40 comprises inorganic particles.
  • the whitening coating 40 comprises inorganic particles.
  • the particles include at least one of aluminum oxide, boehmite, magnesium oxide, titanium oxide, zinc oxide, and silicon oxide.
  • the protective coating 20 is coated on the first side and the second side of the current collector 10 , and the whitening coating 40 and the active material coating 30 are coated on the target side. Specifically, the first area of the protective coating 20 on both sides is coated with the active material coating 30 , and the second area of the protective coating 20 on both sides is coated with the whitening coating 40 . At this time, the protective coating is completely covered by the whitening coating and the active material coating, so that the protective coating does not directly contact the electrolyte, improving the problem of gas generation caused by the side reaction of the protective coating contacting the electrolyte, thereby reducing the expansion rate of the battery.
  • only the second area of the protective coating 20 on one side may be coated with the whitening coating 40 .
  • the whitening coating can reduce the risk of short circuit in the case of mechanical damage such as puncture of the battery, for example, the positive electrode current collector contacts the negative electrode active material coating, or the negative electrode current collector contacts the positive electrode active material coating, thereby improving the safety performance of the battery.
  • the protective coating 20 not coated with the whitening coating 40 does not completely cover the current collector 10.
  • the area of the current collector 10 not covered by the protective coating 20 faces the inside of the core, and it is difficult to short-circuit with the nail during puncture, and the positive electrode sheet is also in contact with it, and the probability of short-circuiting with the negative electrode is also low, and the safety risk is small.
  • the protective coating 20 is only coated on the first side of the current collector 10, and the active material coating 30 and the whitening coating 40 are coated on the target side.
  • the active material coating 30 is coated on the first area of the protective coating 20, and the whitening coating 40 is coated on the second area of the protective coating 20, and the whitening coating 40 is located in the second area away from the center of the winding core.
  • electrode sheet schematic diagrams shown in Figures 1 to 6 are only used to illustrate the relative positions of the current collector 10, the protective coating 20, the active material coating 30 and the whitening coating 40.
  • the width and length of each of the above coatings are only for illustration and do not represent the information or correspondence between the length or width of the current collector 10, the protective coating 20, the active material coating 30 and the whitening coating 40.
  • the electrode sheet provided in the present disclosure is applied to the winding core.
  • the specific process of preparing the winding core based on the electrode sheet can be referred to the description in the related art. In order to avoid repetition, it will not be described here. For the sake of easy understanding, only the finishing glue is briefly described below.
  • the electrode sheet In the process of preparing a winding core based on an electrode sheet, the electrode sheet needs to be wound and a tail glue is adhered to the end of the winding core formed after winding. Therefore, the tail glue is located at the end of the winding core and is bonded and fixed to the outermost surface of the winding core away from the center of the winding core.
  • the second region is disposed near the end of the current collector 10, and the whitening coating 40 is coated on the second region. Therefore, it can be understood that the outermost surface of the winding core away from the center of the winding core is provided with the whitening coating 40, and the whitening coating 40 is located at the end of the winding core.
  • the tail glue 50 will be connected to the whitening coating 40 and cover part of the whitening coating 40, see FIG8 .
  • the protective coating 20 includes conductive powder, conductive agent and adhesive.
  • the difference in grayscale value between the protective coating 20 and the finishing glue is usually small. Therefore, when a charge coupled device (CCD) is used to locate the finishing glue, it is difficult to distinguish between the protective coating 20 and the finishing glue.
  • CCD charge coupled device
  • the gray value of the whitening coating 40 and the end glue of the winding core is increased, and the whitening coating 40 and the end glue can be distinguished more clearly and conveniently when the end glue is positioned using a CCD device, thereby improving the accuracy and convenience of positioning the end glue.
  • the setting of the whitening coating 40 will not cover the active material coating 30, reducing the interference of the whitening coating 40 on the active material coating 30, ensuring that the performance (for example, energy density) of the electrode sheet is not affected.
  • the length of the second region ranges from 50 mm to 200 mm (for example, 50 mm, 70 mm, 100 mm, 120 mm, 150 mm, 170 mm, 200 mm), and the length direction of the second region is parallel to the length direction of the current collector 10 .
  • the length direction of the second region is parallel to the length direction of the current collector 10.
  • the length direction of the second region is the direction of the x-axis shown in FIG1.
  • the length direction of the current collector 10 should be understood as the length direction of the current collector 10 when the electrode sheet is in a flat state before being wound.
  • the length of the second region ranges from 50 mm to 200 mm. Since the length of the second region ranges from 50 mm to 200 mm, the area of the whitening coating 40 is much smaller than the area of the active material coating 30 (i.e., in the same target side, the coating area of the whitening coating is smaller than the coating area of the active material coating), which can reduce the effect of the setting of the whitening coating 40 on the function of the active material coating 30, ensure that the performance of the electrode sheet (e.g., the energy density of the battery) is not affected, and the battery has a higher energy density while ensuring the safety performance of the battery.
  • the performance of the electrode sheet e.g., the energy density of the battery
  • the sum of the coating area of the whitening coating and the coating area of the active material coating is greater than the area of the target side of the protective coating.
  • the protective coating can be prevented from directly contacting the electrolyte, reducing the risk of gas generation, thereby reducing the high-temperature expansion rate of the battery.
  • the resistivity range of the conductive powder is 0.01 ⁇ m to 10 ⁇ m (for example, 0.01 ⁇ m, 0.05 ⁇ m, 0.1 ⁇ m, 0.15 ⁇ m, 0.2 ⁇ m, 0.25 ⁇ m, 0.3 ⁇ m, 0.35 ⁇ m, 0.4 ⁇ m, 0.45 ⁇ m, 0.5 ⁇ m, 0.55 ⁇ m, 0.6 ⁇ m, 0.65 ⁇ m, 0.7 ⁇ m, 0.75 ⁇ m, 0.8 ⁇ m, 0.85 ⁇ m, 0.9 ⁇ m, 0.95 ⁇ m, 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, 9 ⁇ m, 10 ⁇ m).
  • the resistivity of the conductive powder is in the range of 0.1 ⁇ cm to 1 ⁇ m.
  • the resistivity of the conductive powder is in the range of 0.01 ⁇ m to 10 ⁇ m, or preferably, the resistivity of the conductive powder is in the range of 0.1 ⁇ cm to 1 ⁇ m.
  • the specific material of the conductive agent is not limited herein.
  • the conductive agent includes at least one of the following: conductive carbon black, acetylene black, graphite, graphene, carbon nanotubes and carbon nanofibers.
  • the binder includes at least one of the following: polyvinylidene difluoride (PVDF), acrylic modified PVDF, polyacrylate polymer, polyimide, styrene butadiene rubber and styrene acrylic rubber.
  • PVDF polyvinylidene difluoride
  • acrylic modified PVDF acrylic modified PVDF
  • polyacrylate polymer polyacrylate polymer
  • polyimide polyimide
  • styrene butadiene rubber styrene acrylic rubber
  • the proportion of the binder in the protective coating 20 is greater than the proportion of the binder included in the active material coating 30, thereby further improving the bonding force between the protective coating 20 and the current collector 10. The risk of the protective coating 20 falling off when subjected to external force is reduced.
  • the electrode sheet is applied to the winding core, including: a current collector 10, a protective coating 20 and an active material coating 30, the current collector 10 includes a first side surface and a second side surface disposed opposite to each other; the protective coating 20 is coated on the first side surface and/or the second side surface, and the protective coating 20 includes a conductive powder, a conductive agent and an adhesive.
  • the protective coating 20 includes a conductive powder and a conductive agent, the protective coating 20 has better conductive properties, and thus the electrode sheet has better electrical properties.
  • the protective coating 20 includes an adhesive, the bonding performance between the protective coating 20 and the current collector 10 is improved, reducing the probability of the protective coating 20 falling off during mechanical abuse.
  • the present disclosure also provides a winding core, including the above-mentioned electrode sheet.
  • the electrode sheet is the electrode sheet in the above-mentioned embodiment, and the specific structure can refer to the description in the above-mentioned embodiment, which will not be repeated here. Since the electrode sheet in the above-mentioned embodiment is used in the present disclosure, the winding core provided by the present disclosure has all the beneficial effects of the electrode sheet in the above-mentioned embodiment.
  • the above-mentioned electrode sheet is used as the positive electrode sheet.
  • the winding core includes the electrode sheet, the separator and the negative electrode sheet in the above-mentioned embodiment.
  • the electrode sheet, the separator and the negative electrode sheet in the above-mentioned embodiment are stacked in sequence and wound to form a winding core.
  • a protective coating 20 is provided on the current collector 10 of the positive electrode sheet to avoid a short circuit between the current collector 10 of the positive electrode sheet and the negative electrode sheet during mechanical abuse, thereby improving the safety of the battery.
  • the second regions of the protective coating 20 on both sides are coated with the whitening coating 40 .
  • a second region of the protective coating 20 on one side is coated with a whitening coating 40 , and the whitening coating 40 is located in the second region away from the center of the winding core.
  • the present disclosure also provides a battery, the battery comprising the above-mentioned winding core. It should be noted that the battery provided by the present disclosure includes all the technical features in the above-mentioned winding core embodiment and can achieve the same technical effect. To avoid repetition, it will not be repeated here.
  • the battery provided by the present disclosure can be applied to electronic devices, or used as a power battery to provide power for electric vehicles, electric trains, electric bicycles, golf carts and other power vehicles.
  • the electronic device can be a mobile phone, a tablet computer (Tablet Personal Computer), a laptop computer (Laptop Computer) or a notebook computer, a personal digital assistant (Personal Digital Assistant, PDA), a handheld computer, a netbook, an ultra-mobile personal computer (ultra-mobile personal computer, UMPC), a mobile Internet device (Mobile Internet Device, MID), a wearable device (Wearable Device) or a vehicle-mounted device (Vehicle User Equipment, VUE), a pedestrian terminal (Pedestrian User Equipment, PUE) and other terminal side devices, and the wearable device includes: smart watches, bracelets, headphones, glasses, etc. It should be noted that the specific types of the above electronic devices are not limited in the embodiments of the present application.
  • the following will take a specific embodiment as an example to illustrate the structure, preparation process and effect of the electrode sheet, winding core and battery provided by the embodiment of the present disclosure.
  • the preparation process of the electrode sheet, winding core and battery is introduced.
  • the protective coating 20 slurry prepared by stirring. Specifically, 90% by weight of conductive titanium dioxide (ATO-coated TiO 2 ), 2% by weight of carbon black, 1% by weight of carbon nanoparticles and 7% by weight of PVDF were mixed, a certain amount of N-methylpyrrolidone (NMP) was added, the solid content of the slurry was adjusted to 40%, and the protective coating 20 slurry was prepared by stirring.
  • ATO-coated TiO 2 conductive titanium dioxide
  • carbon black 2% by weight of carbon black
  • 1% by weight of carbon nanoparticles and 7% by weight of PVDF were mixed, a certain amount of N-methylpyrrolidone (NMP) was added, the solid content of the slurry was adjusted to 40%, and the protective coating 20 slurry was prepared by stirring.
  • NMP N-methylpyrrolidone
  • the whitening coating 40 slurry is prepared. Specifically, 90% by mass of boehmite and 10% by mass of PVDF are mixed, a certain amount of NMP is added, the solid content of the slurry is adjusted to 40%, and the whitening coating 40 slurry is prepared by stirring.
  • the active material coating 30 of the positive electrode sheet can be prepared using the formula in the related art. Specifically, in this embodiment, 96% by mass of lithium cobalt oxide, 1% by mass of carbon black + 1% by mass of carbon nanotubes and 2% by mass of PVDF are mixed, a certain amount of NMP is added, the solid content of the slurry is adjusted to 70%, and the active material coating 30 slurry of the positive electrode sheet is prepared after stirring.
  • the active material coating 30 of the negative electrode sheet can be selected from Specifically, in this embodiment, 96% by mass of artificial graphite, 1% by mass of carbon black, 1.5% by mass of styrene-butadiene rubber and 1.5% by mass of sodium carboxymethyl cellulose are mixed, deionized water is added, the solid content of the slurry is adjusted to 40%, and the active material coating 30 slurry of the negative electrode sheet is prepared by stirring.
  • the prepared protective coating 20 slurry is coated on two opposite sides of the positive electrode current collector 10, and then the prepared whitening coating 40 slurry is coated on the second area of the protective coating 20, and then the active material coating 30 slurry of the positive electrode sheet is coated on the second area on the protective coating 20, and the positive electrode sheet is obtained after drying. See Table 1 for details.
  • Preparation of negative electrode sheet Specifically, the prepared active material coating 30 slurry of the negative electrode sheet is coated on the negative electrode collector 10 by an extrusion coating process to obtain a negative electrode sheet.
  • the aluminum-plastic film is punched out using a punching mold, and then the rolled core or stacked core is packaged with the punched aluminum-plastic film to obtain a battery cell, which is baked until the moisture content is qualified and then injected with electrolyte.
  • the battery cell is sealed for the second time and folded to basically form the battery cell.
  • Example 1 The method is carried out in accordance with Example 1, except that a whitening coating is coated on the second area of the protective coating on one side and the whitening coating is located in the second area away from the center of the winding core.
  • a whitening coating is coated on the second area of the protective coating on one side and the whitening coating is located in the second area away from the center of the winding core.
  • Example 1 The method is carried out in accordance with Example 1, except that a whitening coating is coated on the second area of the protective coating on one side and the whitening coating is located in the second area close to the center of the winding core.
  • a whitening coating is coated on the second area of the protective coating on one side and the whitening coating is located in the second area close to the center of the winding core.
  • This group of embodiments is used to illustrate the impact when A-B changes.
  • This group of examples is used to illustrate the effects produced when the thickness of the whitening coating is changed.
  • This example group was carried out with reference to Example 1, except that the thickness of the whitening coating was changed, as shown in Table 1 for details.
  • Example 2 This example is carried out with reference to Example 1, except that the sum of the coating area of the whitening coating and the coating area of the active material coating is smaller than the area of the target side of the protective coating, see Table 1 for details.
  • This embodiment is carried out with reference to embodiment 1, except that the coating area of the whitening coating and the coating area of the active material coating are changed, wherein the sum of the coating area of the whitening coating and the coating area of the active material coating is equal to the area of the target side of the protective coating, see Table 1 for details.
  • the method is carried out with reference to Example 1, except that the two back sides of the current collector 10 of the positive electrode sheet are not coated with the protective coating 20 , that is, the battery in Comparative Example 1 does not include the protective coating 20 .
  • Example 2 The same is carried out as in Example 1, except that the positive electrode sheet is not protected by the whitening coating.
  • the open circuit voltage (Open Circuit Voltage (OCV) test test the K value of the battery, and select products with qualified K value.
  • OCV Open Circuit Voltage
  • the battery prepared in the example and the battery prepared in the comparative example were subjected to a needle puncture test. Specifically, the lithium-ion battery was fully charged (100% SOC), and then placed on the test bench of the needle puncture test equipment. A tungsten steel needle with a diameter of 3 mm and a needle tip length of 3.62 mm was pierced through the middle of the battery at a speed of 100 mm/s. If the battery did not catch fire or explode, the test was considered to have passed.
  • the needle puncture pass situation a/b is used to characterize that in any b needle puncture tests, the number of times the test result is passed is a.
  • a certain number of batteries are manufactured in batches, such as M.
  • the CCD visual inspection system and manual inspection are used to inspect M batteries to determine whether the adhesive position of the finishing tape is qualified.
  • the number of unqualified products determined by the manual inspection is A
  • the number of qualified products determined by the manual inspection is B
  • the recognition rate is [1-(A+B)/M]*100%.
  • the battery After the battery is fully charged, it is discharged to the lowest voltage (usually 3.0V).
  • the discharge energy is recorded as E, and the energy density is E/(L*W*H), where L is the length of the battery, W is the width of the battery, and H is the height of the battery.
  • the battery was stored at 60°C for 30 days.
  • the initial thickness was recorded as D1
  • the thickness after storage was recorded as D2
  • the expansion rate was [(D2-D1)/D1]*100%.

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Abstract

本公开提供一种电极片、卷芯和电池。该电极片应用于卷芯，包括：集流体，集流体包括相背设置的第一侧面和第二侧面；保护涂层，保护涂层包括导电粉体、导电剂和粘接剂，保护涂层包括目标侧面，目标侧面背离所述集流体设置；活性材料涂层包括活性材料；在第一侧面未涂覆有保护涂层，且第二侧面涂覆有保护涂层的情况下，活性材料涂层涂覆在目标侧面和第二侧面；在第一侧面和第二侧面均涂覆有所述保护涂层的情况下，活性材料涂层涂覆在目标侧面；增白涂层涂覆在目标侧面，未涂覆有活性材料涂层的区域设置有增白涂层，增白涂层与卷芯的收尾胶的灰度值之差A为40至80。本公开解决了锂离子电池中收尾胶识别困难以及在高温下容易鼓气的问题。

Description

电极片、卷芯和电池 技术领域
本公开涉及锂离子电池技术领域，尤其涉及一种电极片、卷芯和电池。
发明背景
锂离子电池因具有平台电压高、能量密度大、无记忆效应、寿命长等优点，被广泛应用于各类电子设备。在锂离子电池发生穿刺的情况下，正极、负极和隔膜处于部分断裂的状态。
在锂离子电池发生穿刺使得正极片的活性材料涂层脱落的情况下，铝箔会直接被露出并与负极片接触，增大了锂离子电池热失控的风险。因此，现有技术中锂离子电池在发生刺破等机械破坏情况下的安全性较低。
发明内容
本公开提供一种电极片、卷芯和电池，以解决锂离子电池中收尾胶识别困难以及锂离子电池在高温下容易鼓气的问题。
第一方面，本公开提供了一种电极片，应用于卷芯，包括：
集流体，所述集流体包括相背设置的第一侧面和第二侧面；
保护涂层，所述保护涂层包括目标侧面，目标侧面背离所述集流体设置；
活性材料涂层，所述活性材料涂层包括活性材料；
其中，在所述第一侧面未涂覆有所述保护涂层，且所述第二侧面涂覆有所述保护涂层的情况下，所述活性材料涂层涂覆在所述目标侧面和所述第二侧面；
在所述第一侧面和所述第二侧面均涂覆有所述保护涂层的情况下，所述活性材料涂层涂覆在所述目标侧面；
增白涂层，所述增白涂层涂覆在所述目标侧面，未涂覆有活性材料涂层的区域设置有增白涂层，所述增白涂层与卷芯的收尾胶的灰度值之差A为40至80。
在一实例中，所述保护涂层与卷芯的收尾胶的灰度值之差B为10至30，则A＞B；
和/或，所述目标侧面设有第一区域和第二区域，所述第二区域靠近所述集流体的端部设置，所述活性材料涂层涂覆在所述第一区域，所述增白涂层涂覆在所述第二区域。
在一实例中，所述第二区域的长度的范围为50mm～200mm，所述第二区域的长度方向平行于所述集流体的长度方向。
在一实例中，所述增白涂层的厚度为2μm～20μm，优选为5μm～10μm。
在一实例中，A为50至80；
和/或，B为10至20；
和/或，A-B为30至70。
在一实例中，在同一所述目标侧面中，所述增白涂层的涂覆面积小于所述活性材料涂层的涂覆面积；
和/或，所述增白涂层的涂覆面积与所述活性材料涂层的涂覆面积之和不小于所述保护涂层的目标侧面的面积。
第二方面，本公开还提供了一种卷芯，包括如第一方面所述的电极片。
在一实例中，在所述电极片中，两侧的保护涂层的第二区域涂覆有增白涂层。
在一实例中，在所述电极片中，一侧的保护涂层的第二区域涂覆有增白涂层，增白涂层位于远离卷芯中心的第二区域。
第三方面，本公开还提供了一种电池，包括如第二方面所述的卷芯。
在本公开中，电极片，应用于卷芯，包括：集流体、保护涂层和活性材料涂层，集流体包括相背设置的第一侧面和第二侧面；保护涂层涂覆在第一侧面和/或第二侧面。通过保护涂层的设置，为集流体提供了多一层的保护，降低了集流体露出的风险，降低了与负极活性层接触的可能性，提高了电池的安全性。同时，通过设置增白涂层，限定增白涂层与卷芯的收尾胶的灰度值之差A为40至80，增大了增白涂层与卷芯的收尾胶的灰度值，在利用CCD设备定位收尾胶时可以更 明显和便捷地区分增白涂层和收尾胶，增加识别度，从而提高了定位收尾胶的准确度和便捷度；并且，增白涂层涂覆在所述目标侧面，未涂覆有活性材料涂层的区域设置有增白涂层，避免保护涂层与电解液接触，从而降低保护涂层与电解液之间的副反应，改善高温鼓气，降低电池的膨胀率。
附图说明
为了更清楚地说明本公开实施例的技术方案，下面将对本公开实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本公开的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动性的前提下，还可以根据这些附图获取其他的附图。
图1是本公开实施例提供的电极片的剖面示意图之一；
图2是本公开实施例提供的电极片的剖面示意图之二；
图3是本公开实施例提供的电极片的剖面示意图之三；
图4是本公开实施例提供的电极片的剖面示意图之四；
图5是本公开实施例提供的电极片的剖面示意图之五；
图6是本公开实施例提供的电极片的剖面示意图之六；
图7是本公开实施例提供的卷芯的结构示意图之一；
图8是本公开实施例提供的卷芯的结构示意图之二。
具体实施方式
下面将结合本公开实施例中的附图，对本公开实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本公开一部分实施例，而不是全部的实施例。基于本公开中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获取的所有其他实施例，都属于本公开保护的范围。
除非另作定义，本公开中使用的技术术语或者科学术语应当为本公开所属领域内具有一般技能的人士所理解的通常意义。本公开中使用的“第一”、“第二” 以及类似的词语并不表示任何顺序、数量或者重要性，而只是用来区分不同的组成部分。“上”、“下”、“左”、“右”等仅用于表示相对位置关系，当被描述对象的绝对位置改变后，则该相对位置关系也相应地改变。本文中，在没有特别说明的情况下，数据范围均包括端点。
如图1-图6所示，本公开提供了一种电极片，应用于卷芯，包括：
集流体10，所述集流体10包括相背设置的第一侧面和第二侧面；
保护涂层20，所述保护涂层包括目标侧面，目标侧面背离所述集流体10设置；
活性材料涂层30，所述活性材料涂层30包括活性材料；
其中，在所述第一侧面未涂覆有所述保护涂层20，且所述第二侧面涂覆有所述保护涂层20的情况下，所述活性材料涂层30涂覆在所述目标侧面和所述第二侧面；
在所述第一侧面和所述第二侧面均涂覆有所述保护涂层20的情况下，所述活性材料涂层30涂覆在所述目标侧面；
增白涂层40，所述增白涂层40涂覆在所述目标侧面，未涂覆有活性材料涂层的区域设置有增白涂层，所述增白涂层(40)与卷芯的收尾胶的灰度值之差A为40至80(例如，40、45、50、55、60、65、70、75、80)。
其中，所述灰度值可以通过CCD视觉检测系统获得。
在一实例中，A为50至80。
请参见图1，在一种情况下，保护涂层20涂覆在集流体10的第一侧面和第二侧面，所述活性材料涂层30涂覆在所述目标侧面(保护涂层20背离所述集流体10的侧面)。具体地，在两侧的保护涂层20的目标侧面均涂覆有活性材料涂层30。
请参见图2，在另一种情况下，保护涂层20仅涂覆在集流体10的第一侧面，所述活性材料涂层30涂覆在所述保护涂层20的目标侧面以及所述集流体10的第二侧面。
需要说明的是，第一侧面和第二侧面仅用于区分集流体10相背设置的两个侧面，保护涂层20仅涂覆在集流体10的第二侧面的情况可以参见保护涂层20仅涂覆在集流体10的第一侧面的情况，为了避免重复，在此不做赘述。
应理解的是，所述集流体10的具体结构在此不做限定。示例性地，在一实施例中，集流体10为铝箔。
应理解的是，活性材料涂层30包括的活性材料在此不做限定。在具体实现时，所述活性材料涂层30可以采用相关技术中常用的活性材料。示例性地，在一实施例中，活性材料涂层30包括钴酸锂、乙炔黑和聚偏氟乙烯。
所述保护涂层20包括导电粉体、导电剂和粘接剂，其中，所述导电粉体、导电剂和粘接剂的具体比例在此不做限定。由于保护涂层包括导电粉体和导电剂，使得保护涂层具有较好的导电性能，进而使得电极片具有较好的电性能。同时，由于保护涂层包括粘结剂，提高了保护涂层与集流体之间的粘结性能，降低了在机械滥用时保护涂层脱落的概率。
应理解的是，所述导电粉体的具体结构在此不做限定，所述导电粉体可以理解为具有导电性的粉体。在本实施例，保护涂层20采用导电粉体为主料，可以使保护涂层20具有较好的导电能力，进而使锂离子电池具有较好的电性能。
可选地，在一实施例中，所述导电粉体包括无机颗粒和导电包覆层，所述导电包覆层包裹所述无机颗粒。
在本实施例中，所述导体粉体可以理解为是以无机颗粒为核，以导电包覆层为壳的复合导电材料。
可选地，在一实施例中，所述导电包覆层为金属氧化物，或，杂质元素掺杂的金属氧化物。其中，金属氧化物可以为任意金属氧化物，金属氧化物内掺杂的杂质元素也可以为任意元素。例如，在一实施例中，导电包覆层为掺杂锑(Sb)元素的氧化锡(SnO2)，或称为氧化锡锑(Antimony Doped Tin Oxide，ATO)。在另一实施例中，导电包覆层为掺杂氟(F)元素的SnO2，或称为TCO导电玻璃(FTO)。导电包覆层为掺杂锡(Sn)元素的氧化铟(In2O3)，或称为氧化铟锡 (Indium tin oxide，ITO)。
可选地，在一实施例中，导电粉体包括的无机颗粒也可以为任意无机颗粒。例如，在一实施例中，导电粉体包括的无机颗粒包括以下至少一者：二氧化钛、氧化锌、云母粉、石英粉、重晶石、氧化铝、勃姆石、氧化镁和氧化硅。
可选地，在一实施例中，所述导电粉体的Dv50小于5μm(例如，5μm、4.5μm、4μm、3.5μm、3μm、2.5μm、2μm、1.5μm、1μm、0.5μm、0.1μm)。更进一步地，在一实施例中，所述导电粉体的Dv50小于4μm。可选地，在另一实施例中，所述导电粉体的Dv50小于1μm。
应理解，Dv50可以理解为一个样品的累计体积粒度分布百分数达到50％时所对应的粒径。它的物理意义是粒径大于它的颗粒占50％，小于它的颗粒也占50％，因此Dv50也叫中位径或中值粒径。
需要说明的是，活性材料涂层30包括的活性材料的Dv50通常为15μm。在本实施例中，导电粉体的Dv50远小于活性材料涂层30包括的活性材料的Dv50。由此可知，保护涂层20所包括的材料的D50更小，因此在机械滥用导致活性材料涂层30断裂时，保护涂层20断裂的概率较小，从而可以降低集流体10露出的概率，提高电池的安全性。
在一实例中，所述保护涂层20与卷芯的收尾胶的灰度值之差B为10至30(例如，10、12、15、17、20、22、25、27、30)，则A＞B。
在一实例中，B为10至20。
在一实例中，A-B为30至70(例如，30、35、40、45、50、55、60、65、70)。
所述目标侧面设有第一区域和第二区域，所述第二区域靠近所述集流体10的端部设置，在卷芯中，所述端部为所述卷芯中远离卷芯中心的尾部，所述活性材料涂层30涂覆在所述第一区域，所述增白涂层40涂覆在所述第二区域。
在一实施例中，电极片还包括增白涂层40，示例性地，在一实施例中，增白涂层40包括无机颗粒。更进一步地，在另一实施例中，增白涂层40包括的无机 颗粒包括以下至少一者：氧化铝、勃姆石、氧化镁、氧化钛、氧化锌和氧化硅。
请参见图3，在一种情况下，保护涂层20涂覆在集流体10的第一侧面和第二侧面，所述增白涂层40和活性材料涂层30涂覆在所述目标侧面。具体地，在两侧的保护涂层20的第一区域均涂覆有活性材料涂层30，在两侧的保护涂层20的第二区域均涂覆有增白涂层40。此时，保护涂层被增白涂层和活性材料涂层全部覆盖，从而使保护涂层与电解液之间不会直接接触，改善了保护涂层与电解液接触发生副反应引起的产气的问题，进而减低了电池的膨胀率。
当然，如图4所示，在一实施例中，也可以仅一侧的保护涂层20的第二区域涂覆有增白涂层40。
在如图4所示的实施例下，两侧的保护涂层20中仅一侧的保护涂层20的第二区域涂覆有增白涂层40，增白涂层40位于远离卷芯中心的第二区域。此时，增白涂层可以降低在电池发生刺破等机械破坏的情况下短路的风险，例如，正极集流体与负极活性材料涂层接触，或者负极集流体与正极活性材料涂层接触，从而可以提高电池的安全性能。
在另一实施例中，如图5所示，未涂覆有增白涂层40的保护涂层20未完全覆盖集流体10。如图7所示，在卷芯收尾时，集流体10未被保护涂层20覆盖的区域面向卷芯内部，在穿刺的时候此处难以与钉子短路，且与其接触的也为正极片，与负极短路的几率也较低，安全的风险小。
请参见图6，在另一种情况下，保护涂层20仅涂覆在集流体10的第一侧面，所述活性材料涂层30和增白涂层40涂覆在所述目标侧面。具体地，在保护涂层20的第一区域涂覆有活性材料涂层30，在保护涂层20的第二区域涂覆有增白涂层40，增白涂层40位于远离卷芯中心的第二区域。
需要说明的是，图1-图6中所示的电极片示意图仅用于说明集流体10、保护涂层20、活性材料涂层30和增白涂层40之间的相对位置，以上各个涂层的宽度和长度等仅用于示意，不表征集流体10、保护涂层20、活性材料涂层30和增白涂层40的长度或宽度的信息或对应关系。
需要说明的是，本公开提供的电极片应用于卷芯，基于电极片制备卷芯的具体流程可以参见相关技术中的说明，为了避免重复，在此不做赘述。为了方便理解，下面仅对收尾胶进行简要说明。
在基于电极片制备卷芯的过程中，需要卷绕所述电极片且在卷绕后形成的卷芯的收尾处粘接收尾胶。因此，收尾胶位于卷芯的端部，且与卷芯的最外圈远离卷芯中心的表面粘接固定。
在一实施例中，所述第二区域靠近所述集流体10的端部设置，所述增白涂层40涂覆在第二区域，因此可以理解为，卷芯的最外圈远离卷芯中心的表面设有增白涂层40，且增白涂层40位于卷芯的端部。在卷芯收尾处粘接收尾胶时，收尾胶50将与增白涂层40连接，且覆盖部分增白涂层40，请参见图8。
在具体实现时，保护涂层20包括导电粉体、导电剂和粘接剂，保护涂层20与收尾胶的灰度值之差通常较小，因此，利用电荷耦合器件(Charge Coupled Device，CCD)设备定位收尾胶时，难以区分保护涂层20和收尾胶。
通过本公开中增白涂层40的设置，增大了增白涂层40与卷芯的收尾胶的灰度值，在利用CCD设备定位收尾胶时可以更明显和便捷地区分增白涂层40和收尾胶，从而提高了定位收尾胶的准确度和便捷度。同时，增白涂层40的设置不会覆盖活性材料涂层30，减少了增白涂层40对活性材料涂层30的干涉，保证了电极片的性能(例如，能量密度)不受影响。
可选地，在一实施例中，所述第二区域的长度的范围为50mm～200mm(例如，50mm、70mm、100mm、120mm、150mm、170mm、200mm)，所述第二区域的长度方向平行于所述集流体10的长度方向。
应理解的是，所述第二区域的长度方向平行于所述集流体10的长度方向。例如，如图1中所示的直角坐标系为例，第二区域的长度方向为图1中所示的x轴的方向。
应理解的是，集流体10的长度方向应理解为在电极片未卷绕前，处于平铺状态的情况下，所述集流体10的长度方向。
在一实施例中，第二区域的长度的范围为50mm～200mm。由于第二区域的长度范围为50mm～200mm，因此增白涂层40的面积远小于活性材料涂层30的面积(即，在同一所述目标侧面中，所述增白涂层的涂覆面积小于所述活性材料涂层的涂覆面积)，这样可以降低了增白涂层40的设置对活性材料涂层30功能的影响，保证了电极片的性能(例如，电池的能量密度)不受影响，在保证电池的安全性能的情况下，使电池具有较高的能量密度。
可选地，在一实施例中，所述增白涂层的涂覆面积与所述活性材料涂层的涂覆面积之和大于所述保护涂层的目标侧面的面积。此时可以避免保护涂层与电解液直接接触，降低产气的风险，从而降低电池的高温膨胀率。
可选地，在一实施例中，所述导电粉体的电阻率范围为0.01Ω·m～10Ω·m(例如，0.01Ω·m、0.05Ω·m、0.1Ω·m、0.15Ω·m、0.2Ω·m、0.25Ω·m、0.3Ω·m、0.35Ω·m、0.4Ω·m、0.45Ω·m、0.5Ω·m、0.55Ω·m、0.6Ω·m、0.65Ω·m、0.7Ω·m、0.75Ω·m、0.8Ω·m、0.85Ω·m、0.9Ω·m、0.95Ω·m、1Ω·m、2Ω·m、3Ω·m、4Ω·m、5Ω·m、6Ω·m、7Ω·m、8Ω·m、9Ω·m、10Ω·m)。可选地，在另一实施例中，所述导电粉体的电阻率范围为0.1Ω·cm～1Ω·m。
在一实施例中，导电粉体的电阻率范围为0.01Ω·m～10Ω·m，或优选地，导电粉体的电阻率范围为0.1Ω·cm～1Ω·m。通过上述设置，使得保护涂层20具有较好的导电能力，进而使得锂离子电池具有较好的电性能。
应理解的是，所述导电剂的具体材料在此不做限定。例如，在一实施例中，所述导电剂的包括以下至少一者：导电炭黑、乙炔黑、石墨、石墨烯、碳纳米管和碳纳米纤维。
应理解的是，所述粘结剂的具体材料在此不做限定。例如，在一实施例中，所述粘结剂包括以下至少一者：聚偏二氟乙烯(polyvinylidene difluoride，PVDF)、丙烯酸改性PVDF、聚丙烯酸酯类聚合物、聚酰亚胺、丁苯橡胶和苯丙橡胶。
可选地，在一实施例中，保护涂层20内粘结剂的比例大于活性材料涂层30包括的粘接剂的比例，从而进一步地提高保护涂层20与集流体10之间的黏结力， 降低保护涂层20在受到外力作用时脱落的风险。
在本一实施例中，电极片，应用于卷芯，包括：集流体10、保护涂层20和活性材料涂层30，集流体10包括相背设置的第一侧面和第二侧面；保护涂层20涂覆在第一侧面和/或第二侧面，保护涂层20包括导电粉体、导电剂和粘接剂。通过保护涂层20的设置，为集流体10提供了多一层的保护，降低了集流体10露出的风险。由于保护涂层20包括导电粉体和导电剂，使得保护涂层20具有较好的导电性能，进而使得电极片具有较好的电性能。同时，由于保护涂层20包括粘结剂，提高了保护涂层20与集流体10之间的粘结性能，降低了在机械滥用时保护涂层20脱落的概率。
本公开还提供了一种卷芯，包括上述的电极片。在一实施例中，该电极片为上述实施例中的电极片，具体结构可以参照上述实施例中的描述，在此不再赘述。由于在本公开中采用了上述实施例中的电极片，因此本公开提供的卷芯具有上述实施例中电极片的全部有益效果。
需要说明的是，在机械滥用时，正极片的集流体10与负极片发生接触造成的热失控风险较大。因此，在一实施例中，上述的电极片用作正极片。具体地，在一实施例中，卷芯包括上述实施例中的电极片、隔膜和负极片。上述实施例中的电极片、隔膜和负极片依次层叠设置并卷绕形成卷芯。在本实施例中，在正极片的集流体10上设置保护涂层20，可以避免机械滥用时，正极片的集流体10与负极片发生短路，提高了电池的安全性。
在一实例中，在所述电极片中，两侧的保护涂层20的第二区域涂覆有增白涂层40。
在一实例中，在所述电极片中，一侧的保护涂层20的第二区域涂覆有增白涂层40，增白涂层40位于远离卷芯中心的第二区域。
本公开还提供了一种电池，所述电池包括上述卷芯。需要说明的是，本公开所提供的电池包括上述卷芯的实施例中的全部技术特征，并能达到相同的技术效果，为避免重复，此处不再赘述。
需要说明的是，本公开提供的电池，可应用于电子设备，或作为动力电池为电动汽车、电动列车、电动自行车、高尔夫球车等动力车提供动力。
其中，电子设备可以是手机、平板电脑(Tablet Personal Computer)、膝上型电脑(Laptop Computer)或称为笔记本电脑、个人数字助理(Personal Digital Assistant，PDA)、掌上电脑、上网本、超级移动个人计算机(ultra-mobile personal computer，UMPC)、移动上网装置(Mobile Internet Device，MID)、可穿戴式设备(Wearable Device)或车载设备(Vehicle User Equipment，VUE)、行人终端(Pedestrian User Equipment，PUE)等终端侧设备，可穿戴式设备包括：智能手表、手环、耳机、眼镜等。需要说明的是，在本申请实施例并不限定上述电子设备的具体类型。
为了方便理解，下面将以具体的实施例为例，对本公开实施例提供的电极片、卷芯和电池的结构、制备过程以及效果进行说明。首先介绍电极片、卷芯和电池的制备过程。
实施例1
制备保护涂层20浆料。具体地，将90％质量的导电钛白粉(ATO包覆的TiO2)、2％质量的炭黑、1％质量的碳纳米和7％质量的PVDF混合，加入一定量的N-甲基吡咯烷酮(N-Methylpyrrolidone，NMP)，将浆料的固含量调整至40％，经过搅拌配制成保护涂层20浆料。
制备增白涂层40浆料。具体地，将90％质量的勃姆石和10％质量的PVDF混合，加入一定量的NMP，将浆料的固含量调整至40％，经过搅拌配制成增白涂层40浆料。
制备正极片的活性材料涂层30浆料。正极片的活性材料涂层30可以选用相关技术中的配方。具体地，在本实施例中，将96％质量的钴酸锂、1％质量的炭黑+1％质量的碳纳米管和2％质量的PVDF混合，加入一定量的NMP，将浆料的固含量调整至70％，经过搅拌配制成正极片的活性材料涂层30浆料。
制备负极片的活性材料涂层30浆料。负极片的活性材料涂层30可以选用相 关技术中的配方。具体地，在本实施例中，将96％质量的人造石墨、1％质量的炭黑、1.5％质量的丁苯橡胶和1.5％质量的羧甲基纤维素钠混合，加入去离子水，将浆料的固含量调整至40％，经搅拌制备成负极片的活性材料涂层30浆料。
正极片制备。具体地，将制备好的保护涂层20浆料涂覆在正极集流体10的两相对侧上，再将制备好的增白涂层40浆料涂覆在保护涂层20的第二区域，然后将正极片的活性材料涂层30浆料涂覆在保护涂层20上的第二区域，烘干后得到正极片。具体参见表1。
负极片制备。具体地，将制备好的负极片的活性材料涂层30浆料通过挤压涂布的工艺涂覆在负极集流体10上得到负极片。
使用辊压机将正负极片分别辊压到设计厚度，并使用分条机将正负极片分切至设计宽度，然后在极片上焊接极耳并贴上保护胶纸。
将隔膜放在正极片和负极片中间进行卷绕或者叠片，得到卷芯或叠芯，并贴上胶纸固定。
使用冲型模具将铝塑膜进行冲型，然后使用冲型的铝塑膜将卷芯或叠芯封装起来，得到电芯，烘烤至水分合格，注入电解液。
使用锂离子电池化成设备，对电芯进行充放电，使电芯硬化，并分选出电芯的容量。
电芯进行二次封口，并进行折边，使电芯基本成型。
实施例2组
实施例2a
参照实施例1进行，所不同的是，在一侧保护涂层的第二区域涂覆有增白涂层且增白涂层位于远离卷芯中心的第二区域，具体参见表1。
实施例2b
参照实施例1进行，所不同的是，在一侧保护涂层的第二区域涂覆有增白涂层且增白涂层位于靠近卷芯中心的第二区域，具体参见表1。
实施例3组
本组实施例用于说明当A-B发生改变时产生的影响。
本实施例组参照实施例1进行，所不同的是，通过调整A和/或B改变A-B，具体参见表1。
实施例4组
本组实施例用于说明当增白涂层的厚度发生改变时产生的影响。
本实施例组参照实施例1进行，所不同的是，改变增白涂层的厚度，具体参见表1。
实施例5
本实施例参照实施例1进行，所不同的是，增白涂层的涂覆面积与活性材料涂层的涂覆面积之和小于保护涂层的目标侧面的面积，具体参见表1。
实施例6
本实施例参照实施例1进行，所不同的是，改变增白涂层的涂覆面积及活性材料涂层的涂覆面积，其中增白涂层的涂覆面积与活性材料涂层的涂覆面积之和等于保护涂层的目标侧面的面积，具体参见表1。
对比例1
参照实施例1进行，所不同的是，正极片的集流体10的两相背侧均未涂覆有保护涂层20，即对比例1中的电池不包括保护涂层20。
对比例2
参照实施例1进行，所不同的是，所述正极片不保护增白涂层。
对比例3
参照实施例1进行，所不同的是，A为20，B为20即A＝B。
表1

*表示同实施例1；
-表示不存在。
测试例
为了测试实施例制备得到的电池的性能，以及对比例制备得到的电池的性能，对实施例制备得到的电池以及对比例制备得到的电池分别进行开路电压(Open  Circuit Voltage，OCV)测试，测试出电池的K值，挑选出K值合格的产品。
(1)针刺测试
对实施例制备得到的电池以及对比例制备得到的电池分别进行针刺测试。具体地，将锂离子电池充满电(100％SOC)，然后将其放入针刺测试设备的测试台上，将直径为3mm，针尖长度为3.62mm的钨钢针，以100mm/s的速度刺穿电池中间，电池不起火、不爆炸视为测试通过，针刺通过情况a/b用于表征在任意b次针刺测试中，测试结果为通过的次数为a。
(2)识别率测试
电池批量制造一定数量，如M，分别通过CCD视觉检测系统和人工全检对数量为M的电池进行检查判定收尾胶纸的贴胶位置是否合格，CCD视觉检查系统判定的合格品中通过人工全检判定为不合格品数量为A，CCD视觉检查系统判定的不合格品中通过人工全检判定为合格品数量为B，识别率为[1-(A+B)/M]*100％。
(3)能量密度测试
电池充满电后放电至最低电压(一般为3.0V)，放电能量记为E，能量密度为E/(L*W*H),L为电池的长度，W为电池的宽度，H为电池的高度。
(4)膨胀率测试
电池在60℃高温环境下储存30D，初始的厚度记为D1，储存后的厚度记为D2，膨胀率为[(D2-D1)/D1]*100％。
对实施例1～实施例25制备得到的电池以及对比例1～对比例3制备得到的电池的性能测试结果如表2所示。
表2

以上，仅为本公开的具体实施方式，但本公开的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本公开揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本公开的保护范围之内。因此，本公开的保护范围应以权利要求的保护范围为准。

Claims (14)

  1. 一种电极片，应用于卷芯，其特征在于，包括：
    集流体(10)，所述集流体(10)包括相背设置的第一侧面和第二侧面；
    保护涂层(20)，所述保护涂层包括目标侧面，目标侧面背离所述集流体(10)设置；
    活性材料涂层(30)，所述活性材料涂层(30)包括活性材料；
    其中，在所述第一侧面未涂覆有所述保护涂层(20)，且所述第二侧面涂覆有所述保护涂层(20)的情况下，所述活性材料涂层(30)涂覆在所述目标侧面和所述第二侧面；
    在所述第一侧面和所述第二侧面均涂覆有所述保护涂层(20)的情况下，所述活性材料涂层(30)涂覆在所述目标侧面；
    增白涂层(40)，所述增白涂层(40)涂覆在所述目标侧面，未涂覆有活性材料涂层的区域设置有增白涂层，所述增白涂层(40)与卷芯的收尾胶的灰度值之差A为40至80。
  2. 根据权利要求1所述的电极片，其特征在于，所述保护涂层(20)与卷芯的收尾胶的灰度值之差B为10至30，则A＞B；
    和/或，所述目标侧面设有第一区域和第二区域，所述第二区域靠近所述集流体(10)的端部设置，所述活性材料涂层(30)涂覆在所述第一区域，所述增白涂层(40)涂覆在所述第二区域。
  3. 根据权利要求2所述的电极片，其特征在于，所述第二区域的长度的范围为50mm～200mm，所述第二区域的长度方向平行于所述集流体(10)的长度方向。
  4. 根据权利要求1-3中任一项所述的电极片，其特征在于，所述增白涂层的厚度为2μm～20μm，优选为5μm～10μm。
  5. 根据权利要求1-4中任一项所述的电极片，其特征在于，A为50至80；
    和/或，B为10至20；
    和/或，A-B为30至70。
  6. 根据权利要求1-5中任一项所述的电极片，其特征在于，在同一所述目标侧面中，所述增白涂层的涂覆面积小于所述活性材料涂层的涂覆面积；
    和/或，所述增白涂层的涂覆面积与所述活性材料涂层的涂覆面积之和大于等于所述保护涂层的目标侧面的面积。
  7. 根据权利要求1-6中任一项所述的电极片，其特征在于，所述保护涂层(20)包括导电粉体、导电剂和粘接剂，所述导电粉体的Dv50小于5μm，优选为小于1μm。
  8. 根据权利要求7所述的电极片，其特征在于，所述导电粉体的电阻率范围为0.01Ω·m～10Ω·m，优选为0.1Ω·m～1Ω·m。
  9. 根据权利要求7或8所述的电极片，其特征在于，所述导电粉体包括无机颗粒和导电包覆层，所述导电包覆层包裹所述无机颗粒。
  10. 根据权利要求9所述的电极片，其特征在于，所述导电包覆层为金属氧化物，或，杂质元素掺杂的金属氧化物；
    和/或，所述无机颗粒包括以下至少一者：二氧化钛、氧化锌、云母粉、石英粉、重晶石、氧化铝、勃姆石、氧化镁和氧化硅。
  11. 一种卷芯，其特征在于，包括如权利要求1-10中任一项所述的电极片。
  12. 根据权利要求11所述的卷芯，其特征在于，在所述电极片中，两侧的保护涂层(20)的第二区域涂覆有增白涂层(40)。
  13. 根据权利要求11所述的卷芯，其特征在于，在所述电极片中，一侧的保护涂层(20)的第二区域涂覆有增白涂层(40)，增白涂层(40)位于远离卷芯中心的第二区域。
  14. 一种电池，其特征在于，包括如权利要求11-13中任一项所述的卷芯。
PCT/CN2023/130790 2022-11-09 2023-11-09 电极片、卷芯和电池 Ceased WO2024099397A1 (zh)

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