WO2026020309A1 - Cellule de batterie, dispositif de batterie et dispositif électrique - Google Patents

Cellule de batterie, dispositif de batterie et dispositif électrique

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Publication number
WO2026020309A1
WO2026020309A1 PCT/CN2024/106977 CN2024106977W WO2026020309A1 WO 2026020309 A1 WO2026020309 A1 WO 2026020309A1 CN 2024106977 W CN2024106977 W CN 2024106977W WO 2026020309 A1 WO2026020309 A1 WO 2026020309A1
Authority
WO
WIPO (PCT)
Prior art keywords
negative electrode
lithium
battery cell
positive electrode
film layer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/CN2024/106977
Other languages
English (en)
Chinese (zh)
Inventor
牛从酥
杨周飞
李晓伟
魏曦晨
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Contemporary Amperex Technology Co Ltd
Original Assignee
Contemporary Amperex Technology Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Contemporary Amperex Technology Co Ltd filed Critical Contemporary Amperex Technology Co Ltd
Priority to DE212024000184.8U priority Critical patent/DE212024000184U1/de
Priority to PCT/CN2024/106977 priority patent/WO2026020309A1/fr
Priority to CN202510526806.2A priority patent/CN120073230B/zh
Publication of WO2026020309A1 publication Critical patent/WO2026020309A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/204—Racks, modules or packs for multiple batteries or multiple cells
    • H01M50/207—Racks, modules or packs for multiple batteries or multiple cells characterised by their shape
    • H01M50/209—Racks, modules or packs for multiple batteries or multiple cells characterised by their shape adapted for prismatic or rectangular cells
    • 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
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • 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
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0569—Liquid materials characterised by the solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—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
    • H01M4/62—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
    • 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
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • This application relates to a battery cell, a battery device, and an electrical device.
  • Battery cells possess characteristics such as high capacity and long lifespan, making them widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric cars, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes, and power tools. Due to significant advancements in the battery field, higher performance requirements have been placed on batteries. The fast-charging performance, cycle life, and energy density of battery cells still need further improvement.
  • This application provides a battery cell, a battery device, and an electrical device that can improve the fast charging performance, cycle performance, and energy density of the battery cell.
  • this application proposes a battery cell, which includes an electrode assembly comprising a positive electrode, a negative electrode, and a separator.
  • the separator is located between the positive and negative electrode.
  • the positive electrode includes a positive electrode tab, a positive current collector, and a positive electrode film layer disposed on at least one surface of the positive current collector along the thickness direction of the positive electrode and containing a positive active material.
  • the positive electrode tab is disposed on at least one side of the positive current collector.
  • the negative electrode includes a negative electrode tab, a negative current collector, and a negative electrode film layer disposed on at least one surface of the negative current collector along the thickness direction of the negative electrode and containing a negative active material.
  • the negative electrode tab is disposed on at least one side of the negative current collector. In a 100% charged state, the ratio of the total thickness of the negative electrode film layer to the thickness of the negative electrode is 0.95 to 0.97.
  • the volume expansion of the negative electrode sheet during charging is relatively small, allowing the electrolyte to fully wet the negative electrode sheet, improving the migration performance of lithium ions in the negative electrode sheet, reducing the risk of lithium plating in the negative electrode sheet, effectively improving the reliability and cycle performance of the battery cell, and also helping to improve the energy density of the battery cell; moreover, the negative electrode current collector has a smaller proportion and thinner thickness, which is beneficial to improving the fast charging performance of the battery cell and can also improve the energy density of the battery cell.
  • the ratio of the total thickness of the positive electrode film layer in the positive electrode sheet to the thickness of the positive electrode sheet is 0.88 to 0.94.
  • the thickness of the negative electrode current collector is 4 ⁇ m to 6 ⁇ m. When the thickness of the negative electrode current collector is within this range, the current-carrying capacity of the negative electrode current collector is excellent, and the battery cell can have a high energy density.
  • the negative electrode film is disposed on both surfaces of the negative electrode current collector, and the thickness of the negative electrode film on both sides is 110 ⁇ m to 178 ⁇ m when the battery cell is 100% charged.
  • the thickness of the positive current collector is 10 ⁇ m to 15 ⁇ m. When the thickness of the positive current collector is within this range, the current carrying capacity of the positive current collector is excellent, and the battery cell can have a high energy density.
  • the powder resistivity of the negative electrode active material is from 0.005 ⁇ cm to 0.043 ⁇ cm.
  • the relatively low powder resistivity of the negative electrode active material results in relatively low resistance of the negative electrode sheet and less heat generation in the battery cell.
  • the specific capacity of the negative electrode active material at a 0.1C rate is between 350 mAh/g and 480 mAh/g.
  • the specific capacity of the negative electrode active material at a 0.1C rate is within the above range, the energy density of the battery cell is relatively high.
  • the negative electrode active material includes a carbon-based material, which includes graphite particles with a graphitization degree of 92.0% to 94.5%.
  • the graphite particles exhibit superior electrical conductivity, which can reduce heat generation in the negative electrode sheet and the individual battery cell; and can also improve the fast charging performance of the individual battery cell.
  • the carbon coating content is 2% to 5% by mass, based on the mass of the graphite particles.
  • the carbon coating content is within the above range, the internal resistance of the negative electrode sheet can be further reduced, and the heat generation of the battery cell can be reduced.
  • the negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer.
  • the first negative electrode film layer is disposed on the surface of the negative electrode current collector and includes a carbon-based material.
  • the second negative electrode film layer is connected to the side of the first negative electrode film layer away from the negative electrode current collector and also includes a carbon-based material.
  • the carbon-based material in the first negative electrode film layer and the carbon-based material in the second negative electrode film layer each independently include graphite particles, and the volume average particle size Dv50 of the graphite particles in the first negative electrode film layer is greater than or equal to the volume average particle size Dv50 of the graphite particles in the second negative electrode film layer.
  • the carbon-based material in the first negative electrode film layer also includes natural graphite.
  • the tap density of the carbon-based material in the second negative electrode film is between 0.90 g/ cm3 and 1.25 g/ cm3 .
  • the energy density of the battery cell can be improved.
  • the first lithium-containing binder comprises a lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate copolymer, which is derived from lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer, wherein the molar percentages of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer are 30% to 50%: 15% to 45%: 5% to 20%: 20% to 35%.
  • the second lithium-containing binder comprises a lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate copolymer, which is derived from lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer, wherein the molar percentages of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer are 30% to 50%: 15% to 45%: 5% to 20%: 20% to 35%.
  • the powder resistivity of the positive electrode active material ranges from 1 ⁇ cm to 27.5 ⁇ cm.
  • the relatively low powder resistivity of the positive electrode active material results in relatively low resistance of the positive electrode sheet and less heat generation in the battery cell.
  • the positive electrode further includes a positive conductive layer located between the positive electrode film and the positive current collector.
  • the positive conductive layer can further improve the conductivity of the positive electrode and reduce the heat generation of the positive electrode, thereby reducing the heat generation of the battery cell.
  • the thickness of the positive electrode conductive layer is from 0.5 ⁇ m to 2 ⁇ m.
  • the conductivity of the positive electrode sheet can be further improved, the heat generation of the positive electrode sheet can be reduced, thereby reducing the heat generation of the battery cell; and it can also improve the energy density of the battery cell.
  • the positive electrode conductive layer includes one or more of a positive electrode conductive agent and a positive electrode binder.
  • the positive electrode conductive agent in the positive electrode conductive layer can improve the conductivity of the positive electrode conductive layer, thereby improving the conductivity of the positive electrode sheet and reducing the heat generation of the battery cell;
  • the positive electrode binder in the positive electrode conductive layer can improve the adhesion performance between the positive electrode current collector and the positive electrode film layer, thereby improving the structural stability of the positive electrode sheet.
  • the positive electrode conductive agent includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the positive electrode binder includes one or more of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid, and fluorinated acrylate resins.
  • the electrolyte has a conductivity of 13 mS/cm to 20 mS/cm at room temperature.
  • the conductivity of the electrolyte is within this range, the lithium ion migration rate in the electrolyte is relatively high, which can further reduce the internal resistance of the battery cell, thereby reducing heat generation and improving the fast charging performance of the battery cell.
  • the viscosity of the electrolyte at room temperature is between 2.3 mPa ⁇ s and 3.5 mPa ⁇ s.
  • the viscosity of the electrolyte is within this range, the migration rate of lithium ions in the electrolyte is relatively high, which can further reduce the internal resistance of the battery cells, thereby reducing heat generation and improving the fast charging performance of the battery cells.
  • the electrolyte density at room temperature is between 1.05 g/mL and 1.35 g/mL.
  • the migration rate of lithium ions in the electrolyte is higher, which can further reduce the internal resistance of the battery cells, thereby reducing heat generation and improving the fast charging performance of the battery cells.
  • the carboxylic acid ester solvent includes a chain carboxylic acid ester solvent, wherein the chain carboxylic acid ester solvent has a mass content of 5% or more and 75% or less than or equal to 30% to 75% of the organic solvent.
  • the mass content of the chain carboxylic acid ester solvent is within the above range, the viscosity of the electrolyte system is relatively low, which is beneficial to the migration of lithium ions.
  • the chain carboxylic acid ester solvent includes compounds represented by Formula I.
  • R1 includes a hydrogen atom, a halogen atom, a C1 to C5 alkyl group, or a C1 to C5 haloalkyl group
  • R2 includes a C1 to C5 alkyl group or a C1 to C5 haloalkyl group. Therefore, the conductivity of the above-mentioned chain carboxylic acid ester solvents in the embodiments of this application is... The higher level of charging capacity is beneficial for improving the fast charging capability of individual battery cells.
  • R1 includes a hydrogen atom, a halogen atom, a C1 to C3 alkyl group, or a C1 to C3 haloalkyl group.
  • R2 includes C1 to C3 alkyl or C1 to C3 haloalkyl.
  • the chain carboxylic acid ester solvent includes one or more compounds of formulas I-1 to I-8.
  • the organic solvent further includes carbonate solvents, including one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.
  • carbonate solvents including one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.
  • the carbonate solvent includes one or more of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate.
  • the carbonate solvent comprises 25% to 95% by mass in the organic solvent. This mass content of carbonate solvent can further improve the conductivity of the electrolyte, which is beneficial for lithium ion migration.
  • the electrolyte further includes additives, including one or more of carbonate additives, sulfur-containing additives, and lithium salt additives. These additives can improve the interfacial film performance on the positive and/or negative electrode sides, which is beneficial for improving the fast-charging performance of individual battery cells and enhancing cycle performance.
  • the carbonate additives include one or more of vinylene carbonate (VC) and fluoroethylene carbonate (FEC).
  • VC vinylene carbonate
  • FEC fluoroethylene carbonate
  • the sulfur-containing additives include one or more of vinyl sulfate DTD, vinyl disulfate 2-DTD, butenyl sulfite BS, 1,3-propanesulfonate lactone PS, vinyl sulfite ES, and methylene disulfonate MMDS.
  • the lithium salt additive includes one or more of lithium difluorophosphate ( LiPO2F2 ) , lithium difluorooxalate borate (LiDFOB), lithium tetrafluoroborate (LiBF4 ) , and lithium dioxalate borate (LiBOB).
  • LiPO2F2 lithium difluorophosphate
  • LiDFOB lithium difluorooxalate borate
  • LiBF4 lithium tetrafluoroborate
  • LiBOB lithium dioxalate borate
  • the additive has a mass content of 1% to 10% in the electrolyte, optionally 2% to 8%.
  • the above-mentioned mass content of the additive can effectively improve the interfacial film performance on the positive and/or negative electrode sides, which is beneficial to improving the fast charging performance of the battery cell and improving cycle performance.
  • the electrolyte further includes a lithium salt, which includes one or more of fluorosulfonylimide salts and lithium hexafluorophosphate (LiPF6 ) .
  • a lithium salt which includes one or more of fluorosulfonylimide salts and lithium hexafluorophosphate (LiPF6 ) .
  • These lithium salts are readily dissociated, facilitating rapid lithium-ion migration, and the electrolyte system is relatively stable and not easily decomposed, thus improving the cycle performance of the battery cells.
  • the fluorosulfonyl imide salt includes one or more of lithium bisfluorosulfonyl imide (LiFSI) and lithium bistrifluoromethanesulfonate (LiTFSI).
  • LiFSI lithium bisfluorosulfonyl imide
  • LiTFSI lithium bistrifluoromethanesulfonate
  • the lithium salt includes lithium bis(fluorosulfonyl)imide (LiFSI) and lithium hexafluorophosphate (LiPF6 ) , wherein the molar concentration of lithium bis(fluorosulfonyl)imide (LiFSI) is from 0.2 mol/L to 0.5 mol/L, and the molar concentration of lithium hexafluorophosphate (LiPF6 ) is from 0.5 mol/L to 1.0 mol/L.
  • LiFSI lithium bis(fluorosulfonyl)imide
  • LiPF6 lithium hexafluorophosphate
  • the molar concentration ratio of lithium bis(fluorosulfonyl)imide to lithium hexafluorophosphate (LiPF6 ) is 0.2 to 1.0.
  • the thickness of the base film does not exceed 12 ⁇ m, and can be selected from 5 ⁇ m to 12 ⁇ m.
  • the thickness of the base film is within the above range, the migration path of lithium ions in the base film is shorter, which can further reduce the internal resistance of the battery cell, thereby reducing heat generation.
  • the separator includes a porous base film with a porosity of 20% to 70%.
  • the porosity of the separator in the embodiments of this application is within the above range, it can enhance the migration ability of lithium ions in the separator, further reduce the internal resistance of the battery cell, and thus reduce heat generation.
  • the separator includes a porous base film with a porosity of 35% to 60%.
  • porosity of the separator in the embodiments of this application is within the above range, it can improve the migration ability of lithium ions in the separator, further reduce the internal resistance of the battery cells, and thus reduce heat generation.
  • the thickness of the base film is between 6 ⁇ m and 12 ⁇ m. When the thickness of the base film is within this range, the migration path of lithium ions in the base film is shorter, which can further reduce the internal resistance of the battery cell and thus reduce heat generation.
  • the thickness of the base film is 6 ⁇ m to 9 ⁇ m.
  • the migration path of lithium ions in the base film is shorter, which can further reduce the internal resistance of the battery cell, thereby reducing heat generation.
  • the separator includes a base film and a functional layer disposed on at least one side of the base film.
  • the functional layer includes a first functional layer and a second functional layer.
  • the first functional layer is located on one side of the base film and includes first inorganic particles.
  • the second functional layer is located on the other side of the base film and includes composite particles.
  • the composite particles include second inorganic particles and a plurality of non-fluoropolymer particles.
  • the second inorganic particles are attached to the surface of the non-fluoropolymer particles and/or dispersed inside the non-fluoropolymer particles.
  • the first and second functional layers have good heat resistance, which can improve the heat resistance of the separator.
  • the non-fluoropolymer particles include acrylate copolymers.
  • Acrylate copolymers have excellent adhesion properties and high adhesion stability to the base film.
  • the first inorganic particles include one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide. These first inorganic particles can improve the heat resistance of the first functional layer.
  • the second inorganic particles include one or more of silicon oxide, aluminum oxide, boehmite, barium sulfate, calcium oxide, titanium oxide, zinc oxide, magnesium oxide, zirconium oxide, and tin oxide. These second inorganic particles can improve the heat resistance of the first functional layer.
  • the average particle size of the second inorganic particles is between 5 nm and 100 nm.
  • the average particle size of the second inorganic particles is within the above range, it is beneficial to improve the heat resistance and compressive modulus of the composite particles.
  • the positive electrode tabs are disposed on both sides of the positive current collector along the length of the electrode assembly. Distributing the positive electrode tabs on both sides of the positive current collector along its length ensures that the current along the length of the positive current collector is evenly divided between the two positive electrode tabs, resulting in a shorter electron transport path, a more uniform current distribution, and a more uniform delithiation state throughout the positive electrode, thereby improving the charging performance of the battery cell.
  • each positive electrode tab includes a first end face connected to the positive current collector.
  • the dimension of the first end face along the width direction is W1.
  • the sum of the dimensions along the width direction of all first end faces located on the same side of the positive current collector is n*W1.
  • the dimension along the width direction of the positive current collector is W2.
  • n*W1/W2 is greater than or equal to 1/3, where n represents the number of all positive electrode tabs located on the same side of the positive current collector.
  • n*W1/W2 is greater than or equal to 2/3, where n represents the number of all positive electrode tabs located on the same side of the positive current collector.
  • negative electrode tabs are disposed on both sides of the negative electrode current collector along the length direction of the electrode assembly.
  • the placement of negative electrode tabs on both sides of the negative electrode current collector along its length direction ensures that the current in the length direction of the negative electrode current collector is evenly divided between the two negative electrode tabs, resulting in a shorter electron transport path, more uniform current distribution, and a more uniform lithium intercalation state throughout the negative electrode, thereby improving the charging performance of the battery cell.
  • each negative electrode tab includes a second end face connected to the negative electrode current collector.
  • the second end face has a width dimension of W3.
  • the sum of the width dimensions of all second end faces located on the same side of the negative electrode current collector is m*W3.
  • the width dimension of the negative electrode current collector is W4.
  • m*W3/W4 is greater than or equal to 1/3, where m represents the number of all negative electrode tabs located on the same side of the negative electrode current collector.
  • m*W3/W4 is greater than or equal to 2/3, where m represents the number of all negative electrode tabs located on the same side of the negative electrode current collector.
  • the overcurrent area of the negative electrode tab is relatively large, which is beneficial to improving the fast charging performance of the battery cell.
  • the battery cell also includes a positive terminal, which is electrically connected to the positive electrode tab.
  • the positive terminal is directly welded to the positive electrode tab. This reduces the internal resistance of the battery cell, which is beneficial for improving fast charging performance.
  • the current-carrying area of a single positive terminal is greater than or equal to 200 mm2 . This enhanced current-carrying capacity of the positive terminal contributes to improved fast-charging performance.
  • the battery cell also includes a negative terminal, which is electrically connected to the negative electrode tab.
  • the negative terminal is directly welded to the negative electrode tab. This reduces the internal resistance of the battery cell, which is beneficial for improving fast charging performance.
  • the current-carrying area of a single negative terminal is greater than or equal to 200 mm2 . This enhanced current-carrying capacity of the negative terminal contributes to improved fast-charging performance.
  • the charging time for a single battery cell from 10% to 80% state of charge is less than or equal to 12.5 minutes, and can be selected as 6 minutes to 12.5 minutes. A faster charging speed for the battery cell is more conducive to improving fast charging capabilities.
  • this application proposes a battery device, which includes a battery cell according to any embodiment of the first aspect of this application.
  • the charging time for the battery device from 10% state of charge to 80% state of charge is less than or equal to 12.5 minutes, and can be selected as 6 minutes to 12.5 minutes. A faster charging speed of the battery device is more conducive to improving fast charging capabilities.
  • this application proposes an electrical device, which includes the battery device according to any embodiment of the second aspect of this application.
  • Figure 1 is a schematic diagram of the structure of a battery cell provided in some embodiments of this application.
  • the powder resistivity of the material has a well-known meaning in the art and can be tested using methods and equipment well-known in the art, such as using a PRCD1100 powder resistivity meter according to the test standard GB/T30835-2014.
  • the powder compaction density of the positive electrode active material at 30000N is greater than or equal to 2.46 g/ cm3 , and can be selected from 2.46 g/ cm3 to 2.80 g/ cm3 .
  • the powder compaction density of the positive electrode active material at 30000N is 2.46 g/ cm3 , 2.47 g/ cm3 , 2.48 g/ cm3 , 2.49 g/ cm3 , 2.5 g/ cm3 , 2.51 g/ cm3 , etc.
  • the powder compaction density of the material has a well-known meaning in the art and can be tested using methods and equipment well-known in the art.
  • the test is conducted according to the test standard GB/T24533-2009.
  • a certain amount of positive electrode active material is taken as a sample and added to a mold with a bottom area of 1.327 cm2 in a UTM7305 electronic pressure testing machine.
  • the pressure is increased to 3000 kg (equivalent to 30000 N), held for 30 s, then depressurized and held for 10 s.
  • the powder compaction density of the positive electrode active material under a force of 30000 N is then recorded and calculated.
  • the specific charge capacity of the positive electrode active material at a 0.1C rate is between 150 mAh/g and 170 mAh/g.
  • the specific charge capacity of the positive electrode active material at a 0.1C rate is 150 mAh/g, 151 mAh/g, 152 mAh/g, 153 mAh/g, 154 mAh/g, 155 mAh/g, 156 mAh/g, 157 mAh/g, 158 mAh/g, 159 mAh/g, 160 mAh/g, 161 mAh/g, 162 mAh/g, 163 mAh/g, 164 mAh/g, 165 mAh/g, 166 mAh/g, 167 mAh/g, 168 mAh/g, 169 mAh/g, 170 mAh/g, or a range consisting of any two of the above values.
  • the specific capacity of the active material has a meaning known in the art and can be tested using equipment and methods known in the art.
  • the test methods for the first coulombic efficiency and the first discharge specific capacity in Appendix G of the national standard GB/T 24533-2019 can be adopted.
  • a half-coin cell is assembled with lithium metal as the negative electrode and a sample electrode containing the above-mentioned material as the positive electrode.
  • the half-coin cell is tested on a battery tester or other test equipment with equivalent performance at 23°C ⁇ 2°C by charging and discharging at a rate of 0.1C to obtain the coin capacity.
  • the capacity is then divided by the mass of the electrode active material to obtain the charging specific capacity parameter.
  • the mass percentage of olivine-structured lithium phosphate in the positive electrode active material can be greater than or equal to 80% and less than or equal to 100%, and the positive electrode active material of this application can be considered as an olivine-structured lithium phosphate system.
  • the positive electrode active material may also include commonly used positive electrode active materials, such as, but not limited to, at least one of lithium transition metal oxides.
  • lithium transition metal oxides include, but are not limited to, at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds.
  • the lithium phosphate with olivine structure can be phosphate particles or a material obtained by coating and modifying them.
  • the lithium phosphate with olivine structure includes phosphate particles and a coating layer.
  • the coating layer is coated on the surface of the phosphate particles and contains one or more elements selected from C, Fe, Ti, Zr, Hf, Ge and Sn.
  • phosphate particles include one or more of LiFePO4 , LiMnPO4 , LiNiPO4 , and LiCoPO4 .
  • active ions such as Li are de-intercalated and consumed in a single battery cell, resulting in different molar contents of Li in different discharged states.
  • the molar contents of Li represent the initial state of the material, i.e., the state before feeding. When the positive electrode active material is applied to the battery system, the molar contents of Li may change after charge-discharge cycles.
  • Fast ion conductors with a NASICON structure are materials with ultrafast ion conduction capabilities, possessing abundant three-dimensional lithium-ion diffusion and transport channels. They exhibit advantages such as high ion conduction efficiency and strong structural stability during multiple lithium delithiation and lithium intercalation processes. Coating the surface of phosphate particles with fast ion conductors containing a NASICON structure can significantly improve the lithium-ion transport rate during multiple lithium delithiation/intercalation at the positive electrode, enhance the ionic conductivity of the positive electrode active material, improve the fast charging capability of the battery cell, and further increase the specific capacity and energy density of the corresponding battery cell.
  • the coating layer also includes all-carbon.
  • the fast ion conductor layer can be applied to the surface of the phosphate particles, and the carbon coating layer can be located on the surface of the fast ion conductor layer, i.e., the carbon coating layer is located on the side of the fast ion conductor layer away from the phosphate particles.
  • the carbon element and the fast ion conductor can also be layered together.
  • the carbon coating layer gives the positive electrode active material of this application the following advantages:
  • the carbon coating layer in the positive electrode active material of this application provides a suitable channel for electron transport, which can significantly improve the electron conduction rate during multiple lithium delithiation and lithium insertion processes, improve the electronic conductivity of lithium phosphate, improve the charging capacity of the corresponding battery cell, and also improve the energy density.
  • the carbon coating layer of the positive electrode active material in this application is porous, which allows the electrolyte to come into full and effective contact with the lithium phosphate, thereby improving the lithium ion transport rate at the phase interface and enhancing the charging capacity of the battery cell.
  • Coating the surface of lithium phosphate with a carbon coating layer can not only improve the conductivity of lithium phosphate, but also improve the structural stability of the positive electrode active material. This effectively alleviates the iron dissolution phenomenon of the positive electrode active material during long-term storage and cyclic use of battery cells, thereby improving the cycle life of battery cells.
  • the elemental content in the positive electrode active material is defined in a way known in the art and can be detected using equipment and methods known in the art.
  • ICP-OES inductively coupled plasma atomic emission spectrometry
  • the positive electrode sheet is disassembled, cleaned and dried with DMC, and then calcined at high temperature to remove impurities.
  • 0.4g of the positive electrode active material is weighed and 10ml (50% concentration) of aqua regia is added. Then it is placed on a plate at 180°C for 30min. After digestion on the plate, the volume is adjusted to 100mL, and quantitative testing is performed using the standard curve method.
  • the degree of graphitization of the positive electrode active material is 0.15 to 0.32, optionally 0.19 to 0.26.
  • the degree of graphitization of the positive electrode active material is 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, or a range consisting of any two of the above values.
  • the degree of graphitization of the positive electrode active material is within the above range, it is beneficial to improve the conductivity of the positive electrode active material, reduce the heat generation of the positive electrode sheet, and thus reduce the heat generation of the battery cell.
  • the higher the degree of graphitization of the material, the lower the degree of disorder, and the test can be carried out according to the general rules of X-ray diffraction analysis method JIS/K 0131-1996.
  • the carbon content in the olivine-structured lithium phosphate is 1% to 2% by mass, and the specific surface area of the olivine-structured lithium phosphate is 5 m2 /g to 18 m2 /g.
  • the lithium phosphate with olivine structure has a carbon content of 1% to 2% by mass and a specific surface area of 7.5 m2 /g to 14 m2 /g.
  • the mass content of carbon in the lithium phosphate with olivine structure is 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, or any combination of two of the above values.
  • the specific surface area of the lithium phosphate with olivine structure is 5 m2 /g, 6 m2 /g, 7 m2 /g, 8 m2 /g, 9 m2 /g, 10 m2 /g, 11 m2 /g, 12 m2 /g, 13 m2 /g, 14 m2 /g, 15 m2 /g, 16 m2 /g, 17 m2 /g, 18 m2 /g, or any range of two of the above values.
  • the carbon coating layer is loose and porous, which helps to increase the specific surface area of the material, facilitates effective contact between the electrolyte and phosphate particles, and promotes the transport of lithium ions at the phase interface.
  • the mass content of carbon when the mass content of carbon is within the above range, it can significantly improve the conductivity of lithium phosphate with olivine structure, which is beneficial to improving the ionic and electronic conductivity of lithium phosphate with olivine structure, and can improve the rapid charging capability and energy density of battery cells.
  • the specific surface area of the material has a meaning known in the art and can be detected using equipment and methods known in the art. For example, it can be detected according to the testing standard GB/T 19587-2017, using the positive electrode active material as a sample and testing the specific surface area using a Tri-Star 3020 specific surface area and pore size analyzer from Micromeritics, USA.
  • the volume distribution particle size of the positive electrode active material satisfies: 1 ⁇ m ⁇ Dv50 ⁇ 2 ⁇ m, 0.4 ⁇ m ⁇ Dv10 ⁇ 0.7 ⁇ m.
  • the Dv50 of the positive electrode active material can be 1 ⁇ m, 1.1 ⁇ m, 1.15 ⁇ m, 1.2 ⁇ m, 1.25 ⁇ m, 1.3 ⁇ m, 1.35 ⁇ m, 1.4 ⁇ m, 1.45 ⁇ m, 1.5 ⁇ m, 1.55 ⁇ m, 1.6 ⁇ m, 1.65 ⁇ m, 1.7 ⁇ m, 1.75 ⁇ m, 1.8 ⁇ m, 1.85 ⁇ m, 1.9 ⁇ m, 1.95 ⁇ m, 2 ⁇ m, or any range of two of the above values.
  • the Dv10 of the positive electrode active material can be 0.4 ⁇ m, 0.45 ⁇ m, 0.5 ⁇ m, 0.55 ⁇ m, 0.6 ⁇ m, 0.65 ⁇ m, 0.7 ⁇ m, or any combination of two of the above values.
  • the positive electrode active material has a relatively small particle size, resulting in a shorter lithium ion insertion/extraction path and less heat generation. Moreover, the particle size of the positive electrode active material is not too small, so it will not agglomerate during the processing and preparation process, which makes the performance of the positive electrode active material stable.
  • the volume average particle size Dv50 of the material refers to the particle size corresponding to 50% of the volume distribution
  • the volume average particle size Dv10 of the material refers to the particle size corresponding to 10% of the volume distribution. They can be detected using equipment and methods known in the art.
  • the positive electrode active material can be used as a sample, and the Dv50 and Dv10 of the particles can be tested using a Mastersizer 2000E laser particle size analyzer according to the test standard GB/T 19077-2016.
  • the volume distribution particle size of the positive electrode active material refers to the volume distribution particle size of all positive electrode active materials.
  • the olivine-structured lithium phosphate is in particulate form, and the olivine-structured lithium phosphate is formed from secondary particles formed by the agglomeration of primary particles, with the average particle size of the primary particles being 200 nm to 500 nm.
  • the average particle size of the primary particles is 200 nm, 220 nm, 250 nm, 280 nm, 300 nm, 320 nm, 350 nm, 380 nm, 400 nm, 420 nm, 450 nm, 480 nm, 500 nm, or a range consisting of any two of the above values.
  • the average particle size of primary particles is relatively small, the lithium ion insertion/extraction path in the positive electrode active material is shorter, and the heat generation is less.
  • primary particles and secondary particles are terms well known in the art.
  • Secondary particles refer to aggregated particles formed by the aggregation of two or more primary particles.
  • Primary and secondary particles can be easily distinguished by experimental means (such as taking SEM images using a scanning electron microscope).
  • the average particle size of primary particles can be obtained by testing in the SEM image.
  • the SEM test parameters can be set as follows: operating voltage (EHT) of 10.00 kV, using an InLens detector, working distance of 4.6 mm, and magnification of 1000X.
  • the positive electrode film typically comprises multiple positive electrode active material particles, namely, lithium phosphate particles with an olivine structure. These particles vary in size, including minimum and maximum particles. The combination of particles of different sizes increases the compaction density of the positive electrode film and enhances its porosity, thereby improving the fast-charging performance of the battery cell.
  • the minimum particle size of the lithium phosphate containing the olivine structure is from 0.1 ⁇ m to 0.4 ⁇ m, exemplarily 0.1 ⁇ m, 0.15 ⁇ m, 0.2 ⁇ m, 0.25 ⁇ m, 0.3 ⁇ m, 0.35 ⁇ m, 0.4 ⁇ m, or any combination of two of the above values.
  • the minimum particle size is within the above range, agglomeration is less likely to occur during the preparation of the positive electrode film 113.
  • the maximum particle size of the lithium phosphate with an olivine structure is between 15 ⁇ m and 25 ⁇ m, exemplarily 15 ⁇ m, 16 ⁇ m, 17 ⁇ m, 18 ⁇ m, 19 ⁇ m, 20 ⁇ m, 21 ⁇ m, 22 ⁇ m, 23 ⁇ m, 24 ⁇ m, 25 ⁇ m, or any combination of two of the above values.
  • the maximum particle size is within the above range, the migration path of lithium ions during charging and discharging is not too long, which can improve the fast charge and discharge performance of the battery cell.
  • the positive electrode film layer further includes one or more of the following: ternary materials, lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium metamanganese oxide, lithium tartrate, lithium trilithium citrate, lithium nickel oxide, and lithium ferrite.
  • ternary materials lithium phosphate, lithium hydrogen phosphate, lithium sulfate, lithium sulfite, lithium molybdate, lithium oxalate, lithium titanate, lithium tetraborate, lithium metasilicate, lithium metamanganese oxide, lithium tartrate, lithium trilithium citrate, lithium nickel oxide, and lithium ferrite.
  • the ternary material includes Lix3Ay3Nia3Cob3MncM3 (1-a3-b3-c3) Y3z3 , wherein 0 ⁇ x3 ⁇ 2.1 , 0 ⁇ y3 ⁇ 2.1, and 0.9 ⁇ x3 + y3 ⁇ 2.1, 0 ⁇ a3 ⁇ 1, 0 ⁇ b3 ⁇ 1 , 0 ⁇ c3 ⁇ 1, and 0.1 ⁇ a3 + b3 + c3 ⁇ 1, 1.8 ⁇ z3 ⁇ 3.5,
  • A includes one or more of Na, K, and Mg
  • M3 includes one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce
  • Y3 includes one or more of O and F
  • the ternary material includes at least one of LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811), and LiNi 0.80 Co 0.15 Al 0.05 O 2 .
  • the lithium replenishing agent has a mass content of 0.5% to 5% in the positive electrode film layer, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any combination of two of the above values.
  • the mass content of the lithium replenishing agent is within the above range, it can replenish lithium ions to the positive electrode film, compensate for irreversible lithium ion loss in the system, increase capacity, and thereby improve the energy density of the battery cell.
  • the lithium replenishing agent can be located in the same layer as the positive electrode active material or in a different layer.
  • the lithium replenishing agent can be located in the lithium replenishing layer, and the positive electrode active material can be located in the positive electrode active material layer.
  • the positive electrode film layer includes a lithium replenishing layer and a positive electrode active material layer.
  • the positive electrode active material layer can be disposed on at least one side of the positive electrode current collector, and the lithium replenishing layer can be located between the positive electrode active material layer and the positive electrode current collector.
  • the lithium replenishing layer can be disposed on at least one side of the positive electrode current collector, and the positive electrode active material layer can be located between the lithium replenishing layer and the positive electrode current collector.
  • the lithium replenishing layer can be located between the positive electrode active material layer and the positive electrode current collector.
  • the lithium replenishing agent in the lithium replenishing layer can be gradually released into the system to compensate for the lithium loss of the battery system.
  • the positive electrode film layer may optionally include a positive electrode conductive agent.
  • a positive electrode conductive agent includes at least one selected from superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the mass content of the positive electrode conductive agent is ⁇ 5% based on the mass of the positive electrode film layer.
  • the positive electrode film layer may optionally include a positive electrode binder.
  • a positive electrode binder may include at least one selected from polyvinylidene fluoride, polytetrafluoroethylene, a terpolymer of vinylidene fluoride-tetrafluoroethylene-propylene, a terpolymer of vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene, a tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid, and fluorinated acrylate resins.
  • the mass content of the positive electrode binder is ⁇ 5% based on the mass of the positive electrode film layer.
  • the thickness of the positive electrode film layer and the positive electrode current collector are known in the art and can be detected using equipment and methods known in the art.
  • the thickness of the positive electrode sheet can be measured with a micrometer
  • the film layer on the surface of the positive electrode current collector can be removed
  • the thickness of the positive electrode current collector can be measured with a micrometer.
  • the thickness of the positive electrode film layer is the thickness of the positive electrode sheet minus the thickness of the positive electrode current collector.
  • the thickness of the positive electrode film layer is (the thickness of the positive electrode sheet minus the thickness of the positive electrode current collector)/2.
  • the positive electrode film is typically formed by coating a positive electrode slurry onto the positive electrode current collector, followed by drying and cold pressing.
  • the positive electrode slurry is usually formed by dispersing the positive electrode active material, optional conductive agent, optional binder, and any other components in a solvent and stirring until homogeneous.
  • the solvent can be N-methylpyrrolidone (NMP), but is not limited to it.
  • the positive electrode sheet does not exclude other additional functional layers besides the positive electrode film layer.
  • the positive electrode sheet of the present application further includes a positive electrode conductive layer sandwiched between the positive electrode current collector and the positive electrode film layer and disposed on the surface of the positive electrode current collector.
  • the positive electrode sheet of the present application further includes a protective layer covering the surface of the positive electrode film layer.
  • the positive electrode further includes a positive conductive layer located between the positive electrode film and the positive current collector.
  • the positive conductive layer can further improve the conductivity of the positive electrode and reduce the heat generation of the positive electrode, thereby reducing the heat generation of the battery cell.
  • the thickness of the positive electrode conductive layer is from 0.5 ⁇ m to 2 ⁇ m.
  • the thickness of the positive electrode conductive layer can be 0.5 ⁇ m, 0.8 ⁇ m, 1 ⁇ m, 1.2 ⁇ m, 1.5 ⁇ m, 1.6 ⁇ m, 1.8 ⁇ m, 2 ⁇ m, or any combination of two of the above values.
  • the conductivity of the positive electrode sheet can be further improved, the heat generation of the positive electrode sheet can be reduced, thereby reducing the heat generation of the battery cell, and the energy density of the battery cell can also be improved.
  • the thickness of the positive electrode conductive layer has a meaning known in the art and can be detected using equipment and methods known in the art, such as performing a tomographic scan on the positive electrode sheet to directly measure the thickness of the positive electrode conductive layer.
  • the positive conductive layer includes one or more of a positive conductive agent and a positive binder.
  • the mass content of the positive electrode conductive agent in the positive electrode conductive layer is 30% to 50%.
  • the mass content of the positive electrode conductive agent is 30%, 35%, 40%, 45%, 50%, or any combination of two of the above values.
  • the positive electrode conductive agent includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the positive electrode conductive agent in the positive electrode conductive layer can improve the conductivity of the positive electrode conductive layer, thereby improving the conductivity of the positive electrode sheet and reducing the heat generation of the battery cell.
  • the positive electrode binder has a mass content of 50% to 70% in the positive electrode conductive layer.
  • the positive electrode binder includes one or more of polyvinylidene fluoride, polytetrafluoroethylene, a terpolymer of vinylidene fluoride-tetrafluoroethylene-propylene, a terpolymer of vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene, a tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylic acid, and fluorinated acrylate resins.
  • the positive electrode binder in the positive electrode conductive layer can improve the adhesion between the positive electrode current collector and the positive electrode film layer, thereby enhancing the structural stability of the positive electrode sheet.
  • the resistivity of the negative electrode active material powder is from 0.005 ⁇ cm to 0.043 ⁇ cm, optionally 0.04 ⁇ cm.
  • the resistivity of the negative electrode active material powder can be 0.043 ⁇ cm, 0.04 ⁇ cm, 0.035 ⁇ cm, 0.03 ⁇ cm, 0.025 ⁇ cm, 0.02 ⁇ cm, 0.015 ⁇ cm, 0.01 ⁇ cm, 0.005 ⁇ cm, or a range consisting of any two of the above values.
  • the powder resistivity of the negative electrode active material is relatively low, which results in relatively low resistance of the negative electrode sheet and less heat generation in the battery cell.
  • the powder resistivity of the negative electrode active material has a well-known meaning in the art and can be detected using equipment and methods well-known in the art, such as the powder resistivity test method for the positive electrode active material described above.
  • the compacted powder density of the negative electrode active material at 20,000 N pressure is 1.5 g/ cm3 to 1.85 g/ cm3 , optionally 1.55 g/ cm3 to 1.65 g/ cm3 .
  • the compacted powder density of the negative electrode active material at 20,000 N pressure is 1.5 g/ cm3 , 1.55 g/ cm3 , 1.6 g/ cm3 , 1.65 g/ cm3 , 1.7 g/ cm3 , 1.75 g/ cm3 , 1.8 g/ cm3 , 1.85 g/ cm3 , or a range consisting of any two of the above values.
  • the powder compaction density of the negative electrode active material at 20000N is within the above range, it can improve the energy density of the battery cell. Furthermore, since the negative electrode active material in the negative electrode film can be stacked more tightly, the contact resistance between particles is smaller, which can further reduce the resistance of the electrode sheet, thereby reducing heat generation.
  • the powder compaction density of the material has a meaning known in the art and can be tested using methods and equipment known in the art, according to the testing standard GB/T24533-2009.
  • take... A certain amount of negative electrode active material was used as a sample and added to a mold with a bottom area of 1.327 cm2 in a UTM7305 electronic pressure testing machine. The pressure was increased to 2000 kg (equivalent to 20000 N), held for 30 seconds, then depressurized and held for 10 seconds. The compaction density of the negative electrode active material under a force of 20000 N was then recorded and calculated.
  • the specific charge capacity of the negative electrode active material at a 0.1C rate is between 350 mAh/g and 480 mAh/g.
  • the specific charge capacity of the negative electrode active material at a 0.1C rate is 350 mAh/g, 355 mAh/g, 360 mAh/g, 365 mAh/g, 370 mAh/g, 375 mAh/g, 380 mAh/g, 385 mAh/g, 390 mAh/g, 395 mAh/g, 400 mAh/g, 410 mAh/g, 420 mAh/g, 430 mAh/g, 440 mAh/g, 450 mAh/g, 460 mAh/g, 470 mAh/g, 480 mAh/g, or a range consisting of any two of the above values.
  • the specific capacity of the negative electrode active material at a 0.1C rate is within the above range, the energy density of the battery cell is relatively high.
  • the charging capacity of the negative electrode active material at a rate of 0.1C is a well-known concept in the art and can be detected using well-known equipment and methods in the art.
  • the detection method is as described above for the charging capacity test method of the positive electrode active material at a rate of 0.1C.
  • the negative electrode active material includes a layered carbon-based material.
  • Carbon-based materials have high cycle stability and can improve the cycle performance of the battery cell.
  • the mass percentage of carbon-based material in the negative electrode active material can be greater than or equal to 80% and less than or equal to 100%.
  • the positive electrode active material of this application is mainly a lithium phosphate system with an olivine structure, and the negative electrode active material is mainly a carbon-based material system. When used together, the cycle performance of the battery cell is excellent.
  • the carbon-based material includes graphite particles with a graphitization degree of 92.0% to 94.5%.
  • the graphitization degree of the graphite particles is 92.0%, 92.5%, 93%, 93.5%, 94%, 94.5%, or a range consisting of any two of the above values.
  • the graphite particles When the degree of graphitization of graphite particles is within the above range, the graphite particles have excellent electrical conductivity, which can reduce the heat generation of the negative electrode sheet and the heat generation of the battery cell; and can also improve the fast charging performance of the battery cell.
  • the graphite particles include artificial graphite and a carbon coating layer.
  • the artificial graphite includes secondary particles, which in turn include multiple primary particles.
  • the carbon coating layer coats the surface of the artificial graphite.
  • the carbon in the carbon coating layer is primarily amorphous carbon, which refers to transitional carbon materials with a very low degree of graphitization and crystallization, exhibiting an approximately amorphous morphology (or lacking a fixed shape and periodic structural regularity).
  • amorphous carbon refers to the product of carbonization treatment of an organic carbon source.
  • Artificial graphite includes secondary particles. There are more migration paths for lithium ions in artificial graphite, and the migration paths in primary particles are shorter, which can improve the migration rate of lithium ions.
  • the carbon coating layer has more end faces and defects, which increases the number of sites where lithium ions can be inserted and extracted, resulting in better conductivity of the carbon coating layer. This can reduce the internal resistance of the negative electrode and reduce the heat generation of the battery cell.
  • the carbon coating content is 2% to 5% by mass, based on the mass of the graphite particles.
  • the carbon coating content is 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any range of two of the above values.
  • the mass content of the carbon coating is within the above range, it can further reduce the internal resistance of the negative electrode and reduce the heat generation of the battery cell.
  • the graphite particles can be prepared using methods known in the art, such as: providing artificial graphite and an organic carbon source, mixing the two, and then carbonizing them to form a carbon coating layer on at least a portion of the surface of the artificial graphite particles.
  • the organic carbon source includes one or more of coal tar pitch, petroleum asphalt, phenolic resin, and coconut shell. More preferably, the organic carbon source includes petroleum asphalt.
  • the softening point of coal tar pitch or petroleum asphalt is below 250°C.
  • the carbonization treatment time is 1 hour to 6 hours.
  • the carbon-based material may further include natural graphite.
  • the carbon-based material may include graphite particles, or it may include both graphite particles and natural graphite.
  • the carbon-based material is graphite particles.
  • the negative electrode active material may also include a silicon-based material.
  • the introduction of silicon-based materials can increase the capacity of the negative electrode active material and improve the energy density of the battery cell.
  • the mass content of silicon element in the silicon-based material is 0.3% to 10.0%, optionally 1% to 6%.
  • the mass content of silicon element in the silicon-based material is 0.3%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, 5.2%, 5.5%, 5.8%, 6%, 6.2%, 6.5%, 6.8%, 7%, 7.2%, 7.5%, 7.8%, 8%, 8.2%, 8.5%, 8.8%, 9%, 9.2%, 9.5%, 9.8%, 10%, or a range consisting of any two of the above values.
  • the thickness of the first negative electrode film is between 15 ⁇ m and 70 ⁇ m, for example, 15 ⁇ m, 16 ⁇ m, 17 ⁇ m, 18 ⁇ m, 19 ⁇ m, 20 ⁇ m, 21 ⁇ m, 22 ⁇ m, 23 ⁇ m, 24 ⁇ m, 25 ⁇ m, 26 ⁇ m, 27 ⁇ m, 28 ⁇ m, 29 ⁇ m, 30 ⁇ m, 35 ⁇ m, 40 ⁇ m, 43 ⁇ m, 45 ⁇ m, 50 ⁇ m, 55 ⁇ m, 60 ⁇ m, 65 ⁇ m, 66 ⁇ m, 67 ⁇ m, 68 ⁇ m, 69 ⁇ m, 70 ⁇ m, or any combination of two of the above values.
  • the first and second negative electrode films can be modulated to increase the gradient porosity difference between the upper and lower layers, reduce the tortuosity of lithium-ion transport, and improve the fast charging capability of the battery cell.
  • a battery charging upper limit voltage of 3.65V and a battery discharging cutoff voltage of 2.0V will be used for explanation.
  • the lithium element in the lithium-containing binder can exist in ionic form, which can increase the number of freely moving lithium ions in the negative electrode film layer, shorten the distance for lithium ions to diffuse to the surface of the negative electrode film layer, improve the lithium ion insertion/extraction rate, and improve the fast charging performance of the battery cell.
  • the lithium-containing binder of the above-mentioned material can provide a certain number of lithium ions to the negative electrode film layer, improve the fast charging performance of the battery cell, and is not prone to swelling during charging and discharging, with a stable structure, which improves the cycle performance of the negative electrode film layer during fast charging and discharging.
  • the first negative electrode film layer further includes a first lithium-containing binder
  • the second negative electrode film layer further includes a second lithium-containing binder, wherein the mass content of the first lithium-containing binder relative to the mass of the first negative electrode film layer is less than or equal to the mass content of the second lithium-containing binder relative to the mass of the second negative electrode film layer. More optionally, the mass content of the first lithium-containing binder relative to the mass of the first negative electrode film layer is less than the mass content of the second lithium-containing binder relative to the mass of the second negative electrode film layer.
  • the first lithium-containing binder comprises a lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate copolymer, which is derived from lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer, and hydroxyethyl acrylate monomer, wherein the molar percentages of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer, and hydroxyethyl acrylate monomer are 30% to 50%: 15% to 45%: 5% to 20%: 20% to 35%.
  • the molar percentages of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer, and hydroxyethyl acrylate monomer are 35%: 30%: 15%: 20%, or 40%, 20%, 10%, 30%, or 45%, 15%, 20%, 20%, etc.
  • the first lithium-containing binder and the second lithium-containing binder can be made of the same material or different materials.
  • the first negative electrode film layer further includes a negative electrode binder
  • the second negative electrode film layer further includes a negative electrode binder.
  • the negative electrode binder in the first negative electrode film layer and the negative electrode binder in the second negative electrode film layer each independently include styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resin (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), and polyacrylamide. At least one of PAM, polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).
  • the total content of the first lithium-containing binder and the negative electrode binder in the first negative electrode film layer is greater than the total content of the second lithium-containing binder and the negative electrode binder in the second negative electrode film layer, and the mass content of the first lithium-containing binder relative to the mass of the first negative electrode film layer is less than the mass content of the second lithium-containing binder relative to the mass of the second negative electrode film layer.
  • the negative electrode film layer may optionally include a negative electrode conductive agent.
  • a negative electrode conductive agent may include at least one selected from superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the mass content of the negative electrode conductive agent is ⁇ 5% based on the total weight of the negative electrode film layer.
  • the negative electrode film layer may optionally include a negative electrode binder.
  • the mass content of the negative electrode binder is ⁇ 5% based on the total weight of the negative electrode film layer.
  • the negative electrode film layer may optionally include other additives.
  • other additives may include thickeners, dispersants, etc., such as sodium carboxymethyl cellulose (CMC-Na), PTC thermistor materials, etc.
  • the mass content of other additives is ⁇ 2% based on the total weight of the negative electrode film layer.
  • the porosity of the negative electrode film is 40% to 55%.
  • the porosity of the negative electrode film is 40%, 45%, 50%, 55%, or any combination of two of the above values.
  • the porosity of the negative electrode film can be measured using the gas displacement method according to standard GB/T24586.
  • Porosity P (V1-V2)/V1*100%, where V1 is the apparent volume of the sample and V2 is the actual volume of the sample.
  • the negative electrode film is typically formed by coating a negative electrode slurry onto the negative electrode current collector, followed by drying and cold pressing.
  • the negative electrode slurry is usually formed by dispersing the negative electrode active material, optional conductive agent, optional binder, and other optional additives in a solvent and stirring until homogeneous.
  • the solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited to these.
  • the negative electrode sheet does not exclude other additional functional layers besides the negative electrode film layer.
  • the negative electrode sheet of the present application further includes a negative electrode conductive layer sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector.
  • the negative electrode sheet of the present application further includes a protective layer covering the surface of the negative electrode film layer.
  • the negative electrode sheet further includes a negative electrode conductive layer, which is located between the negative electrode film layer and the negative electrode current collector.
  • the negative electrode conductive layer can further improve the conductivity of the negative electrode sheet and reduce the heat generation of the negative electrode sheet, thereby reducing the heat generation of the battery cell.
  • the thickness of the negative electrode conductive layer is from 0.5 ⁇ m to 2 ⁇ m.
  • the thickness of the negative electrode conductive layer can be 0.5 ⁇ m, 0.8 ⁇ m, 1 ⁇ m, 1.2 ⁇ m, 1.5 ⁇ m, 1.6 ⁇ m, 1.8 ⁇ m, 2 ⁇ m, or any combination of two of the above values.
  • the conductivity of the negative electrode sheet can be further improved, the heat generation of the negative electrode sheet can be reduced, thereby reducing the heat generation of the battery cell, and the energy density of the battery cell can also be improved.
  • the negative electrode conductive layer includes one or more of a negative electrode conductive agent and a negative electrode binder.
  • the negative electrode conductive agent in the negative electrode conductive layer can improve the conductivity of the negative electrode conductive layer, thereby improving the conductivity of the negative electrode sheet and reducing the heat generation of the battery cell.
  • the negative electrode binder in the negative electrode conductive layer can improve the bonding performance between the negative electrode current collector and the negative electrode film layer, thereby improving the structural stability of the negative electrode sheet.
  • the negative electrode conductive layer may optionally include other additives.
  • other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc.
  • the mass content of the negative electrode conductive agent in the negative electrode conductive layer is 20% to 40%.
  • the mass content of the negative electrode conductive agent is 20%, 25%, 30%, 35%, 40%, or any combination of two of the above values.
  • the negative electrode conductive agent includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the negative electrode binder has a mass content of 60% to 80% in the negative electrode conductive layer.
  • the negative electrode binder includes one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin, polyvinyl alcohol, sodium alginate, and carboxymethyl chitosan.
  • SBR styrene-butadiene rubber
  • SR-1B water-soluble unsaturated resin
  • acrylic resin polyvinyl alcohol
  • sodium alginate sodium alginate
  • carboxymethyl chitosan carboxymethyl chitosan
  • the ratio CB of the capacity of the negative electrode film per unit area to the capacity of the positive electrode film per unit area in a single battery cell is from 1.05 to 1.30, and optionally from 1.07 to 1.15.
  • the ratio CB of the capacity of the negative electrode film per unit area to the capacity of the positive electrode film per unit area in a single battery cell is 1.05, 1.07, 1.1, 1.12, 1.15, 1.18, 1.2, 1.22, 1.25, 1.28, 1.3, or a range of any two of the above values.
  • the CB value has a well-known meaning in the art and can be detected using well-known equipment and methods in the art.
  • the capacity of the negative electrode film per unit area and the capacity of the positive electrode film per unit area can be calculated respectively, and the ratio between the two can be calculated to obtain the CB value.
  • the capacity per unit area of the positive electrode film refers to the actual delithiation capacity of the positive electrode active material.
  • the testing method is as follows: Disassemble the battery in a Braun glove box (PRS340/11-119-11), remove the positive electrode sheet, and assemble it into a CR2430 semi-coin cell with a positive electrode and lithium sheet.
  • the positive electrode sheet area is a mm2 .
  • the capacity per unit area of the negative electrode film refers to the actual lithium intercalation capacity of the negative electrode active material.
  • the testing method is as follows: The battery is disassembled in a Braun glove box (PRS340/11-119-11), the negative electrode is removed, and assembled into a CR2430 semi-coin cell with a negative electrode and lithium sheet. The area of the negative electrode is f mm2 .
  • the assembled semi-coin cell is then left to stand for 3 hours. The test is conducted at 25°C.
  • Lithium insertion is performed by discharging at 0.1C in the voltage range of 2V-0V, followed by lithium extraction by charging at 0.05C to 2V. This cycle is repeated twice.
  • the discharge capacity of the second cycle is recorded as Z mAh.
  • the actual battery design has a negative electrode length of h mm and a width of i mm.
  • the number of surfaces of the negative electrode active material coated on the negative electrode current collector is d. Therefore, the lithium insertion capacity of the negative electrode is Z/f*h*i*d.
  • the separator includes a porous base membrane.
  • the base film includes at least one of glass fiber, nonwoven fabric, and polyolefin.
  • the base film can be a single-layer film or a multi-layer composite film, without particular limitation.
  • the materials of each layer can be the same or different, without particular limitation.
  • the polyolefin includes at least one of polyethylene, polypropylene, and polyvinylidene fluoride.
  • the porosity of the base membrane is 20% to 70%, optionally 35% to 60%.
  • the porosity of the base membrane is 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, or any range of two of the above values.
  • the porosity of the base film in the embodiments of this application is within the above-mentioned range, it can enhance the migration ability of lithium ions in the separator, further reduce the internal resistance of the battery cell, and thus reduce heat generation.
  • porosity refers to the percentage of the volume of the pores in the separator to the total volume of the separator. Porosity can be tested according to the standard GB/T 36363-2018 "Polyolefin Separators for Battery Cells". It should be noted that the actual testing process may differ slightly from the standard due to differences in testing instruments, testing errors, and to minimize the impact on porosity testing, in order to obtain more accurate test values.
  • the thickness of the base film is 6 ⁇ m to 12 ⁇ m, optionally 6 ⁇ m to 9 ⁇ m.
  • the thickness of the base film is 6 ⁇ m, 6.5 ⁇ m, 7 ⁇ m, 7.5 ⁇ m, 8 ⁇ m, 8.5 ⁇ m, 9 ⁇ m, 9.5 ⁇ m, 10 ⁇ m, 10.5 ⁇ m, 11 ⁇ m, 11.5 ⁇ m, 12 ⁇ m, or any range of two of the above values.
  • the migration path of lithium ions in the base film is shorter, which can further reduce the internal resistance of the battery cell and thus reduce heat generation.
  • the separator can be a base film.
  • the separator further includes a functional layer disposed on at least one side of the base film.
  • the functional layer may include inorganic particles to improve the heat resistance of the separator.
  • the functional layer is disposed on both sides of the base film.
  • the functional layer includes a first functional layer and a second functional layer.
  • the first functional layer is located on one side of the base film and includes first inorganic particles.
  • the second functional layer is located on the other side of the base film and includes composite particles.
  • the composite particles include second inorganic particles and a plurality of non-fluoropolymer particles. The second inorganic particles are attached to the surface of the non-fluoropolymer particles and/or dispersed inside the non-fluoropolymer particles.
  • the first and second functional layers have good heat resistance, which can improve the heat resistance of the separator.
  • the first functional layer may include an adhesive, optionally including at least one of a fluorinated adhesive or a polyacrylic adhesive, such as polyvinylidene fluoride.
  • an adhesive optionally including at least one of a fluorinated adhesive or a polyacrylic adhesive, such as polyvinylidene fluoride.
  • the thickness of the base film has a meaning known in the art and can be detected using known meanings and equipment.
  • a newly prepared separator can be taken as a sample, or a battery cell that has been completely discharged (discharged to the lower limit cutoff voltage so that the battery's state of charge is about 0% SOC) can be disassembled in reverse, the separator can be obtained from the battery cell, and the separator can be dried and used as a sample.
  • the separator can be cut with an ion beam cutter to form a cross section, and then the thickness of the separator and its various layers can be measured using a scanning electron microscope.
  • the average particle size of the second inorganic particles is 5 nm to 100 nm, optionally 10 nm to 100 nm, or optionally 5 nm to 20 nm.
  • the average particle size of the second inorganic particles is 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, or any combination of two of the above values.
  • the average particle size of the second inorganic particles is within the above range, it is beneficial to improve the heat resistance and compressive modulus of the composite particles.
  • the average particle size of the second inorganic particles has a meaning known in the art and can be detected using equipment and methods known in the art. For example, after obtaining the separator membrane and drying it, the separator membrane is used as a sample. The separator membrane is then cut with an ion beam cutter to form a cross-section. Subsequently, the separator membrane is measured using a scanning electron microscope. The particle size of the second inorganic particles in the membrane is determined by measuring the particle size of multiple, for example, 50, second inorganic particles and calculating their average value as the average particle size of the second inorganic particles.
  • the electrolyte has a density of 1.05 g/mL to 1.35 g/mL at room temperature, such as 25°C.
  • the electrolyte density is 1.05 g/mL, 1.10 g/mL, 1.15 g/mL, 1.2 g/mL, 1.25 g/mL, 1.3 g/mL, 1.35 g/mL, or a range of any two of the above values.
  • Electrolytes consist of organic solvents and electrolyte salts.
  • the types of organic solvents and electrolyte salts are not specifically limited and can be selected according to actual needs.
  • the organic solvent includes a chain carboxylic acid ester solvent, wherein the chain carboxylic acid ester solvent comprises, by mass, 5% and 75% of the organic solvent, optionally 30% to 75%.
  • the mass content of the chain carboxylic acid ester solvent is 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or a range of any two of the above values.
  • the viscosity of the electrolyte system is relatively low, which is conducive to the migration of lithium ions.
  • the viscosity of the electrolyte system is relatively low, which is conducive to the migration of lithium ions.
  • the chain carboxylic acid ester solvent includes compounds represented by Formula I.
  • R 1 includes a hydrogen atom, a halogen atom, a C1 to C5 alkyl group, or a C1 to C5 haloalkyl group.
  • R1 includes a hydrogen atom, a halogen atom, a C1 to C3 alkyl group, or a C1 to C3 haloalkyl group. Further optionally, R1 includes a hydrogen atom, a halogen atom, a C1 to C2 alkyl group, or a C1 to C2 haloalkyl group.
  • R2 comprises a C1 to C3 alkyl or a C1 to C3 haloalkyl. More optionally, R2 comprises a C1 to C2 alkyl or a C1 to C2 haloalkyl.
  • the halogenated alkyl group includes one or more of fluoroalkyl, chloroalkyl, bromoalkyl and iodoalkyl groups, and optionally, the halogenated alkyl group includes fluoroalkyl.
  • the organic solvent also includes carbonate solvents.
  • the carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate. More preferably, the carbonate solvent includes one or more of ethylene carbonate, dimethyl carbonate, and methyl ethyl carbonate.
  • the carbonate solvent in the organic solvent has a mass content of 25% to 95%, optionally 25% to 70%.
  • the mass content of the carbonate solvent in the organic solvent is 25%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 40%, 45%, 48%, 50%, 55%, 60%, 65%, 70%, or any combination of two of the above values.
  • the carbonate solvent at the above mass contents can further improve the conductivity of the electrolyte at room temperature, which is beneficial for lithium ion migration.
  • the carbonate solvent includes one or more of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate, and the carbonate solvent content is 25% to 95% by mass.
  • the electrolyte also contains additives, which may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, and additives that improve battery low-temperature power performance.
  • additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, and additives that improve battery low-temperature power performance.
  • the additive comprises one or more of carbonate additives, sulfur-containing additives, and lithium salt additives, optionally at least two. These additives can improve the interfacial film performance on the positive and/or negative electrode sides, which is beneficial for improving the fast-charging performance of individual battery cells and enhancing cycle performance.
  • the additive has a mass content of 1% to 10% in the electrolyte, optionally 2% to 8%, and more preferably 3.5% to 8%.
  • the additive has a mass content of 1%, 2%, 3%, 3.5%, 4%, 5%, 6%, 7%, 8%, 9%, 10% in the electrolyte, or a range of any two of the above values.
  • the additives mentioned above can effectively improve the interfacial film performance on the positive and/or negative electrode sides, which is beneficial to improving the fast charging performance of battery cells and improving cycle performance.
  • carbonate additives include one or more of vinylene carbonate (VC) and fluoroethylene carbonate (FEC).
  • VC vinylene carbonate
  • FEC fluoroethylene carbonate
  • sulfur-containing additives include one or more of vinyl sulfate DTD, vinyl disulfate 2-DTD, butenyl sulfite BS, 1,3-propanesulfonate lactone PS, vinyl sulfite ES, and methylene disulfonate MMDS.
  • the lithium salt additive includes one or more of lithium difluorophosphate ( LiPO2F2 ) , lithium difluorooxalate borate (LiDFOB), lithium tetrafluoroborate (LiBF4 ) , and lithium dioxalate borate (LiBOB).
  • LiPO2F2 lithium difluorophosphate
  • LiDFOB lithium difluorooxalate borate
  • LiBF4 lithium tetrafluoroborate
  • LiBOB lithium dioxalate borate
  • the mass content of vinylene carbonate (VC) in the electrolyte is 0.5% to 9%, and optionally 2% to 6%.
  • the mass content of fluoroethylene carbonate (FEC) in the electrolyte is 0.1% to 4%, and optionally 0.5% to 3%.
  • the mass content of vinylene carbonate (VC) in the electrolyte is 0.5% to 9%, and the mass content of fluoroethylene carbonate (FEC) in the electrolyte is 0.1% to 4%.
  • the mass content of vinylene carbonate (VC) in the electrolyte is 2% to 6%, and the mass content of fluoroethylene carbonate (FEC) in the electrolyte is 0.5% to 3%.
  • the electrolyte salt includes a lithium salt, which includes one or more of fluorosulfonylimide salts and lithium hexafluorophosphate (LiPF6 ) .
  • a lithium salt which includes one or more of fluorosulfonylimide salts and lithium hexafluorophosphate (LiPF6 ) .
  • These lithium salts are readily dissociated, facilitating rapid lithium-ion migration, and the electrolyte system is relatively stable and not easily decomposed, thus improving the cycle performance of the battery cells.
  • the fluorosulfonyl imide salt includes one or more of lithium bisfluorosulfonyl imide (LiFSI) and lithium bistrifluoromethanesulfonate (LiTFSI).
  • LiFSI lithium bisfluorosulfonyl imide
  • LiTFSI lithium bistrifluoromethanesulfonate
  • the lithium salt includes lithium bis(fluorosulfonyl)imide (LiFSI) and lithium hexafluorophosphate (LiPF6 ) , wherein the molar concentration of lithium bis(fluorosulfonyl)imide (LiFSI) is from 0.2 mol/L to 0.5 mol/L, and the molar concentration of lithium hexafluorophosphate (LiPF6 ) is from 0.5 mol/L to 1.0 mol/L.
  • LiFSI lithium bis(fluorosulfonyl)imide
  • LiPF6 lithium hexafluorophosphate
  • the molar concentration of lithium bis(fluorosulfonyl)imide is 0.4 mol/L to 0.5 mol/L
  • the molar concentration of lithium hexafluorophosphate (LiPF6 ) is 0.7 mol/L.
  • the molar concentration of lithium bis(fluorosulfonyl)imide is 0.5 mol/L
  • the molar concentration of lithium hexafluorophosphate (LiPF6 ) is 0.5 mol/L.
  • the molar concentration of lithium bis(fluorosulfonyl)imide is 0.2 mol/L
  • the molar concentration of lithium hexafluorophosphate (LiPF6 ) is 0.8 mol/L.
  • the ratio of the molar concentration of lithium bis(fluorosulfonyl)imide to the molar concentration of lithium hexafluorophosphate (LiPF6 ) is from 0.2 to 1.0, and optionally from 0.2 to 0.5.
  • the ratio of the molar concentration of lithium bis(fluorosulfonyl)imide to the molar concentration of lithium hexafluorophosphate (LiPF6 ) is 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, or a range of any two of the above values.
  • the types and contents of inorganic components/lithium salts in the electrolyte are of a well-known nature in the art, and can be detected using equipment and methods known in the art.
  • the concentration of inorganic components/lithium salts in the electrolyte can be qualitatively or quantitatively analyzed by ion chromatography using standard JY/T020-1996 "General Rules for Ion Chromatography Analysis".
  • freshly prepared electrolyte can be used as a sample.
  • the free electrolyte from fresh batteries is used as a sample, or the free electrolyte from batteries that have been completely discharged (discharged to the lower cutoff voltage so that the battery's state of charge is about 0% SOC) is obtained from the reverse disassembly of the batteries and analyzed using ion chromatography.
  • the types and contents of organic components in the electrolyte are defined in the art and can be detected using equipment and methods known in the art.
  • the organic components in the electrolyte can be qualitatively and quantitatively analyzed by gas chromatography using GB/T9722-2006 "General Rules for Gas Chromatography of Chemical Reagents".
  • freshly prepared electrolyte can be used as a sample
  • the free electrolyte of a fresh battery can be used as a sample
  • a battery that has been completely discharged discharged to the lower limit cutoff voltage so that the battery's state of charge is approximately 0% SOC
  • the free electrolyte obtained from the battery can be used as a sample for detection using ion chromatography.
  • Chain-like carboxylic acid ester solvents and carbonate solvents e.g., ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate
  • the mass content of each component is calculated with the mass of the organic solvent representing 100%.
  • Carbonate additives such as vinylene carbonate and fluoroethylene carbonate
  • sulfur-containing additives such as sulfur-containing additives
  • lithium salt additives are used as additives in the electrolyte.
  • the mass content of each component is calculated based on the mass of the electrolyte as 100%.
  • the battery cell satisfies: d/A ⁇ 3.5 g/Ah, optionally 2.40 g/Ah ⁇ d/A ⁇ 3.3 g/Ah, where d represents the mass of electrolyte in the battery cell in grams (g), and A represents the rated capacity of the battery cell in Ah.
  • d/A can be 3.5 g/Ah, 3.3 g/Ah, 3.2 g/Ah, 3.0 g/Ah, 2.8 g/Ah, 2.5 g/Ah, 2.45 g/Ah, 2.4 g/Ah, or a range of any two of the above values.
  • d/A reflects the electrolyte's liquid retention capacity.
  • the electrolyte can effectively wet the positive and negative electrode plates and improve the migration rate of lithium ions in the liquid phase, which is beneficial to improving the fast charging capability of the battery cell.
  • the d/A ratio of a single battery cell can be understood as the liquid retention coefficient, which can be tested using equipment and methods known in the art.
  • the liquid retention coefficient can be described using GB/T31486-2015 "Electrical Performance Requirements and Test Methods for Power Batteries for Electric Vehicles", taking a battery charging upper limit voltage of 3.65V and a battery discharge cut-off voltage of 2.0V as an example.
  • the battery cell is charged to 3.65V at 0.33C, then charged at a constant voltage to 0.05C, and then discharged at a constant current of 0.33C to 2.0V.
  • the discharged capacity A is used as the denominator.
  • the battery cell is weighed as M0.
  • the positive electrode, negative electrode, separator, and electrolyte are disassembled, with the free electrolyte remaining in a bag.
  • All the solid components are placed in a 60°C oven and baked for at least 4 hours (including but not limited to the positive electrode, negative electrode, separator, and other mechanical parts of the disassembled battery cell that contribute to M0).
  • all components of the battery cell are weighed again as M1, with the weight difference between M0 and M1 as the numerator.
  • the liquid retention coefficient is equal to the weight difference d between M0 and M1 divided by the capacity A.
  • the positive electrode, separator, and negative electrode can be fabricated into an electrode assembly using a winding process and/or a stacking process.
  • Figures 1 and 2 show schematic diagrams of the structure of a single battery cell.
  • the battery cell 7 may include a housing 20.
  • the casing 20 of the battery cell 7 can be a rigid casing, such as a hard plastic casing, an aluminum casing, a steel casing, etc.
  • the casing 20 of the battery cell 7 can also be a pouch, such as a pouch-type pouch.
  • the material of the pouch can be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).
  • the electrode assembly 10 When the electrode assembly 10 has a stacked structure, from the perspective of its shape, the electrode assembly 10 includes a flat area.
  • the electrode assembly 10 may also include a bent area.
  • the separator when the separator adopts a one-piece structure, the separator is bent multiple times and then stacked with the positive electrode and the negative electrode to form the electrode assembly 10.
  • the negative electrode adopts a one-piece structure, the negative electrode is bent multiple times and then stacked with the positive electrode and the separator to form the electrode assembly.
  • the following description will take the example of the electrode assembly 10 only including a flat area.
  • the electrode assembly 10 When the electrode assembly 10 has a wound structure, from a structural point of view, the electrode assembly 10 includes a positive electrode sheet, a negative electrode sheet, and a separator.
  • the positive electrode sheet can be a single piece
  • the negative electrode sheet can be a single piece
  • the separator can be a single piece.
  • the separator is disposed between the positive electrode sheet and the negative electrode sheet.
  • the positive electrode sheet After being wound, the positive electrode sheet includes a first straight section and a positive electrode tab 111.
  • the number of the first straight sections is at least one, and can be at least two.
  • the positive electrode sheet also includes a first bent section.
  • the first bent section and the first straight section are arranged along the winding direction of the electrode assembly 10, and the first bent section is connected to the first straight section.
  • the positive electrode tab is connected to the first straight section.
  • the first straight section and the first bent section constitute a component of the main body 12.
  • the negative electrode sheet After being wound, the negative electrode sheet includes a second straight section and a negative electrode tab 112.
  • the number of the second straight sections is at least one, and can be at least two.
  • the negative electrode sheet also includes a second bent section.
  • the second bent section and the second straight section are arranged along the winding direction of the electrode assembly 10, and the second bent section is connected to the second straight section.
  • the negative electrode tab 112 is connected to the second straight section.
  • the second straight section and the second bent section constitute the main body 12.
  • the first straight section and the second straight section are alternately stacked, and the first bent section and the second bent section are alternately stacked.
  • the electrode assembly 10 includes a flat region and a bent region.
  • the flat region includes a first flat segment and a second flat segment, wherein the number of first flat segments is at least one, optionally at least two, and the number of second flat segments is at least one, optionally at least two.
  • the bent region includes a first bent segment and a second bent segment, wherein the number of first bent segments is at least one, optionally at least two, and the number of second bent segments is at least one, optionally at least two.
  • the lithium plating area in the flat region occupies 0% to 3% of the flat region area. A smaller lithium plating area results in higher reliability of the battery cell.
  • the base material of the casing 21 includes steel. Steel has high mechanical strength, is not easily deformed, and can improve the reliability and cycle performance of the battery cell.
  • the base material refers to the material with the highest proportion of material in the casing 21.
  • the thickness of the casing 21 is 0.1 mm to 0.5 mm, and optionally 0.2 mm to 0.35 mm.
  • the thickness of the casing 21 is 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, or any combination of two of the above values.
  • the mechanical strength of the casing 21 is high, which can improve the reliability and cycle performance of the battery cell; and the casing 21 occupies less space, while having more internal space, which is beneficial for increasing the energy density of the battery cell.
  • the positive electrode tab 111 is disposed on at least one side of the main body 12. Specifically, the positive electrode tab 111 is disposed on at least one side of the positive current collector, and can be disposed on both sides of the positive current collector. It can be disposed on both sides of the positive current collector along the length direction of the positive electrode sheet, or disposed on at least one side of the positive current collector along the width direction of the positive electrode sheet. Optionally, the positive electrode tab 111 is disposed on both sides of the positive current collector along the length direction.
  • the number of positive electrode tabs 111 located on the same side of the main body 12 is at least one, and optionally at least two.
  • the number of positive electrode tabs 111 located on the same side of the positive current collector can be at least one, for example, one or at least two.
  • the at least two positive electrode tabs 111 can increase the current-carrying area and can evenly distribute the current, improving the current uniformity in the positive electrode sheet 11, which is beneficial to further improving the fast charging performance of the battery cell 7.
  • each positive electrode tab 111 includes a first end face connected to the positive current collector.
  • the first end face has a dimension W1 in the width direction.
  • the sum of the dimensions of all first end faces on the same side of the positive current collector along the width direction is n*W1, and the dimension of the positive current collector along the width direction is W2.
  • n*W1/W2 is greater than or equal to 1/3, where n represents the number of all positive electrode tabs 111 located on the same side of the positive current collector.
  • n*W1/W2 is greater than or equal to 2/3, where n represents the number of all positive electrode tabs 111 located on the same side of the positive current collector.
  • n*W1/W2 is 1/3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 2/3, 0.7, 0.75, 0.8, 0.85, 0.9 or any two of the above values.
  • the overcurrent area of the positive electrode tab 111 is relatively large, which is beneficial to improving the fast charging performance of the battery cell 7.
  • the negative electrode tab 112 is disposed on at least one side of the negative electrode current collector, or on both sides of the negative electrode current collector. It can be disposed on both sides of the negative electrode current collector along the length direction of the negative electrode sheet, or on at least one side of the negative electrode current collector along the width direction of the negative electrode sheet. Optionally, the negative electrode tab 112 is disposed on both sides of the negative electrode current collector along the length direction.
  • the number of negative electrode tabs 112 located on the same side of the main body 12 is at least one, and optionally at least two.
  • the number of negative electrode tabs 112 located on the same side of the negative electrode current collector can be at least one, for example, one or at least two.
  • the at least two negative electrode tabs 112 can increase the current-carrying area and can evenly distribute the current, improving the current uniformity in the negative electrode sheet, which is beneficial to further improving the fast charging performance of the battery cell 7.
  • each negative electrode tab 112 includes a second end face connected to the negative electrode current collector.
  • the second end face has a width dimension of W3.
  • the sum of the width dimensions of all second end faces located on the same side of the negative electrode current collector is m*W3.
  • the width dimension of the negative electrode current collector is W4.
  • m*W3/W4 is greater than or equal to 1/3, where m represents the number of all negative electrode tabs 112 located on the same side of the negative electrode current collector.
  • m*W3/W4 is greater than or equal to 2/3, where m represents the number of all negative electrode tabs 112 located on the same side of the negative electrode current collector.
  • m*W3/W4 is 1/3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 2/3, 0.7, 0.75, 0.8, 0.85, 0.9 or a range of any two of the above values.
  • the overcurrent area of the negative electrode tab 112 is relatively large, which is beneficial to improving the fast charging performance of the battery cell 7.
  • the battery cell 7 further includes a positive terminal 31, which is electrically connected to a positive electrode tab 111.
  • the positive terminal 31 and the positive electrode tab 111 are welded together, and the positive terminal 31 and the positive electrode tab 111 can be connected by an adapter, or they can be connected without an adapter.
  • the positive terminal 31 and the positive electrode tab 111 are directly welded together without an adapter, which can reduce the resistance at the connection point and help reduce the overall internal resistance of the battery cell 7.
  • the number of positive terminals 31 is at least one, and optionally at least two.
  • the number of positive terminals 31 located on the same side of the positive current collector is at least one, and optionally at least two. At least two positive terminals 31 can increase the overall current carrying capacity of the positive terminals 31.
  • the flow area of a single positive terminal 31 is greater than or equal to 200 mm2 , and can be selected from 200 mm2 to 800 mm2 .
  • the flow area of the positive terminal 31 can be understood as the cross-sectional area of the positive terminal 31, which is perpendicular to the thickness direction of the positive terminal 31.
  • the flow area of a single positive terminal 31 can be 200 mm2 , 210 mm2 , 250 mm2 , 280 mm2 , 300 mm2 , 320 mm2 , 350 mm2 , 380 mm2 , 400 mm2 , 450 mm2 , 500 mm2 , 550 mm2 , 600 mm2 , 650 mm2 , 700 mm2 , 750 mm2 , 800 mm2 , or a range of any two of the above values.
  • the battery cell 7 further includes a negative terminal 32, which is electrically connected to a negative electrode tab 112.
  • the negative terminal 32 and the negative electrode tab 112 are welded together, and the negative terminal 32 and the negative electrode tab 112 can be connected by an adapter, or they can be connected without an adapter.
  • the negative terminal 32 and the negative electrode tab 112 are directly welded together without an adapter, which can reduce the resistance at the connection point and help reduce the overall internal resistance of the battery cell 7.
  • the number of negative extrema 32 is at least one, and optionally at least two.
  • the number of negative terminals 32 located on the same side of the negative current collector is at least one, and optionally at least two. At least two negative terminals 32 can increase the current carrying capacity of the negative terminals 32.
  • the flow area of a single negative terminal 32 is greater than or equal to 200 mm2 , and can be selected from 200 mm2 to 800 mm2 .
  • the flow area of the negative terminal 32 can be understood as the cross-sectional area of the negative terminal 32, which is perpendicular to the thickness direction of the negative terminal 32.
  • the flow area of a single negative terminal 32 can be 200 mm2 , 210 mm2 , 250 mm2 , 280 mm2 , 300 mm2 , 320 mm2 , 350 mm2 , 380 mm2 , 400 mm2 , 450 mm2 , 500 mm2 , 550 mm2 , 600 mm2 , 650 mm2 , 700 mm2 , 750 mm2 , 800 mm2 , or a range of any two of the above values.
  • the battery cell 7 according to the implementation of this application can be assembled into a battery module 6.
  • the number of battery cells 7 contained in the battery module 6 can be one or more, and the specific number can be adjusted according to the application and capacity of the battery module 6.
  • the battery module 6 may also include a housing with a accommodating space, within which multiple battery cells 7 are housed.
  • the battery module 6 can also be assembled into a battery pack 2, and the number of battery modules 6 contained in the battery pack 2 can be adjusted according to the application and capacity of the battery pack.
  • the battery device described herein can be either a battery module 6 or a battery pack 2.
  • the battery pack 2 may include a housing 5 and multiple battery modules 6 disposed within the housing 5.
  • the housing 5 includes a first housing portion 5a and a second housing portion 5b, and the housing 5 has a receiving space 5c.
  • the first housing portion 5a is used to cover the second housing portion 6.
  • the housing 5b forms an enclosed space for accommodating the battery modules 6.
  • Multiple battery modules 6 can be arranged in any manner within the housing 5.
  • the first housing portion 5a and the second housing portion 5b overlap each other, and together they define a receiving space 5c for accommodating a single battery cell.
  • the second housing portion 5b can be a hollow structure with one open end, and the first housing portion 5a can be a plate-like structure.
  • the first housing portion 5a covers the open side of the second housing portion 5b to form a housing 5 with the receiving space 5c.
  • both the first housing portion 5a and the second housing portion 5b can be hollow structures with one open side, with the open side of the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the receiving space 5c.
  • the first housing portion 5a and the second housing portion 5b can be of various shapes, such as cylinders, cuboids, etc.
  • a sealing element such as sealant or sealing ring, can also be provided between the first housing part 5a and the second housing part 5b.
  • the first box section 5a covers the top of the second box section 5b
  • the first box section 5a can also be called the upper box cover
  • the second box section 5b can also be called the lower box.
  • the temperature of the external environment in which the battery pack 2 is located is room temperature, for example, 30°C.
  • the charging process of the battery pack 2 or any individual battery cell comprising the battery pack 2 from 10% state of charge to 80% state of charge includes multiple charging steps.
  • the difference between the maximum state of charge of any charging step and the maximum state of charge of its adjacent charging step is less than or equal to 5% state of charge, such as 1% state of charge, 1.5% state of charge, 2% state of charge, 2.5% state of charge, 3% state of charge, 3.5% state of charge, 4% state of charge, 4.5% state of charge, 5% state of charge, or any range of any two of the above values.
  • the charging steps from 10% to 80% for the battery pack 2 or any individual battery cell comprising the battery pack 2 can be performed as follows:
  • the charging time for the battery pack 2 or any individual battery cell comprising the battery pack 2 from 20% state of charge to 80% state of charge is less than or equal to 12.5 minutes, optionally between 6 minutes and 12.5 minutes, and the ambient temperature of the battery pack 2 at 10% state of charge is room temperature, for example, 30°C.
  • the charging time for the battery pack 2 from 10% state of charge to 80% state of charge is 12.5 minutes, 12 minutes, 11.5 minutes, 11 minutes, 10.5 minutes, 10 minutes, 9.5 minutes, 9 minutes, 8.5 minutes, 8 minutes, 7.5 minutes, 7 minutes, 6.5 minutes, 6 minutes, or a range of any two of the above values.
  • the volumetric energy density of the battery cell is from 390 Wh/L to 500 Wh/L, optionally from 410 Wh/L to 470 Wh/L.
  • the volumetric energy density of the battery cell is 390 Wh/L, 400 Wh/L, 410 Wh/L, 420 Wh/L, 430 Wh/L, 440 Wh/L, 450 Wh/L, 460 Wh/L, 470 Wh/L, 480 Wh/L, 490 Wh/L, 500 Wh/L, or a range of any two of the above values.
  • the volumetric energy density of the battery cell is relatively high.
  • the volumetric energy density of a single battery cell has a meaning known in the art and can be detected using equipment and methods known in the art.
  • the following description uses a battery charging upper limit voltage of 3.65V and a battery discharging cutoff voltage of 2.0V as an example.
  • a second aspect of this application provides an electrical device, which includes at least one of the battery cell, battery module, or battery pack described in this application.
  • the battery cell, battery module, or battery pack can be the power source of the electrical device or the energy storage unit of the electrical device.
  • the electrical device can be a vehicle, mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, or power tool, etc.
  • Vehicles can be gasoline-powered vehicles, natural gas-powered vehicles, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc.; spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc.; electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc.; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the above-described electrical device.
  • Electrical devices can be equipped with individual battery cells, battery modules, or battery packs depending on their usage requirements.
  • FIG. 5 is a schematic diagram of an example electrical device 1.
  • This electrical device 1 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.
  • a battery pack or battery module can be used.
  • the electrical device 1 is equipped with a battery pack 2, which can be located at the bottom, head, or tail of the electrical device 1.
  • the battery pack 2 can be used to supply power to the electrical device 1.
  • the battery pack 2 can serve as the operating power source for the electrical device 1, and can also serve as the driving power source for the electrical device 1, replacing or partially replacing fuel oil or natural gas to provide driving power for the electrical device 1.
  • the following charging methods can be selected for the charging process of electrical devices:
  • the charging time for the electrical device from 10% state of charge to 80% state of charge is less than or equal to 12.5 minutes, optionally between 6 minutes and 12.5 minutes, and the ambient temperature of the battery pack 2 in the electrical device at 20% state of charge is room temperature, for example, 30°C.
  • the charging time for the battery pack 2 in the electrical device from 10% state of charge to 80% state of charge is 12.5 minutes, 12 minutes, 11.5 minutes, 11 minutes, 10.5 minutes, 10 minutes, 9.5 minutes, 9 minutes, 8.5 minutes, 8 minutes, 7.5 minutes, 7 minutes, 6.5 minutes, 6 minutes, or a range of any two of the above values.
  • the positive electrode includes a positive current collector, a positive conductive layer on the positive current collector, and a positive film layer.
  • the positive current collector is made of aluminum foil.
  • the positive electrode conductive layer on the positive electrode current collector is a film formed by uniformly mixing the positive electrode conductive agent superconducting carbon, the positive electrode binder polyvinylidene fluoride (PVDF), and the solvent N-methylpyrrolidone (NMP), coating it on the surface of the current collector, and drying it.
  • the thickness is 1 ⁇ m.
  • the mass content of the positive electrode conductive agent in the positive electrode conductive layer is 40%, and the mass content of the positive electrode binder is 60%.
  • the positive electrode film layer comprises a film layer formed by uniformly coating a positive electrode slurry (solvent being N-methylpyrrolidone, NMP) onto the surface of a positive electrode conductive layer, followed by drying and cold pressing.
  • the positive electrode film layer comprises positive electrode active material, binder polyvinylidene fluoride (PVDF), and conductive agent acetylene black in a weight ratio of 97:2:1.
  • the positive electrode active material includes lithium iron phosphate and a coating layer.
  • the coating layer is coated on the surface of the lithium iron phosphate and includes lithium titanium iron phosphate ( Li2FeTi ( PO4 ) 3 ) and amorphous carbon.
  • the positive electrode active material has a Dv50 of 1.6 ⁇ m, a Dv10 of 0.64 ⁇ m, a minimum particle size of 0.2 ⁇ m, and a maximum particle size of 18 ⁇ m.
  • the negative electrode includes a negative current collector, a negative conductive layer on the negative current collector, and a negative film layer.
  • the negative current collector is a copper foil.
  • the negative electrode conductive layer on the negative electrode current collector is a film formed by uniformly mixing superconducting carbon, styrene-butadiene rubber (SBR), sodium carboxymethyl cellulose (CMC-Na), and water, and then coating it onto the surface of the negative electrode current collector and drying it.
  • the thickness is 1 ⁇ m.
  • the mass content of the negative electrode conductive agent in the negative electrode conductive layer is 35%, the mass content of the negative electrode binder in the negative electrode conductive layer is 60%, and the mass content of the thickener in the negative electrode conductive layer is 5%.
  • the negative electrode film layer comprises a film layer formed by uniformly coating a negative electrode slurry (with deionized water as the solvent) onto the surface of a negative electrode conductive layer, followed by drying and cold pressing.
  • the negative electrode film layer includes a first negative electrode film layer and a second negative electrode film layer.
  • the first negative electrode film layer is located on the surface of the negative electrode conductive layer, and the second negative electrode film layer is located on the surface of the first negative electrode film layer.
  • the first negative electrode film layer comprises graphite particles in a mass ratio of 96.5:0.5:0.5:1.5:1, conductive agent acetylene black, a first lithium-containing binder (lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate copolymer, wherein the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer is 35%:30%:15%:20%), negative electrode binder styrene-butadiene rubber, and thickener sodium carboxymethyl cellulose.
  • the lithium content in the first lithium-containing binder is 4.8% by mass.
  • the Dv50 of the graphite particles is 11.3 ⁇ m.
  • the graphite particles include artificial graphite and a carbon coating layer. The carbon coating layer coats the surface of the artificial graphite, and the carbon coating layer has a mass content of 3.5%.
  • the second negative electrode film layer comprises graphite particles in a mass ratio of 97.5:0.5:0.5:0.5:1, conductive agent acetylene black, a second lithium-containing binder (lithium acrylate-acrylonitrile-acrylamide-hydroxyethyl acrylate copolymer, wherein the molar ratio of lithium acrylate monomer, acrylonitrile monomer, acrylamide monomer and hydroxyethyl acrylate monomer is 35%:30%:15%:20%), negative electrode binder styrene-butadiene rubber, and thickener sodium carboxymethyl cellulose.
  • the lithium content in the second lithium-containing binder is 4.8% by mass.
  • the Dv50 of the graphite particles is 11.3 ⁇ m.
  • the graphite particles include artificial graphite and a carbon coating layer. The carbon coating layer coats the surface of the artificial graphite, and the carbon coating layer has a mass content of 3.5%.
  • the separator includes a base membrane, which is a 7 ⁇ m polyethylene film layer with a porosity of 42%.
  • the electrolyte consists of organic solvents, lithium salts, and additives.
  • the organic solvents include 60% chain carboxylic acid ester solvents (ethyl acetate) and 40% carbonate solvents (30% ethylene carbonate EC and 10% dimethyl carbonate). The mass content of each component in the organic solvents is calculated based on the mass of the organic solvents.
  • the additive content is 6.5%, which includes vinylene carbonate (VC), fluoroethylene carbonate (FEC), vinyl sulfite (ES), and lithium difluorooxalate borate (LiDFOB) in a mass ratio of 5:0.5:0.5:0.5.
  • VC vinylene carbonate
  • FEC fluoroethylene carbonate
  • ES vinyl sulfite
  • LiDFOB lithium difluorooxalate borate
  • the lithium salts include 1 mol/L lithium hexafluorophosphate (LiPF6 ) .
  • the electrolyte has a conductivity of 16.4 mS/cm at room temperature.
  • the positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation, thus obtaining an electrode assembly.
  • the electrode assembly is placed in an outer packaging shell, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a battery cell is obtained.
  • Battery cells were prepared using a method similar to that of Example 1. The difference from Example 1 is that the thickness, compaction density, and coating weight of the positive and negative electrode sheets were adjusted, as shown in Tables 1 and 2.
  • Battery cells were prepared using a method similar to that of Example 1. The difference from Example 1 is that the thickness, compaction density, and coating weight of the positive and negative electrode sheets were adjusted, as shown in Tables 1 and 2.
  • the charging time for a single battery cell to charge from 10% SOC to 80% SOC is determined by the following charging steps.
  • the charging time differences between different embodiments are adjusted based on the charging rate of Embodiment 1 to achieve the corresponding charging time.
  • a single battery cell is charged from 10% SOC to 80% SOC using the above charging process, then charged at 0.33C to 3.65V, allowed to rest for 30 minutes, and then discharged at 1C to 10% SOC. This constitutes one charge-discharge cycle. This charge-discharge cycle is repeated 1000 times.
  • the cycle capacity retention rate of the battery cell is calculated; a higher cycle capacity retention rate indicates better cycle performance of the battery cell. Based on the charging rate adjustment in Example 1, the actual charging rate in different examples is adjusted according to the charging time from 10% to 80% SOC.
  • the ratio of the total thickness of the negative electrode film to the thickness of the negative electrode sheet is less than 0.95.
  • the thickness of the negative electrode film is relatively thin, resulting in a lower energy density of the battery cell.
  • the ratio of the total thickness of the negative electrode film to the thickness of the negative electrode sheet is greater than 0.97, which may result in higher internal resistance, leading to a longer charging time. Furthermore, the excessive volume expansion of the negative electrode sheet makes it difficult for the electrolyte to flow back, resulting in insufficient electrolyte wetting in the negative electrode film layer. This makes the negative electrode sheet prone to problems such as lithium plating, which leads to a shortened cycle life of the battery cell.
  • the ratio of the total thickness of the negative electrode film to the thickness of the negative electrode sheet is 0.95 to 0.97. This results in relatively small volume expansion of the negative electrode sheet during charging, allowing the electrolyte to fully wet the negative electrode sheet, improving the migration performance of lithium ions in the negative electrode sheet, reducing the risk of lithium plating, effectively improving the reliability and cycle performance of the battery cell, and contributing to the improvement of the energy density of the battery cell. Furthermore, the negative electrode current collector has a small proportion and a thinner thickness, which is beneficial to improving the fast charging performance of the battery cell.
  • the embodiments of this application further adjust the ratio of the total thickness of the positive electrode film layer to the thickness of the positive electrode sheet to 0.88 to 0.94, which can further improve the fast charging performance, cycle performance and energy density of the battery cell.
  • the embodiments of this application further improve the fast charging performance, cycle performance and energy density of the battery cell by adjusting the thickness of the positive current collector to 10 ⁇ m to 15 ⁇ m and/or the thickness of the negative current collector to 4 ⁇ m to 6 ⁇ m.
  • the embodiments of this application further adjust the coating weight of the single-sided positive electrode film layer to 200mg/ 1540.25mm2 to 370mg/ 1540.25mm2 ; and/or the coating weight of the single-sided negative electrode film layer to 90mg/ 1540.25mm2 to 170mg/ 1540.25mm2 , which can further improve the fast charging performance, cycle performance and energy density of the battery cell.
  • the embodiments of this application further adjust the compaction density of the single-sided positive electrode film layer of the battery cell to 2.5 g/ cm3 to 2.8 g/ cm3 when the battery cell is at 100% charge; and/or the compaction density of the single-sided negative electrode film layer of the battery cell to 1.15 g/ cm3 to 1.36 g/ cm3 when the battery cell is at 100% charge, thereby further improving the fast charging performance, cycle performance and energy density of the battery cell.

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Abstract

L'invention concerne une cellule de batterie (7), un dispositif de batterie et un dispositif électrique (1). La cellule de batterie (7) comprend un ensemble électrode (10) ; l'ensemble électrode (10) comprend une feuille d'électrode positive, une feuille d'électrode négative et un séparateur ; le séparateur est situé entre la feuille d'électrode positive et la feuille d'électrode négative ; la feuille d'électrode positive comprend une languette d'électrode positive (111), une partie de collecte de courant d'électrode positive et une couche de film d'électrode positive disposée sur au moins une surface de la partie de collecte de courant d'électrode positive dans le sens de l'épaisseur de la feuille d'électrode positive et comprenant un matériau actif d'électrode positive ; la languette d'électrode positive (111) est disposée sur au moins un côté de la partie de collecte de courant d'électrode positive ; la feuille d'électrode négative comprend une languette d'électrode négative (112), une partie de collecte de courant d'électrode négative et une couche de film d'électrode négative disposée sur au moins une surface de la partie de collecte de courant d'électrode négative dans le sens de l'épaisseur de la feuille d'électrode négative et comprenant un matériau actif d'électrode négative ; et la languette d'électrode négative (112) est disposée sur au moins un côté de la partie de collecte de courant d'électrode négative. Lorsque la cellule de batterie (7) est chargée à 100 %, le rapport entre l'épaisseur totale de la couche de film d'électrode négative dans la feuille d'électrode négative et l'épaisseur de la feuille d'électrode négative est de 0,95 à 0,97. Les performances en matière de charge rapide, de cycle et de densité d'énergie de la cellule de batterie (7) peuvent être améliorées.
PCT/CN2024/106977 2024-07-23 2024-07-23 Cellule de batterie, dispositif de batterie et dispositif électrique Pending WO2026020309A1 (fr)

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DE212024000184.8U DE212024000184U1 (de) 2024-07-23 2024-07-23 Batteriezelle, Batterievorrichtung und stromverbrauchende Vorrichtung
PCT/CN2024/106977 WO2026020309A1 (fr) 2024-07-23 2024-07-23 Cellule de batterie, dispositif de batterie et dispositif électrique
CN202510526806.2A CN120073230B (zh) 2024-07-23 2025-04-25 电池单体、电池装置和用电装置

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CN117461158A (zh) * 2022-05-24 2024-01-26 宁德时代新能源科技股份有限公司 正极活性材料、正极极片、二次电池、电池模块、电池包和用电装置
CN117652038A (zh) * 2022-07-05 2024-03-05 宁德时代新能源科技股份有限公司 电极组件、二次电池、电池模块、电池包及用电装置
CN117878383A (zh) * 2024-03-08 2024-04-12 宁德时代新能源科技股份有限公司 电池单体、电池和用电装置
CN118198469A (zh) * 2024-03-22 2024-06-14 宁德时代新能源科技股份有限公司 二次电池及用电装置

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