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WO2023082924A1 - 极片、锂离子电池、电池模块、电池包及用电装置 - Google Patents

极片、锂离子电池、电池模块、电池包及用电装置 Download PDF

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Publication number
WO2023082924A1
WO2023082924A1 PCT/CN2022/124953 CN2022124953W WO2023082924A1 WO 2023082924 A1 WO2023082924 A1 WO 2023082924A1 CN 2022124953 W CN2022124953 W CN 2022124953W WO 2023082924 A1 WO2023082924 A1 WO 2023082924A1
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Prior art keywords
lithium
pole piece
active material
electrolyte
surfactant
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PCT/CN2022/124953
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English (en)
French (fr)
Inventor
黄瑛
姚斌
王红
刘江
刘珍
Original Assignee
宁德时代新能源科技股份有限公司
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Priority to EP22891723.3A priority Critical patent/EP4362138A1/en
Priority to KR1020247000849A priority patent/KR20240019317A/ko
Priority to JP2024503511A priority patent/JP2024526876A/ja
Publication of WO2023082924A1 publication Critical patent/WO2023082924A1/zh
Priority to US18/658,950 priority patent/US20240290973A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—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
    • H01M4/5835—Comprising fluorine or fluoride salts
    • 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
    • H01M10/0567—Liquid materials characterised by the additives
    • 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
    • H01M10/0568—Liquid materials characterised by the solutes
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • H01M50/258—Modular batteries; Casings provided with means for assembling
    • 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
    • H01M2220/10—Batteries in stationary systems, e.g. emergency power source in plant
    • 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
    • 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
    • H01M2220/30—Batteries in portable systems, e.g. mobile phone, laptop
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the technical field of lithium batteries, in particular to a pole piece, a lithium ion battery, a battery module, a battery pack and an electrical device.
  • Lithium-ion battery is a kind of secondary battery.
  • lithium-ion battery includes positive pole piece, negative pole piece, electrolyte and separator.
  • active ions are intercalated and extracted back and forth between the positive electrode and the negative electrode.
  • the electrolyte is the carrier of ion transmission in the lithium-ion battery, and plays the role of conducting ions between the positive and negative electrodes of the lithium-ion battery, which is the guarantee for the high-voltage, high-specific-energy performance of the lithium-ion battery.
  • the electrolyte is generally prepared from high-purity organic solvents, electrolyte lithium salts, necessary additives and other raw materials under certain conditions and in a certain proportion.
  • lithium-ion batteries have been widely used in high-tech products such as automobiles and mobile phones. With the continuous expansion of the application field of lithium-ion batteries, it is necessary to continuously improve the performance of lithium-ion batteries in all aspects.
  • the present application is made in view of the above-mentioned problems, and its purpose is to provide a pole piece that can improve the rate performance, discharge capacity and service life of a lithium-ion battery, and a lithium-ion battery and a battery module including the pole piece. , battery packs and electrical devices.
  • the first aspect of the present application provides a pole piece, the pole piece includes a current collector and an active material layer arranged on at least one surface of the current collector, and the active material layer contains surface active material. agent lithium salt.
  • the affinity between the lithium salt and the electrolyte is used to effectively reduce the surface tension of the electrolyte, improve the wettability of the electrolyte to the pole piece, and reduce the battery life.
  • Interfacial impedance improves the utilization efficiency of active materials, thereby improving the rate performance, discharge capacity and service life of lithium-ion batteries.
  • the surface of the active material layer facing away from the current collector is provided with a functional layer, and the functional layer also contains the lithium salt of the surfactant.
  • the amount of the surfactant lithium salt in the active material layer is 0.00175-0.00875 mol.
  • the lithium salt of the surfactant can be selected from at least one of lithium bistrifluoromethanesulfonimide, lithium nitrate, lithium perchlorate or lithium chloride.
  • the active material layer sequentially includes several active material sub-layers stacked in the direction away from the current collector, and the coating quality per unit area changes from small to large, and the several active material
  • the amount of the surfactant lithium salt contained in the sublayer also varies from small to large.
  • the active material layer in the pole piece is coated with multiple layers, and the lithium salt of the surfactant is also doped into each active material sub-layer respectively, and the lithium salt of the surfactant in each active material sub-layer
  • the changing law of the dosage is consistent with the changing law of the coating quality of the active material in the active material sub-layer, so that each active material sub-layer can play a pore-forming role.
  • the active material layer sequentially includes a first active material sublayer and a second active material sublayer stacked in a direction away from the current collector, and the unit area of the first active material sublayer is
  • the coating mass is recorded as CW 1 , 0.150g/1540.25mm 2 ⁇ CW 1 ⁇ 0.200g/1540.25mm 2 ;
  • the coating mass per unit area of the second active material sublayer is recorded as CW 2 , and CW 2 ⁇ 0.200g/ 1540.25mm 2 ;
  • the amount of the lithium salt of the surfactant in the first active material sublayer is denoted as M 1
  • the amount of the lithium salt of the surfactant in the second active material sublayer is denoted as M 2.
  • M 1 /(M 1 +M 2 +M 3 ) is 10% to 30%.
  • M 1 /(M 1 +M 2 +M 3 ) is 20%;
  • M 2 /(M 1 +M 2 +M 3 ) is 20% ⁇ 40%, optional, M 2 /(M 1 +M 2 +M 3 ) is 30%;
  • M 3 /(M 1 +M 2 +M 3 ) is 30%-70%, optionally, M 3 /(M 1 +M 2 +M 3 ) is 50%.
  • the pole piece is a positive pole piece or a negative pole piece.
  • the second aspect of the present application provides a lithium-ion battery, including a positive pole piece, a negative pole piece, a separator spaced between the positive pole piece and the negative pole piece, and an electrolyte, wherein the positive pole piece and/or The negative pole piece is the pole piece provided in the first aspect of the present application.
  • the electrolyte is selected from an ester electrolyte, an ether electrolyte or an aqueous electrolyte.
  • the electrolyte is a pure solvent electrolyte. That is, the electrolyte only contains the solvent and does not contain the electrolyte lithium salt.
  • the electrolyte does not contain electrolyte lithium salt, that is, all the lithium salt is incorporated as a surfactant into the active material layer on the surface of the electrode or the functional coating on the surface of the active material layer, and the electrolyte solvent is directly used as the electrolyte to inject the battery
  • the electrolyte solvent infiltrates the pole piece, the lithium salt of the surfactant in the pole piece dissolves in the electrolyte solution, which can play the role of conducting ions.
  • the pure solvent is used as the electrolyte to inject the battery.
  • the advantage is that the viscosity of the pure solvent is low, so the wettability of the pole piece will be better, and the lithium salt of the surfactant mixed into the pole piece can be further realized. Pores are used to prepare porous electrodes to better promote the wettability of the electrolyte to the pole piece.
  • the solvent in the electrolyte is at least one selected from ethylene carbonate, diethyl carbonate, dimethyl carbonate or ethyl methyl carbonate.
  • the sum of the amount of the substance of the surfactant lithium salt is denoted as Mp; the amount of the substance of the lithium salt in the electrolyte is denoted as Ms; the total volume of the electrolyte is denoted as Vs; then the lithium ion battery meets: (Mp+Ms)/Vs is 1 ⁇ 2mol/L; optional, (Mp+Ms)/Vs is 1mol/L .
  • the doping concentration of the surfactant lithium salt in the pole piece is within an appropriate range, it is beneficial to the wettability of the electrolyte to the pole piece, and at the same time, it will not have adverse effects on the ion conductivity and increase the polarization of the battery, ensuring Overall electrochemical performance of lithium-ion batteries.
  • the third aspect of the present application further provides a battery module, which includes the lithium-ion battery of the second aspect of the present application.
  • the fourth aspect of the present application further provides a battery pack, which includes the lithium ion battery of the second aspect of the present application or the battery module of the third aspect of the present application.
  • the fifth aspect of the present application also provides an electric device, which includes the lithium-ion battery of the second aspect of the present application or the battery module of the third aspect of the present application or the battery pack of the fourth aspect of the present application; wherein, the lithium-ion battery or A battery module or battery pack is used as a power source or an energy storage unit for an electric device.
  • Fig. 1 is the scanning electron micrograph of the wetting angle photo of the negative pole sheet and the electrolyte that do not contain surfactant lithium salt in the active material layer;
  • Fig. 2 is the scanning electron micrograph of the wetting angle photo of the negative pole sheet and the electrolyte containing the low concentration surfactant lithium salt in the active material layer;
  • Fig. 3 is the scanning electron micrograph of the wetting angle photo of the negative pole sheet and the electrolyte containing the high concentration surfactant lithium salt in the active material layer;
  • FIG. 4 is a schematic diagram of a lithium-ion battery according to an embodiment of the present application.
  • Fig. 5 is an exploded view of a lithium-ion battery according to an embodiment of the present application shown in Fig. 4;
  • FIG. 6 is a schematic diagram of a battery module according to an embodiment of the present application.
  • FIG. 7 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • Fig. 8 is an exploded view of the battery pack according to an embodiment of the present application shown in Fig. 7;
  • FIG. 9 is a schematic diagram of an electrical device in which a lithium-ion battery is used as a power source according to an embodiment of the present application.
  • ranges disclosed herein are defined in terms of lower and upper limits, and a given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive and may be combined arbitrarily, ie any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are contemplated. Additionally, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-5.
  • the numerical range "a-b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article, and "0-5" is only an abbreviated representation of the combination of these values.
  • a certain parameter is an integer ⁇ 2
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed in sequence, and may also include steps (b) and (a) performed in sequence.
  • steps (c) means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c) , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b) and so on.
  • the “comprising” and “comprising” mentioned in this application mean open or closed.
  • the “comprises” and “comprises” may mean that other components not listed may also be included or included, or only listed components may be included or included.
  • the term "or” is inclusive unless otherwise stated.
  • the phrase "A or B” means “A, B, or both A and B.” More specifically, the condition "A or B” is satisfied by either of the following: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; or both A and B are true (or exist).
  • the present application proposes a pole piece, the pole piece includes a current collector and an active material layer disposed on at least one surface of the current collector, and the active material layer contains a surfactant Lithium salt.
  • ⁇ SV ⁇ SL + ⁇ LV ⁇ cos ⁇
  • ⁇ SV is the surface tension of the electrode sheet
  • ⁇ SL is the surface tension of the interface between the electrolyte and the electrode
  • ⁇ LV is the surface tension of the electrolyte itself
  • ⁇ is the wetting angle between the electrolyte and the electrode.
  • the surface tension of the electrolyte determines the size of the contact angle: the smaller the surface tension of the electrolyte, the smaller the interface contact angle, and the infiltration of the electrolyte to the electrode sheet Sex is better.
  • the applicant proposes: doping the lithium salt of the surfactant in the active material layer of the pole piece, when the pole piece is removed from the electrolyte, the lithium salt of the surfactant is partially or completely dissolved in the electrolyte, and the lithium salt of the surfactant is used to
  • the affinity between the salt and the electrolyte can effectively reduce the surface tension of the electrolyte and improve the wettability of the electrolyte to the pole piece, thereby improving the rate performance, discharge capacity and service life of the lithium-ion battery.
  • the inherent definition of surfactant is: a substance that can significantly reduce the surface tension of the target solution.
  • the surfactant lithium salt described in this application refers to the lithium salt that can significantly reduce the surface tension of the electrolyte.
  • the surface of the active material layer facing away from the current collector is provided with a functional layer, and the functional layer also contains the lithium salt of the surfactant.
  • both the active material layer and the functional layer contain a lithium salt of a surfactant.
  • the lithium salt of the surfactant is selected from lithium bistrifluoromethanesulfonimide (LiTFSI), lithium nitrate (LiNO 3 ), lithium perchlorate (LiClO 4 ), lithium chloride (LiCl) at least one of the lithium bistrifluoromethanesulfonimide (LiTFSI), lithium nitrate (LiNO 3 ), lithium perchlorate (LiClO 4 ), lithium chloride (LiCl) at least one of the lithium salt of the surfactant.
  • LiTFSI lithium bistrifluoromethanesulfonimide
  • LiNO 3 lithium nitrate
  • LiClO 4 lithium perchlorate
  • LiCl lithium chloride
  • the amount of the surfactant lithium salt in the active material layer is 0.00175 ⁇ 0.00875 mol.
  • Fig. 1 is the scanning electron micrograph of the wetting angle photo of the negative electrode pole piece and the electrolyte that does not contain surfactant lithium salt in the pole piece or on the surface of the pole piece; The scanning electron micrograph of the photo of the wetting angle of the negative electrode pole piece of the lithium salt of the surfactant and the electrolyte; Fig.
  • FIG. 3 is a scan of the photo of the wetting angle of the negative pole piece of the negative pole piece and the electrolyte containing the high concentration surfactant lithium salt in the pole piece or the surface of the pole piece Electron micrograph.
  • the wetting angle test results in Figures 1 to 3 show that the coating of surfactant lithium salt can effectively improve the wetting effect between the electrolyte and the surface of the negative electrode sheet.
  • the coating of low concentration surfactant lithium salt has shown The effectiveness of improving the wetting effect is shown, and as the concentration of the lithium salt of the surfactant used increases, the wetting effect is also better.
  • the active material layer sequentially includes several active material sublayers stacked in a direction away from the current collector, and the coating mass per unit area varies from small to large.
  • the amount of the surfactant lithium salt contained in the sublayer also varies from small to large.
  • the active material layer in the pole piece is coated with multiple layers, and the lithium salt of the surfactant is also doped into each active material sub-layer respectively, and the lithium salt of the surfactant in each active material sub-layer
  • the changing law of the dosage is consistent with the changing law of the coating quality of the active material in the active material sub-layer, so that each active material sub-layer can play a pore-forming role.
  • the active material layer sequentially includes a first active material sublayer and a second active material sublayer stacked in a direction away from the current collector, and the unit area of the first active material sublayer is
  • the coating mass is recorded as CW 1 , 0.150g/1540.25mm 2 ⁇ CW 1 ⁇ 0.200g/1540.25mm 2 ;
  • the coating mass per unit area of the second active material sublayer is recorded as CW 2 , and CW 2 ⁇ 0.200g/ 1540.25mm 2 ;
  • the amount of the lithium salt of the surfactant in the first active material sublayer is denoted as M 1
  • the amount of the lithium salt of the surfactant in the second active material sublayer is denoted as M 2.
  • M 1 /(M 1 +M 2 +M 3 ) is 10% to 30%.
  • M 1 /(M 1 +M 2 +M 3 ) is 20%;
  • M 2 /(M 1 +M 2 +M 3 ) is 20% ⁇ 40%, optional, M 2 /(M 1 +M 2 +M 3 ) is 30%;
  • M 3 /(M 1 +M 2 +M 3 ) is 30%-70%, optionally, M 3 /(M 1 +M 2 +M 3 ) is 50%.
  • the pole piece is a positive pole piece or a negative pole piece.
  • a lithium-ion battery including a positive electrode sheet, a negative electrode sheet, a separator spaced between the positive electrode sheet and the negative electrode sheet, and an electrolyte, wherein the positive electrode
  • the sheet and/or the negative electrode sheet is the electrode sheet provided in the first aspect of the present application.
  • the electrolyte includes an ester electrolyte, an ether electrolyte or an aqueous electrolyte.
  • the electrolyte is a pure solvent electrolyte. That is, the electrolyte only contains the solvent and does not contain the electrolyte lithium salt.
  • the electrolyte does not contain electrolyte lithium salt, that is, all the lithium salt is incorporated as a surfactant into the active material layer on the surface of the electrode or the functional coating on the surface of the active material layer, and the electrolyte solvent is directly used as the electrolyte to inject the battery
  • the electrolyte solvent infiltrates the pole piece, the lithium salt of the surfactant in the pole piece dissolves in the electrolyte solution, which can play the role of conducting ions.
  • the pure solvent is used as the electrolyte to inject the battery.
  • the advantage is that the viscosity of the pure solvent is low, so the wettability of the pole piece will be better, and the lithium salt of the surfactant mixed into the pole piece can be further realized. Pores are used to prepare porous electrodes to better promote the wettability of the electrolyte to the pole piece.
  • the solvent in the electrolyte is at least one selected from ethylene carbonate, diethyl carbonate, dimethyl carbonate or ethyl methyl carbonate.
  • the sum of the amount of the substance of the surfactant lithium salt is denoted as Mp; the amount of the substance of the lithium salt in the electrolyte is denoted as Ms; the total volume of the electrolyte is denoted as Vs; then the lithium ion battery meets: (Mp+Ms)/Vs is 1 ⁇ 2mol/L; optional, (Mp+Ms)/Vs is 1mol/L .
  • the doping concentration of the surfactant lithium salt in the pole piece is within an appropriate range, it is beneficial to the wettability of the electrolyte to the pole piece, and at the same time, it will not have adverse effects on the ion conductivity and increase the polarization of the battery, ensuring Overall electrochemical performance of lithium-ion batteries.
  • a lithium-ion battery typically includes a positive pole piece, a negative pole piece, an electrolyte, and a separator.
  • active ions are intercalated and extracted back and forth between the positive electrode and the negative electrode.
  • the electrolyte plays the role of conducting ions between the positive pole piece and the negative pole piece.
  • the separator is arranged between the positive pole piece and the negative pole piece, which mainly plays a role in preventing the short circuit of the positive and negative poles, and at the same time allows ions to pass through.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector.
  • the positive electrode active material layer contains a surfactant lithium salt.
  • the surface of the positive electrode active material layer away from the current collector is provided with a functional layer, and the functional layer also contains a surfactant lithium salt.
  • the positive electrode current collector has two opposing surfaces in its own thickness direction, and the positive electrode active material layer is disposed on any one or both of the two opposing surfaces of the positive electrode current collector.
  • the positive electrode current collector can be a metal foil or a composite current collector.
  • aluminum foil can be used as the metal foil.
  • the composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyethylene terephthalic acid It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene glycol ester
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the positive electrode active material layer also contains a positive electrode active material.
  • the positive electrode active material may be a positive electrode active material known in the art for batteries.
  • the positive active material may include at least one of the following materials: olivine-structured lithium-containing phosphate, lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials of batteries can also be used. These positive electrode active materials may be used alone or in combination of two or more.
  • lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO 2 ), lithium nickel oxides (such as LiNiO 2 ), lithium manganese oxides (such as LiMnO 2 , LiMn 2 O 4 ), lithium Nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1/3 Co 1/3 Mn 1/3 O 2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (also abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (also abbreviated as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (also abbreviated as NCM 622 ), LiNi At least one of 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi
  • the olivine structure contains Examples of lithium phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (also may be abbreviated as LFP)), composite materials of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), lithium manganese phosphate and carbon At least one of a composite material, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also may be abbreviated as LFP)
  • composite materials of lithium iron phosphate and carbon such as LiMnPO 4
  • LiMnPO 4 lithium manganese phosphate and carbon
  • the positive active material layer may optionally further include a binder.
  • the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene At least one of ethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • the positive active material layer optionally further includes a conductive agent.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the positive electrode sheet can be prepared in the following manner: the above-mentioned components used to prepare the positive electrode sheet, such as positive electrode active material, surfactant lithium salt (such as containing surfactant lithium in the positive electrode active material layer Salt), conductive agent, binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector and dried.
  • a solvent such as N-methylpyrrolidone
  • a positive electrode functional layer is also provided on the surface of the positive electrode active material layer, and the positive electrode functional layer also contains a lithium salt of the surfactant, the lithium salt of the surfactant is further configured into an aqueous solution of a certain concentration and coated on the surface of the positive electrode sheet. Drying, and finally after cold pressing and other processes, the positive electrode sheet can be obtained.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector.
  • the negative electrode active material layer contains a surfactant lithium salt.
  • the surface of the negative electrode active material layer facing away from the current collector is provided with a functional layer, and the functional layer also contains a lithium salt of surfactant.
  • the negative electrode current collector has two opposing surfaces in its own thickness direction, and the negative electrode active material layer is disposed on any one or both of the two opposing surfaces of the negative electrode current collector.
  • the negative electrode current collector can use a metal foil or a composite current collector.
  • copper foil can be used as the metal foil.
  • the composite current collector may include a base layer of polymer material and a metal layer formed on at least one surface of the base material of polymer material.
  • Composite current collectors can be formed by metal materials (copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyethylene terephthalic acid It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • the negative electrode active material layer also includes a negative electrode active material.
  • the negative electrode active material can be a negative electrode active material known in the art for batteries.
  • the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, lithium titanate, and the like.
  • the silicon-based material may be selected from at least one of elemental silicon, silicon-oxygen compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.
  • the tin-based material may be selected from at least one of simple tin, tin oxide compounds and tin alloys.
  • the present application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials of batteries can also be used. These negative electrode active materials may be used alone or in combination of two or more.
  • the negative active material layer optionally further includes a binder.
  • the binder can be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), poly At least one of methacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative active material layer may optionally further include a conductive agent.
  • the conductive agent can be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the negative electrode active material layer may optionally include other additives, such as thickeners (such as sodium carboxymethylcellulose (CMC-Na)) and the like.
  • thickeners such as sodium carboxymethylcellulose (CMC-Na)
  • the negative electrode sheet can be prepared in the following manner: the above-mentioned components used to prepare the negative electrode sheet, such as negative electrode active material, surfactant lithium salt (such as containing surfactant lithium in the negative electrode active material layer Salt), conductive agent, binder and any other components are dispersed in a solvent (such as deionized water) to form negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector and dried. If a negative electrode functional layer is also provided on the surface of the negative electrode active material layer, and the negative electrode functional layer also contains a lithium salt of a surfactant, the lithium salt of a surfactant is further configured into an aqueous solution of a certain concentration and coated on the surface of the negative electrode sheet. Drying, and finally after cold pressing and other processes, the negative electrode sheet can be obtained.
  • the above-mentioned components used to prepare the negative electrode sheet such as negative electrode active material, surfactant lithium salt (such as containing surfactant lithium in the negative electrode active material layer Salt), conductive
  • the electrolyte plays the role of conducting ions between the positive pole piece and the negative pole piece.
  • the electrolyte solution includes an electrolyte salt and an organic solvent.
  • the electrolyte in this application can be selected from ester electrolyte, ether electrolyte or water electrolyte. In some embodiments, the electrolyte includes only organic solvents.
  • the electrolyte lithium salt may be selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, At least one of lithium methanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium difluorooxalate borate, lithium difluorodifluorooxalatephosphate and lithium tetrafluorooxalatephosphate.
  • the organic solvent may be selected from at least one of ethylene carbonate, diethyl carbonate, dimethyl carbonate, or ethyl methyl carbonate.
  • the electrolyte may optionally include additives.
  • additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain performances of the battery, such as additives that improve battery overcharge performance, additives that improve high-temperature or low-temperature performance of batteries, and the like.
  • a separator is also included in the lithium ion battery.
  • the present application has no particular limitation on the type of isolation membrane, and any known porous structure isolation membrane with good chemical stability and mechanical stability can be selected.
  • the material of the isolation film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the separator can be a single-layer film or a multi-layer composite film, without any particular limitation. When the separator is a multilayer composite film, the materials of each layer may be the same or different, and there is no particular limitation.
  • the positive pole piece, the negative pole piece and the separator can be made into an electrode assembly through a winding process or a lamination process.
  • a lithium ion battery can include an outer packaging.
  • the outer package can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer packaging of the lithium-ion battery can be a hard case, such as a hard plastic case, aluminum case, steel case, and the like.
  • the outer packaging of the lithium-ion battery can also be a soft bag, such as a bag-type soft bag.
  • the material of the soft case may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.
  • FIG. 4 shows a lithium-ion battery 5 with a square structure as an example.
  • the outer package may include a housing 51 and a cover 53 .
  • the housing 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plates enclose to form an accommodating cavity.
  • the casing 51 has an opening communicating with the accommodating cavity, and the cover plate 53 can cover the opening to close the accommodating cavity.
  • the positive pole piece, the negative pole piece and the separator can be formed into an electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the accommodating chamber. Electrolyte is infiltrated in the electrode assembly 52 .
  • the number of electrode assemblies 52 contained in the lithium-ion battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • the lithium-ion battery can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.
  • FIG. 6 is a battery module 4 as an example.
  • a plurality of lithium-ion batteries 5 may be arranged in sequence along the length direction of the battery module 4 .
  • they can also be arranged in other arbitrary ways.
  • the plurality of lithium ion batteries 5 can be fixed by fasteners.
  • the battery module 4 may also include a housing with an accommodating space, and a plurality of lithium-ion batteries 5 are accommodated in the accommodating space.
  • the above-mentioned battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box body 2 and a lower box body 3 , the upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery module 4 .
  • Multiple battery modules 4 can be arranged in the battery box in any manner.
  • the present application also provides an electric device, which includes at least one of the lithium ion battery, battery module, or battery pack provided in the present application.
  • the lithium ion battery, battery module, or battery pack can be used as a power source of the electric device, and can also be used as an energy storage unit of the electric device.
  • the electric devices may include mobile devices (such as mobile phones, notebook computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, etc.) , electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but not limited thereto.
  • a lithium-ion battery, a battery module or a battery pack can be selected according to its use requirements.
  • FIG. 9 is an example of an electrical device.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
  • a battery pack or a battery module can be used.
  • a device may be a cell phone, tablet, laptop, or the like.
  • the device is usually required to be light and thin, and a lithium-ion battery can be used as a power source.
  • the surfactant lithium salt LiTFSI was formulated into an aqueous solution of a certain concentration, and coated on the surface of the negative electrode sheet to prepare the negative electrode functional layer, and then dried at 85° C. for 12 hours to obtain the negative electrode sheet.
  • the cold-pressed negative electrode sheet is trimmed, cut into pieces, and stripped; dried at 110° C. for 4 hours under vacuum conditions, and the tabs are welded to make a negative electrode sheet of a lithium-ion battery.
  • the surfactant lithium salt LiTFSI was mixed with NMP to form an organic solution with a certain concentration, which was coated on the surface of the positive electrode sheet to prepare the positive electrode functional layer, and then dried at 85°C for 12 hours to obtain the positive electrode sheet.
  • the cold-pressed positive electrode sheet is trimmed, cut into pieces, and divided into strips; dried at 85°C for 4 hours under vacuum conditions, and the tabs are welded to make the positive electrode sheet of the lithium-ion battery.
  • the positive electrode sheet, negative electrode sheet, and separator (PE film, containing ceramic coating) of the lithium-ion battery prepared according to the above-mentioned process are made into a soft-packed battery cell through a winding process, and the capacity is tested after liquid injection, high-temperature standing, and formation.
  • the preparation method of the lithium-ion batteries of Examples 2-9 and Comparative Examples 1-2 is similar to the lithium-ion battery of Example 1, except that the composition and product parameters of the battery pole pieces are adjusted.
  • the difference between the lithium-ion batteries of Examples 11-14 and the lithium-ion battery of Example 1 is that in Examples 11-14, the active material layer of the pole piece is coated in layers (specifically: positive and negative electrodes first
  • the coating mass per unit area of the active material sublayer is 0.2g/1540.25mm 2
  • the coating mass per unit area of the second active material sublayer of the positive and negative electrodes is 0.15/1540.25mm 2
  • the size of the pole piece is 42*49.5mm 2 .
  • the surfactant lithium salt LiTFSI was also doped into each active material sublayer respectively.
  • the capacity test method here is the constant current and constant voltage test method, and the current value and voltage range are set for testing.
  • the first step charge 0.33C to 3.65V
  • the second step 3.65V constant voltage charging, the cut-off condition is: 0.05C,
  • Step 3 Let stand for 5 minutes
  • Step 4 Discharge from 0.33C to 2.5V, and measure capacity performance data at the end of discharge.
  • Step 1 Charge from 0.5C to 3.65V
  • the second step 3.65V constant voltage charging, the cut-off condition is: 0.05C,
  • the third step stand still for 5 minutes
  • Step 4 Discharge from 0.5C to 2.5V
  • Step 5 Cycle the first step to the fourth step 5 times
  • Step 6 Charge from 0.7C to 3.65V
  • Step 7 3.65V constant voltage charging, the cut-off condition is: 0.05C,
  • Step 8 Stand still for 5 minutes
  • Step 9 Discharge from 0.7C to 2.5V
  • Step 10 Repeat steps 6 to 9 5 times.
  • test the battery with 1C, 1.2C, 1.5C, and 2C respectively, run 5 laps of charge and discharge for each current density, and obtain the rate performance data.
  • the amount of the substance of the lithium salt of the surfactant in the first active material sublayer is denoted as M 1
  • the amount of the substance of the lithium salt of the surfactant in the second active material sublayer is denoted as M 2
  • the amount of the surfactant lithium salt in the functional layer is denoted as M 3 .
  • the sum of the amount of the surfactant lithium salt is denoted as Mp
  • the amount of the lithium salt in the electrolyte is denoted as Ms
  • the total volume of the electrolyte is denoted as Vs.
  • Examples 1-9 add surfactant lithium salt to the active material layer and functional layer on the surface of the pole piece, and use the surfactant lithium
  • the affinity between the salt and the electrolyte can effectively reduce the surface tension of the electrolyte and improve the wettability of the electrolyte to the pole piece. Therefore, the discharge capacity and rate performance of the lithium-ion battery are significantly better than those without surfactants added to the surface of the pole piece. Comparative example 1 of lithium salt.
  • the performance data of the lithium-ion battery of Examples 1 to 5 and Comparative Example 2 are compared: in the active material layer and the functional layer of the pole piece, the sum of the amount of the surfactant lithium salt is denoted as Mp; The amount of the salt substance is recorded as Ms; the total volume of the electrolyte is recorded as Vs; when (Mp+Ms)/Vs is 1-2mol/L, the doping concentration of the surfactant lithium salt in the pole piece is in the appropriate range Inside, it is not only beneficial to the infiltration of the electrolyte on the pole piece, but also does not affect the ionic conductivity or increase the polarization of the battery, so as to ensure the overall electrochemical performance of the lithium-ion battery.
  • the substance amount Ms of the electrolyte lithium salt in the electrolytic solution was zero.
  • the electrolyte solvent is directly used as the electrolyte to inject into the battery.
  • the role of ions The pure solvent is used as the electrolyte to inject the battery.
  • the viscosity of the pure solvent is low, so the wettability of the pole piece will be better.
  • Porous electrodes are prepared to better promote the wettability of the electrolyte to the pole piece, so the lithium ion batteries of Examples 6-9 also have better capacity performance and rate performance.
  • the active material layer of the lithium-ion battery includes two active material sub-layers with different coating masses per unit area, and the lithium salt of the surfactant is also doped into each active material sub-layer and the surface layer respectively according to a reasonable ratio.
  • the lithium-ion battery has better capacity performance and rate performance.
  • the present application is not limited to the above-mentioned embodiments.
  • the above-mentioned embodiments are merely examples, and within the scope of the technical solutions of the present application, embodiments that have substantially the same configuration as the technical idea and exert the same effects are included in the technical scope of the present application.
  • various modifications conceivable by those skilled in the art are added to the embodiments, and other forms constructed by combining some components in the embodiments are also included in the scope of the present application. .

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Abstract

本申请提供了一种极片、锂离子电池、电池模块、电池包及用电装置。本申请提供的极片包括集流体和设于所述集流体的至少一个表面的活性物质层，所述活性物质层中包含表面活性剂锂盐。本申请利用表面活性剂锂盐与电解液的亲和性，有效降低电解液的表面张力，提升电解液对极片的浸润性，降低电池界面阻抗，提高活物质的利用效率，从而实现对锂离子电池的倍率性能、放电容量和使用寿命的改善。

Description

极片、锂离子电池、电池模块、电池包及用电装置
相关申请的交叉引用
本申请要求享有于2021年11月12日提交的名称为“极片、锂离子电池、电池模块、电池包及用电装置”的中国专利申请202111337252.X的优先权，该申请的全部内容通过引用并入本文中。
技术领域
本申请涉及锂电池技术领域，尤其涉及一种极片、锂离子电池、电池模块、电池包和用电装置。
背景技术
锂离子电池是一种二次电池，通常情况下，锂离子电池包括正极极片、负极极片、电解液和隔离膜。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解液是锂离子电池中离子传输的载体，在锂电池正、负极之间起到传导离子的作用，是锂离子电池获得高电压、高比能等性能的保证。电解液一般由高纯度的有机溶剂、电解质锂盐、必要的添加剂等原料，在一定条件下、按一定比例配制而成的。
目前，锂离子电池已广泛应用于汽车、手机等高科技产品中，随着锂离子电池应用的领域不断扩大，还需要对锂离子电池的各方面性能不断改进。
发明内容
本申请是鉴于上述课题而进行的，其目的在于，提供一种可使锂离子电池的倍率性能、放电容量及使用寿命的得到改善的极片，以及包括该极片的锂离子电池、电池模块、电池包及用电装置。
为了达到上述目的，本申请的第一方面提供了一种极片，所述极 片包括集流体和设于所述集流体的至少一个表面的活性物质层，所述活性物质层中包含表面活性剂锂盐。
本申请通过在极片的活性物质层中掺杂表面活性剂锂盐，利用锂盐与电解液的亲和性，有效降低电解液的表面张力，提升电解液对极片的浸润性，降低电池界面阻抗，提高活物质的利用效率，从而实现对锂离子电池的倍率性能、放电容量和使用寿命的改善。
在任意实施方式中，所述活性物质层背离所述集流体的表面设有功能层，所述功能层中也包含所述表面活性剂锂盐。
在任意实施方式中，所述活性物质层中的所述表面活性剂锂盐的物质的量为0.00175～0.00875mol。
在任意实施方式中，所述表面活性剂锂盐可选自双三氟甲磺酰亚胺锂、硝酸锂、高氯酸锂或氯化锂中的至少一种。
在任意实施方式中，所述活性物质层在远离所述集流体的方向上依次包括层叠设置的、单位面积涂覆质量由小到大变化的若干个活性物质子层，所述若干个活性物质子层中包含的表面活性剂锂盐的物质的量也由小到大变化。在这些实施方式中，极片中的活性物质层采用多层涂布，表面活性剂锂盐也分别掺杂进入各个活性物质子层中，且各个活性物质子层中的表面活性剂锂盐的用量变化规律与活性物质子层中活性物质涂布质量的变化规律相符合，从而对每个活性物质子层发挥造孔作用。
在任意实施方式中，所述活性物质层在远离所述集流体的方向上依次包括层叠设置的第一活性物质子层和第二活性物质子层，所述第一活性物质子层的单位面积涂覆质量记为CW 1，0.150g/1540.25mm 2≤CW 1≤0.200g/1540.25mm 2；所述第二活性物质子层的单位面积涂覆质量记为CW 2，CW 2≥0.200g/1540.25mm 2；所述第一活性物质子层中的表面活性剂锂盐的物质的量记为M 1，所述第二活性物质子层中的表面活性剂锂盐的物质的量记为M 2，所述功能层中的表面活性剂锂盐的物质的量记为M 3，则：M 1/(M 1+M 2+M 3)为10％～30％，可选的，M 1/(M 1+M 2+M 3)为20％；M 2/(M 1+M 2+M 3)为20％～40％，可选的，M 2/(M 1+M 2+M 3)为30％；M 3/(M 1+M 2+M 3) 为30％～70％，可选的，M 3/(M 1+M 2+M 3)为50％。
在任意实施方式中，所述极片为正极极片或负极极片。
本申请的第二方面提供一种锂离子电池，包括正极极片、负极极片、间隔于正极极片和负极极片之间的隔离膜、电解液，其中，所述正极极片和/或所述负极极片为本申请第一方面所提供的极片。
在任意实施方式中，所述电解液选自酯类电解液、醚类电解液或水系电解液。
在任意实施方式中，所述电解液为纯溶剂电解液。即电解液中仅包含溶剂，不包含电解质锂盐。当电解液中不包含电解质锂盐时，也就是将所有锂盐作为表面活性剂掺入电极表面的活性物质层或活性物质层表面的功能涂层中，直接使用电解液溶剂作为电解液注入电池中，当电解液溶剂浸润极片后，极片中的表面活性剂锂盐溶解在电解液中，即可发挥导离子的作用。采用纯溶剂作为电解液注入电池，优点为纯溶剂的粘度较低，因而对极片的浸润性会更好，而混入极片中的表面活性剂锂盐溶解后，也可进一步实现给电极造孔，制备多孔电极，更好地促进电解液对极片的浸润性。
在任意实施方式中，所述电解液中的溶剂选自碳酸乙烯酯、碳酸二乙酯、碳酸二甲酯或碳酸甲乙酯中的至少一种。
在任意实施方式中，在所述极片的活性物质层和功能层中，所述表面活性剂锂盐的物质的量之和记为Mp；所述电解液中锂盐的物质的量记为Ms；所述电解液的总体积记为Vs；则所述锂离子电池满足：(Mp+Ms)/Vs为1～2mol/L；可选的，(Mp+Ms)/Vs为1mol/L。当表面活性剂锂盐在极片中的掺杂浓度在合适范围内，在有利于电解液对极片的浸润性的同时，不产生影响离子电导率和增大电池极化的不利影响，保证锂离子电池的整体电化学性能。
本申请的第三方面还提供一种电池模块，其中，包括本申请第二方面的锂离子电池。
本申请的第四方面还提供一种电池包，其中，包括本申请第二方面的锂离子电池或者本申请第三方面的电池模块。
本申请的第五方面还提供一种用电装置，其包括本申请第二方面 的锂离子电池或本申请第三方面的电池模块或本申请第四方面的电池包；其中，锂离子电池或电池模块或电池包用作用电装置的电源或能量存储单元。
本申请二方面所提供的锂离子电池、第三方面所提供的电池模块、第四方面所提供的电池包、第五方面提供的用电装置，由于包括了本申请第一方面的极片，因而具有较好的倍率性能、放电容量以及较长使用寿命。
附图说明
图1为活性物质层中未包含表面活性剂锂盐的负极极片与电解液的浸润角照片的扫描电镜图；
图2为活性物质层中包含低浓度表面活性剂锂盐的负极极片与电解液的浸润角照片的扫描电镜图；
图3为活性物质层中包含高浓度表面活性剂锂盐的负极极片与电解液的浸润角照片的扫描电镜图；
图4是本申请一实施方式的锂离子电池的示意图；
图5是图4所示的本申请一实施方式的锂离子电池的分解图；
图6是本申请一实施方式的电池模块的示意图；
图7是本申请一实施方式的电池包的示意图；
图8是图7所示的本申请一实施方式的电池包的分解图；
图9是本申请一实施方式的锂离子电池用作电源的用电装置的示意图。
附图标记说明：
1电池包；2上箱体；3下箱体；4电池模块；5锂离子电池；51壳体；52电极组件；53顶盖组件。
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的锂离子电池、电池模块、电池包和电学装置的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际 相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60-120和80-110的范围，理解为60-110和80-120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。在本申请中，除非有其他说明，数值范围“a-b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0-5”表示本文中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包 括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
极片
本申请的一个实施方式中，本申请提出了一种极片，所述极片包括集流体和设于所述集流体的至少一个表面的活性物质层，所述活性物质层中包含表面活性剂锂盐。
本申请基于如下发明构思而提出：在锂离子电池内部，当电解液浸润效果不好时，离子传输路径变远，阻碍了锂离子在正负极之间的穿梭，未接触电解液的极片无法参与电池电化学反应，同时电池界面电阻增大，影响锂电池的倍率性能、放电容量和使用寿命。在锂离子电池内部，电解液与电极的界面浸润性可由杨氏公式表示：
γ SV＝γ SL+γ LV×cosθ
其中，γ SV为电极片的表面张力；γ SL为电解液与电极接触面的表面张力；γ LV为电解液自身的表面张力；θ为电解液与电极的浸润角。
由上述公式可知，在电极片和气相界面不变的情况下，电解液的表面张力决定了接触角的大小：电解液的表面张力越小，界面接触角越小，电解液对极片的浸润性则越好。基于此，申请人提出：在极片的活性物质层中掺杂表面活性剂锂盐，当极片与电解液解除，表面活性剂锂盐部分或全部溶解于电解液中，利用表面活性剂锂盐与电解液的亲和性，有效降低电解液的表面张力，提升电解液对极片的浸润性，从而实现对锂离子电池的倍率性能、放电容量和使用寿命的改善。其中，表面活性剂(surfactant)的固有定义是：能使目标溶液表面张力显著下降的物质。本申请中所述的表面活性剂锂盐即是指能使电解液表面张力显著下降的锂盐。
在一些实施方式中，所述活性物质层背离所述集流体的表面设有功能层，所述功能层中也包含所述表面活性剂锂盐。在这些实施方式 中，活性物质层与功能层中都包含表面活性剂锂盐，当极片与电解液解除，极片的活性物质层及功能层中的表面活性剂锂盐部分或全部溶解于电解液中，共同发挥降低电解液的表面张力、提升电解液对极片浸润性的作用，从而实现对锂离子电池的倍率性能、放电容量和使用寿命的改善。
在一些实施方式中，所述表面活性剂锂盐选自双三氟甲磺酰亚胺锂(LiTFSI)、硝酸锂(LiNO 3)、高氯酸锂(LiClO 4)、氯化锂(LiCl)中的至少一种。
在一些实施方式中，所述活性物质层中的所述表面活性剂锂盐的物质的量为0.00175～0.00875mol。
发明人选取双三氟甲磺酰亚胺锂盐作为表面活性剂锂盐，配置了浓度分别为5％、10％的水溶液，涂覆于负极极片表面。随后测试了两种不同浓度涂覆的负极极片与电解液的浸润角，测试结果如图1-3所示。其中，图1为极片中或极片表面未包含表面活性剂锂盐的负极极片与电解液的浸润角照片的扫描电镜图；图2为极片中或极片表面包含低浓度表面活性剂锂盐的负极极片与电解液的浸润角照片的扫描电镜图；图3为极片中或极片表面包含高浓度表面活性剂锂盐的负极极片与电解液的浸润角照片的扫描电镜图。图1～图3中的浸润角测试结果表明：表面活性剂锂盐的涂覆可有效地改善电解液与负极极片表面的浸润效果，其中，低浓度表面活性剂锂盐的涂覆已显示出提高浸润效果的有效性，且随着所用的表面活性剂锂盐的浓度增加，浸润效果也越好。
在一些实施方式中，所述活性物质层在远离所述集流体的方向上依次包括层叠设置的、单位面积涂覆质量由小到大变化的若干个活性物质子层，所述若干个活性物质子层中包含的表面活性剂锂盐的物质的量也由小到大变化。在这些实施方式中，极片中的活性物质层采用多层涂布，表面活性剂锂盐也分别掺杂进入各个活性物质子层中，且各个活性物质子层中的表面活性剂锂盐的用量变化规律与活性物质子层中活性物质涂布质量的变化规律相符合，从而对每个活性物质子层发挥造孔作用。
在一些实施方式中，所述活性物质层在远离所述集流体的方向上依次包括层叠设置的第一活性物质子层和第二活性物质子层，所述第一活性物质子层的单位面积涂覆质量记为CW 1，0.150g/1540.25mm 2≤CW 1≤0.200g/1540.25mm 2；所述第二活性物质子层的单位面积涂覆质量记为CW 2，CW 2≥0.200g/1540.25mm 2；所述第一活性物质子层中的表面活性剂锂盐的物质的量记为M 1，所述第二活性物质子层中的表面活性剂锂盐的物质的量记为M 2，所述功能层中的表面活性剂锂盐的物质的量记为M 3，则：M 1/(M 1+M 2+M 3)为10％～30％，可选的，M 1/(M 1+M 2+M 3)为20％；M 2/(M 1+M 2+M 3)为20％～40％，可选的，M 2/(M 1+M 2+M 3)为30％；M 3/(M 1+M 2+M 3)为30％～70％，可选的，M 3/(M 1+M 2+M 3)为50％。
在任意实施方式中，所述极片为正极极片或负极极片。
锂离子电池
本申请的另一个实施方式中，提供了一种锂离子电池，包括正极极片、负极极片、间隔于正极极片和负极极片之间的隔离膜、电解液，其中，所述正极极片和/或所述负极极片为本申请第一方面所提供的极片。
在一些实施方式中，所述电解液包括酯类电解液、醚类电解液或水系电解液。
在一些实施方式中，所述电解液为纯溶剂电解液。即电解液中仅包含溶剂，不包含电解质锂盐。当电解液中不包含电解质锂盐时，也就是将所有锂盐作为表面活性剂掺入电极表面的活性物质层或活性物质层表面的功能涂层中，直接使用电解液溶剂作为电解液注入电池中，当电解液溶剂浸润极片后，极片中的表面活性剂锂盐溶解在电解液中，即可发挥导离子的作用。采用纯溶剂作为电解液注入电池，优点为纯溶剂的粘度较低，因而对极片的浸润性会更好，而混入极片中的表面活性剂锂盐溶解后，也可进一步实现给电极造孔，制备多孔电极，更好地促进电解液对极片的浸润性。
在一些实施方式中，所述电解液中的溶剂选自碳酸乙烯酯、碳酸二乙酯、碳酸二甲酯或碳酸甲乙酯中的至少一种。
在一些实施方式中，在所述极片的活性物质层和功能层中，所述表面活性剂锂盐的物质的量之和记为Mp；所述电解液中锂盐的物质的量记为Ms；所述电解液的总体积记为Vs；则所述锂离子电池满足：(Mp+Ms)/Vs为1～2mol/L；可选的，(Mp+Ms)/Vs为1mol/L。当表面活性剂锂盐在极片中的掺杂浓度在合适范围内，在有利于电解液对极片的浸润性的同时，不产生影响离子电导率和增大电池极化的不利影响，保证锂离子电池的整体电化学性能。
另外，以下适当参照附图对本申请的锂离子电池、电池模块、电池包和用电装置进行说明。
通常情况下，锂离子电池包括正极极片、负极极片、电解液和隔离膜。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解液在正极极片和负极极片之间起到传导离子的作用。隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使离子通过。
[正极极片]
正极极片包括正极集流体以及设置在正极集流体至少一个表面的正极活性物质层，本一些实施方式中，所述正极活性物质层中包含表面活性剂锂盐。在一些实施方式中，所述正极活性物质层背离所述集流体的表面设有功能层，所述功能层中也包含表面活性剂锂盐。
作为示例，正极集流体具有在其自身厚度方向相对的两个表面，正极活性物质层设置在正极集流体相对的两个表面的其中任意一者或两者上。
在一些实施方式中，所述正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
正极活性物质层中还包含正极活性材料。在一些实施方式中，正 极活性材料可采用本领域公知的用于电池的正极活性材料。作为示例，正极活性材料可包括以下材料中的至少一种：橄榄石结构的含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物。但本申请并不限定于这些材料，还可以使用其他可被用作电池正极活性材料的传统材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。其中，锂过渡金属氧化物的示例可包括但不限于锂钴氧化物(如LiCoO 2)、锂镍氧化物(如LiNiO 2)、锂锰氧化物(如LiMnO 2、LiMn 2O 4)、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物(如LiNi 1/3Co 1/3Mn 1/3O 2(也可以简称为NCM 333)、LiNi 0.5Co 0.2Mn 0.3O 2(也可以简称为NCM 523)、LiNi 0.5Co 0.25Mn 0.25O 2(也可以简称为NCM 211)、LiNi 0.6Co 0.2Mn 0.2O 2(也可以简称为NCM 622)、LiNi 0.8Co 0.1Mn 0.1O 2(也可以简称为NCM 811)、锂镍钴铝氧化物(如LiNi 0.85Co 0.15Al 0.05O 2)及其改性化合物等中的至少一种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸铁锂(如LiFePO 4(也可以简称为LFP))、磷酸铁锂与碳的复合材料、磷酸锰锂(如LiMnPO 4)、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料中的至少一种。
在一些实施方式中，正极活性物质层还可选地包括粘结剂。作为示例，所述粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种。
在一些实施方式中，正极活性物质层还可选地包括导电剂。作为示例，所述导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，可以通过以下方式制备正极极片：将上述用于制备正极极片的组分，例如正极活性材料、表面活性剂锂盐(如在正极活性物质层中包含表面活性剂锂盐)、导电剂、粘结剂和任意其他的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成正极浆料；将正极浆料涂覆在正极集流体上，烘干。如在正极活性物质层表面还设有正极功能层，正极功能层中也包含表面活性剂锂盐，则进一步地 将表面活性剂锂盐配置成一定浓度的水溶液，涂覆于正极极片表面，烘干，最后经冷压等工序后，即可得到正极极片。
[负极极片]
负极极片包括负极集流体以及设置在负极集流体至少一个表面上的负极活性物质层，在一些实施方式中，所述负极活性物质层中包含表面活性剂锂盐。在一些实施方式中，所述负极活性物质层背离所述集流体的表面设有功能层，所述功能层中也包含表面活性剂锂盐。
作为示例，负极集流体具有在其自身厚度方向相对的两个表面，负极活性物质层设置在负极集流体相对的两个表面中的任意一者或两者上。
在一些实施方式中，所述负极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
负极活性物质层中还包括负极活性材料。在一些实施方式中，负极活性材料可采用本领域公知的用于电池的负极活性材料。作为示例，负极活性材料可包括以下材料中的至少一种：人造石墨、天然石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂等。所述硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的至少一种。所述锡基材料可选自单质锡、锡氧化合物以及锡合金中的至少一种。但本申请并不限定于这些材料，还可以使用其他可被用作电池负极活性材料的传统材料。这些负极活性材料可以仅单独使用一种，也可以将两种以上组合使用。
在一些实施方式中，负极活性物层还可选地包括粘结剂。所述粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的至少一种。
在一些实施方式中，负极活性物质层还可选地包括导电剂。导电剂可选自超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，负极活性物质层还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))等。
在一些实施方式中，可以通过以下方式制备负极极片：将上述用于制备负极极片的组分，例如负极活性材料、表面活性剂锂盐(如在负极活性物质层中包含表面活性剂锂盐)、导电剂、粘结剂和任意其他组分分散于溶剂(例如去离子水)中，形成负极浆料；将负极浆料涂覆在负极集流体上，烘干。如在负极活性物质层表面还设有负极功能层，负极功能层中也包含表面活性剂锂盐，则进一步地将表面活性剂锂盐配置成一定浓度的水溶液，涂覆于负极极片表面，烘干，最后经冷压等工序后，即可得到负极极片。
[电解液]
电解液在正极极片和负极极片之间起到传导离子的作用。在一些实施方式中，电解液包括电解质盐和有机溶剂。本申请中的电解液可选自酯类电解液、醚类电解液或水系电解液。在一些实施方式中，电解液仅包括有机溶剂。
在一些实施方式中，电解质锂盐可选自六氟磷酸锂、四氟硼酸锂、高氯酸锂、六氟砷酸锂、双氟磺酰亚胺锂、双三氟甲磺酰亚胺锂、三氟甲磺酸锂、二氟磷酸锂、二氟草酸硼酸锂、二草酸硼酸锂、二氟二草酸磷酸锂及四氟草酸磷酸锂中的至少一种。
在一些实施方式中，有机溶剂可选自碳酸乙烯酯、碳酸二乙酯、碳酸二甲酯或碳酸甲乙酯中的至少一种。
在一些实施方式中，所述电解液还可选地包括添加剂。例如添加剂可以包括负极成膜添加剂、正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温或低温性能的添加剂等。
[隔离膜]
在一些实施方式中，锂离子电池中还包括隔离膜。本申请对隔离 膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。
在一些实施方式中，隔离膜的材质可选自玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。
在一些实施方式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
在一些实施方式中，锂离子电池可包括外包装。该外包装可用于封装上述电极组件及电解质。
在一些实施方式中，锂离子电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。锂离子电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。
本申请对锂离子电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图4是作为一个示例的方形结构的锂离子电池5。
在一些实施方式中，参照图5，外包装可包括壳体51和盖板53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53能够盖设于所述开口，以封闭所述容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于所述容纳腔内。电解液浸润于电极组件52中。锂离子电池5所含电极组件52的数量可以为一个或多个，本领域技术人员可根据具体实际需求进行选择。
在一些实施方式中，锂离子电池可以组装成电池模块，电池模块所含二次电池的数量可以为一个或多个，具体数量本领域技术人员可根据电池模块的应用和容量进行选择。
图6是作为一个示例的电池模块4。参照图6，在电池模块4中，多个锂离子电池5可以是沿电池模块4的长度方向依次排列设置。当 然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个锂离子电池5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个锂离子电池5容纳于该容纳空间。
在一些实施方式中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以为一个或多个，具体数量本领域技术人员可根据电池包的应用和容量进行选择。
图7和图8是作为一个示例的电池包1。参照图7和图8，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
另外，本申请还提供一种用电装置，所述用电装置包括本申请提供的锂离子电池、电池模块、或电池包中的至少一种。所述锂离子电池、电池模块、或电池包可以用作所述用电装置的电源，也可以用作所述用电装置的能量存储单元。所述用电装置可以包括移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等，但不限于此。
作为所述用电装置，可以根据其使用需求来选择锂离子电池、电池模块或电池包。
图9是作为一个示例的用电装置。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对锂离子电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化，可以采用锂离子电池作为电源。
实施例
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具 体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
一、锂离子电池的制备
实施例1
1、负极极片制备
(1)将负极活性材料人造石墨、表面活性剂锂盐LiTFSI、导电剂、粘接剂聚偏氟乙烯(PVDF)按一定质量比溶于溶剂N-甲基吡咯烷酮中，在500～700r/min下搅拌3～4h得到混合均匀的负极浆料。将负极浆料通过刮刀均匀涂布在集流体铜箔的正反两面上，随后在85℃下干燥12h。
(2)将表面活性剂锂盐LiTFSI配置成一定浓度的水溶液，涂覆于负极极片表面，制备负极功能层，随后在85℃下干燥12h，得到负极极片。
(3)最后，将冷压后的负极极片进行切边、裁片、分条；在110℃真空条件下干燥4h，焊接极耳，制成锂离子电池的负极片。
2、正极极片制备
(1)将正极活性材料磷酸铁锂(LiFePO4)、表面活性剂锂盐LiTFSI、导电剂Super-P、粘接剂聚偏氟乙烯(PVDF)按96：2：2质量比溶于溶剂N-甲基吡咯烷酮中，混合均匀制成正极浆料。将正极浆料均匀涂布在集流体铝箔的正反两面上，随后在85℃下烘干。
(2)将表面活性剂锂盐LiTFSI融入NMP配置成一定浓度的有机溶液，涂覆于正极极片表面，制备正极功能层，随后在85℃下干燥12h，得到正极极片。
(3)最后，将冷压后的正极极片进行切边、裁片、分条；在85℃真空条件下干燥4h，焊接极耳，制成锂离子电池的正极片。
3、电解液制备
在含水量<10ppm的氩气气氛手套箱中，将EC、PC、DMC按照重量比为EC:PC:DMC＝3:3:3进行混合后，得到混合有机溶剂，再将充分干燥的锂盐LiPF6溶解于上述混合有机溶剂中，搅拌均匀后，获 得电解液，其中LiPF6的浓度为1mol/L。
4、锂离子电池制备
将根据前述工艺制备的锂离子电池的正极片、负极片以及隔离膜(PE膜，含有陶瓷涂层)经过卷绕工艺制作成软包电芯后注液、高温静置、化成后测试容量。
实施例2～9、对比例1～2
实施例2～9、对比例1～2的锂离子电池与实施例1的锂离子电池的制备方法相似，只是调整了电池极片的组成和产品参数。
实施例11～14
实施例11～14的锂离子电池与实施例1的锂离子电池的区别在于，实施例11-14对极片的活性物质层采用了分层涂布的方式(具体为：正、负极第一活性物质子层的单位面积涂覆质量为0.2g/1540.25mm 2，正、负极第二活性物质子层的单位面积涂覆质量为0.15/1540.25mm 2，极片尺寸为42*49.5mm 2。实施例11-14中，表面活性剂锂盐LiTFSI也分别掺杂进入各个活性物质子层中。
二、锂离子电池的性能测试
1、容量性能测试
此处的容量测试方法为恒流恒压测试法，设定电流值和电压区间来进行测试，以磷酸铁锂电池为例：
第一步：0.33C充电到3.65V，
第二步：3.65V恒压充电，截止条件为：0.05C，
第三步：静置5分钟，
第四步：0.33C放电到2.5V，放电截止测得容量性能数据。
2、倍率性能测试
第一步：0.5C充电到3.65V，
第二步：3.65V恒压充电，截止条件为：0.05C，
第三步：静置5min，
第四步：0.5C放电到2.5V，
第五步：循环第一步到第四步5次，
第六步：0.7C充电到3.65V，
第七步：3.65V恒压充电，截止条件为：0.05C，
第八步：静置5min，
第九步：0.7C放电到2.5V，
第十步：循环第六步到第九步5次。
依照上述测试顺序，依次增大测试电流，分别用1C、1.2C、1.5C、2C对电池进行测试，每个电流密度分别跑5圈充放电，得到倍率性能数据。
实施例1～14、对比例1～2的锂离子电池的参数及性能检测数据如表1和表2所示。
表1和表2中：第一活性物质子层中的表面活性剂锂盐的物质的量记为M 1，第二活性物质子层中的表面活性剂锂盐的物质的量记为M 2，功能层中的表面活性剂锂盐的物质的量记为M 3。极片的活性物质层和功能层中，表面活性剂锂盐的物质的量之和记为Mp；电解液中锂盐的物质的量记为Ms；电解液的总体积记为Vs。
Figure PCTCN2022124953-appb-000001
Figure PCTCN2022124953-appb-000002
将实施例1～9和对比例1的锂离子电池的性能数据进行对比：实施例1～9在极片表面的活性物质层和功能层中添加了表面活性剂锂盐，利用表面活性剂锂盐与电解液的亲和性，有效降低电解液的表面张力，提升电解液对极片的浸润性，因而锂离子电池的放电容量和倍率性能都明显优于未在极片表面添加表面活性剂锂盐的对比例1。
将实施例1～5和对比例2的锂离子电池的性能数据进行对比：极片的活性物质层和功能层中，表面活性剂锂盐的物质的量之和记为Mp；电解液中锂盐的物质的量记为Ms；电解液的总体积记为Vs；当(Mp+Ms)/Vs为1～2mol/L时，表面活性剂锂盐在极片中的掺杂浓度在合适范围内，既利于电解液对极片的浸润，又不会影响离子电导率或增大电池极化，保证锂离子电池的整体电化学性能。
实施例6～9中，电解液中的电解质锂盐的物质的量Ms为0。当电解液中不含电解质锂盐，直接使用电解液溶剂作为电解液注入电池中，当电解液溶剂浸润极片后，极片中的表面活性剂锂盐溶解在电解液中，即可发挥导离子的作用。采用纯溶剂作为电解液注入电池，纯溶剂的粘度较低，因而对极片的浸润性会更好，而混入极片中的表面活性剂锂盐溶解后，也可进一步实现给电极造孔，制备多孔电极，更好地促进电解液对极片的浸润性，因而实施例6～9的锂离子电池也具有较好的容量性能和倍率性能。
实施例10～14中，锂离子电池的活性物质层包括单位面积涂覆质量不同的两个活性物质子层，表面活性剂锂盐也按照合理的比例分别掺杂进入各个活性物质子层和表面功能层中，从而发挥更好的造孔作用，使锂离子电池具有较好的容量性能和倍率性能。
需要说明的是，本申请不限定于上述实施方式。上述实施方式仅为示例，在本申请的技术方案范围内具有与技术思想实质相同的构成、发挥相同作用效果的实施方式均包含在本申请的技术范围内。此外，在不脱离本申请主旨的范围内，对实施方式施加本领域技术人员能够想到的各种变形、将实施方式中的一部分构成要素加以组合而构筑的其它方式也包含在本申请的范围内。

Claims (16)

  1. 一种极片，其特征在于，所述极片包括集流体和设于所述集流体的至少一个表面的活性物质层，所述活性物质层中包含表面活性剂锂盐。
  2. 根据权利要求1所述的极片，其特征在于，所述活性物质层背离所述集流体的表面设有功能层，所述功能层中也包含所述表面活性剂锂盐。
  3. 根据权利要求1或2所述的极片，其特征在于，所述表面活性剂锂盐选自双三氟甲磺酰亚胺锂、硝酸锂、高氯酸锂、氯化锂中的至少一种。
  4. 根据权利要求1所述的极片，其特征在于，
    所述活性物质层中的所述表面活性剂锂盐的物质的量为0.00175～0.00875mol。
  5. 根据权利要求1至4中任一项所述的极片，其特征在于，所述活性物质层在远离所述集流体的方向上依次包括层叠设置的、单位面积涂覆质量由小到大变化的若干个活性物质子层，所述若干个活性物质子层中包含的表面活性剂锂盐的物质的量也由小到大变化。
  6. 根据权利要求5所述的极片，其特征在于，
    所述活性物质层在远离所述集流体的方向上依次包括层叠设置的第一活性物质子层和第二活性物质子层，
    所述第一活性物质子层的单位面积涂覆质量记为CW 1，0.150g/1540.25mm 2≤CW 1≤0.200g/1540.25mm 2；所述第二活性物质子层的单位面积涂覆质量记为CW 2，CW 2≥0.200g/1540.25mm 2；
    所述第一活性物质子层中的表面活性剂锂盐的物质的量记为M 1， 所述第二活性物质子层中的表面活性剂锂盐的物质的量记为M 2，所述功能层中的表面活性剂锂盐的物质的量记为M 3，则：
    M 1/(M 1+M 2+M 3)为10％～30％，可选的，M 1/(M 1+M 2+M 3)为20％；
    M 2/(M 1+M 2+M 3)为20％～40％，可选的，M 2/(M 1+M 2+M 3)为30％；
    M 3/(M 1+M 2+M 3)为30％～70％，可选的，M 3/(M 1+M 2+M 3)为50％。
  7. 根据权利要求1至6中任一项所述的极片，其特征在于，所述极片为正极极片或负极极片。
  8. 一种锂离子电池，包括正极极片、负极极片、间隔于正极极片和负极极片之间的隔离膜、电解液，其特征在于，所述正极极片和/或所述负极极片为权利要求1至7中任一项所述的极片。
  9. 根据权利要求8所述的锂离子电池，其特征在于，所述电解液选自酯类电解液、醚类电解液或水系电解液。
  10. 根据权利要求8或9所述的锂离子电池，其特征在于，所述电解液为纯溶剂电解液。
  11. 根据权利要求8至10中任一项所述的锂离子电池，其特征在于，
    所述电解液中的溶剂选自碳酸乙烯酯、碳酸二乙酯、碳酸二甲酯或碳酸甲乙酯中的至少一种。
  12. 根据权利要求9至11中任一项所述的锂离子电池，其特征在于，在所述极片的活性物质层和功能层中，所述表面活性剂锂盐的物质的量之和记为Mp；所述电解液中锂盐的物质的量记为Ms；所 述电解液的总体积记为Vs；则所述锂离子电池满足：(Mp+Ms)/Vs为1～2mol/L。
  13. 根据权利要求12所述的锂离子电池，其特征在于，(Mp+Ms)/Vs为1mol/L。
  14. 一种电池模块，其特征在于，包括根据权利要求8至13中任一项所述的锂离子电池。
  15. 一种电池包，其特征在于，包括根据权利要求8至13中任一项所述的锂离子电池或根据权利要求14所述的电池模块。
  16. 一种用电装置，其特征在于，包括选自权利要求8至13中任一项所述的锂离子电池、权利要求14所述的电池模块或权利要求15所述的电池包中的至少一种。
PCT/CN2022/124953 2021-11-12 2022-10-12 极片、锂离子电池、电池模块、电池包及用电装置 WO2023082924A1 (zh)

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