WO2025130263A1 - 一种电极片和电池 - Google Patents

一种电极片和电池 Download PDF

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Publication number
WO2025130263A1
WO2025130263A1 PCT/CN2024/123658 CN2024123658W WO2025130263A1 WO 2025130263 A1 WO2025130263 A1 WO 2025130263A1 CN 2024123658 W CN2024123658 W CN 2024123658W WO 2025130263 A1 WO2025130263 A1 WO 2025130263A1
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WO
WIPO (PCT)
Prior art keywords
electrode sheet
electrode
sheet according
active material
tensile force
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Pending
Application number
PCT/CN2024/123658
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English (en)
French (fr)
Inventor
王迪
陈田田
蒋欢
谢继春
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Zhuhai Cosmx Battery Co Ltd
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Zhuhai Cosmx Battery Co Ltd
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Application filed by Zhuhai Cosmx Battery Co Ltd filed Critical Zhuhai Cosmx Battery Co Ltd
Priority to EP24905753.0A priority Critical patent/EP4738449A1/en
Publication of WO2025130263A1 publication Critical patent/WO2025130263A1/zh
Anticipated expiration legal-status Critical
Pending 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
    • 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
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • 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 present application relates to an electrode sheet and a battery, belonging to the technical field of lithium-ion batteries.
  • Lithium-ion batteries are widely used in electronics, communications, electric vehicles and other fields due to their advantages such as high energy efficiency, wide operating temperature range and environmental friendliness.
  • electrode sheets As an important component of lithium-ion batteries, electrode sheets have a crucial impact on the performance of lithium-ion batteries.
  • the preparation of electrode sheets often adopts a wet process, using organic solvents to prepare slurry for coating, and then obtaining electrode sheets after drying and rolling.
  • organic solvents are prone to pollution, and the solvents need to be dried and removed later, resulting in great energy waste and increasing production costs.
  • electrode sheets are prone to cracking, poor toughness, stratification and other phenomena, and cannot further improve energy density.
  • the electrode sheet provided by the present invention can significantly improve the breaking tensile force and adhesion of the electrode sheet by limiting the composition and structure of the electrode sheet, increase the tensile strength of the electrode sheet, and reduce the risk of band breakage.
  • the electrode sheet can be directly applied to the battery and can significantly improve the cycle performance and thickness expansion rate of the battery.
  • the present invention also provides a battery, which has excellent performance in terms of cycle performance and thickness expansion rate, etc. due to comprising the above-mentioned electrode sheet.
  • an electrode sheet comprising a current collector and an electrode film disposed on at least one functional surface of the current collector;
  • the electrode film includes fibers, and at least a portion of the fibers extend along a first direction of the electrode sheet.
  • the second direction is perpendicular to the first direction.
  • the electrode sheet as described above, wherein the ratio of the breaking tensile force of the electrode sheet in the first direction to the breaking tensile force of the electrode sheet in the second direction is (1-2):1, preferably, (1.02-1.52):1.
  • the unit of the breaking tensile force of the electrode sheet in the first direction is kgf, and the unit of the thickness of the electrode sheet is ⁇ m.
  • the electrode sheet as described above, wherein the breaking tensile force of the electrode sheet in the first direction is 3-6 kgf; and/or,
  • the breaking tensile force of the electrode sheet in the second direction is 2 to 5.5 kgf; and/or,
  • the thickness of the electrode sheet is 65-350 ⁇ m.
  • the active material body comprises LiCoO2, LiMn2O4 , LiMnO2 , LiNiO2 , LiFePO4 , LiMnPO4 , LiCoxNi1 -xO2 , LiCoxNi1 - xyAlyO2 , wherein 0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1 , or
  • the active material body includes at least one of artificial graphite, natural graphite, soft carbon, hard carbon, mesophase carbon microspheres, Si, SiO x , Si-C, and SiO x -C.
  • the electrode sheet as described above, wherein the ratio of the size of a single fiber in the first direction to the median particle size of the active material body is 1:(1-4000), preferably 1:(1-400).
  • the median particle size of the active material body is 250 nm to 30 ⁇ m.
  • the electrode sheet as described above, wherein the electrode sheet further comprises a glue layer, and the glue layer is located between the current collector and the electrode film.
  • the adhesive layer includes an adhesive and a conductive agent;
  • the adhesive includes at least one of polyvinylidene fluoride, styrene-butadiene rubber, EVA hot melt adhesive, TPR hot melt adhesive, polyolefin hot melt adhesive, polyamide hot melt adhesive, polyester hot melt adhesive, polyethylene hot melt adhesive, polyester amide hot melt adhesive, and/or
  • the conductive agent includes at least one of conductive carbon black, carbon nanotubes and graphene.
  • the fibers include at least one of fibrous polytetrafluoroethylene, polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, fluorinated ethylene propylene copolymer, polyvinyl pyrrolidone, polyethylene oxide, carboxymethyl cellulose, styrene-butadiene rubber, polyacrylic acid, hot melt adhesive, and polyethylene.
  • the electrode film further comprises a recessed portion, the recessed portion is located on a surface of the electrode film away from the current collector, and/or the recessed portion is located inside the electrode film.
  • the recess is filled with a lithium-containing compound
  • the lithium-containing compound includes at least one of lithium oxide, lithium carbonate, and lithium fluoride.
  • a second aspect of the present invention provides a battery, comprising the electrode sheet described in the first aspect.
  • the fibers in the electrode sheet provided by the present invention extend along the first direction of the electrode sheet, which can increase the adhesion between the electrode film and the current collector, and at the same time better transmit stress, enhance the breaking tension of the electrode sheet in the first direction, reduce the risk of tape breakage during rolling, and improve process efficiency, thereby ensuring that the electrode sheet can be used in a long cycle. Stability in the process.
  • the battery provided by the present invention because it includes the above-mentioned electrode sheet, has excellent electrochemical properties, for example, excellent cycle performance and low thickness expansion rate.
  • FIG1 is a top view SEM image of an electrode sheet at a first magnification in one embodiment of the present invention
  • FIG2 is a top view SEM image of an electrode sheet at a second magnification in one embodiment of the present invention.
  • FIG3 is a cross-sectional SEM image of an electrode sheet in one embodiment of the present invention.
  • FIG. 4 is a schematic diagram of the structure of an electrode sheet in one embodiment of the present invention.
  • the X direction is the length direction of the electrode sheet
  • the Y direction is the width direction of the electrode sheet
  • the Z direction is the thickness direction of the electrode sheet.
  • an electrode sheet comprising a current collector 3 and an electrode film 1 arranged on at least one functional surface of the current collector; the electrode film comprises fibers, at least part of the fibers extend along a first direction of the electrode sheet.
  • the present invention does not limit the specific shapes of the electrode sheet and the current collector, which may be conventional rectangular parallelepiped shapes in the art.
  • the current collector has two largest and opposite functional surfaces, which are used to set the electrode film.
  • the electrode film in the electrode sheet of the present invention can be set on only one functional surface of the current collector, or on both functional surfaces of the current collector.
  • Electrode membranes are used to generate electrochemical reactions, thereby converting chemical energy into electrical energy.
  • the electrode membrane components of the present invention include at least an active material body and a binder, wherein the active material
  • the body at least includes active materials and conductive agents; the active materials are used to produce electrochemical reactions, the conductive agents are used to improve the conductivity of the electrode film, and the binder is used to bind the active materials and the conductive agents to form a complete electrode film.
  • fiber refers to continuous or discontinuous filaments.
  • the fiber is a filamentary structure formed by a binder through a fibrillation method or an electrostatic spraying method.
  • the present invention does not limit the specific material of the fiber, and can specifically be a binder commonly used in the art.
  • the fiber can be fibrous polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), ethylene-tetrafluoroethylene copolymer (ETEF), fluorinated ethylene propylene copolymer (FEP), polyvinyl pyrrolidone (PVP), polyethylene oxide (PEO), carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyacrylic acid (PAA), hot melt adhesive, polyethylene (PE) at least one.
  • PTFE polytetrafluoroethylene
  • PVDF polyvinylidene fluoride
  • ETEF ethylene-tetrafluoroethylene copolymer
  • FEP fluorinated ethylene propylene copolymer
  • PVP polyvinyl pyrrolidone
  • PEO polyethylene oxide
  • CMC carboxymethyl cellulose
  • SBR styrene-butadiene rubber
  • PAA polyacrylic acid
  • hot melt adhesive
  • the fiber and the active material body are in line-surface contact, which increases the contact area between the fiber and the active material body, enables a tighter connection between the fiber and the active material body, improves the flexibility of the electrode sheet, and prevents cracking and powdering.
  • the distribution of fibers in the electrode sheet will affect the mechanical properties of the electrode sheet.
  • the present invention can significantly increase the breaking tensile force of the electrode sheet and reduce the risk of breaking by limiting at least part of the fibers to extend along the first direction of the electrode sheet, thereby significantly improving the cycle performance of the battery and reducing the thickness expansion rate.
  • the first direction of the electrode sheet refers to the extension direction of the electrode sheet, for example, the length direction or width direction of the electrode sheet.
  • the extension direction of the fiber is consistent with the extension direction of the electrode sheet.
  • the extension direction of the fiber is consistent with the length direction of the electrode sheet, which ensures that the fiber and the active material body form a closer bond, increases the tensile strength of the electrode sheet in the length direction, and enables it to withstand greater tension.
  • the present invention does not limit the breaking tension of the electrode sheet in its extension direction.
  • the breaking tension of the electrode sheet in the first direction is greater than or equal to the breaking tension of the electrode sheet in the second direction; the second direction is perpendicular to the first direction.
  • the electrode sheet will extend along the rolling direction during the rolling process, and the electrode sheet will be wound along the winding direction during the winding process. Therefore, the electrode sheet needs to withstand a certain tensile strength in the rolling direction and the winding direction.
  • the breaking tension of the electrode sheet in the first direction is limited to be greater than or equal to the breaking tension of the electrode sheet in the second direction, the electrode sheet is prevented from breaking during the rolling process, and at the same time, the electrode is prevented from breaking.
  • the sheet was subjected to excessive force during the winding process and cracked.
  • the second direction refers to the width direction of the electrode sheet.
  • the electrode membrane at least 90% by mass of the fibers extend along the first direction of the electrode sheet, that is, the angle between the extension direction of at least 90% by mass of the fibers and the first direction of the electrode sheet is 0°. In some embodiments, the angle between the extension direction of the fibers and the first direction of the electrode sheet is 0 to 30°.
  • the ratio of the breaking force of the electrode sheet in the first direction to the breaking force of the electrode sheet in the second direction is (1-2):1.
  • the ratio of the breaking force of the electrode sheet in the first direction to the breaking force of the electrode sheet in the second direction is (1.02-1.52):1, which can not only reduce the resistance and interface reaction inside the electrode sheet and improve the electrochemical performance of the battery, but also improve the mechanical stability of the battery and extend the service life of the battery.
  • the thickness of the electrode film will affect the load of the active material, and thus affect the energy density of the battery.
  • the ratio of the breaking force of the electrode sheet in the first direction to the thickness of the electrode sheet is (0.008-0.1):1, where the unit of the breaking force of the electrode sheet in the first direction is kgf, and the unit of the thickness of the electrode sheet is ⁇ m.
  • the thickness of the electrode sheet is equal to the sum of the thickness of the current collector and the thickness of the electrode film.
  • the present invention does not limit the specific values of the breaking force and thickness of the electrode sheet, which can be determined according to actual conditions.
  • the breaking force of the electrode sheet in the first direction is 3-6 kgf, preferably 4.3-5 kgf; and/or, the breaking force of the electrode sheet in the second direction is 2-5.5 kgf, preferably 3.3-4.2 kgf; and/or, the thickness of the electrode sheet is 65-350 ⁇ m.
  • the breaking tension of the current collector in the second direction is less than the breaking tension of the current collector in the first direction.
  • the ratio between the breaking tension of the current collector in the first direction and the breaking tension of the current collector in the second direction is (0.67-2.75):1, preferably (0.875-1.67):1, to ensure the strength of the electrode sheet during processing and reduce the risk of tape breakage.
  • the breaking tensile force of the current collector in the first direction is 3 to 5.5 kgf, preferably 3.5-5kgf; the breaking tensile force of the current collector in the second direction is 2-4.5kgf, preferably 3-4kgf.
  • the electrode film includes a plurality of fibers and a plurality of active material bodies, and the size of at least some of the fibers in the first direction is larger than the median particle size of the active material body.
  • the size of the fiber in the first direction actually refers to the length of the fiber, and the median particle size of the active material body refers to the particle size corresponding to a cumulative volume fraction of 50%.
  • the size of the fiber in the first direction actually refers to the absolute size of all fibers in the first direction, that is, the size spanned in the first direction.
  • the ratio of the size of a single fiber in the first direction to the median particle size of the active material body is 1:(1-4000), ensuring that multiple fibers can span the active material body, bonding and fixing the active material body, thereby reducing the cyclic expansion rate.
  • the present invention does not limit the specific size of the fiber and the active material body.
  • the size of the fiber in the first direction is 250 nm to 1 mm; and/or the median particle size of the active material body is 250 nm to 30 ⁇ m.
  • the fibers in the thickness direction of the electrode sheet, extend along the thickness direction of the electrode sheet. That is, when viewed in the thickness direction of the electrode sheet, the fibers are distributed along the thickness direction of the electrode sheet.
  • the fiber is a bonding component connecting multiple active material bodies.
  • adjacent active material bodies are connected by fibers along the thickness direction of the electrode sheet.
  • the fibers make the active material bodies more closely connected to each other. This further ensures that the fibers play a bonding and fixing role on the active material bodies, thereby reducing the cycle expansion rate.
  • the present invention does not limit the specific types of active materials and conductive agents in the active material body.
  • the conductive agent can be at least one of conductive carbon black, carbon fiber, conductive graphite, graphene, carbon nanotubes, acetylene black, Ketjen black, copper, nickel, aluminum, silver, and gold;
  • the active material can be a positive electrode active material or a negative electrode active material;
  • the positive electrode active material includes at least one of LiCoO2 , LiMn2O4 , LiMnO2 , LiNiO2 , LiFePO4, LiMnPO4 , LiCo x Ni1- xO2 (0 ⁇ x ⁇ 1), and LiCo x Ni1 -xyAlyO2 ( 0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1);
  • the negative electrode active material includes at least one of artificial graphite, natural graphite, soft carbon, hard carbon, mesophase carbon microbeads, Si, SiOx , Si-C
  • the present invention does not limit the preparation method of the above-mentioned electrode sheet, and it can be prepared by conventional methods in the art.
  • the active material, the conductive agent and the binder are mixed, and then an external high shear force is applied to fibrillate the binder to form a fiber network, and the active material and the conductive agent are bonded to form an electrode film after extrusion.
  • the electrode film and the current collector are compounded to obtain an electrode sheet.
  • a dry electrode process has higher requirements on the working pressure, rolling accuracy and uniformity of the rolling equipment.
  • the active material layer can be made by a dry method, that is, the active material, fiber particles and conductive agent are dry mixed without using a solvent to make a composite material with a solid content concentration of substantially 100%.
  • Dry mixing refers to the following method: the active material and the fiber particles are mixed without using a solvent in a state where the solid content concentration is substantially 100%.
  • a first conductive agent other than the active material and the fiber particles may also be added.
  • the solid content concentration in the dry mixing is also substantially 100%.
  • the glue layer slurry is coated on the current collector and dried to form a hot melt current collector, and then the composite material is rolled into a sheet to make a sheet-shaped active material layer. Furthermore, the hot melt current collector and the active material layer are stacked and hot pressed to form a pole piece.
  • the existing wet method for preparing pole pieces in its production process, it is necessary to mix the solvent, active material and binder into slurry, then apply the slurry on the surface of the current collector, and then dry the slurry coating on the surface of the current collector to volatilize the solvent. It can be seen that the drying process of the wet method makes the battery production process more complicated and reduces the production efficiency.
  • the active material and fiber particles are mixed to form a composite material, the composite material is rolled into a sheet, and then the sheet active material layer is hot-pressed with the hot melt current collector. There is no need to dry the slurry coating on the surface of the current collector to volatilize the solvent, thereby simplifying the pole piece production process and improving the battery production efficiency.
  • the preparation process of the above-mentioned electrode sheet includes the following steps: premixing the binder, the conductive agent, and the active material, and obtaining an electrode film through shearing and rolling treatment; and then compounding the electrode film onto the current collector through hot pressing treatment to obtain an electrode sheet.
  • the rotation speed is 300 to 10,000 rpm
  • the temperature is 0 to 90° C.
  • the time is 10 to 600 min.
  • the molecular chains of the binder are fully expanded to form fibers, and the formed fibers can fully bond the active material body formed by the active material and the conductive agent; finally, a hot pressing process is performed to obtain an electrode film.
  • the present invention does not impose any specific restrictions on the premixing process, as long as the above-mentioned rotation speed, temperature and time are met.
  • the premixing process can be performed in a blender.
  • the shearing process may be performed in a jet mill.
  • the premixed materials are fluidized in the jet mill through the nozzles.
  • the accelerated materials converge at the intersection of the jets of several nozzles, causing violent collision, friction and shearing to achieve fiberization of the binder and obtain dough-like materials.
  • the dough-like materials are extruded through a screw pump and rolled.
  • the feed rate of the jet mill is 150-9000g/min.
  • the present invention does not specifically limit the rolling process, and it can be a rolling process commonly used in the art, such as rolling in an open mill.
  • the rolling direction during the rolling process is consistent with the first direction, which helps to achieve at least part of the fibers extending along the first direction of the electrode sheet.
  • the present invention does not specifically limit the hot pressing treatment, and it can be a hot pressing treatment commonly used in the art, such as a multi-stage hot pressing film forming process.
  • the raw material system including the conductive agent, the binder and the active material is premixed through a specific process, which can achieve sufficient mixing of the conductive agent, the binder and the active material, and is helpful for the subsequent shearing treatment; then, the raw material system after the premixing treatment is sheared by a specific process, which can make the raw material system after the premixing treatment fully fiberized, thereby obtaining the electrode membrane of the present invention.
  • the electrode sheet further includes a glue layer 2, which is located between the current collector and the electrode film;
  • the glue layer includes a binder and a conductive agent.
  • the binder is used to improve the adhesion between the glue layer and the current collector and the adhesion between the glue layer and the electrode film
  • the conductive agent is used to improve the conductivity of the glue layer.
  • the conductive agent can also increase the roughness of the glue layer and increase the specific surface area of the glue layer, thereby further improving the adhesion and peeling force between the glue layer and the current collector and between the glue layer and the electrode film.
  • the glue layer includes an adhesive and a conductive agent.
  • the binder can be polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), or hot melt adhesive
  • the hot melt adhesive includes EVA hot melt adhesive, TPR hot melt adhesive, polyolefin hot melt adhesive, polyamide (PA) hot melt adhesive, polyester (PES) hot melt adhesive, polyethylene (LDPE, HDPE) hot melt adhesive and polyester amide (PEA) hot melt adhesive, etc.
  • the conductive agent can be a conductive agent with a large specific surface area such as conductive carbon black, carbon nanotubes, and graphene.
  • the electrode film also includes a recessed portion, which is located on the side surface of the electrode film away from the current collector, and/or the recessed portion is located inside the electrode film.
  • the present invention does not limit the formation process of the recess.
  • the recess can be formed on the surface or inside of the electrode film by a laser method.
  • the recess is formed on the surface of the electrode film by physical embossing.
  • a solid electrolyte interface (SEI) is formed on the surface of the electrode sheet, resulting in irreversible lithium loss.
  • SEI solid electrolyte interface
  • a lithium supplement is usually added to the electrode sheet to achieve lithium supplementation.
  • the recess is filled with a lithium-containing compound.
  • the lithium-containing compound is, for example, at least one of lithium oxide, lithium carbonate, and lithium fluoride. Filling the recess with a lithium-containing compound helps to reduce irreversible lithium loss.
  • the lithium-containing compound, the binder, the conductive agent, and the active material are premixed, and the electrode film is obtained by shearing and hot pressing.
  • the electrode film is obtained by adding the lithium-containing compound to the raw material system.
  • the above-mentioned electrode sheet is applied to the battery.
  • the lithium-containing compound reacts with the electrolyte to generate lithium ions, which make up for the lithium ions required to generate the SEI film and improve the initial efficiency of the battery.
  • a second aspect of the present invention provides a battery, comprising the electrode sheet according to the first aspect.
  • the electrode sheet includes a negative electrode sheet and a positive electrode sheet
  • the negative electrode sheet, the positive electrode sheet and the separator can form a battery cell in the battery, wherein at least one of the negative electrode sheet and the positive electrode sheet is the electrode sheet of the first aspect.
  • a battery for charging/discharging can be formed by installing the battery cell and the protection circuit together inside the battery housing. The quality of the battery cell directly determines the quality of the battery. Due to the use of the above-mentioned electrode sheet, the battery of the present invention has excellent performance in terms of cycle performance and thickness expansion rate.
  • the present invention is further described below by specific examples and comparative examples.
  • the reagents, materials and instruments used below are all conventional reagents, conventional materials and conventional instruments, which can be commercially available, and the reagents and materials involved can also be synthesized by conventional synthesis methods.
  • Artificial graphite, polytetrafluoroethylene and conductive carbon are added to a dispersing device for full dry mixing to obtain a uniformly dispersed mixture; the above mixture is added to a jet mill, and after dispersion for 25 minutes at a feeding speed of 150 g/min, the polytetrafluoroethylene is fiberized to obtain a dough-like negative electrode material; wherein the mass ratio of artificial graphite, polytetrafluoroethylene and conductive carbon is 97: 2:1;
  • the negative electrode material is extruded and drawn by a screw pump, and rolled by a hot roller press to obtain a negative electrode film, wherein the extrusion and drawing temperature is 100° C., the rolling pressure is 20 t, the rolling speed is 5 m/min, and the rolling direction is controlled so that the fiber extends along the first direction;
  • the negative electrode film was composited to the two surfaces of a copper foil with a thickness of 10 ⁇ m by multi-stage hot pressing to obtain a negative electrode sheet F1 with a thickness of 50 ⁇ m.
  • the ratio of the fiber size in the first direction to the median particle size of the active material body was 1:1000.
  • the preparation process is basically the same as that of Example 1, except that:
  • the parameters of the hot roller press were adjusted to obtain a negative electrode sheet F2 with a thickness of 65 ⁇ m, and the ratio of the size of the fiber in the first direction to the median particle size of the active material body was 1:400.
  • the preparation process is basically the same as that of Example 1, except that:
  • the parameters of the hot roller press were adjusted to obtain a negative electrode sheet F3 with a thickness of 100 ⁇ m, and the ratio of the size of the fiber in the first direction to the median particle size of the active material body was 1:200.
  • the preparation process is basically the same as that of Example 1, except that:
  • the parameters of the hot roller press were adjusted to obtain a negative electrode sheet F4 with a thickness of 350 ⁇ m, and the ratio of the size of the fiber in the first direction to the median particle size of the active material body was 1:100.
  • the positive electrode material is extruded and rolled by a screw pump to obtain a positive electrode film
  • the positive electrode film is composited onto the current collector through multi-stage hot calendering to obtain a positive electrode sheet Z1.
  • the thickness of the positive electrode sheet Z1 is 50 ⁇ m, and the ratio of the size of the fiber in the first direction to the median particle size of the active material body is 1:1000.
  • the preparation process is basically the same as that of Example 5, except that:
  • the parameters of the hot roller press were adjusted to obtain a positive electrode sheet Z2 with a thickness of 65 ⁇ m, and the ratio of the size of the fiber in the first direction to the median particle size of the active material body was 1:400.
  • the preparation process is basically the same as that of Example 5, except that:
  • the parameters of the hot roller press were adjusted to obtain a positive electrode sheet Z3 with a thickness of 100 ⁇ m, and the ratio of the size of the fiber in the first direction to the median particle size of the active material body was 1:200.
  • the preparation process is basically the same as that of Example 5, except that:
  • the parameters of the hot roller press were adjusted to obtain a positive electrode sheet Z4 with a thickness of 350 ⁇ m, and the ratio of the size of the fiber in the first direction to the median particle size of the active material body was 1:100.
  • a negative electrode sheet F11 was produced in the same manner as in Example 1 except that the parameters of the hot roller press were adjusted so that the fiber filaments did not extend in the first direction.
  • the positive electrode sheet Z11 was produced in the same manner as in Example 5 except that the parameters of the hot roller press were adjusted so that the fiber filaments did not extend in the first direction.
  • the preparation process is basically the same as that of Example 1, except that:
  • the parameters of the hot roller press were adjusted so that the breaking force of the negative electrode sheet in the first direction was smaller than the breaking force of the negative electrode sheet in the second direction, and the ratio of the size of the fiber in the first direction to the median particle size of the active material body was 1:500, thereby obtaining the negative electrode sheet F12 of this comparative example.
  • the preparation process is basically the same as that of Comparative Example 2, except that:
  • the parameters of the hot roller press were adjusted so that the ratio of the size of the fiber in the first direction to the median particle size of the active material body was 1:5000, thereby obtaining the negative electrode sheet F13 of this comparative example.
  • the positive electrode sheet, the separator (purchased from Asahi Kasei ND522), and the negative electrode sheet are welded to the positive and negative electrode tabs and then wound to obtain a battery cell, the battery cell is placed in an aluminum-plastic film packaging shell and sealed, and then an electrolyte is injected, and a lithium-ion battery is obtained after formation and sorting;
  • the electrolyte includes a solvent, a lithium salt and an additive.
  • the solvent is a mixed solvent of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate in a mass ratio of 3:4:3.
  • the lithium salt is lithium hexafluorophosphate.
  • the concentration of the lithium salt in the electrolyte is 1.2 mol/L.
  • the additives include fluoroethylene carbonate and vinylene carbonate.
  • the mass content of fluoroethylene carbonate in the electrolyte is 3wt%, and the mass content of vinylene carbonate in the electrolyte is 1wt%.
  • the positive electrode sheet Z1 is matched with the negative electrode sheet F1
  • the positive electrode sheet Z1 is matched with the negative electrode sheet F2
  • the positive electrode sheet Z1 is matched with the negative electrode sheet F3
  • the positive electrode sheet Z1 is matched with the negative electrode sheet F4
  • the positive electrode sheet Z2 is matched with the negative electrode sheet F1
  • the positive electrode sheet Z3 is matched with the negative electrode sheet F1
  • the positive electrode sheet Z4 is matched with the negative electrode sheet F1
  • the positive electrode sheet Z11 is matched with the negative electrode sheet F11
  • the positive electrode sheet Z11 is matched with the negative electrode sheet F12
  • the positive electrode sheet Z11 is matched with the negative electrode sheet F13
  • the obtained lithium-ion batteries are respectively recorded as D1, D2, D3, D4, D5, D6, D7, D8, D9, and D10.
  • the positive electrode sheet, negative electrode sheet and current collector were cut into test samples with a width of 15 ⁇ 0.25 mm and a length of 75 ⁇ 0.5 mm, respectively.
  • a universal tensile testing machine was used with a gauge length of 50 ⁇ 0.5 mm and a stretching speed of 200 mm/min.
  • the positive electrode sheet, negative electrode sheet and current collector were stretched along the first direction and the second direction, respectively, to test the maximum tensile force required for fracture.
  • the battery was charged to 4.45V at 1C constant current, then charged to a cut-off current of 0.05C at constant voltage, left to stand for 5 minutes, and discharged to 3.0V at 1C constant current. This was the first cycle, and the above process was repeated 300 times.
  • At least part of the fibers in the electrode sheets of Examples 1-8 extend along the first direction of the electrode sheets, while the fibers in the electrode sheet of Comparative Example 1 do not extend along the first direction of the electrode sheets.
  • the breaking tensile forces of the electrode sheets in Examples 1-8 in the first direction are all higher than those in Comparative Example 1, indicating that the electrode sheets of the examples can withstand a significantly higher tensile force range than the comparative examples. It also indicates that making at least part of the fibers extend along the first direction of the electrode sheets can help increase the breaking tensile force of the electrode sheets in the first direction.
  • Comparative Examples 1-8 show that controlling the thickness of the electrode sheet can help further reduce the frequency of roller-breaking.
  • the cycle performance and thickness expansion rate of the battery made using the electrode sheet of the embodiment are better, indicating that the fibers in the embodiment better wrap the active material, which helps to alleviate the cycle expansion caused by the deintercalation and extraction of lithium ions from the active material.

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Abstract

一种电极片和电池，所述电极片包括集流体、设置在所述集流体至少一个功能表面的电极膜；所述电极膜包括纤维，至少部分所述纤维沿着所述电极片的第一方向延伸。通过限定电极片的组成和结构，能够显著提高电极片的断裂拉力和粘结性，增加电极片的抗拉强度，降低断带风险，将该电极片应用于电池中，能够显著提升电池的循环性能和厚度膨胀率。

Description

一种电极片和电池
本申请要求于2023年12月21日提交中国专利局、申请号为202311773277.3、申请名称为“一种电极片和电池”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
本申请涉及一种电极片和电池，属于锂离子电池技术领域。
背景技术
锂离子电池由于具有能量利用效率高、工作温度宽、环境友好等优点，而被广泛应用于电子、通讯、电动等领域。电极片作为锂离子电池的重要部件，对锂离子电池的性能会产生至关重要的影响。目前在电极片的制备常采用湿法工艺，利用有机溶剂制备浆料进行涂布，经干燥和辊压后，得到电极片。但是有机溶剂容易造成污染，且后续需要将溶剂干燥去除，产生极大的能源浪费，增加了生产成本。且电极片易产生开裂、韧性差、分层等现象，无法进一步提升能量密度。
现阶段，为了提升电池的能量密度，减少电极制备过程中的耗能，降低生产成本，大多利用干法电极工艺制备电极，干法电极工艺相较于湿法工艺对辊压设备的工作压力、辊压精度以及均匀度提出了更高要求，且压实力度更大，导致在辊压过程中容易出现易断裂、脱粉等问题。因此，如何提升电极片的断裂拉力，降低辊压过程中的断带风险，是本领域亟待解决的技术问题。
发明内容
本发明提供的电极片，通过限定电极片的组成和结构，能够显著提高电极片的断裂拉力和粘结性，增加电极片的抗拉强度，降低断带风险，该电极片可直接应用于电池中，能够显著提升电池的循环性能和厚度膨胀率。
本发明还提供一种电池，由于包括上述电极片，该电池在循环性能和厚度膨胀率等方面表现优异。
本发明的第一方面，提供一种电极片，电极片包括集流体、设置在所述集流体至少一个功能表面的电极膜；
所述电极膜包括纤维，至少部分所述纤维沿着所述电极片的第一方向延伸。
如上所述的电极片，其中，所述纤维的延伸方向与所述电极片的第一方向的夹角为0～30°。
如上所述的电极片，其中，所述电极片在第一方向上的断裂拉力大于等于所述电极片在第二方向上的断裂拉力；
所述第二方向垂直于所述第一方向。
如上所述的电极片，其中，所述电极片在第一方向上的断裂拉力与所述电极片在第二方向上的断裂拉力的比值为(1～2)：1，优选地，(1.02～1.52)：1。
如上所述的电极片，其中，所述电极片在第一方向上的断裂拉力与所述电极片厚度的比值为(0.008～0.1)：1；
其中，所述电极片在第一方向上的断裂拉力的单位为kgf，所述电极片厚度的单位为μm。
如上所述的电极片，其中，所述电极片在第一方向上的断裂拉力为3～6kgf；和/或，
所述电极片在第二方向上的断裂拉力为2～5.5kgf；和/或，
所述电极片的厚度为65～350μm。
如上所述的电极片，其中，所述集流体在第二方向上的断裂拉力小于所述集流体在第一方向上的断裂拉力。
如上所述的电极片，其中，所述集流体在第一方向上的断裂拉力和所述集流体在第二方向上的断裂拉力的比值为(0.67～2.75)：1，优选地，(0.875～1.67)：1。
如上所述的电极片，其中，所述电极膜还包括活性物质体，至少部分所述纤维在第一方向的尺寸大于所述活性物质体的中值粒径。
如上所述的电极片，其中，所述活性物质体包括LiCoO2、LiMn2O4、LiMnO2、LiNiO2、LiFePO4、LiMnPO4、LiCoxNi1-xO2、LiCoxNi1-x-yAlyO2，其中，0≤x≤1，0≤y≤1，或者，
所述活性物质体包括人造石墨、天然石墨、软碳、硬碳、中间相碳微球，Si、SiOx、Si-C、SiOx-C中的至少一种。
如上所述的电极片，其中，单根所述纤维在第一方向的尺寸与所述活性物质体的中值粒径的比值为1:(1～4000)，优选地，1:(1～400)。
如上所述的电极片，其中，单根所述纤维在第一方向的尺寸为250nm～1mm；和/或，
所述活性物质体的中值粒径为250nm～30μm。
如上所述的电极片，其中，在所述电极片的厚度方向上，所述纤维沿着所述电极片的厚度方向延伸。
如上所述的电极片，其中，沿着所述电极片的厚度方向，相邻的活性物质体之间通过所述纤维相连。
如上所述的电极片，其中，所述电极片还包括胶层，所述胶层位于所述集流体和所述电极膜之间。
如上所述的电极片，其中，所述胶层包括粘结剂和导电剂；所述粘结剂包括聚偏二氟乙烯、丁苯橡胶、EVA类热熔胶、TPR类热熔胶、聚烯烃类热熔胶、聚酰胺类热熔胶、聚酯类热熔胶、聚乙烯类热熔胶、聚酯酰胺类热熔胶中的至少一种，和/或
所述导电剂包括导电炭黑、碳纳米管、石墨烯中的至少一种。
如上所述的电极片，其中，所述纤维包括纤维状的聚四氟乙烯、聚偏二氟乙烯、乙烯-四氟乙烯共聚物、氟化乙烯丙烯共聚物、聚乙烯吡咯烷酮、聚氧化乙烯、羧甲基纤维素、丁苯橡胶、聚丙烯酸、热熔胶、聚乙烯中的至少一种。
如上所述的电极片，其中，所述电极膜还包括凹部，所述凹部位于所述电极膜远离集流体的一侧表面，和/或，所述凹部位于所述电极膜的内部。
如上所述的电极片，其中，所述凹部内填充有含锂化合物，所述含锂化合物包括氧化锂、碳酸锂、氟化锂中的至少一种。
本发明的第二方面，提供一种电池，包括第一方面所述的电极片。
本发明的实施，至少具有以下有益效果：
本发明提供的电极片中纤维沿着电极片的第一方向延伸，能够增加电极膜与集流体的粘结性，同时更好地传递应力，增强电极片在第一方向上的断裂拉力，降低辊压过程中的断带风险，提高制程效率，从而保证电极片在长循环 过程中的稳定性。
本发明提供的电池，由于包括上述的电极片，因此具有优异的电化学性能，例如，优异的循环性能和较低的厚度膨胀率。
附图说明
图1是本发明一实施方式中电极片在第一放大倍数下的俯视SEM图；
图2是本发明一实施方式中电极片在第二放大倍数下的俯视SEM图；
图3是本发明一实施方式中电极片的截面SEM图；
图4是本发明一实施方式中电极片的结构示意图。
附图标记说明：
1-电极膜；2-胶层；3-集流体。
具体实施方式
为使本申请实施例的目的、技术方案和优点更加清楚，下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
图1至图4中，X方向为电极片的长度方向，Y方向为电极片的宽度方向，Z方向为电极片的厚度方向。
本发明的第一方面，提供一种电极片，电极片包括集流体3、设置在集流体至少一个功能表面的电极膜1；电极膜包括纤维，至少部分纤维沿着电极片的第一方向延伸。
本发明不限定电极片、集流体的具体形状，可以是本领域常规的长方体状。
集流体具有最大且相对的两个功能表面，这两个功能表面用于设置电极膜。本发明的电极片中的电极膜可以仅设置在集流体的一个功能表面，或者同时设置在集流体的两个功能表面。
电极膜用于发生电化学反应，从而将化学能转化为电能。
本发明的电极膜组分至少包括活性物质体和粘结剂，其中，活性物质 体至少包括活性物质、导电剂；活性物质用于发生电化学反应，导电剂用于提高电极膜的导电性，粘结剂用于粘结活性物质和导电剂，从而形成完整的电极膜。
其中，纤维指的是连续或不连续的细丝。在一些实施方式中，纤维是由粘结剂经原纤化法或者静电喷涂法形成的丝状结构。本发明不限定纤维的具体材质，具体可以是本领域常用的粘结剂，示例性地，纤维可以为纤维状的聚四氟乙烯(PTFE)、聚偏二氟乙烯(PVDF)、乙烯-四氟乙烯共聚物(ETEF)、氟化乙烯丙烯共聚物(FEP)、聚乙烯吡咯烷酮(PVP)、聚氧化乙烯(PEO)、羧甲基纤维素(CMC)、丁苯橡胶(SBR)、聚丙烯酸(PAA)、热熔胶、聚乙烯(PE)中的至少一种。
纤维与活性物质体呈现线-面接触，增加了纤维与活性物质体的接触面积，使得纤维和活性物质体之间实现更紧密的连接，提高电极片的柔韧性，防止开裂掉粉。
电极片中的纤维的分布方式会影响电极片的力学性能。本发明通过限定至少部分纤维沿着电极片的第一方向延伸，能够显著提高电极片的断裂拉力，降低断带风险，从而显著提升电池的循环性能和降低厚度膨胀率。
其中，电极片的第一方向是指电极片的延伸方向，例如，电极片的长度方向或者宽度方向。也就是说，纤维的延伸方向与电极片的延伸方向一致。
如图1所示，当第一方向是电极片的长度方向(X方向)时，纤维的延伸方向与电极片的长度方向一致，这样保证纤维与活性物质体形成更紧密的结合，增加电极片在长度方向上的抗拉强度，使其能够承受更大的拉力。
本发明不限定电极片在其延伸方向上的断裂拉力，在一些实施例中，电极片在第一方向上的断裂拉力大于等于电极片在第二方向上的断裂拉力；第二方向垂直于第一方向。电极片在辊压过程中会沿着辊压方向延展，电极片在卷绕过程中沿着卷绕方向卷绕，因此，电极片在辊压方向和卷绕方向上需要承受一定的抗拉强度，当辊压方向和卷绕方向均与第一方向一致时，通过限定电极片在第一方向上的断裂拉力大于等于电极片在第二方向上的断裂拉力，这样避免电极片在辊压过程中发生断带，同时，防止电极 片在卷绕过程中受力过大而发生开裂。
当第一方向是电极片的长度方向时，第二方向是指电极片的宽度方向。
电极膜中，至少90％质量分数的纤维沿着电极片的第一方向延伸，也就是说，至少90％质量分数的纤维的延伸方向与电极片的第一方向的夹角为0°，在一些实施例中，纤维的延伸方向与电极片的第一方向的夹角为0～30°。
将电极片应用于电池中，电池在充放电过程中不可避免的发生膨胀和收缩。在一些实施例中，电极片在第一方向上的断裂拉力与电极片在第二方向上的断裂拉力的比值为(1～2)：1。通过限定电极片在第一方向和第二方向上的断裂拉力比值，可有效缓解在充放电过程中电极片在第一方向、第二方向上的膨胀，尤其能够缓解电极片在第一方向上的膨胀，优选电极片在第一方向上的断裂拉力与第二方向上的断裂拉力的比值为(1.02～1.52)：1，这样不仅能够减少电极片内部的电阻和界面反应，提高电池的电化学性能，而且还能够提高电池的机械稳定性，延长电池的使用寿命。
电极膜的厚度会影响活性物质的负载量，进而影响电池的能量密度。在一些实施例中，电极片在第一方向上的断裂拉力与电极片厚度的比值为(0.008～0.1)：1，其中，电极片在第一方向上的断裂拉力的单位为kgf，电极片厚度的单位为μm。这样保证在电极片机械强度的同时，能够增加电池中活性物质的负载量，提高电池的能量密度(单位体积或单位重量下储存的电能量)，确保电池在相同尺寸具有更高的容量。
其中，电极片的厚度等于集流体的厚度与电极膜的厚度之和。
本发明不限定电极片的断裂拉力、厚度的具体数值，可以根据实际情况确定。例如，在一些实施例中，电极片在第一方向上的断裂拉力为3～6kgf，优选为4.3～5kgf；和/或，电极片在第二方向上的断裂拉力为2～5.5kgf，优选为3.3～4.2kgf；和/或，电极片的厚度为65～350μm。
本发明中，集流体在第二方向上的断裂拉力小于集流体在第一方向上断裂拉力。集流体在第一方向上的断裂拉力和集流体在第二方向上的断裂拉力之间的比值为(0.67～2.75)：1，优选为(0.875～1.67)：1，保证电极片在加工过程中的强度，减少断带风险。
进一步地，集流体在第一方向上的断裂拉力为3～5.5kgf，优选为 3.5～5kgf；集流体在第二方向上的断裂拉力为2～4.5kgf，优选为3～4kgf。
电极膜中包括多根纤维和多个活性物质体，至少部分纤维在第一方向的尺寸大于活性物质体的中值粒径。其中，纤维在第一方向上的尺寸实质上是指纤维的长度，活性物质体的中值粒径是指累计体积分数为50％所对应的粒径。纤维在第一方向上的尺寸实际上是指所有纤维的在第一方向上绝对尺寸，即在第一方向所跨越的尺寸。
在一些实施例中，单根纤维在第一方向的尺寸与活性物质体的中值粒径的比值为1:(1～4000)，保证多根纤维能够跨越活性物质体，对活性物质体起到粘结和固定作用，从而降低循环膨胀率。
本发明不限定纤维、活性物质体的具体尺寸，在一些实施例中，纤维在第一方向的尺寸为250nm～1mm；和/或，活性物质体的中值粒径为250nm～30μm。
在一些实施例中，在电极片的厚度方向上，纤维沿着电极片的厚度方向延伸。也就是说，在电极片的厚度方向上观察，纤维沿着电极片的厚度方向分布。
纤维为连接多个活性物质体之间的粘结部件，在一些实施例中，沿着电极片的厚度方向，相邻的活性物质体之间通过纤维相连。通过纤维使活性物质体彼此之间连接更紧密。这样进一步保证纤维对活性物质体起到粘结和固定作用，从而降低循环膨胀率。
本发明不限定活性物质体中活性物质、导电剂的具体类型，例如，在一些实施例中，导电剂可以是导电炭黑、碳纤维、导电石墨、石墨烯、碳纳米管、乙炔黑、科琴黑、铜、镍、铝、银、金中的至少一种；活性物质可以是正极活性材料或者负极活性材料；示例性地，正极活性材料包括LiCoO2、LiMn2O4、LiMnO2、LiNiO2、LiFePO4、LiMnPO4、LiCoxNi1-xO2(0≤x≤1)、LiCoxNi1-x-yAlyO2(0≤x≤1，0≤y≤1)中的至少一种；负极活性材料包括人造石墨、天然石墨、软碳、硬碳、中间相碳微球、Si、SiOx、Si-C、SiOx-C中的至少一种，此时，电极膜中硅的质量含量为3～100％。
本发明不限定上述电极片的制备方法，可以采用本领域常规的方法制备。例如，将活性物质、导电剂和粘结剂混合，然后施加外部的高剪切力，使粘结剂纤化后形成纤维网络，粘合活性物质与导电剂，经挤压后形成电极膜，最后将电极膜与集流体进行复合，得到电极片。这样的干法电极工艺相较于湿法工艺对辊压设备的工作压力、辊压精度以及均匀度提出了更高要求，本发明 通过限定至少部分纤维沿着电极片的第一方向延伸，避免电极片在辊压过程中容易出现断裂、脱粉等问题。
在一实例中，活性物质层可以通过干法制作，即将活性物质、纤维颗粒和导电剂不使用溶剂地进行干式混合，制作成固体成分浓度实质为100％的复合材料。干式混合是指如下方式：在固体成分浓度实质为100％的状态下，将活性物质与纤维颗粒不使用溶剂地进行混合。在进行干式混合时，也可以添加除了活性物质和纤维颗粒之外的第一导电剂等。在添加除了活性物质和纤维颗粒之外的材料的情况下，干式混合中的固体成分浓度实质上也为100％。
随后，将胶层浆料涂布到集流体上，烘干后形成热熔集流体，再通过将上述复合材料压延而成为片状，从而制作成片状的活性物质层。并且，将热熔集流体和活性物质层层叠并进行热压，以形成极片。
相比于现有的湿法制备极片，在其制作过程中，需要将溶剂、活性物质和粘结剂混合制成浆料，然后将浆料涂布在集流体表面，再对集流体表面的浆料涂层进行干燥处理以使得溶剂挥发。由此可见，湿法的干燥工序使得电池的制作工序较为复杂，降低制备效率。在本发明的实施例中，通过采用干法制备极片，不需要使用溶剂，将活性物质和纤维颗粒混合制成复合材料，将复合材料压延成片状，然后将该片状活性物质层与热熔集流体热压即可，无需对集流体表面的浆料涂层进行干燥处理以使溶剂挥发，从而简化了极片的制作工序，提高了电池的制备效率。
在一种实施方式中，上述电极片的制备过程包括以下步骤：将粘结剂、导电剂、活性物质进行预混处理，经剪切处理以及辊压处理，得到电极膜；再将电极膜经过热压处理复合到集流体上，得到电极片。
其中，预混处理中，转速为300～10000转/分钟，温度为0～90℃，时间为10～600min。
具体地，在剪切处理过程中，粘结剂的分子链充分展开，形成纤维，所形成的纤维能够将由活性物质与导电剂形成的活性物质体充分粘结；最后进行热压处理，得到电极膜。
本发明对预混处理不做具体限定，只要满足上述的转速、温度以及时间即可。在一些实施例中，可以在搅拌机中进行预混处理。
本发明对剪切处理不做具体限定，在一些实施例中，可以在气流磨 设备中进行剪切处理。预混后的物料在气流磨设备中，经喷嘴使物料呈流态化，被加速的物料在数个喷嘴的喷射气流交汇点汇合，产生剧烈的碰撞、磨擦、剪切而实现粘结剂的纤维化，得到面团状的物料，将面团状的物料经螺杆泵挤出，进行辊压处理。其中，气流磨设备的给料速度为150～9000g/min。
本发明对辊压处理不做具体限定，可以为本领域常用的辊压处理，例如在开炼机中进行辊压处理。在一种可能的实施方式中，辊压处理时辊压方向与第一方向一致，有助于实现至少部分纤维沿着电极片的第一方向延伸。
本发明对热压处理不做具体限定，可以为本领域常用的热压处理，例如多级热压成膜处理。
本发明的电极膜的制备方法中，通过特定的工艺对包括导电剂、粘结剂以及活性物质的原料体系进行预混处理，能够实现导电剂、粘结剂以及活性物质的充分混合，有助于后续剪切处理的进行；接着以特定的工艺对预混处理后的原料体系进行剪切处理，能够使预混处理后的原料体系充分纤维化，从而得到本发明的电极膜。
为了提升电极膜和集流体之间的粘结性，在一些实施例中，电极片还包括胶层2，胶层位于集流体和电极膜之间；胶层包括粘结剂和导电剂。粘结剂用于提高胶层与集流体的粘结性以及胶层与电极膜的粘结性，导电剂用于提高胶层的导电性，同时，导电剂还能够增加胶层的粗糙度，增大胶层的比表面积，从而进一步提高胶层与集流体之间以及胶层与电极膜之间的粘结力和剥离力。
其中，胶层包括粘结剂和导电剂。
其中，粘结剂可以是聚偏二氟乙烯(PVDF)、丁苯橡胶(SBR)，也可以是热熔胶，热熔胶包括EVA类热熔胶、TPR类热熔胶、聚烯烃类热熔胶、聚酰胺(PA)类热熔胶、聚酯(PES)类热熔胶、聚乙烯(LDPE、HDPE)类热熔胶和聚酯酰胺(PEA)类热熔胶等。导电剂可以是导电炭黑、碳纳米管、石墨烯等比表面积较大的导电剂。在一些实施例中，电极膜还包括凹部，凹部位于电极膜远离集流体的一侧表面，和/或，凹部位于电极膜的内部。通过形成若干个凹部，可有效增加电解液的浸润通道，提高电解液浸润性，有助于提 高锂离子的传输速度，提高充电倍率。
本发明不限定凹部的形成过程，在一种实施方式中，可通过激光法在电极膜的表面或内部形成凹部，在另一种实施方式中，利用物理压花的方式在电极膜表面形成凹部。
在锂离子电池的首次循环过程中，电极片的表面会形成固体电解质界面(SEI)，从而导致产生不可逆的锂损失。通常在电极片中增加补锂剂以实现补锂。在一些实施例中，凹部内填充有含锂化合物。含锂化合物例如氧化锂、碳酸锂、氟化锂中的至少一种。通过在凹部中填充含锂化合物，有助于减少不可逆的锂损失。
在本发明的具体实施过程中，将含锂化合物、粘结剂、导电剂、活性物质进行预混处理，经剪切处理以及热压处理，得到电极膜。通过在原料体系中加入含锂化合物，制得电极膜。此外，将上述电极片应用于电池中，注液过程中，含锂化合物和电解液发生反应，生成锂离子，弥补生成SEI膜所需的锂离子，提高电池的首效。
本发明的第二方面，提供一种电池，包括上述第一方面的电极片。
具体的，电极片包括负极片、正极片，负极片、正极片以及隔膜可以形成电池中的电芯，其中负极片、正极片中的至少一个为上述第一方面的电极片。通过将电芯与保护电路共同安装在电池壳体内部后就可以形成用于充/放电的电池。电芯的质量直接决定了电池的质量，由于采用上述电极片，因此，本发明的电池在循环性能和厚度膨胀率等方面表现优异。
下面通过具体实施例和对比例对本发明作进一步的说明。如无特别说明，下述所使用到的试剂、材料以及仪器均为常规试剂、常规材料以及常规仪器，均可商购获得，所涉及的试剂、材料也可通过常规合成方法合成获得。
实施例1
本实施例的负极片制备过程包括以下步骤：
将人造石墨、聚四氟乙烯、导电碳加入分散设备中进行充分干混，得到分散均匀的混合料；将上述混合料加入到气流磨设备中，在给料速度为150g/min的条件下，经分散25min后，实现聚四氟乙烯的纤维化，得到面团状的负极材料；其中，人造石墨、聚四氟乙烯、导电碳的质量比为97： 2：1；
将负极材料经螺杆泵挤出拉丝、经热辊压机进行辊压，得到负极电极膜，其中，挤出拉丝的温度为100℃，辊压的压力为20t，辊压速度为5m/min，控制辊压方向使得纤维沿着第一方向延伸；
将负极电极膜经过多级热压复合到厚度为10μm的铜箔的两个表面上，得到厚度为50μm的负极片F1，纤维在第一方向上的尺寸和活性物质体的中值粒径的比值为1:1000。
实施例2
与实施例1的制备过程基本一致，区别在于：
调整热辊压机的参数，得到厚度为65μm的负极片F2，纤维在第一方向上的尺寸和活性物质体的中值粒径的比值为1:400。
实施例3
与实施例1的制备过程基本一致，区别在于：
调整热辊压机的参数，得到厚度为100μm的负极片F3，纤维在第一方向上的尺寸和活性物质体的中值粒径的比值为1:200。
实施例4
与实施例1的制备过程基本一致，区别在于：
调整热辊压机的参数，得到厚度为350μm的负极片F4，纤维在第一方向上的尺寸和活性物质体的中值粒径的比值为1:100。
实施例5
本实施例的正极片制备过程包括以下步骤：
将钴酸锂、聚四氟乙烯、导电碳加入分散设备中进行充分干混，得到分散均匀的混合料；将上述混合料加入到气流磨设备中，在给料速度为150g/min的条件下分散25min，经过充分分散以及聚四氟乙烯的纤维化，得到面团状的正极材料；其中，钴酸锂、聚四氟乙烯、导电碳的质量比为97：2：1；
将正极材料经螺杆泵挤出辊压，得到正极电极膜；
将正极电极膜经过多级热压延复合到集流体上，得到正极片Z1，正极片Z1的厚度为50μm，纤维在第一方向上的尺寸和活性物质体的中值粒径的比值为1:1000。
实施例6
与实施例5的制备过程基本一致，区别在于：
调整热辊压机的参数，得到厚度为65μm的正极片Z2，纤维在第一方向上的尺寸和活性物质体的中值粒径的比值为1:400。
实验例7
与实施例5的制备过程基本一致，区别在于：
调整热辊压机的参数，得到厚度为100μm的正极片Z3，纤维在第一方向上的尺寸和活性物质体的中值粒径的比值为1:200。
实验例8
与实施例5的制备过程基本一致，区别在于：
调整热辊压机的参数，得到厚度为350μm的正极片Z4，纤维在第一方向上的尺寸和活性物质体的中值粒径的比值为1:100。
对比例1
1、负极片的制备
调整热辊压机参数，使得纤维丝不沿第一方向延伸，除此之外，与实施例1同样操作而制作负极片F11。
2、正极片的制备
调整热辊压机参数，使得纤维丝不沿第一方向延伸，除此之外，与实施例5同样操作而制作正极片Z11。
对比例2
与实施例1的制备过程基本一致，区别在于：
调整热辊压机参数，使得负极片在第一方向上的断裂拉力小于负极片在第二方向上的断裂拉力，纤维在第一方向上的尺寸和活性物质体的中值粒径的比值为1:500，得到本对比例的负极片F12。
对比例3
与对比例2的制备过程基本一致，区别在于：
调整热辊压机参数，使得纤维在第一方向上的尺寸和活性物质体的中值粒径的比值为1:5000，得到本对比例的负极片F13。
试验例
1、锂离子电池的制备
将正极片、隔膜(购买自旭化成ND522)、负极片经过焊接正负极极耳后卷绕得到电芯，将电芯置于铝塑膜包装外壳中并封口，然后注入电解液，经过化成、分选后得到锂离子电池；
其中，电解液包括溶剂、锂盐和添加剂，溶剂为碳酸乙烯酯、碳酸二甲酯和碳酸甲乙酯质量比为3：4：3的混合溶剂，锂盐为六氟磷酸锂，锂盐在电解液中的浓度为1.2mol/L，添加剂包括氟代碳酸乙烯酯和的碳酸亚乙烯酯，氟代碳酸乙烯酯在电解液中的质量含量为3wt％，碳酸亚乙烯酯在电解液中的质量含量为1wt％。
具体的，在上述制备过程中，将正极片Z1搭配负极片F1、正极片Z1搭配负极片F2、正极片Z1搭配负极片F3、正极片Z1搭配负极片F4、正极片Z2搭配负极片F1、正极片Z3搭配负极片F1、正极片Z4搭配负极片F1、正极片Z11搭配负极片F11、正极片Z11搭配负极片F12、正极片Z11搭配负极片F13，得到的锂离子电池依次记为D1、D2、D3、D4、D5、D6、D7、D8、D9、D10。
2、电极片的性能测试
将上述正极片、负极片、集流体分别裁切成宽度为15±0.25mm、长度为75±0.5mm的测试样品，利用万能拉力机，设置标距为50±0.5mm，拉伸速度为200mm/min，分别沿着第一方向、第二方向拉伸正极片、负极片、集流体，测试断裂所需最大的拉力。
2)使用扫描电子显微镜测试不同放大倍数的正极片、负极片的形貌；用氩离子气体裁切极片截面，使用扫描电子显微镜测试极片的截面形貌；
3)极片辊压500m断带次数:统计辊压500m极片过程中的断带次数。
3、电池性能测试
1)容量保持率测试
在25℃下，将电池以1C恒流充电至4.45V，再恒压充电至截止电流0.05C，静置5min，以1C恒流放电至3.0V，此为首次循环，重复上述过程300次。根据电池循环300次的容量保持率(％)＝300次循环后的放电容量/首次循环后的放电容量×100％计算容量保持率。
2)厚度膨胀率测试
测试循环前电池50％SOC状态下的初始PPG厚度记为P1，循环300圈 后，测试电池的在100％SOC下的PPG厚度记为P2，则厚度膨胀率％＝(P2-P1)/P1×100％。
测试结果如表1和表2所示。
表1
表2
根据表1可知，实施例1-8的电极片中至少部分纤维沿着电极片的第一方向延伸，而对比例1的电极片中纤维不沿着电极片的第一方向延伸，实施例1-8中电极片在第一方向上的断裂拉力均高于对比例1的，说明实施例的电极片能承受拉力范围明显高于对比例，也说明通过使至少部分纤维沿着电极片的第一方向延伸，有助于提升电极片在第一方向上的断裂拉力。
对比实施例1-8和对比例2可知，通过限定电极片在第一方向上的断裂 拉力大于等于电极片在第二方向上的断裂拉力，能够进一步降低断带风险。
对比实施例1-8和对比例3可知，通过限定单根纤维在第一方向的尺寸与活性物质体的中值粒径的比值，有助于进一步降低断带风险。
对比实施例1-8可知，通过控制电极片的厚度，有助于进一步减少了辊压断带的频率。
根据表2可知，在相同电极片厚度下，采用实施例的电极片制得的电池的循环性能和厚度膨胀率表现更优异，说明实施例中的纤维更好的包裹活性物质，有助于缓解了由于活性物质脱嵌锂离子产生的循环膨胀。
以上详细描述了本发明的较佳具体实施例以及试验验证。应当理解，本领域的普通技术无需创造性劳动就可以根据本发明的构思作出诸多修改和变化。因此，凡本技术领域中技术人员依本发明的构思在现有技术的基础上通过逻辑分析、推理或者有限的实验可以得到的技术方案，皆应在本发明的保护范围内。

Claims (20)

  1. 一种电极片，其特征在于，所述电极片包括集流体、设置在所述集流体至少一个功能表面的电极膜；
    所述电极膜包括纤维，至少部分所述纤维沿着所述电极片的第一方向延伸。
  2. 根据权利要求1所述的电极片，其特征在于，所述纤维的延伸方向与所述电极片的第一方向的夹角为0～30°。
  3. 根据权利要求1所述的电极片，其特征在于，所述电极片在第一方向上的断裂拉力大于等于所述电极片在第二方向上的断裂拉力；
    所述第二方向垂直于所述第一方向。
  4. 根据权利要求1所述的电极片，其特征在于，所述电极片在第一方向上的断裂拉力与所述电极片在第二方向上的断裂拉力的比值为(1～2)：1，优选地，(1.02～1.52)：1。
  5. 根据权利要求1所述的电极片，其特征在于，所述电极片在第一方向上的断裂拉力与所述电极片厚度的比值为(0.008～0.1)：1；
    其中，所述电极片在第一方向上的断裂拉力的单位为kgf，所述电极片厚度的单位为μm。
  6. 根据权利要求1-5任一项所述的电极片，其特征在于，所述电极片在第一方向上的断裂拉力为3～6kgf；和/或，
    所述电极片在第二方向上的断裂拉力为2～5.5kgf；和/或，
    所述电极片的厚度为65～350μm。
  7. 根据权利要求1-5任一项所述的电极片，其特征在于，所述集流体在第二方向上的断裂拉力小于所述集流体在第一方向上的断裂拉力。
  8. 根据权利要求7所述的电极片，其特征在于，所述集流体在第一方向上的断裂拉力和所述集流体在第二方向上的断裂拉力的比值为(0.67～2.75)：1，优选地，(0.875～1.67)：1。
  9. 根据权利要求1-5任一项所述的电极片，其特征在于，所述电极膜还包括活性物质体，至少部分所述纤维在第一方向的尺寸大于所述活性物质体的中值粒径。
  10. 根据权利要求9所述的电极片，其特征在于，所述活性物质体包括 LiCoO2、LiMn2O4、LiMnO2、LiNiO2、LiFePO4、LiMnPO4、LiCoxNi1-xO2、LiCoxNi1-x-yAlyO2，其中，0≤x≤1，0≤y≤1，或者，
    所述活性物质体包括人造石墨、天然石墨、软碳、硬碳、中间相碳微球，Si、SiOx、Si-C、SiOx-C中的至少一种。
  11. 根据权利要求9所述的电极片，其特征在于，单根所述纤维在第一方向的尺寸与所述活性物质体的中值粒径的比值为1:(1～4000)，优选地，1:(1～400)。
  12. 根据权利要求11所述的电极片，其特征在于，单根所述纤维在第一方向的尺寸为250nm～1mm；和/或，
    所述活性物质体的中值粒径为250nm～30μm。
  13. 根据权利要求1-5任一项所述的电极片，其特征在于，在所述电极片的厚度方向上，所述纤维沿着所述电极片的厚度方向延伸。
  14. 根据权利要求1所述的电极片，其特征在于，沿着所述电极片的厚度方向，相邻的活性物质体之间通过所述纤维相连。
  15. 根据权利要求1所述的电极片，其特征在于，所述电极片还包括胶层，所述胶层位于所述集流体和所述电极膜之间。
  16. 根据权利要求15所述的电极片，其特征在于，所述胶层包括粘结剂和导电剂；
    所述粘结剂包括聚偏二氟乙烯、丁苯橡胶、EVA类热熔胶、TPR类热熔胶、聚烯烃类热熔胶、聚酰胺类热熔胶、聚酯类热熔胶、聚乙烯类热熔胶、聚酯酰胺类热熔胶中的至少一种，和/或，
    所述导电剂包括导电炭黑、碳纳米管、石墨烯中的至少一种。
  17. 根据权利要求1所述的电极片，其特征在于，所述纤维包括纤维状的聚四氟乙烯、聚偏二氟乙烯、乙烯-四氟乙烯共聚物、氟化乙烯丙烯共聚物、聚乙烯吡咯烷酮、聚氧化乙烯、羧甲基纤维素、丁苯橡胶、聚丙烯酸、热熔胶、聚乙烯中的至少一种。
  18. 根据权利要求1-4任一项所述的电极片，其特征在于，所述电极膜还包括凹部，所述凹部位于所述电极膜远离集流体的一侧表面，和/或，所述凹部位于所述电极膜的内部。
  19. 根据权利要求18所述的电极片，其特征在于，所述凹部内填充有含 锂化合物；
    其中，所述含锂化合物包括氧化锂、碳酸锂、氟化锂中的至少一种。
  20. 一种电池，其特征在于，包括权利要求1-19任一项所述的电极片。
PCT/CN2024/123658 2023-12-21 2024-10-09 一种电极片和电池 Pending WO2025130263A1 (zh)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105514323A (zh) * 2016-01-20 2016-04-20 大连理工大学 一种新型高性能静电纺聚芳醚砜酮锂电池隔膜的制备方法
JP2017130451A (ja) * 2016-01-19 2017-07-27 株式会社ダイセル 結着剤、電極用スラリー、電極及びその製造方法並びに二次電池
CN110085806A (zh) * 2019-04-30 2019-08-02 湖北锂诺新能源科技有限公司 硅碳负极及其制备方法与锂离子电池
CN116230868A (zh) * 2023-03-13 2023-06-06 江苏正力新能电池技术有限公司 极片及其制作方法和电池
JP2023097854A (ja) * 2021-12-28 2023-07-10 藤森工業株式会社 電極フィルム原反、電極、電極積層体、電気化学デバイス及び機器
CN117525278A (zh) * 2023-12-21 2024-02-06 珠海冠宇电池股份有限公司 一种电极片和电池

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017130451A (ja) * 2016-01-19 2017-07-27 株式会社ダイセル 結着剤、電極用スラリー、電極及びその製造方法並びに二次電池
CN105514323A (zh) * 2016-01-20 2016-04-20 大连理工大学 一种新型高性能静电纺聚芳醚砜酮锂电池隔膜的制备方法
CN110085806A (zh) * 2019-04-30 2019-08-02 湖北锂诺新能源科技有限公司 硅碳负极及其制备方法与锂离子电池
JP2023097854A (ja) * 2021-12-28 2023-07-10 藤森工業株式会社 電極フィルム原反、電極、電極積層体、電気化学デバイス及び機器
CN116230868A (zh) * 2023-03-13 2023-06-06 江苏正力新能电池技术有限公司 极片及其制作方法和电池
CN117525278A (zh) * 2023-12-21 2024-02-06 珠海冠宇电池股份有限公司 一种电极片和电池

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