WO2022143859A1 - 一种极片和锂离子电池 - Google Patents

一种极片和锂离子电池 Download PDF

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Publication number
WO2022143859A1
WO2022143859A1 PCT/CN2021/142831 CN2021142831W WO2022143859A1 WO 2022143859 A1 WO2022143859 A1 WO 2022143859A1 CN 2021142831 W CN2021142831 W CN 2021142831W WO 2022143859 A1 WO2022143859 A1 WO 2022143859A1
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Prior art keywords
active layer
pole piece
groove
current collector
thickness
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PCT/CN2021/142831
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English (en)
French (fr)
Inventor
孙雷明
张健
张双虎
彭冲
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珠海冠宇电池股份有限公司
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Application filed by 珠海冠宇电池股份有限公司 filed Critical 珠海冠宇电池股份有限公司
Priority to JP2022580864A priority Critical patent/JP2023531306A/ja
Priority to KR1020237004963A priority patent/KR20230043125A/ko
Priority to EP21914590.1A priority patent/EP4160721A1/en
Publication of WO2022143859A1 publication Critical patent/WO2022143859A1/zh
Priority to US18/146,308 priority patent/US20230125464A1/en

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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
    • 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
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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
    • 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
    • H01M10/0585—Construction or manufacture of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat 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
    • 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
    • H01M4/04—Processes of manufacture in general
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • 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
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/139—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • 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
    • H01M4/621—Binders
    • 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
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • 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
    • 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
    • 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
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • 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
    • H01M4/70—Carriers or collectors characterised by shape or form
    • 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
    • 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

Definitions

  • the invention relates to a pole piece and a lithium ion battery, and relates to the technical field of lithium ion batteries.
  • lithium-ion batteries are developing in the direction of high energy density and fast charging rate.
  • connection position of the tabs is adjusted from the edge of the pole piece to the middle position on the side of the pole piece to reduce the impedance of the lithium-ion battery.
  • the present invention provides a pole piece for solving the problem of poor cycle performance of a lithium ion battery caused by the pole lug connection method.
  • a first aspect of the present invention provides a pole piece, the pole piece includes a current collector, a first active layer, and a second active layer, the first active layer is disposed on the surface of the current collector, and is provided with a first groove , the second active layer is divided into a first part disposed in the first groove and a second part disposed in the first active layer away from the surface of the current collector;
  • the first part is provided with a second groove
  • the tab is disposed at the second groove and is electrically connected with the current collector
  • the thickness of the first part of the second active layer is smaller than that of the first active layer and the second active layer. The total thickness of the second portion of the two active layers.
  • the pole piece used in the prior art usually includes a current collector and an active layer arranged on the surface of the current collector, and a groove is opened in the middle of the side of the active layer, and the groove is connected with a tab in a corresponding area on the current collector , in order to solve the problem of poor cycle performance of the lithium ion battery caused by this kind of tab connection, the present invention reduces the thickness of the active layer around the position where the tab is located.
  • FIG. Figure 1b is a top view of a pole piece provided by an embodiment of the present invention
  • Figure 1c is a left side view of a pole piece provided by an embodiment of the present invention.
  • the pole piece includes a current collector 1 , the first active layer 2, the second active layer 3 and the tabs 4, wherein the first active layer 2 is provided on the surface of the current collector 1, and the first active layer 2 is provided with a first groove, and the second active layer is provided with a first groove.
  • the first part is arranged in the first groove and is in contact with the surface of the current collector 1, the second part of the second active layer is arranged on the upper surface of the first active layer 1 away from the current collector 1, and the first part of the second active layer is in the middle of the side surface
  • a second groove is provided for connecting the tab 4, and the thickness of the first part of the second active layer is less than the total thickness of the first active layer and the second part of the second active layer, so that the thickness of the active layer around the tab is Below the active layer thickness far away from the pole tab area;
  • the definition of the thickness of the pole piece is the same as the prior art, that is, the longest side in the pole piece is the length of the pole piece, the shortest side is the height of the pole piece, and the intermediate The side of the longest side and the shortest side is the width of the pole piece, that is, the longer side in Figure 1a is the length of the pole piece, the shorter side is the height of the pole piece, and the shorter side in Figure 1b is the width of the pole piece, and the
  • the value of the side is the length of the pole piece
  • the value of the high side is the thickness of the pole piece
  • the value of the wide side is the width of the pole piece
  • the length and width of the first groove and the second groove and the pole piece are same as the thickness direction.
  • the thickness of the first active layer should be appropriately reduced, that is, the thickness of the second active layer is greater than the thickness of the first active layer.
  • the first part of the second active layer is arranged in the first groove, the force during the subsequent pole piece rolling process is small, resulting in a difference in thickness between the first part and the second part of the second active layer.
  • the thickness of the first portion of the second active layer is greater than the thickness of the second portion.
  • the existing coating equipment needs to be improved to ensure the position and area of the first groove, which will not only increase the manufacturing cost, but also be unfavorable for the preparation of other pole piece structures , therefore, the width of the first groove can be increased to make it the same as the width of the current collector, that is, the first groove divides the first active layer into two independent parts, and the blank part in the middle is the first groove groove.
  • FIG. 2a is a front view of a pole piece provided by another embodiment of the present invention
  • FIG. 2b is a top view of a pole piece provided by another embodiment of the present invention
  • the pole piece includes a current collector 1, a first The active layer 2, the second active layer 3 and the tab 4, the first active layer 1 is provided with a first groove, and the width of the first groove is the same as the width of the current collector 1, that is, the first groove will
  • the layer 2 is divided into left and right parts, the first part of the second active layer 3 is arranged in the first groove, and the second part of the second active layer 3 is arranged on the upper surface of the first active layer 2 away from the current collector 1 , since the width of the first groove is the same as the width of the current collector, the second part of the second active layer 3 is also divided into two independent parts left and right.
  • the center of the vertical projection of the second groove on the current collector is at the intersection of the diagonal lines of the vertical projection area of the second groove on the current collector. in the slot.
  • the center of the vertical projection of the second groove on the current collector is located in the first groove.
  • the second groove The groove is arranged in the center of the first groove, so that the thickness of the active layer on both sides of the tab is the same.
  • the applicant's research found that the area ratio of the cross-section of the first groove and the second groove in the length direction has a greater impact on the performance of the lithium ion battery.
  • the vertical projected area is 1%-50% of the vertical projected area of the first groove on the current collector.
  • those skilled in the art can determine the width of the first groove and the second groove, and adjust the area ratio of the two by adjusting the length range of the two.
  • the average particle size of the active material in the second active layer is 5-20 ⁇ m, and the graphitization degree is 90%-98%.
  • the pole piece provided by the present invention is also suitable for the positive pole piece, and when the pole piece is the positive pole piece, the material of the first active layer usually uses a high-viscosity material to improve the safety performance of the lithium ion battery, but due to the high viscosity of the material, When the area where the first groove is located in the first active layer is cleaned, the highly viscous substances cannot be thoroughly cleaned, so that there is a residue of highly viscous substances in the area corresponding to the first groove, which affects the connection between the tab and the current collector, resulting in the The ear cannot be attached in the middle of the side of the current collector.
  • the use of the pole piece structure provided by the present invention can effectively avoid this problem, that is, the first active layer uses a highly viscous substance, and only the second active layer needs to be cleaned subsequently, and the first active layer does not need to be cleaned.
  • Substance means that the active layer material includes a binder with a molecular weight of 800,000-2,000,000, and the mass of the binder is 3%-40% of the total mass of the first active layer.
  • the thickness of the first active layer and the second active layer in the pole piece has a great influence on the performance of the lithium ion battery.
  • the inventors of the present application found that when the thickness ratio of the first active layer increases, the cycle of the lithium ion battery will be reduced. The performance will be degraded moderately, therefore, the thickness of the first active layer is 5%-80% of the total thickness of the second portion of the first active layer and the second active layer.
  • FIG. 3 is a front view of a positive pole piece provided by an embodiment of the present invention. As shown in FIG. 3 , when the pole piece is a positive pole piece, The thickness of the first portion of the second active layer is higher than that of the first active layer.
  • the pole piece structure provided by the present invention, those skilled in the art can combine the existing pole piece preparation methods. Specifically, firstly, the first active layer slurry and the second active layer slurry are prepared; secondly, the prepared The first active layer slurry is coated on the surface of the current collector, and blank coating is performed in the area corresponding to the first groove to obtain the first active layer provided with the first groove, and then according to the conventional pole piece coating process Coating the second active layer slurry, wherein part of the second active layer slurry fills the first groove under the action of gravity to obtain the first part of the second active layer, and the remaining part of the second active layer slurry obtains the second active layer. In the second part, finally, the active layer located in the first part in the first groove is cleaned to obtain a second groove, and the pole piece is obtained by arranging the tabs in the second groove and electrically connecting with the current collector.
  • the current collector can be an aluminum foil
  • the positive electrode active material includes lithium cobaltate, lithium manganate, lithium nickelate, At least one of nickel-cobalt lithium manganate, lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium phosphate, lithium-rich manganese-based material, and lithium nickel-cobalt aluminate;
  • the current collector can be copper foil, and the negative electrode active material includes at least one of artificial graphite, natural graphite, and modified graphite;
  • the binder and conductive agent used in the positive electrode sheet and the negative electrode sheet are the same.
  • the binder can include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, At least one of polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polymethylmethacrylate, polytetrafluoroethylene, polyhexafluoropropylene, and styrene-butadiene rubber (SBR)
  • the conductive agent can include at least one of conductive carbon black, carbon nanotubes, conductive graphite, and graphene; the negative electrode sheet can also include a thickening agent, and the thickening agent can be sodium carboxymethyl cellulose.
  • the second groove is used for connecting the tabs, and therefore, along the width direction of the current collector, the width of the second groove is smaller than the width of the first groove.
  • the vertical projected area of the second groove on the current collector can be increased, so that the vertical projected area of the second groove on the current collector is larger than that of the current collector.
  • the area of the fluid upper tab connection area is smaller than that of the current collector.
  • FIG. 4 is a top view of a tab provided by another embodiment of the present invention. As shown in FIG. 4 , the length and width of the first groove are both larger than the area of the tab connection area on the current collector, so that the tab 4 and the current collector are easily connected. 1 connection.
  • the width of the second groove is 1-2 times the width of the tab connecting area
  • the length of the second groove is 1-2 times the length of the tab connecting area
  • the present invention provides a pole piece. By reducing the thickness of the active layer near the tab, the charging risk at the connection position of the tab is improved to a certain extent, and the cycle performance of the lithium ion battery is improved.
  • a second aspect of the present invention provides a lithium ion battery, comprising any one of the above-mentioned pole pieces.
  • the present invention provides a pole piece, and those skilled in the art can prepare a lithium ion battery based on the pole piece provided by the present invention and in combination with the prior art.
  • the lithium ion battery provided by the invention has better cycle performance.
  • the charging risk at the connection position of the tab is improved to a certain extent, and the cycle performance of the lithium ion battery is improved.
  • the pole piece provided by the present invention can be applied to either the positive pole piece or the negative pole piece.
  • the pole piece structure provided by the present invention can avoid the problem that the pole tab cannot be connected to the center of the side surface of the current collector due to the existence of high viscosity substances in the first active layer.
  • the lithium ion battery provided by the present invention has better cycle performance.
  • 1a is a front view of a pole piece provided by an embodiment of the present invention.
  • FIG. 1b is a top view of a pole piece provided by an embodiment of the present invention.
  • 1c is a left side view of a pole piece provided by an embodiment of the present invention.
  • FIG. 2a is a front view of a pole piece provided by another embodiment of the present invention.
  • FIG. 2b is a top view of a pole piece provided by another embodiment of the present invention.
  • FIG. 3 is a front view of a pole piece provided by yet another embodiment of the present invention.
  • FIG. 4 is a top view of a pole piece provided by yet another embodiment of the present invention.
  • the pole piece provided in this embodiment is a positive pole piece.
  • the front view of its structure is shown in Figure 3, the top view is shown in Figure 4, and the left side view is shown in Figure 1c, wherein:
  • the current collector is aluminum foil with a width of 79mm;
  • the width of the first groove is 79mm and the length is 15mm;
  • the width of the second groove is 25mm and the length is 10mm;
  • the thickness of the first active layer is 10 ⁇ m, and the thickness of the second active layer is 80 ⁇ m;
  • the materials used in the first active layer are highly viscous substances, including lithium cobaltate, conductive carbon and polyvinylidene fluoride, wherein the molecular weight of polyvinylidene fluoride is 800,000, and the mass of polyvinylidene fluoride is the total mass of the first active layer 20%.
  • the pole piece provided in this embodiment is a negative electrode piece, and the front view of its structure is shown in Figure 2a, the top view is shown in Figure 4, and the left side view is shown in Figure 1c, wherein:
  • the current collector is copper foil with a width of 81mm;
  • the width of the first groove is 81mm and the length is 50mm;
  • the width of the second groove is 25mm and the length is 10mm;
  • the thickness of the first active layer is 50 ⁇ m, and the thickness of the second active layer is 50 ⁇ m;
  • the active material used in the second active layer is graphite, the average particle size of the graphite is 15 ⁇ m, and the degree of graphitization is 94%.
  • the pole piece provided in this embodiment is a negative electrode piece, and the front view of its structure is shown in FIG. 3 , the top view is shown in FIG. 4 , and the left side view is shown in FIG. 1c , wherein:
  • the current collector is copper foil with a width of 81mm;
  • the width of the first groove is 81mm and the length is 50mm;
  • the width of the second groove is 25mm and the length is 10mm;
  • the thickness of the first active layer is 30 ⁇ m, and the thickness of the second active layer is 70 ⁇ m;
  • the active material used in the second active layer is graphite, the average particle size of the graphite is 15 ⁇ m, and the degree of graphitization is 94%.
  • the pole piece provided in this embodiment is a negative pole piece, and the front view of its structure is shown in Figure 3, the top view is shown in Figure 4, and the left side view is shown in Figure 1c, wherein:
  • the current collector is copper foil with a width of 81mm;
  • the width of the first groove is 81mm and the length is 50mm;
  • the width of the second groove is 25mm and the length is 10mm;
  • the thickness of the first active layer is 40 ⁇ m, and the thickness of the second active layer is 60 ⁇ m;
  • the active material used in the second active layer is graphite, the average particle size of the graphite is 15 ⁇ m, and the degree of graphitization is 94%.
  • the pole piece provided in this embodiment is a negative pole piece, and the front view of its structure is shown in Figure 2a, the top view is shown in Figure 4, and the left side view is shown in Figure 1c, wherein:
  • the current collector is copper foil with a width of 81mm;
  • the width of the first groove is 81mm and the length is 50mm;
  • the width of the second groove is 25mm and the length is 10mm;
  • the thickness of the first active layer is 50 ⁇ m, and the thickness of the second active layer is 50 ⁇ m;
  • the active material used in the second active layer is graphite, the average particle size of the graphite is 10 ⁇ m, and the degree of graphitization is 92%.
  • the pole piece provided in this embodiment is a negative pole piece, and the front view of its structure is shown in Figure 2a, the top view is shown in Figure 4, and the left side view is shown in Figure 1c, wherein:
  • the current collector is copper foil with a width of 81mm;
  • the width of the first groove is 81mm and the length is 50mm;
  • the width of the second groove is 25mm and the length is 10mm;
  • the thickness of the first active layer is 50 ⁇ m, and the thickness of the second active layer is 50 ⁇ m;
  • the active material used in the second active layer is graphite, the average particle size of the graphite is 10 ⁇ m, and the degree of graphitization is 95%.
  • the pole piece provided in this embodiment is a negative pole piece, and the front view of its structure is shown in Figure 2a, the top view is shown in Figure 4, and the left side view is shown in Figure 1c, wherein:
  • the current collector is copper foil with a width of 81mm;
  • the width of the first groove is 81mm and the length is 50mm;
  • the width of the second groove is 25mm and the length is 10mm;
  • the thickness of the first active layer is 50 ⁇ m, and the thickness of the second active layer is 50 ⁇ m;
  • the active material used in the second active layer is graphite, the average particle size of the graphite is 15 ⁇ m, and the degree of graphitization is 92%.
  • the pole piece provided in this embodiment is a negative electrode piece, and the front view of its structure is shown in Figure 2a, the top view is shown in Figure 4, and the left side view is shown in Figure 1c, wherein:
  • the current collector is copper foil with a width of 81mm;
  • the width of the first groove is 81mm and the length is 50mm;
  • the width of the second groove is 25mm and the length is 10mm;
  • the thickness of the first active layer is 50 ⁇ m, and the thickness of the second active layer is 50 ⁇ m;
  • the active material used in the second active layer is graphite, the average particle diameter of the graphite is 15 ⁇ m, and the degree of graphitization is 95%.
  • the pole piece provided in this comparative example is a positive pole piece, which includes a current collector and an active layer arranged on the surface of the current collector, and the pole tab is connected to the most edge side of the current collector, wherein:
  • the current collector is aluminum foil with a width of 79mm;
  • the thickness of the active layer was 90 ⁇ m.
  • the pole piece provided in this comparative example is a negative pole piece, which includes a current collector and a first active layer and a second active layer arranged on the surface of the current collector.
  • a groove is arranged between the sides of the first active layer and the second active layer, and the tabs are connected to each other. within this groove, where:
  • the current collector is copper foil with a width of 81mm;
  • the width of the groove is 25mm and the length is 10mm;
  • the total thickness of the first active layer and the second active layer was 100 ⁇ m.
  • lithium ion batteries were prepared by matching negative electrode pieces/positive electrode pieces, separators and electrolytes with the same structure, for example, Example 1 and Comparative Example 1 is a positive electrode sheet, then the structure of the corresponding negative electrode sheet is the same as that of the positive electrode sheet.
  • Examples 2-8 and Comparative Example 2 are negative electrode sheets, then the structure of the corresponding positive electrode sheet is the same as that of the negative electrode sheet, and the cycle performance of the lithium ion battery is affected. carry out testing.
  • the positive electrode material was purchased from Xiamen Xia Tungsten New Energy Materials Co., Ltd.
  • the negative electrode material was purchased from Shanghai Shanshan Technology Co., Ltd.
  • the diaphragm was purchased from Dongguan Zhuo Gao Electronic Technology Co., Ltd.
  • the electrolyte was purchased from Shenzhen Xinzhoubang Technology Co., Ltd. .
  • the performance test method of lithium-ion battery is:
  • the lithium-ion batteries prepared on the basis of Example 1 and Comparative Example 1 were subjected to a 2C/0.7C charge-discharge cycle test at 25°C to calculate their cycle retention (%); and a temperature sensor was used to monitor the surface temperature of the cell, The difference between the maximum value and the initial temperature is recorded as the temperature rise (°C) of the lithium-ion battery, and the test results are shown in Table 1.
  • the lithium-ion batteries prepared on the basis of Examples 2-8 and Comparative Example 2 were subjected to a 2C/0.7C charge-discharge cycle test at 25°C/10°C, and their cycle retention rates (%) were calculated respectively.
  • the test results are shown in Table 2.
  • Example 2 25°C cycle retention rate 10°C cycle retention rate
  • Example 2 85.10% 83.00%
  • Example 3 86.10% 84.00%
  • Example 4 85.50% 83.00%
  • Example 5 86.00% 84.50%
  • Example 6 84.90% 83.30%
  • Example 7 85.30% 83.50%
  • Example 8 83.00% 82.60% Comparative Example 2 82.00% 81.00%
  • the lithium-ion batteries provided in Examples 1-8 all have good cycle performance; according to the data provided in Examples 2-4, as the proportion of the first active layer in the total thickness of the active layer increases, The performance of lithium-ion batteries will be moderately decreased, therefore, the thickness of the first active layer should be controlled; according to the data provided in Examples 5-8, in the negative electrode sheet, with the average particle size and The increase in the degree of graphitization reduces the cycle retention rate of lithium-ion batteries.

Abstract

本发明提供一种极片和锂离子电池。本发明第一方面提供了一种极片，所述极片包括集流体、第一活性层、第二活性层，所述第一活性层设置于集流体的表面，并设置有第一凹槽，所述第二活性层分为设置于所述第一凹槽内的第一部分和设置于第一活性层远离集流体表面的第二部分；其中，所述第一部分上设置有第二凹槽，极耳设置于所述第二凹槽处并与所述集流体电连接，第二活性层的第一部分的厚度小于第一活性层和第二活性层的第二部分的总厚度。本发明提供的极片，通过降低极耳附近活性层的厚度，在一定程度上改善了极耳连接位置的充电风险，提高了锂离子电池的循环性能。

Description

一种极片和锂离子电池
本申请要求于2020年12月30日提交中国专利局、申请号为202011628654.0、申请名称为“一种极片和锂离子电池”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明涉及一种极片和锂离子电池，涉及锂离子电池技术领域。
背景技术
随着5G时代的到来，锂离子电池的地位显得愈发重要。目前锂离子电池向着能量密度高，快充能倍率大的方向不断发展。目前，采用将极耳的连接位置从极片边缘调整到极片侧面中间位置的方式，以降低锂离子电池的阻抗。
但是，当极耳的位置发生改变后，会使极耳周围电流密度增加，并且随着锂离子电池的循环，会析出锂离子，导致锂离子电池的循环性能变差。因此，如何解决由该种极耳连接方式导致的锂离子电池循环性能变差的问题受到了越来越多的关注。
发明内容
本发明提供了一种极片，用于解决由于该种极耳连接方式导致的锂离子电池循环性能变差的问题。
本发明第一方面提供了一种极片，所述极片包括集流体、第一活性层、第二活性层，所述第一活性层设置于集流体的表面，并设置有第一凹槽，所述第二活性层分为设置于所述第一凹槽内的第一部分和设置于第一活性层远离集流体表面的第二部分；
其中，所述第一部分上设置有第二凹槽，极耳设置于所述第二凹槽处并与所述集流体电连接，第二活性层的第一部分的厚度小于第一活性层和第二活性层的第二部分的总厚度。
目前，现有技术中使用的极片通常包括集流体和设置在集流体表面的活 性层，且活性层侧面中间位置开设有凹槽，该凹槽在集流体上的对应区域内连接有极耳，为了解决由该种极耳连接方式导致的锂离子电池循环性能变差的问题，本发明将极耳所在位置四周的活性层厚度降低，具体地，图1a为本发明一实施例提供的极片的主视图，图1b为本发明一实施例提供的极片的俯视图，图1c为本发明一实施例提供的极片的左视图，如图1a-1c所示，极片包括集流体1、第一活性层2、第二活性层3和极耳4，其中，第一活性层2设置于集流体1表面，并且第一活性层2上设置有第一凹槽，第二活性层中第一部分设置于该第一凹槽内与集流体1的表面接触，第二活性层中第二部分设置于第一活性层1远离集流体1的上表面，第二活性层的第一部分侧面中间设置有第二凹槽，用于连接极耳4，第二活性层的第一部分的厚度小于第一活性层和第二活性层的第二部分的总厚度，使得靠近极耳周围的活性层厚度低于远离极耳区域的活性层厚度；其中，本申请对极片厚度的定义与现有技术相同，即极片中的最长边为极片的长，最短边为极片的高，介于最长边和最短边的边为极片的宽，即图1a中较长边为极片的长，较短边为极片的高，图1b中较短边为极片的宽，长边的值即为极片的长度，高边的值即为极片的厚度，宽边的值即为极片的宽度，并且，第一凹槽和第二凹槽与极片的长度、宽度和厚度方向相同。本发明提供的极片，通过降低极耳周围活性层的总厚度，一定程度上改善了极耳连接位置的充电风险，提高了锂离子电池的循环性能。
在一种具体实施方式中，为了进一步提高锂离子电池的循环性能，应适当降低第一活性层的厚度，即所述第二活性层的厚度大于所述第一活性层的厚度。此外，由于第二活性层的第一部分设置在第一凹槽内，在后续极片辊压过程中受力较小，导致第二活性层第一部分和第二部分的厚度出现差异，具体地，所述第二活性层的第一部分的厚度大于所述第二部分的厚度。
根据图1a-1c所示的极片结构，需要对现有的涂布设备进行改进，才能保证第一凹槽的位置和面积，不仅会增加制备成本，而且也不利于其他极片结构的制备，因此，可将第一凹槽的宽度变大，使其与集流体的宽度相同，即第一凹槽将第一活性层分为独立的两个部分，中间空白的部分即为第一凹槽。例如：
图2a为本发明又一实施例提供的极片的主视图，图2b为本发明又一实施例提供的极片的俯视图，如图2a-2b所示，极片包括集流体1、第一活性层 2、第二活性层3和极耳4，第一活性层1设置有第一凹槽，且第一凹槽的宽度与集流体1的宽度相同，即第一凹槽将第一活性层2分为左右两个部分，第二活性层3的第一部分设置在该第一凹槽内，且第二活性层3的第二部分设置在于第一活性层2远离集流体1的上表面，由于第一凹槽的宽度与集流体的宽度相同，第二活性层3的第二部分也被分为左右两个独立地部分。
可以理解的是，以第二凹槽在集流体上竖直投影区域的对角线的交点为中心，所述第二凹槽在所述集流体上竖直投影的中心位于所述第一凹槽内。
继续参考图1b或2b可知，所述第二凹槽在所述集流体上竖直投影的中心位于所述第一凹槽内，为了进一步提高锂离子电池的循环性能，可尽量将第二凹槽设置于第一凹槽的中心，使得极耳两侧活性层的厚度相同。
经申请人研究发现，第一凹槽和第二凹槽在长度方向上的截面的面积比对锂离子电池的性能影响较大，具体地，所述第二凹槽在所述集流体上的竖直投影面积为所述第一凹槽在所述集流体上的竖直投影面积的1％-50％。在具体制备过程中，本领域技术人员可确定第一凹槽和第二凹槽的宽度，通过调节二者的长度范围调节二者的面积比。
为了提高锂离子电池的快充性能，当极片为负极片时，第二活性层中活性物质的平均粒径为5-20μm，石墨化度为90％-98％。
本发明提供的极片同样适用于正极片，并且当极片为正极片时，第一活性层的材料通常使用高粘性物质以提高锂离子电池的安全性能，但是由于该物质的粘度较大，当对第一活性层中第一凹槽所在区域进行清洗时，高粘性物质无法彻底清洗干净，使得第一凹槽对应区域内存在高粘性物质残留，影响极耳与集流体的连接，导致极耳无法连接在集流体侧面的中间位置。因此，使用本发明提供的极片结构可有效避免该问题，即第一活性层使用高粘性物质，并且后续仅需对第二活性层进行清洗，无需清洗第一活性层，具体地，高粘性物质是指活性层材料中包括分子量为800000-2000000的粘接剂，且所述粘接剂的质量为所述第一活性层总质量的3％-40％。
此外，极片中第一活性层和第二活性层的厚度对锂离子电池性能影响较大，经本申请发明人研究发现，当第一活性层的厚度比例增大时，锂离子电池的循环性能会适度的下降，因此，所述第一活性层的厚度为所述第一活性层和所述第二活性层的第二部分的总厚度的5％-80％。
当极片为正极片时，应适当降低第一活性层的厚度，例如，图3为本发 明一实施例提供的正极片的主视图，如图3所示，当极片为正极片时，第二活性层的第一部分的厚度要高于第一活性层的厚度。
在本发明提供的极片结构的基础上，本领域技术人员可结合现有的极片制备方法进行，具体地，首先制备得到第一活性层浆液和第二活性层浆液；其次，将制备得到的第一活性层浆液涂布在集流体表面，并在第一凹槽所对应的区域进行空白涂布，得到设置有第一凹槽的第一活性层，接着按照常规的极片涂布工艺涂布第二活性层浆液，其中，部分第二活性层浆液在重力的作用下填充第一凹槽，得到第二活性层的第一部分，其余部分的第二活性层浆液得到第二活性层的第二部分，最后，清洗位于第一凹槽内第一部分中部分区域的活性层，得到第二凹槽，并将极耳设置在第二凹槽内与集流体电连接后得到该极片。
本领域技术人员可结合现有技术选择正极片和负极片的材料，例如，当极片为正极片时，集流体可以为铝箔，正极活性物质包括钴酸锂、锰酸锂、镍酸锂、镍钴锰酸锂、磷酸铁锂、磷酸锰铁锂、磷酸钒锂、磷酸钒氧锂、富锂锰基材料、镍钴铝酸锂中的至少一种；
当极片为负极片时，集流体可以为铜箔，负极活性物质包括人造石墨、天然石墨、改性石墨中的至少一种；
正极片和负极片所使用的粘接剂和导电剂相同，具体地，粘结剂可以包括聚偏氟乙烯(PVDF)、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯、聚六氟丙烯和丁苯橡胶(SBR)中的至少一种；导电剂可以包括导电炭黑、碳纳米管、导电石墨、石墨烯中的至少一种；负极片中还可以包括增稠剂，增稠剂可以为羧甲基纤维素钠。
可以理解的是，第二凹槽用于连接极耳，因此，沿集流体宽度方向，所述第二凹槽的宽度小于所述第一凹槽的宽度。
在实际制备过程中，为了方便极耳与集流体的连接，可将第二凹槽在集流体上的竖直投影面积变大，使第二凹槽在集流体上的竖直投影面积大于集流体上极耳连接区的面积。
图4为本发明再一实施例提供的极耳的俯视图，如图4所示，第一凹槽的长度、宽度均大于集流体上极耳连接区的面积，以便于极耳4与集流体1的连接。
进一步地，所述第二凹槽的宽度为所述极耳连接区宽度的1-2倍，所述第二凹槽的长度为所述极耳连接区长度的1-2倍。
综上，本发明提供了一种极片，通过降低极耳附近的活性层的厚度，在一定程度上改善了极耳连接位置的充电风险，提高了锂离子电池的循环性能。
本发明第二方面提供了一种锂离子电池，包括上述任一一种极片。
本发明提供了一种极片，本领域技术人员在本发明提供的极片的基础上，结合现有技术制备得到锂离子电池。本发明提供的锂离子电池具备较好的循环性能。
本发明的实施，至少具有以下优势：
1、本发明提供的极片，通过降低极耳附近活性层的厚度，在一定程度上改善了极耳连接位置的充电风险，提高了锂离子电池的循环性能。
2、本发明提供的极片对于正极片或负极片均可适用。
3、当极片为正极片时，本发明提供的极片结构可避免由于第一活性层中高粘性物质的存在导致无法将极耳连接在集流体侧面中心的问题。
4、本发明提供的锂离子电池，具有较好的循环性能。
附图说明
图1a为本发明一实施例提供的极片的主视图；
图1b为本发明一实施例提供的极片的俯视图；
图1c为本发明一实施例提供的极片的左视图；
图2a为本发明又一实施例提供的极片的主视图；
图2b为本发明又一实施例提供的极片的俯视图；
图3为本发明再一实施例提供的极片的主视图；
图4为本发明再一实施例提供的极片的俯视图。
附图标记说明：
1：集流体；
2：第一活性层；
3：第二活性层；
4：极耳。
具体实施方式
为使本发明的目的、技术方案和优点更加清楚，下面将结合本发明的实施例，对本发明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发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
实施例1
本实施例提供的极片为正极片，其结构的主视图如图3所示，俯视图如图4所示，左视图如图1c所示，其中：
集流体为铝箔，宽度为79mm；
第一凹槽的宽度为79mm，长度为15mm；
第二凹槽的宽度为25mm，长度为10mm；
第一活性层的厚度为10μm，第二活性层的厚度为80μm；
第一活性层所使用的材料为高粘性物质，包括钴酸锂、导电碳以及聚偏氟乙烯，其中，聚偏氟乙烯的分子量为800000，聚偏氟乙烯的质量为第一活性层总质量的20％。
实施例2
本实施例提供的极片为负极片，其结构主视图如图2a所示，俯视图如4所示，左视图如图1c所示，其中：
集流体为铜箔，宽度为81mm；
第一凹槽的宽度为81mm，长度为50mm；
第二凹槽的宽度为25mm，长度为10mm；
第一活性层的厚度为50μm，第二活性层的厚度为50μm；
第二活性层所使用的活性物质为石墨，石墨的平均粒径为15μm，石墨化度为94％。
实施例3
本实施例提供的极片为负极片，其结构主视图如图3所示，俯视图如图4 所示，左视图如图1c所示，其中：
集流体为铜箔，宽度为81mm；
第一凹槽的宽度为81mm，长度为50mm；
第二凹槽的宽度为25mm，长度为10mm；
第一活性层的厚度为30μm，第二活性层的厚度为70μm；
第二活性层所使用的活性物质为石墨，石墨的平均粒径为15μm，石墨化度为94％。
实施例4
本实施例提供的极片为负极片，其结构主视图如图3所示，俯视图如图4所示，左视图如图1c所示，其中：
集流体为铜箔，宽度为81mm；
第一凹槽的宽度为81mm，长度为50mm；
第二凹槽的宽度为25mm，长度为10mm；
第一活性层的厚度为40μm，第二活性层的厚度为60μm；
第二活性层所使用的活性物质为石墨，石墨的平均粒径为15μm，石墨化度为94％。
实施例5
本实施例提供的极片为负极片，其结构主视图如图2a所示，俯视图如图4所示，左视图如图1c所示，其中：
集流体为铜箔，宽度为81mm；
第一凹槽的宽度为81mm，长度为50mm；
第二凹槽的宽度为25mm，长度为10mm；
第一活性层的厚度为50μm，第二活性层的厚度为50μm；
第二活性层所使用的活性物质为石墨，石墨的平均粒径为10μm，石墨化度为92％。
实施例6
本实施例提供的极片为负极片，其结构主视图如图2a所示，俯视图如图4所示，左视图如图1c所示，其中：
集流体为铜箔，宽度为81mm；
第一凹槽的宽度为81mm，长度为50mm；
第二凹槽的宽度为25mm，长度为10mm；
第一活性层的厚度为50μm，第二活性层的厚度为50μm；
第二活性层所使用的活性物质为石墨，石墨的平均粒径为10μm，石墨化度为95％。
实施例7
本实施例提供的极片为负极片，其结构主视图如图2a所示，俯视图如图4所示，左视图如图1c所示，其中：
集流体为铜箔，宽度为81mm；
第一凹槽的宽度为81mm，长度为50mm；
第二凹槽的宽度为25mm，长度为10mm；
第一活性层的厚度为50μm，第二活性层的厚度为50μm；
第二活性层所使用的活性物质为石墨，石墨的平均粒径为15μm，石墨化度为92％。
实施例8
本实施例提供的极片为负极片，其结构主视图如图2a所示，俯视图如4所示，左视图如图1c所示，其中：
集流体为铜箔，宽度为81mm；
第一凹槽的宽度为81mm，长度为50mm；
第二凹槽的宽度为25mm，长度为10mm；
第一活性层的厚度为50μm，第二活性层的厚度为50μm；
第二活性层所使用的活性物质为石墨，石墨的平均粒径为15μm，石墨化度为95％。
对比例1
本对比例提供的极片为正极片，包括集流体和设置在集流体表面的活性层，极耳连接在集流体最边缘一侧，其中：
集流体为铝箔，宽度为79mm；
活性层的厚度为90μm。
对比例2
本对比例提供的极片为负极片，包括集流体和设置在集流体表面的第一活性层和第二活性层，第一活性层和第二活性层侧面中间设置有凹槽，极耳连接在该凹槽内，其中：
集流体为铜箔，宽度为81mm；
凹槽的宽度为25mm，长度为10mm；
第一活性层和第二活性层的总厚度为100μm。
在本发明实施例1-8以及对比例1-2提供的极片的基础上，搭配结构相同的负极片/正极片、隔膜和电解液制备得到锂离子电池，例如，实施例1和对比例1为正极片，则相应负极片的结构与正极片结构相同，实施例2-8和对比例2为负极片，则相应正极片的结构与负极片结构相同，并对锂离子电池的循环性能进行测试。
其中，正极材料购自厦门厦钨新能源材料有限公司，负极材料购自上海杉杉科技有限公司，隔膜购自东莞市卓高电子科技有限公司，电解液购自深圳新宙邦科技股份有限公司。
锂离子电池的性能测试方法为：
将实施例1以及对比例1基础上制备得到的锂离子电池在25℃条件下进行2C/0.7C的充放电循环测试，计算其循环保持率(％)；并用温度传感器监控电芯表面温度，将最大值与初始温度的差值记为锂离子电池的温升(℃)，测试结果见表1。
将实施例2-8以及对比例2基础上制备得到的锂离子电池在25℃/10℃条件下进行2C/0.7C的充放电循环测试，分别计算其循环保持率(％)，测试结果见表2。
表1 实施例1以及对比例1提供的锂离子电池的性能测试结果
  25℃循环保持率 电芯表面温升
实施例1 84.80％ 13℃
对比例1 83.90％ 16℃
表2 实施例2-8以及对比例2提供的锂离子电池的循环性能测试结果
  25℃循环保持率 10℃循环保持率
实施例2 85.10％ 83.00％
实施例3 86.10％ 84.00％
实施例4 85.50％ 83.00％
实施例5 86.00％ 84.50％
实施例6 84.90％ 83.30％
实施例7 85.30％ 83.50％
实施例8 83.00％ 82.60％
对比例2 82.00％ 81.00％
由表1-2可知，实施例1-8提供的锂离子电池均具有较好的循环性能；根据实施例2-4提供的数据，随着第一活性层占活性层总厚度比例的增加，锂离子电池的性能会适度下降，因此，应当控制第一活性层的厚度；根据实施例5-8提供的数据，在负极片中，随着第二活性层中负极活性物质的平均粒径和石墨化度的提高，锂离子电池的循环保持率会降低。
最后应说明的是：以上各实施例仅用以说明本发明的技术方案，而非对其限制；尽管参照前述各实施例对本发明进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本发明各实施例技术方案的范围。

Claims (10)

  1. 一种极片，其特征在于，所述极片包括集流体、第一活性层、第二活性层，所述第一活性层设置于集流体的表面，并设置有第一凹槽，所述第二活性层分为设置于所述第一凹槽内的第一部分和设置于第一活性层远离集流体表面的第二部分；
    其中，所述第一部分上设置有第二凹槽，极耳设置于所述第二凹槽处并与所述集流体电连接，第二活性层的第一部分的厚度小于第一活性层和第二活性层的第二部分的总厚度。
  2. 根据权利要求1所述的极片，其特征在于，所述第二活性层的厚度大于所述第一活性层的厚度；和/或，所述第二活性层的第一部分的厚度大于所述第二部分的厚度。
  3. 根据权利要求1所述的极片，其特征在于，所述第一凹槽的宽度与所述集流体的宽度相同。
  4. 根据权利要求1所述的极片，其特征在于，所述第二凹槽在所述集流体上的竖直投影面积为所述第一凹槽在所述集流体上的竖直投影面积的1％-50％。
  5. 根据权利要求1-4任一项所述的极片，其特征在于，所述极片为负极片，第二活性层中负极活性物质的平均粒径为5-20μm，石墨化度为90％-98％。
  6. 根据权利要求1-4任一项所述的极片，其特征在于，所述极片为正极片，所述第一活性层中粘接剂的分子量为800000-2000000，所述粘接剂的质量为所述第一活性层总质量的3％-40％。
  7. 根据权利要求1所述的极片，其特征在于，所述第一活性层的厚度为所述第一活性层和所述第二活性层的第二部分总厚度的5％-80％。
  8. 根据权利要求1所述的极片，其特征在于，沿集流体宽度方向，所述第二凹槽的宽度小于所述第一凹槽的宽度。
  9. 根据权利要求1所述的极片，其特征在于，所述第二凹槽的宽度为极耳连接区宽度的1-2倍，所述第二凹槽的长度为极耳连接区长度的1-2倍。
  10. 一种锂离子电池，其特征在于，包括上述权利要求1-9任一项所述的极片。
PCT/CN2021/142831 2020-12-30 2021-12-30 一种极片和锂离子电池 WO2022143859A1 (zh)

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