WO2025252004A1 - Additif électrolytique et son procédé de préparation, batterie secondaire et dispositif électronique - Google Patents

Additif électrolytique et son procédé de préparation, batterie secondaire et dispositif électronique

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Publication number
WO2025252004A1
WO2025252004A1 PCT/CN2025/098149 CN2025098149W WO2025252004A1 WO 2025252004 A1 WO2025252004 A1 WO 2025252004A1 CN 2025098149 W CN2025098149 W CN 2025098149W WO 2025252004 A1 WO2025252004 A1 WO 2025252004A1
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WO
WIPO (PCT)
Prior art keywords
electrolyte
group
substituted
additive
unsubstituted
Prior art date
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Pending
Application number
PCT/CN2025/098149
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English (en)
Chinese (zh)
Inventor
马强
王梦实
黄振军
王博
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Huawei Technologies Co Ltd
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Huawei Technologies Co Ltd
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Publication date
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Publication of WO2025252004A1 publication Critical patent/WO2025252004A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • 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 the field of battery technology, and in particular to an electrolyte additive and its preparation method, a secondary battery, and an electronic device.
  • Electrolytes as components that conduct ions and stabilize the positive and negative electrode interfaces, are crucial for the stable operation of batteries.
  • additives such as fluoroethylene carbonate, vinylene carbonate, and ethylene sulfate are added to the electrolyte.
  • These additives can form an SEI (Solid Electrolyte Interphase) film on the positive and negative electrode surfaces during the formation or capacity testing stages, preventing the solvent in the electrolyte from being reduced and decomposed, thus improving battery cycle life.
  • SEI Solid Electrolyte Interphase
  • alloy anodes silicon, phosphorus, etc.
  • lithium metal anodes have higher specific capacity, they exhibit volume expansion, leading to repeated rupture of the SEI film and thickening of the interface layer. This necessitates high levels of additives to maintain the SEI film's later-stage cycle repair; however, high levels of additives not only increase interfacial impedance but also negatively impact the long-cycle performance of the battery system.
  • This application provides an electrolyte additive and its preparation method, an electrolyte containing the electrolyte additive, a secondary battery containing the electrolyte, and an electronic device containing the secondary battery.
  • the electrolyte additive includes not only fluorine atoms or fluorine-containing substituents, but also cyano groups, which can generate a solid electrolyte interface film rich in inorganic components, improving the ionic conductivity and stability of the solid electrolyte interface film. Therefore, it can subsequently improve the battery's cycle performance and high-temperature storage performance.
  • an electrolyte additive comprising a first additive and/or a second additive;
  • R1 and R4 are independently selected from either fluorine atoms or fluorine-containing substituents
  • R2 and R3 are independently selected from one of the following: substituted or unsubstituted alkylene nitrile group, substituted or unsubstituted alkoxynitrile group, substituted or unsubstituted alkenyl nitrile group, substituted or unsubstituted alkenyl nitrile group, substituted or unsubstituted aryl nitrile group, and substituted or unsubstituted aryl nitrile group.
  • x is 1 or 2
  • y is 1 or 2.
  • R1 and R4 in the electrolyte additives provided in this application can be selected from fluorine atoms or fluorine-containing substituents, which can form inorganic compounds such as lithium fluoride, lithium nitride, and sulfides on the positive and negative electrode surfaces, generating a solid electrolyte interface film with high conductivity and high stability. This reduces CEI and SEI dissolution and lowers interfacial impedance. Subsequently, it can improve the rate performance and transmission performance of the battery.
  • R2 and R3 include nitrile substituents, such as substituted nitrile groups.
  • nitrile substituents include cyano groups (-CN), which can preferentially complex with transition metal ions in the high-voltage cathode material, inhibiting the dissolution of transition metal ions, reducing side reactions between the electrolyte and the cathode material, and suppressing further oxidative decomposition of the electrolyte, thereby improving the high-voltage stability of the electrolyte.
  • the electrolyte with this additive can form a highly stable solid electrolyte interface film, exhibiting stronger resistance to negative electrode material expansion and improved compatibility with the negative electrode material. Therefore, the electrolyte additive provided in this application embodiment can improve the stability and ionic conductivity of the electrolyte at high voltages, thereby enhancing the battery's high-temperature storage performance and cycle performance.
  • a high-capacity (e.g., silicon) negative electrode material the electrolyte with this additive can form a highly stable solid electrolyte interface film, exhibiting stronger resistance to negative electrode material expansion and improved compatibility with the negative electrode material. Therefore, the electrolyte additive provided in this application embodiment can improve the stability and ionic conductivity of the electrolyte at high voltages, thereby enhancing the battery's high-temperature storage performance and cycle performance.
  • the fluorinated substituents include fluorinated alkyl groups, fluorinated alkoxy groups, fluorinated alkenyl groups, fluorinated alkenoxy groups, fluorinated aryl groups, or fluorinated aryloxy groups.
  • the interfacial film formed on the electrode surface contains a certain amount of stable fluoride, which is beneficial for effectively protecting the electrode. This improves the stability of the interfacial film, thereby improving the battery cycle performance and high-temperature storage performance.
  • the number of carbon atoms corresponding to fluorinated alkyl groups and fluorinated alkoxy groups is 1-20; the number of carbon atoms corresponding to fluorinated alkenyl groups and fluorinated alkenoxy groups is 2-20; the number of carbon atoms corresponding to fluorinated aryl groups, fluorinated aryloxy groups, substituted or unsubstituted arylene nitrile groups and substituted or unsubstituted aryloxynitrile groups is 6-20; the number of carbon atoms corresponding to substituted or unsubstituted alkylene nitrile groups and substituted or unsubstituted alkeneoxynitrile groups is 2-20; and the number of carbon atoms corresponding to substituted or unsubstituted alkenylene nitrile groups and substituted or unsubstituted alkenoxynitrile groups is 3-20.
  • a smaller number of carbon atoms facilitates control of the additive's
  • the substituents in the substituted alkylene nitrile group, substituted alkoxynitrile group, substituted alkenyl nitrile group, substituted alkenyl nitrile group, substituted aryl nitrile group, and substituted aryloxynitrile group are independently selected from one or more of fluorine, chlorine, bromine, iodine, alkyl group, haloalkyl group, alkoxy group, haloalkoxy group, alkenyl group, haloalkenyl group, alkenyloxy group, haloalkenyloxy group, aryl group, haloaryl group, aryloxy group, or haloaryloxy group.
  • the halogen in the haloalkyl group, haloalkoxy group, haloalkenyl group, haloalkenoxy group, haloaryl group, or haloaryloxy group is independently selected from one or more of fluorine, chlorine, bromine, and iodine.
  • the electrolyte additive structure proposed in this application includes the aforementioned substituents: alkylene nitrile groups, alkeneoxynitrile groups, alkenyl nitrile groups, alkenyloxynitrile groups, arylene nitrile groups, and aryloxynitrile groups.
  • these groups is a cyano group (-CN), which can preferentially complex with transition metal ions in the high-voltage cathode material, inhibiting the dissolution of transition metal ions, reducing side reactions between the electrolyte and the cathode material, and inhibiting further oxidative decomposition of the electrolyte, thereby improving the high-voltage stability of the electrolyte. This, in turn, improves the battery's cycle performance and high-temperature storage performance.
  • the electrolyte additive includes at least one of the structures shown in formulas (3) to (10):
  • the electrolyte additive in this embodiment includes at least one of the above structures, enabling the electrolyte to form a highly stable solid electrolyte interface film on the positive and negative electrode surfaces.
  • a high-capacity (e.g., silicon) negative electrode material is used, the solid electrolyte interface film exhibits stronger resistance to expansion of the negative electrode material, and its compatibility with the negative electrode material is also improved. This, in turn, enhances the battery's cycle performance and high-temperature storage performance.
  • embodiments of this application also provide a method for preparing an electrolyte additive, the method comprising:
  • the acid-binding agent is mixed with the solvent to obtain the first solution.
  • a first reaction substrate comprising at least one of a substituted or unsubstituted alkylene nitrile group compound, a substituted or unsubstituted alkoxynitrile group compound, a substituted or unsubstituted alkenyl nitrile group compound, a substituted or unsubstituted alkenyl nitrile group compound, a substituted or unsubstituted aryl nitrile group compound, and a substituted or unsubstituted aryl nitrile group compound.
  • a second reaction substrate which includes a fluorine-substituent compound.
  • the first reaction substrate, the second reaction substrate, and the first solution are reacted to prepare the electrolyte additive described in the first aspect above.
  • the electrolyte additives prepared by the above method can form inorganic compounds such as lithium fluoride, lithium nitride, and sulfides on the surfaces of the positive and negative electrodes, generating a solid electrolyte interface film with high conductivity and high stability. Simultaneously, they can preferentially complex with transition metal ions in the high-voltage positive electrode material, inhibiting the dissolution of transition metal ions, reducing side reactions between the electrolyte and the positive electrode material, and suppressing further oxidative decomposition of the electrolyte, thereby improving the high-voltage stability of the electrolyte.
  • embodiments of this application also provide a battery electrolyte, comprising: an electrolyte salt, an organic solvent, and the electrolyte additives described above.
  • the electrolyte provided in this application embodiment can form a solid electrolyte interface film with high conductivity and high stability on the surfaces of the positive and negative electrodes.
  • the electrolyte additives in the electrolyte can preferentially complex with transition metal ions in the high-voltage positive electrode material, inhibiting the dissolution of transition metal ions, reducing side reactions between the electrolyte and the positive electrode material, and suppressing further oxidative decomposition of the electrolyte, resulting in high high-voltage stability.
  • the electrolyte exhibits stronger resistance to expansion of the negative electrode material and also improves its compatibility with the negative electrode material. This, in turn, improves the battery's high-temperature storage performance and cycle performance.
  • the electrolyte additive has a mass percentage content of 0.05%-10% in the electrolyte.
  • the electrolyte additive has a mass percentage content of 0.05%-5% in the electrolyte.
  • the embodiments of this application can maintain them within a suitable range in the electrolyte, promoting the formation of a highly stable solid electrolyte interface film on the positive and negative electrode surfaces. This, in turn, improves the rate performance, cycle performance, and high-temperature storage performance of the subsequent battery.
  • the organic solvent includes one or more of carbonate solvents, carboxylic acid ester solvents, or ether solvents
  • the carbonate solvent includes one or more of cyclic carbonate solvents or linear carbonate solvents.
  • the cyclic carbonate solvent accounts for 10%-50% by mass in the electrolyte.
  • the cyclic carbonate solvent accounts for 20%-40% of the electrolyte by mass.
  • the present application embodiments ensure that the content of cyclic carbonates in the electrolyte is appropriate, preventing the electrolyte viscosity from being too high and avoiding slow ion transport in the electrolyte, which would reduce the cycle performance of the battery.
  • the mass ratio of electrolyte additive to cyclic carbonate solvent is 0.01:1 to 0.5:1.
  • the mass ratio of electrolyte additive to cyclic carbonate solvent is 0.02:1 to 0.3:1.
  • this embodiment of the application ensures that the content of cyclic carbonates in the electrolyte is appropriate, preventing excessive electrolyte viscosity and reduced electrolyte conductivity. Simultaneously, it prevents the cyclic carbonate solvents and other organic solvents, such as carboxylic acid ester solvents, from oxidizing and decomposing at the battery cathode under high temperature/high pressure conditions, generating large amounts of gas. Furthermore, it facilitates the formation of a highly stable interfacial film on the electrode surface by the electrolyte additives. This improves the high-temperature cycle performance and safety of the battery.
  • the molar concentration of the electrolyte salt in the electrolyte is 0.01 mol/L to 5.0 mol/L.
  • the electrolyte salt includes one or more of lithium, sodium, potassium, magnesium, zinc, or aluminum salts.
  • the electrolyte salt includes one or more of the following : MClO4 , MBF4 , MPF6 , MAsF6 , MPO2F2 , MCF3SO3 , MTDI , MB( C2O4 ) 2 , MBF2C2O4, M[( CF3SO2 ) 2N ], M[( FSO2 ) 2N ], or M[ ( CmF2m +1SO2 ) ( CnF2n + 1SO2 )N], wherein M is lithium , sodium, or potassium , and m and n are natural numbers.
  • the electrolyte additive also includes other additives, including one or more of film-forming additives, overcharge prevention additives, wetting agents, and flame retardants.
  • other additives include one or more of the following: biphenyl, fluorobenzene, vinylene carbonate, trifluoromethyl vinyl carbonate, ethylene ethylene carbonate, 1,3-propanesulfonate lactone, 1,4-butanesulfonate lactone, vinyl sulfate, vinyl sulfite, methanedisulfonate, succinic acid nitrile, adiponitrile, 1,2-bis(2-cyanoethoxy)ethane, 1,3,6-hexanetrionitrile, trimethyl phosphate, triethyl phosphate, trimethyl phosphite, triethyl phosphite, (ethoxy)pentafluorocyclotriphosphazene, hexafluorocyclotriphosphazene, tris(trimethylsilyl)phosphate, and tris(trimethylsilyl)borate.
  • embodiments of this application also provide a secondary battery, including a positive electrode, a negative electrode, a separator located between the positive electrode and the negative electrode, and the electrolyte described in the third aspect, wherein the electrolyte fills the space between the positive electrode and the negative electrode.
  • embodiments of this application also provide an electronic device, which includes a housing, electronic components and a battery housed within the housing, wherein the battery powers the electronic components and includes the secondary battery described in the fourth aspect.
  • Figure 1 is a schematic diagram of the structure of a lithium-ion battery provided in an embodiment of this application;
  • Figure 2 is a schematic diagram of the test results of an embodiment 1 and comparative examples 1, 2, and 3 provided in this application;
  • Figure 3 is a schematic diagram of the test results of an embodiment 3 and comparative examples 4 and 5 provided in this application;
  • Figure 4 is a schematic diagram of the structure of an electronic device provided in an embodiment of this application.
  • At least one of a, b, or c can represent: a, b, c, a-b, a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.
  • the terms "first" and "second” are used in the embodiments of this application to distinguish the same or similar items with basically the same function and effect.
  • a rechargeable battery also known as a rechargeable battery or a storage battery, is a battery that can be recharged after being discharged to activate its active materials and continue to be used.
  • Cathode In a galvanic cell, the electrode with the highest potential, where current flows out, is the positive electrode and gains electrons, thus undergoing reduction. In an electrolytic cell, the positive electrode is connected to the positive terminal of the power source and loses electrons, thus undergoing oxidation.
  • Negative electrode In a galvanic cell, the electrode with the lowest potential, where current flows, is the negative electrode and loses electrons, thus undergoing oxidation. In an electrolytic cell, the negative electrode is connected to the negative terminal of the power source and gains electrons, thus undergoing reduction.
  • Electrolyte The medium that provides ion exchange between the positive and negative electrodes of a battery.
  • the main function of the separator is to separate the positive and negative electrodes of the battery to prevent the two electrodes from contacting and short-circuiting. In addition, it also allows electrolyte ions to pass through.
  • Film-forming additives are substances that preferentially decompose on the material surface to form an interfacial film compared to organic solvents, and can significantly improve battery performance.
  • Solid Electrolyte Interphase (SEI) Film During the initial charge and discharge of a battery, the electrode material and the electrolyte react at the solid-liquid interface, forming a passivation layer covering the surface of the electrode material.
  • this passivation layer is an interface layer with the characteristics of a solid electrolyte. It is an electronic insulator but an excellent conductor of Li+, allowing Li+ ions to freely intercalate and deintercalate through this passivation layer.
  • Electrochemical interface refers to the interface protective film or cathode electrolyte interface (film), which is a passivation film layer with solid electrolyte properties.
  • high-voltage lithium cobalt oxide positive electrodes such as high-voltage lithium cobalt oxide positive electrodes
  • higher specific capacity negative electrodes such as silicon/lithium metal negative electrodes
  • high-voltage lithium cobalt oxide materials undergo severe side reactions with the electrolyte; on the other hand, these negative electrode materials experience large volume expansion during cycling, leading to continuous rupture/reorganization of the SEI film and thickening of the interface layer. Therefore, more or more effective film-forming additives are needed to form the interface film to maintain cycle stability.
  • an electrolyte additive which includes a first additive and/or a second additive.
  • R1 and R4 are independently selected from either fluorine atoms or fluorine-containing substituents
  • R2 and R3 are independently selected from one of the following: substituted or unsubstituted alkylene nitrile group, substituted or unsubstituted alkoxynitrile group, substituted or unsubstituted alkenyl nitrile group, substituted or unsubstituted alkenyl nitrile group, substituted or unsubstituted aryl nitrile group, and substituted or unsubstituted aryloxynitrile group.
  • x is 1 or 2
  • y is 1 or 2.
  • R1 and R4 in the electrolyte additives provided in this application can be selected from fluorine atoms or fluorine-containing substituents, which can form inorganic compounds such as lithium fluoride, lithium nitride, and sulfides on the positive and negative electrode surfaces, thereby generating a solid electrolyte interface film with high conductivity and high stability. This reduces CEI and SEI dissolution and lowers interface impedance. Subsequently, it can improve the rate performance and transmission performance of the battery.
  • R2 and R3 include nitrile substituents, such as substituted nitrile groups.
  • nitrile substituents include cyano groups (-CN), which preferentially complex with transition metal ions in the high-voltage cathode material, inhibiting the dissolution of transition metal ions, reducing side reactions between the electrolyte and the cathode material, and suppressing further oxidative decomposition of the electrolyte, thereby improving the high-voltage stability of the electrolyte.
  • Side reactions such as the generation of large amounts of gas, can worsen electrolyte wetting between the separator and the positive and negative electrodes, causing battery volume expansion, electrode/separator misalignment, and increased battery polarization.
  • Electrolyte oxidative decomposition such as the evolution of oxygen and the generation of highly oxidizing Co3 + /Ni4 + at the cathode, can lead to continuous decomposition of the electrolyte on the positive and negative electrode surfaces, resulting in increased battery impedance and capacity degradation.
  • the electrolyte with this additive can form a highly stable solid electrolyte interface film, exhibiting stronger resistance to negative electrode material expansion and improved compatibility with the negative electrode material. Therefore, the electrolyte additive provided in this application embodiment can improve the stability and ionic conductivity of the electrolyte at high voltages, thereby enhancing the battery's high-temperature storage performance and cycle performance.
  • a high-capacity (e.g., silicon) negative electrode material the electrolyte with this additive can form a highly stable solid electrolyte interface film, exhibiting stronger resistance to negative electrode material expansion and improved compatibility with the negative electrode material. Therefore, the electrolyte additive provided in this application embodiment can improve the stability and ionic conductivity of the electrolyte at high voltages, thereby enhancing the battery's high-temperature storage performance and cycle performance.
  • FIG. 1 is a schematic diagram of the structure of a lithium-ion battery provided in an embodiment of this application.
  • the lithium-ion battery includes a positive electrode 10, a negative electrode 20, a separator 30, and an electrolyte 40.
  • the separator 30 is disposed between the positive electrode 10 and the negative electrode 20, and the electrolyte 40 fills the space between the positive electrode 10 and the negative electrode 20 and wets the separator 30.
  • the electrolyte 40 fills the space between the positive electrode 10 and the negative electrode 20 and wets the separator 30.
  • the positive electrode active material 102 of the positive electrode 10 pass through the electrolyte 40, and then insert into the negative electrode active material 202 of the negative electrode 20.
  • lithium ions are extracted from the negative electrode active material 202, pass through the electrolyte 40, and then insert into the positive electrode active material 102.
  • the positive electrode 10 includes a positive electrode current collector 101 and a positive electrode material layer coated on the surface of the positive electrode current collector 101.
  • the positive electrode material layer may also include a certain amount of binder, conductive agent and other components.
  • the positive electrode current collector 101 can be a metal foil (e.g., aluminum foil, gold foil, platinum foil, etc.) or a carbon-coated metal foil.
  • the positive electrode active material 102 can reversibly insert/deintercalate active ions (e.g., lithium ions, sodium ions, potassium ions, magnesium ions, zinc ions, or aluminum ions).
  • the positive electrode active material 102 includes, but is not limited to, at least one of transition metal oxides such as lithium, sodium, potassium, magnesium, zinc, and aluminum, Prussian blue (white) compounds, and polyanionic compounds such as lithium, sodium, potassium, magnesium, zinc, and aluminum.
  • the positive electrode active material 102 can be lithium cobalt oxide ( LiCoO2 , abbreviated LCO).
  • the positive electrode active material 102 may further include at least one of lithium cobalt oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium nickel manganese oxide, and lithium nickel oxide.
  • the binder may be, for example, polyvinylidene fluoride (PVDF), and the conductive agent may be, for example, conductive carbon black (super P), amorphous carbon, carbon nanotubes, carbon fibers, graphene, etc.
  • PVDF polyvinylidene fluoride
  • the conductive agent may be, for example, conductive carbon black (super P), amorphous carbon, carbon nanotubes, carbon fibers, graphene, etc.
  • the above-described positive electrode current collector 101, positive electrode active material 102, binder, and conductive agent used to prepare the positive electrode 10 are merely illustrative examples, and the embodiments of this application do not limit their application. Taking the positive electrode active material
  • the negative electrode 20 includes a negative electrode current collector 201 and a negative electrode material layer coated on the surface of the negative electrode current collector 201.
  • the negative electrode material layer may also include a certain amount of binder, conductive agent and other components.
  • the negative electrode current collector 201 can be a metal foil (e.g., copper foil, aluminum foil, gold foil, platinum foil, etc.) or a carbon-coated metal foil.
  • the negative electrode active material 202 can include at least one of the following: natural graphite, artificial graphite, mesophase microcarbon spheres, hard carbon, soft carbon, and porous carbon materials.
  • the negative electrode active material 202 can be one or more of the following: carbon-based materials, tin-based materials, silicon-based materials, phosphorus-based materials, lithium titanate ( Li4Ti5O12 ), lithium materials, sodium materials, potassium materials, magnesium materials, zinc materials, or aluminum materials capable of intercalating and deintercalating active ions.
  • Carbon-based materials include, but are not limited to, one or more of graphite, hard carbon, soft carbon, mesophase carbon microspheres, graphene, and porous carbon.
  • Tin-based materials include, but are not limited to, one or more of tin, tin-carbon, tin-oxygen, and tin metal compounds;
  • phosphorus-based materials include, but are not limited to, one or more of red phosphorus, black phosphorus, and phosphorus compounds;
  • sodium materials include, but are not limited to, metallic sodium or sodium alloys.
  • Silicon-based materials include, but are not limited to, one or more of silicon, silicon-carbon, silicon-oxygen, or silicon metal compounds.
  • Lithium materials include metallic lithium or lithium alloys.
  • Lithium alloys include at least one of lithium-silicon alloys, lithium-sodium alloys, lithium-potassium alloys, lithium-aluminum alloys, lithium-tin alloys, and lithium-indium alloys.
  • Potassium materials include metallic potassium or potassium alloys.
  • Magnesium materials include metallic magnesium or magnesium alloys.
  • Zinc materials include metallic zinc or zinc alloys.
  • Aluminum materials include metallic aluminum or aluminum alloys.
  • the binder may be one or more of sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyacrylic acid (PAA), and lithium polyacrylate (LiPAA).
  • the conductive agent may be conductive carbon black (super P), acetylene black, carbon nanotubes, graphene, amorphous carbon, etc.
  • the negative electrode current collector 201, negative electrode active material 202, binder, and conductive agent described above for preparing the negative electrode 20 are merely illustrative examples, and the embodiments of this application do not limit their application.
  • the separator 30 blocks electrons from passing through while allowing ions to pass through.
  • the separator 30 includes, but is not limited to, single-layer polypropylene (PP), single-layer polyethylene (PE), double-layer PP/PE, double-layer PP/PP, triple-layer PP/PE/PP, ceramic-coated PE, and solid electrolyte-coated PE.
  • the electrolyte 40 is the transport medium for lithium ions during transport between the positive electrode 10 and the negative electrode 20.
  • the electrolyte 40 includes an organic solvent, an electrolyte salt, and an electrolyte additive. Both the electrolyte salt and the electrolyte additive are dissolved in the organic solvent.
  • the organic solvent may be a non-aqueous organic solvent, and the organic solvent may include, but is not limited to, at least one of carbonate solvents, carboxylic acid ester solvents, and ether solvents.
  • carbonate solvents include, but are not limited to, one or more of dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, trifluoromethyl ethylene carbonate, bis(2,2,2-trifluoroethyl) carbonate, and (2,2,2-trifluoroethyl)methyl carbonate.
  • Ether solvents include, but are not limited to, one or more of tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, dimethoxymethane, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, and bis(2,2,2-trifluoroethyl) ether.
  • Carboxylic acid ester solvents include, but are not limited to, one or more of methyl formate, ethyl formate, ethyl acetate, propyl acetate, propyl propionate, methyl difluoroacetate, and methyl trifluoroacetate.
  • Carbonate solvents may also include cyclic carbonate solvents and linear carbonate solvents.
  • Cyclic carbonate solvents include, but are not limited to, one or more of ethylene carbonate (EC), propylene carbonate (PC), and trifluoromethyl ethylene carbonate.
  • Linear carbonate solvents include, but are not limited to, one or more of diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), bis(2,2,2-trifluoroethyl) carbonate, and (2,2,2-trifluoroethyl)methyl carbonate.
  • DEC diethyl carbonate
  • EMC ethyl methyl carbonate
  • DMC dimethyl carbonate
  • bis(2,2,2-trifluoroethyl) carbonate 2,2,2-trifluoroethyl)methyl carbonate.
  • the introduction of linear carbonate solvents is helpful in reducing the viscosity of battery electrolytes, and they have high compatibility with cycl
  • the cyclic carbonate solvent has a mass percentage content of 10%-50% in the electrolyte. Specifically, the cyclic carbonate solvent has a mass percentage content of 20%-40% in the electrolyte.
  • the value of the cyclic carbonate solvent can be, for example, 10%, 20%, 30%, 40%, 50%, or any number between any two of the above values, which are all acceptable ranges.
  • the present application embodiments ensure that the content of cyclic carbonates in the electrolyte is appropriate, preventing the electrolyte viscosity from being too high and avoiding slow ion transport in the electrolyte, which would reduce the cycle performance of the battery.
  • the electrolyte additive has a mass percentage content of 0.05%-10% in the electrolyte.
  • the electrolyte additive has a mass percentage content of 0.5%-5% in the electrolyte.
  • the value of the electrolyte additive in the electrolyte can be, for example, 0.05%, 0.1%, 0.5%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, 8.0%, 10%, or any number between any two of the above values, all of which are acceptable ranges.
  • the embodiments of this application can maintain them within a suitable range in the electrolyte, promoting the formation of a highly stable solid electrolyte interface film on the positive and negative electrode surfaces. This, in turn, improves the rate performance, cycle performance, and high-temperature storage performance of the subsequent battery.
  • the mass ratio of electrolyte additive to cyclic carbonate solvent is from 0.01:1 to 0.5:1. Specifically, the mass ratio of electrolyte additive to cyclic carbonate solvent is from 0.02:1 to 0.3:1.
  • the mass ratio of the electrolyte additive to the cyclic carbonate solvent is from 0.01:1 to 0.5:1.
  • This ratio can typically, but is not limited to, values such as 0.01:1, 0.05:1, 0.08:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, and any two of these values. These are all acceptable ranges; for example, the ratio can be between 0.01:1 and 0.08:1, between 0.05:1 and 0.1:1, between 0.1:1 and 0.3:1, between 0.2:1 and 0.5:1, or any other two values.
  • this embodiment of the application ensures that the content of cyclic carbonates in the electrolyte is appropriate, preventing excessive electrolyte viscosity and reduced electrolyte conductivity. Simultaneously, it prevents the cyclic carbonate solvents and other organic solvents, such as carboxylic acid ester solvents, from oxidizing and decomposing at the battery cathode under high temperature/high pressure conditions, generating large amounts of gas. Furthermore, it facilitates the formation of a highly stable interfacial film on the electrode surface by the electrolyte additives. This improves the high-temperature cycle performance and safety of the battery.
  • the electrolyte salt includes one or more of lithium salt, sodium salt, potassium salt, magnesium salt, zinc salt, or aluminum salt.
  • Electrolyte salts include, but are not limited to, one or more of the following: MClO4, MBF4, MPF6, MAsF6, MPO2F2, MCF3SO3 , MTDI , MB ( C2O4 ) 2, MBF2C2O4, M[(CF3SO2)2N], M[(FSO2)2N ] or M [ ( CmF2m + 1SO2 ) ( CnF2n + 1SO2 ) N ], where M is lithium, sodium or potassium , and m and n are natural numbers.
  • the molar concentration of the electrolyte salt can be 0.01 mol/L to 5.0 mol/L.
  • the molar concentration of the electrolyte salt can be, for example, 0.01 mol/L, 0.1 mol/L, 0.5 mol/L, 0.8 mol/L, 1.0 mol/L, 1.2 mol/L, 1.5 mol/L, 1.8 mol/L, 2.0 mol/L, 3.0 mol/L, 4.0 mol/L, or 5.0 mol/L, or any value between 0.01 mol/L and 5.0 mol/L, and is not listed here. It should be understood that, in practical applications, a certain degree of measurement and testing system error is permissible within the concentration range of the electrolyte salt in the electrolyte solution. Values within the range of system error are those defined in the embodiments of this application.
  • the electrolyte additive may include at least one of a first additive or a second additive.
  • the first additive may refer to formula (1) above, and the second additive may refer to formula (2) above.
  • the fluorinated substituents may include fluorinated alkyl groups, fluorinated alkoxy groups, fluorinated alkenyl groups, fluorinated alkenoxy groups, fluorinated aryl groups, or fluorinated aryloxy groups.
  • fluorinated alkyl group, fluorinated alkoxy group, fluorinated alkenyl group, fluorinated alkenoxy group, fluorinated aryl group, or fluorinated aryloxy group can be straight-chain or branched.
  • the number of carbon atoms corresponding to the fluorinated alkyl group and the fluorinated alkoxy group is 1-20
  • the number of carbon atoms corresponding to the fluorinated alkenyl group and the fluorinated alkenoxy group is 2-20
  • the number of carbon atoms corresponding to the fluorinated aryl group and the fluorinated aryloxy group is 6-20.
  • the number of carbon atoms in fluorinated alkyl groups and fluorinated alkoxy groups can be 1-10, specifically, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.
  • the number of carbon atoms in fluorinated alkenyl groups and fluorinated alkenoxy groups can be 2-6, specifically, for example, 2, 3, 4, 5, or 6.
  • the number of carbon atoms in fluorinated aryl groups and fluorinated aryloxy groups can be 6-10, specifically, for example, 6, 7, 8, 9, or 10.
  • a smaller number of carbon atoms allows for better control of the additive's molecular weight, thus facilitating subsequent control of the electrolyte viscosity.
  • the interfacial film formed on the electrode surface contains a certain amount of stable fluoride, which is beneficial for effectively protecting the electrode. This improves the stability of the interfacial film, thereby improving the battery cycle performance and high-temperature storage performance.
  • the substituent groups in the substituted alkylene nitrile group, substituted alkoxynitrile group, substituted alkenyl nitrile group, substituted alkenyl nitrile group, substituted aryl nitrile group, and substituted aryloxynitrile group are independently selected from one or more of fluorine, chlorine, bromine, iodine, alkyl group, haloalkyl group, alkoxy group, haloalkoxy group, alkenyl group, haloalkenyl group, alkenyloxy group, haloalkenyloxy group, aryl group, haloaryl group, aryloxy group, or haloaryloxy group.
  • the halogenation can be fully halogenated or partially halogenated.
  • the substituent groups can be linear, branched, or cyclic.
  • the halogen in the haloalkyl group, haloalkoxy group, haloalkenyl group, haloalkenoxy group, haloaryl group, or haloaryloxy group is independently selected from one or more of fluorine, chlorine, bromine, and iodine.
  • R2 and R3 can be independently selected from alkylene nitrile groups, alkeneoxynitrile groups, alkenyl nitrile groups, alkenyloxynitrile groups, arylene nitrile groups, and aryloxynitrile groups, including the aforementioned substituent groups.
  • these groups is a cyano group (-CN), which can preferentially complex with transition metal ions in the high-voltage cathode material, inhibiting the dissolution of transition metal ions, reducing side reactions between the electrolyte and the cathode material, and inhibiting further oxidative decomposition of the electrolyte, thereby improving the high-voltage stability of the electrolyte. This, in turn, improves the battery's cycle performance and high-temperature storage performance.
  • the number of carbon atoms corresponding to the substituted or unsubstituted alkylene nitrile group and the substituted or unsubstituted alkoxynitrile group is 2-20
  • the number of carbon atoms corresponding to the substituted or unsubstituted alkenyl nitrile group and the substituted or unsubstituted alkenyl nitrile group is 3-20
  • the number of carbon atoms corresponding to the substituted or unsubstituted aryl nitrile group and the substituted or unsubstituted aryl nitrile group is 6-20.
  • the substituted or unsubstituted alkylene nitrile groups and substituted or unsubstituted alkoxynitrile groups can have 2-10 carbon atoms, specifically, for example, 2, 3, 4, 5, 6, 7, 8, 9, or 10 carbon atoms.
  • the substituted or unsubstituted alkenyl nitrile groups and substituted or unsubstituted alkenyloxynitrile groups can have 3-6 carbon atoms, specifically, for example, 3, 4, 5, or 6 carbon atoms.
  • the substituted or unsubstituted aryl nitrile groups and substituted or unsubstituted aryloxynitrile groups can have 6-10 carbon atoms, specifically, for example, 6, 7, 8, 9, or 10 carbon atoms.
  • a smaller number of carbon atoms is beneficial for controlling the molecular weight of the additive, thereby facilitating better control of the electrolyte viscosity in subsequent processes.
  • the substituted or unsubstituted alkylene nitrile group, the substituted or unsubstituted alkoxynitrile group, the substituted or unsubstituted alkenyl nitrile group, the substituted or unsubstituted alkenyl nitrile group, the substituted or unsubstituted aryl nitrile group, or the substituted or unsubstituted aryl nitrile group can be linear or branched.
  • the electrolyte additive includes at least one of the structures shown in formulas (3) to (10):
  • the electrolyte additive in this embodiment includes at least one of the above structures, enabling the electrolyte to form a highly stable solid electrolyte interface film on the positive and negative electrode surfaces.
  • a high-capacity (e.g., silicon) negative electrode material is used, the solid electrolyte interface film exhibits stronger resistance to expansion of the negative electrode material, and its compatibility with the negative electrode material is also improved. This, in turn, enhances the battery's cycle performance and high-temperature storage performance.
  • the electrolyte additive also includes other additives, including one or more of film-forming additives, overcharge prevention additives, wetting agents, and flame retardants.
  • the film-forming additives may include, but are not limited to, one or more of vinylene carbonate (VC), ethylene ethylene carbonate (VEC), fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), 1,3-propanesulfonate lactone (PS), 1,3-propenesulfonate lactone (PST), 1,4-butanesulfonate lactone (BS), vinyl sulfate (DTD), vinyl sulfite (ES), methanedisulfonate methylene sulphate (MMDS), dimethyl sulfate, dimethyl sulfite (DS), diethyl sulfite, diethyl sulfate, 4-methylethylene sulfate, and tris(trimethylsilyl)borate.
  • VC vinylene carbonate
  • Overcharge protection additives may include one or more of biphenyl (BP), succinic anhydride (SN), glutaronitrile, adiponitrile (ADN), 1,2-bis(2-cyanoethoxy)ethane (DENE), and 1,3,6-hexanetrionitrile (HTCN), which generally also improve the high-voltage performance of the battery.
  • Wetting agents can improve the wettability of the battery electrolyte to the electrodes; exemplary wetting agents may include fluorobenzene, etc.
  • Exemplary flame retardants may include one or more of phosphate esters (such as trimethyl phosphate, triethyl phosphate, tri(trimethylsilyl) phosphate), phosphite esters (such as trimethyl phosphite, triethyl phosphite), and cyclotriphosphazenes (such as (ethoxy)pentafluorocyclotriphosphazene, hexafluorocyclotriphosphazene).
  • phosphate esters such as trimethyl phosphate, triethyl phosphate, tri(trimethylsilyl) phosphate
  • phosphite esters such as trimethyl phosphite, triethyl phosphite
  • cyclotriphosphazenes such as (ethoxy)pentafluorocyclotriphosphazene, hexafluorocyclotriphosphazene.
  • the electrolyte additives shown in formula (1) or formula (2) above can be prepared by different methods, and the specific preparation method is not limited.
  • the sample can be prepared in the following manner: the method includes:
  • the acid-binding agent is mixed with the solvent to obtain the first solution;
  • a first reaction substrate comprising at least one of a substituted or unsubstituted alkylene nitrile group compound, a substituted or unsubstituted alkoxynitrile group compound, a substituted or unsubstituted alkenyl nitrile group compound, a substituted or unsubstituted alkenyl nitrile group compound, a substituted or unsubstituted aryl nitrile group compound, and a substituted or unsubstituted aryl nitrile group compound.
  • a second reaction substrate which includes a fluorine-substituent compound.
  • the first reaction substrate, the second reaction substrate, and the first solution are reacted to prepare the electrolyte additive provided in the above-described embodiments of this application.
  • the acid-binding agent includes at least one of inorganic bases and organic base compounds.
  • the acid-binding agent includes, but is not limited to, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium phosphate, potassium phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, triethylamine, N,N-dimethylcyclohexylamine, pyridine, pyrimidine, quinoline, etc.
  • Solvents include, but are not limited to, one or more of ethane, cyclohexane, dichloromethane, chloroform, diethyl ether, petroleum ether, benzene, toluene, chlorobenzene, fluorobenzene, acetone, acetonitrile, methanol, ethanol, tetrahydrofuran, nitromethane, dimethyl sulfoxide, N,N-dimethylformamide, ethyl acetate, and butyl acetate. It should be noted that the embodiments of this application do not specifically limit the type and amount of the above solvents used.
  • the first reaction substrate may include, but is not limited to, at least one of iminodiacetonitrile, imino(1-acetonitrile)-2-propionitrile, and imino(1-acetonitrile)-p-methylenephenylacetonitrile.
  • the second reaction substrate may include, but is not limited to, at least one of trifluoromethanesulfonic anhydride, trifluoroethylsulfinic anhydride, fluorosulfinic anhydride, and fluorosulfinic anhydride. It should be noted that the embodiments of this application do not specifically limit the types and amounts of the first and second reaction substrates used.
  • the system was placed at -15°C and allowed to stand for a period of time to allow it to cool down. After the system temperature stabilized, a mixture of trifluoromethanesulfonic anhydride and dichloromethane was added dropwise at a uniform rate (1 drop/second). After titration, the system was transferred to room temperature and stirred overnight. The next day, the product was transferred to a 250 mL separatory funnel, and 50 mL of ultrapure water was added for quenching. After stirring and standing, the upper liquid phase was separated from the system, and the acidity was tested using pH paper. The above steps (quenching process, separation of the upper liquid phase, and acidity test) were repeated several times until the upper liquid phase was no longer acidic.
  • This application also provides a method for preparing an electrolyte, the method comprising: preparing the required organic solvent in an inert or closed environment; dissolving a fully dried electrolyte salt in the organic solvent and stirring to form a homogeneous solution; then adding an electrolyte additive to the homogeneous solution and mixing thoroughly to obtain the electrolyte.
  • the mass percentages of the organic solvent, electrolyte salt, and electrolyte additive in the electrolyte, as well as the mass ratio between the organic solvent and the electrolyte additive may be affected by the formation of an interfacial film after actual battery formation, capacity testing, or cycling. Therefore, a certain measurement error is permissible. Values within this error range can be understood as falling within the range defined in the embodiments of this application. Alternatively, if the mass percentages of the electrolyte solvent and additive tested after formation, capacity testing, or cycling are still within the aforementioned range, they can be understood as falling within the range defined in the embodiments of this application.
  • ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) are mixed to form an organic solvent.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • PP propyl propionate
  • LiPF6 lithium hexafluorophosphate
  • LiDFOB lithium difluorooxalate borate
  • Electrolyte additive A see Formula 3 above
  • fluoroethylene carbonate (FEC), and 1,3-propanesulfonate lactone (PS) are then added to the above solution and mixed uniformly to obtain a lithium secondary battery electrolyte (Example 1).
  • the concentration of LiPF6 is 1.0 mol/L
  • the concentration of LiDFOB is 0.05 mol/L
  • the mass percentages of EC, DEC, PC, and PP in the electrolyte are 15%, 20%, 12.5%, and 30%, respectively
  • the mass percentages of electrolyte additive A, FEC, and PS in the electrolyte are 2%, 5%, and 3%, respectively.
  • Lithium-ion secondary batteries are manufactured using the following methods:
  • PVDF polyvinylidene fluoride
  • LiCoO2 lithium cobalt oxide
  • NMP N-methylpyrrolidone
  • the positive electrode, negative electrode and PE separator prepared above are used to make a battery cell, which is then packaged with polymer and filled with the lithium secondary battery electrolyte prepared in Example 1 above. After formation and other processes, a 4Ah soft-pack lithium secondary battery is made.
  • ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) are mixed to form an organic solvent.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • PP propyl propionate
  • LiPF6 lithium hexafluorophosphate
  • LiDFOB lithium difluorooxalate borate
  • electrolyte additive D Formulamula 6 above
  • fluoroethylene carbonate (FEC) fluoroethylene carbonate
  • PS 1,3-propanesulfonate lactone
  • the concentration of LiPF6 is 1.0 mol/L
  • the concentration of LiDFOB is 0.05 mol/L
  • the mass percentages of EC, DEC, PC, and PP in the electrolyte are 15%, 20%, 12.5%, and 30%, respectively
  • the mass percentages of electrolyte additive D, FEC, and PS in the electrolyte are 2%, 5%, and 3%, respectively.
  • Lithium secondary batteries were prepared using the lithium secondary battery electrolyte prepared in Example 2, and the preparation method was the same as in Example 1.
  • ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) are mixed to form an organic solvent.
  • fully dried lithium hexafluorophosphate ( LiPF6 ) and lithium difluorooxalate borate (LiDFOB) are dissolved in the organic solvent and stirred to form a homogeneous solution.
  • electrolyte additive F Formmula 8 above
  • fluoroethylene carbonate (FEC), and 1,3-propanesulfonate lactone (PS) are added to the solution and mixed uniformly to obtain a lithium secondary battery electrolyte (Example 3).
  • the concentration of LiPF6 is 1.0 mol/L
  • the concentration of LiDFOB is 0.05 mol/L
  • the mass percentages of EC, DEC, PC, and PP in the electrolyte are 15%, 20%, 12.5%, and 30%, respectively
  • the mass percentages of F, FEC, and PS in the electrolyte are 2%, 5%, and 3%, respectively.
  • the lithium secondary battery is prepared by the following method: 2% polyvinylidene fluoride (PVDF), 2% conductive agent super P and 96% lithium cobalt oxide ( LiCoO2 ) are weighed and added to N-methylpyrrolidone (NMP) in sequence. The mixture is stirred and mixed evenly. The slurry is coated on aluminum foil current collector, dried, cold pressed and slit to obtain the positive electrode sheet.
  • PVDF polyvinylidene fluoride
  • LiCoO2 lithium cobalt oxide
  • NMP N-methylpyrrolidone
  • the positive electrode, negative electrode and PE separator prepared above are used to make a battery cell, which is then packaged with polymer and filled with the lithium secondary battery electrolyte prepared in Example 3 above. After formation and other processes, a 4Ah soft-pack lithium secondary battery is made.
  • ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) are mixed to form an organic solvent.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • PP propyl propionate
  • LiPF6 lithium hexafluorophosphate
  • LiDFOB lithium difluorooxalate borate
  • Electrolyte additive F (Formula 8 above), fluoroethylene carbonate (FEC), and 1,3-propanesulfonate lactone (PS) are then added to the solution and mixed thoroughly to obtain a lithium secondary battery electrolyte (Example 4).
  • the concentration of LiPF6 is 1.0 mol/L
  • the concentration of LiDFOB is 0.05 mol/L
  • the mass percentages of EC, DEC, PC, and PP in the electrolyte are 15%, 18%, 12.5%, and 30%, respectively
  • the mass percentages of F, FEC, and PS in the electrolyte are 4%, 5%, and 3%, respectively.
  • a lithium secondary battery was prepared using the lithium secondary battery electrolyte prepared in Example 4, and the preparation method was the same as in Example 3.
  • ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) are mixed to form an organic solvent.
  • fully dried lithium hexafluorophosphate ( LiPF6 ) and lithium difluorooxalate borate (LiDFOB) are dissolved in the organic solvent and stirred to form a homogeneous solution.
  • electrolyte additive G Formmula 9 above
  • fluoroethylene carbonate (FEC), and 1,3-propanesulfonate lactone (PS) are added to the solution and mixed uniformly to obtain a lithium secondary battery electrolyte (Example 5).
  • the concentration of LiPF6 is 1.0 mol/L
  • the concentration of LiDFOB is 0.05 mol/L
  • the mass percentages of EC, DEC, PC, and PP in the electrolyte are 15%, 20%, 12.5%, and 30%, respectively
  • the mass percentages of G, FEC, and PS in the electrolyte are 2%, 5%, and 3%, respectively.
  • Lithium secondary batteries were prepared using the lithium secondary battery electrolyte prepared in Example 5, and the preparation method was the same as in Example 3.
  • ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) are mixed to form an organic solvent.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • PP propyl propionate
  • LiPF6 lithium hexafluorophosphate
  • LiDFOB lithium difluorooxalate borate
  • Electrolyte additive H (Formula 10 above), fluoroethylene carbonate (FEC), and 1,3-propanesulfonate lactone (PS) are then added to the solution and mixed thoroughly to obtain a lithium secondary battery electrolyte (Example 6).
  • the concentration of LiPF6 is 1.0 mol/L
  • the concentration of LiDFOB is 0.05 mol/L
  • the mass percentages of EC, DEC, PC, and PP in the electrolyte are 15%, 20%, 12.5%, and 30%, respectively
  • the mass percentages of H, FEC, and PS in the electrolyte are 2%, 5%, and 3%, respectively.
  • Lithium secondary batteries were prepared using the lithium secondary battery electrolyte prepared in Example 6, and the preparation method was the same as in Example 3.
  • ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) are mixed to form an organic solvent.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • PP propyl propionate
  • LiPF6 lithium hexafluorophosphate
  • LiDFOB lithium difluorooxalate borate
  • electrolyte additive A (Formula 3 above), electrolyte additive F (Formula 8 above), fluoroethylene carbonate (FEC), and 1,3-propanesulfonate lactone (PS) are added to the above solution and mixed uniformly to obtain a lithium secondary battery electrolyte (Example 7).
  • the concentration of LiPF6 was 1.0 mol/L
  • the concentration of LiDFOB was 0.05 mol/L
  • the mass percentages of EC, DEC, PC and PP in the electrolyte were 15%, 18%, 12.5% and 30%, respectively
  • the mass percentages of A, F, FEC and PS in the electrolyte were 2%, 2%, 5% and 3%, respectively.
  • Lithium secondary batteries were prepared using the lithium secondary battery electrolyte prepared in Example 7, and the preparation method was the same as in Example 3.
  • ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) are mixed to form an organic solvent.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • PP propyl propionate
  • LiPF6 lithium hexafluorophosphate
  • LiDFOB lithium difluorooxalate borate
  • electrolyte additive G (Formula 9 above), electrolyte additive H (Formula 10 above), fluoroethylene carbonate (FEC), and 1,3-propanesulfonate lactone (PS) are added to the above solution and mixed uniformly to obtain a lithium secondary battery electrolyte (Example 8).
  • the concentration of LiPF6 was 1.0 mol/L
  • the concentration of LiDFOB was 0.05 mol/L
  • the mass percentages of EC, DEC, PC and PP in the electrolyte were 15%, 20%, 12.5% and 30%, respectively
  • the mass percentages of G, H, FEC and PS in the electrolyte were 1%, 1%, 5% and 3%, respectively.
  • a lithium secondary battery was prepared using the lithium secondary battery electrolyte prepared in Example 8, and the preparation method was the same as in Example 3.
  • ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) are mixed to form an organic solvent.
  • fully dried lithium hexafluorophosphate ( LiPF6 ) and lithium difluorooxalate borate (LiDFOB) are dissolved in the organic solvent and stirred to form a homogeneous solution.
  • electrolyte additive G Formmula 9 above
  • fluoroethylene carbonate (FEC), and 1,3-propanesulfonate lactone (PS) are added to the solution and mixed uniformly to obtain a lithium secondary battery electrolyte (Example 9).
  • the concentration of LiPF6 is 1.0 mol/L
  • the concentration of LiDFOB is 0.05 mol/L
  • the mass percentages of EC, DEC, PC, and PP in the electrolyte are 20%, 10%, 30%, and 19%, respectively
  • the mass percentages of G, FEC, and PS in the electrolyte are 0.5%, 5%, and 3%, respectively.
  • Lithium secondary batteries were prepared using the lithium secondary battery electrolyte prepared in Example 9, and the preparation method was the same as in Example 3.
  • ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) are mixed to form an organic solvent.
  • fully dried lithium hexafluorophosphate ( LiPF6 ) and lithium difluorooxalate borate (LiDFOB) are dissolved in the organic solvent and stirred to form a homogeneous solution.
  • electrolyte additive G Formmula 9 above
  • fluoroethylene carbonate (FEC), and 1,3-propanesulfonate lactone (PS) are added to the solution and mixed uniformly to obtain a lithium secondary battery electrolyte (Example 10).
  • the concentration of LiPF6 is 1.0 mol/L
  • the concentration of LiDFOB is 0.05 mol/L
  • the mass percentages of EC, DEC, PC, and PP in the electrolyte are 5%, 24.5%, 5%, and 40%, respectively
  • the mass percentages of G, FEC, and PS in the electrolyte are 5%, 5%, and 3%, respectively.
  • a lithium secondary battery was prepared using the lithium secondary battery electrolyte prepared in Example 10, and the preparation method was the same as in Example 3.
  • ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) are mixed to form an organic solvent.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • PP propyl propionate
  • LiPF6 lithium hexafluorophosphate
  • LiDFOB lithium difluorooxalate borate
  • the electrolyte additive G (Formula 9 above), fluoroethylene carbonate (FEC), and 1,3-propanesulfonate lactone (PS) are added to the solution and mixed uniformly to obtain a lithium secondary battery electrolyte (Example 11).
  • the concentration of LiPF6 is 1.0 mol/L
  • the concentration of LiDFOB is 0.05 mol/L
  • the mass percentages of EC, DEC, PC, and PP in the electrolyte are 20%, 10.3%, 30%, and 19%, respectively
  • the mass percentages of G, FEC, and PS in the electrolyte are 0.2%, 5%, and 3%, respectively.
  • the lithium secondary battery is prepared by the following method: 2% polyvinylidene fluoride (PVDF), 2% conductive agent super P and 96% lithium cobalt oxide ( LiCoO2 ) are weighed and added to N-methylpyrrolidone (NMP) in sequence. The mixture is stirred and mixed evenly. The slurry is coated on aluminum foil current collector, dried, cold pressed and slit to obtain the positive electrode sheet.
  • PVDF polyvinylidene fluoride
  • LiCoO2 lithium cobalt oxide
  • NMP N-methylpyrrolidone
  • the positive electrode, negative electrode and PE separator prepared above are used to make a battery cell, which is then packaged with polymer and filled with the lithium secondary battery electrolyte prepared in Example 11 above. After formation and other processes, a 4Ah soft-pack lithium secondary battery is made.
  • ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) are mixed to form an organic solvent.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • PP propyl propionate
  • LiPF6 lithium hexafluorophosphate
  • LiDFOB lithium difluorooxalate borate
  • Electrolyte additive G (Formula 9 above), fluoroethylene carbonate (FEC), and 1,3-propanesulfonate lactone (PS) are then added to the solution and mixed thoroughly to obtain a lithium secondary battery electrolyte (Example 12).
  • the concentration of LiPF6 is 1.0 mol/L
  • the concentration of LiDFOB is 0.05 mol/L
  • the mass percentages of EC, DEC, PC, and PP in the electrolyte are 5%, 23.5%, 5%, and 40%, respectively
  • the mass percentages of G, FEC, and PS in the electrolyte are 6%, 5%, and 3%, respectively.
  • a lithium secondary battery was prepared using the lithium secondary battery electrolyte prepared in Example 12, and the preparation method was the same as in Example 11.
  • ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) are mixed to form an organic solvent.
  • fully dried lithium hexafluorophosphate ( LiPF6 ) and lithium difluorooxalate borate (LiDFOB) are dissolved in the organic solvent and stirred to form a homogeneous solution.
  • electrolyte additive F Formmula 8 above
  • vinylene carbonate (VC), and vinyl sulfate (DTD) are added to the solution and mixed uniformly to obtain a lithium secondary battery electrolyte (Example 13).
  • the concentration of LiPF6 is 1.0 mol/L
  • the concentration of LiDFOB is 0.05 mol/L
  • the mass percentages of EC, DEC, PC, and PP in the electrolyte are 15%, 20%, 12.5%, and 30%, respectively
  • the mass percentages of F, VC, and DTD in the electrolyte are 2%, 5%, and 3%, respectively.
  • a lithium secondary battery was prepared using the lithium secondary battery electrolyte prepared in Example 13, and the preparation method was the same as in Example 11.
  • ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) are mixed to form an organic solvent.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • PP propyl propionate
  • LiPF6 lithium hexafluorophosphate
  • LiDFOB lithium difluorooxalate borate
  • succinate (SN), fluoroethylene carbonate (FEC), and 1,3-propanesulfonate lactone (PS) are added to the above solution and mixed uniformly to obtain a lithium secondary battery electrolyte (Comparative Example 1).
  • the concentration of LiPF6 is 1.0 mol/L
  • the concentration of LiDFOB is 0.05 mol/L
  • the mass percentages of EC, DEC, PC, and PP in the electrolyte are 15%, 20%, 12.5%, and 30%, respectively.
  • the mass percentages of SN, FEC, and PS in the electrolyte are 2%, 5%, and 3%, respectively.
  • the lithium secondary battery is prepared by the following method: 2% polyvinylidene fluoride (PVDF), 2% conductive agent super P and 96% lithium cobalt oxide ( LiCoO2 ) are weighed and added to N-methylpyrrolidone (NMP) in sequence. The mixture is stirred and mixed evenly. The slurry is coated on aluminum foil current collector, dried, cold pressed and slit to obtain the positive electrode sheet.
  • PVDF polyvinylidene fluoride
  • LiCoO2 lithium cobalt oxide
  • NMP N-methylpyrrolidone
  • the positive electrode, negative electrode and PE separator prepared above are used to make a battery cell, which is then packaged with polymer and filled with the lithium secondary battery electrolyte prepared in Comparative Example 1. After formation and other processes, a 4Ah soft-pack lithium secondary battery is made.
  • ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) are mixed to form an organic solvent.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • PP propyl propionate
  • LiPF6 lithium hexafluorophosphate
  • LiDFOB lithium difluorooxalate borate
  • N,N-dimethyltrifluoromethanesulfonamide (I), fluoroethylene carbonate (FEC), and 1,3-propanesulfonate lactone (PS) are added to the solution and mixed thoroughly to obtain a lithium secondary battery electrolyte (Comparative Example 2).
  • the concentration of LiPF6 was 1.0 mol/L
  • the concentration of LiDFOB was 0.05 mol/L
  • the mass percentages of EC, DEC, PC and PP in the electrolyte were 15%, 20%, 12.5% and 30%, respectively.
  • the mass percentages of N,N-dimethyltrifluoromethylsulfonamide (I), FEC and PS in the electrolyte were 2%, 5% and 3%, respectively.
  • N,N-dimethyl-trifluoromethylsulfonamide (I) is:
  • Lithium secondary batteries were prepared using the lithium secondary battery electrolyte prepared in Comparative Example 2, and the preparation method was the same as that in Comparative Example 1.
  • ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) are mixed to form an organic solvent.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • PP propyl propionate
  • LiPF6 lithium hexafluorophosphate
  • LiDFOB lithium difluorooxalate borate
  • N,N-dimethyltrifluoromethanesulfonamide, succinate (SN), fluoroethylene carbonate (FEC), and 1,3-propanesulfonate lactone (PS) are added to the solution and mixed thoroughly to obtain a lithium secondary battery electrolyte (Comparative Example 3).
  • the concentration of LiPF6 was 1.0 mol/L
  • the concentration of LiDFOB was 0.05 mol/L
  • the mass percentages of EC, DEC, PC, and PP in the electrolyte were 15%, 20%, 12.5%, and 30%, respectively.
  • the mass percentages of N,N-dimethyltrifluoromethanesulfonamide (I), succinate (SN), FEC, and PS in the electrolyte were 1%, 1%, 5%, and 3%, respectively.
  • N,N-dimethyl-trifluoromethylsulfonamide (I) is:
  • a lithium secondary battery was prepared using the lithium secondary battery electrolyte prepared in Comparative Example 3, and the preparation method was the same as that in Comparative Example 1.
  • ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) are mixed to form an organic solvent.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • PP propyl propionate
  • LiPF6 lithium hexafluorophosphate
  • LiDFOB lithium difluorooxalate borate
  • 1,2-bis(2-cyanoethoxy)ethane (DENE), fluoroethylene carbonate (FEC), and 1,3-propanesulfonate lactone (PS) are added to the solution and mixed thoroughly to obtain a lithium secondary battery electrolyte (Comparative Example 4).
  • the concentration of LiPF6 is 1.0 mol/L
  • the concentration of LiDFOB is 0.05 mol/L
  • the mass percentages of EC, DEC, PC, and PP in the electrolyte are 15%, 20%, 12.5%, and 30%, respectively.
  • the mass percentages of DENE, FEC, and PS in the electrolyte are 2%, 5%, and 3%, respectively.
  • the lithium secondary battery is prepared by the following method: 2% polyvinylidene fluoride (PVDF), 2% conductive agent super P and 96% lithium cobalt oxide ( LiCoO2 ) are weighed and added to N-methylpyrrolidone (NMP) in sequence. The mixture is stirred and mixed evenly. The slurry is coated on aluminum foil current collector, dried, cold pressed and slit to obtain the positive electrode sheet.
  • PVDF polyvinylidene fluoride
  • LiCoO2 lithium cobalt oxide
  • NMP N-methylpyrrolidone
  • the positive electrode, negative electrode and PE separator prepared above are used to make a battery cell, which is then packaged with polymer and filled with the lithium secondary battery electrolyte prepared in Comparative Example 1. After formation and other processes, a 4Ah soft-pack lithium secondary battery is made.
  • ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) are mixed to form an organic solvent.
  • LiPF6 lithium hexafluorophosphate
  • LiDFOB lithium difluorooxalate borate
  • J N,N-dimethyl-fluorosulfonamide
  • FEC fluoroethylene carbonate
  • PS 1,3-propanesulfonate lactone
  • the concentration of LiPF6 was 1.0 mol/L
  • the concentration of LiDFOB was 0.05 mol/L
  • the mass percentages of EC, DEC, PC and PP in the electrolyte were 15%, 20%, 12.5% and 30%, respectively.
  • the mass percentages of N,N-dimethyl-fluorosulfonamide (J), FEC and PS in the electrolyte were 2%, 5% and 3%, respectively.
  • a lithium secondary battery was prepared using the lithium secondary battery electrolyte prepared in Comparative Example 5, and the preparation method was the same as that in Comparative Example 4.
  • ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) are mixed to form an organic solvent.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • PP propyl propionate
  • LiPF6 lithium hexafluorophosphate
  • LiDFOB lithium difluorooxalate borate
  • N,N-dimethyl-fluorosulfonamide (J), 1,2-bis(2-cyanoethoxy)ethane (DENE), fluoroethylene carbonate (FEC), and 1,3-propanesulfonate lactone (PS) are added to the solution and mixed thoroughly to obtain a lithium secondary battery electrolyte (Comparative Example 6).
  • the concentration of LiPF6 was 1.0 mol/L
  • the concentration of LiDFOB was 0.05 mol/L
  • the mass percentages of EC, DEC, PC and PP in the electrolyte were 15%, 18%, 12.5% and 30%, respectively.
  • the mass percentages of N,N-dimethyl-fluorosulfonamide (J), DENE, FEC and PS in the electrolyte were 2%, 2%, 5% and 3%, respectively.
  • Lithium secondary batteries were prepared using the lithium secondary battery electrolyte prepared in Comparative Example 6, and the preparation method was the same as that in Comparative Example 4.
  • ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) are mixed to form an organic solvent.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • PP propyl propionate
  • LiPF6 lithium hexafluorophosphate
  • LiDFOB lithium difluorooxalate borate
  • a lithium secondary battery was prepared using the lithium secondary battery electrolyte prepared in Comparative Example 7, and the preparation method was the same as that in Comparative Example 4.
  • ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), and propyl propionate (PP) are mixed to form an organic solvent.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • PP propyl propionate
  • LiPF6 lithium hexafluorophosphate
  • LiDFOB lithium difluorooxalate borate
  • J N,N-dimethyl-fluorosulfonamide
  • VC vinylene carbonate
  • DTD vinyl sulfate
  • the concentration of LiPF6 is 1.0 mol/L
  • the concentration of LiDFOB is 0.05 mol/L
  • the mass percentages of EC, DEC, PC, and PP in the electrolyte are 15%, 20%, 12.5%, and 30%, respectively.
  • the mass percentages of N,N-dimethyl-fluorosulfonamide (J), VC, and DTD in the electrolyte are 2%, 5%, and 3%, respectively.
  • a lithium secondary battery was prepared using the lithium secondary battery electrolyte prepared in Comparative Example 8, and the preparation method was the same as that in Comparative Example 4.
  • the capacity retention rate (%) discharge capacity of the 300th cycle / discharge capacity of the 1st cycle ⁇ 100%.
  • capacity retention rate (%) remaining capacity / initial capacity ⁇ 100%.
  • the lithium secondary batteries in Examples 1-2 of this application exhibit a 25°C cycle capacity retention rate of 86.1%-86.3% and a 60°C storage capacity retention rate of 91.3%-91.8%. Both are higher than the 25°C cycle capacity retention rate (81.4%-83.4%) and 60°C storage capacity retention rate (85.1%-86.6%) of the lithium secondary batteries in Comparative Examples 1-3. Therefore, it can be demonstrated that using the electrolyte additive provided in the embodiments of this application can significantly improve the battery's cycle performance and high-temperature storage performance.
  • electrolyte additive A has a trifluoromethyl substituent group at one end. This group can form a film on the surfaces of the positive electrode material LCO and the graphite negative electrode, creating a stable interfacial film containing compounds such as lithium fluoride, lithium nitride, and sulfides. This reduces side reactions in contact between the electrolyte and the positive and negative electrodes, improving the battery's coulombic efficiency and cycle performance.
  • electrolyte additive A includes a nitrile group (-CN), which can complex with Co ions in the positive electrode material LCO, inhibiting the dissolution of transition metal ions and further oxidative decomposition of the electrolyte, thus improving the high-voltage stability of the electrolyte and enhancing the battery's high-temperature storage and cycle performance.
  • -CN nitrile group
  • Comparative Example 1 While the succinic anion (SN) used in Comparative Example 1 can complex with Co ions in the LCO cathode material, it cannot form a stable interfacial film.
  • N,N-dimethyltrifluoromethanesulfonamide (I) can form an interfacial film on both the positive and negative electrode surfaces, but it lacks nitrile groups and cannot complex with Co ions in the LCO cathode material, thus failing to effectively inhibit the dissolution of transition metal ions and reducing the stability of the interfacial film.
  • Comparative Example 3 uses a combination of N,N-dimethyltrifluoromethanesulfonamide and succinic anion; the use of multiple additives in combination increases battery impedance. Furthermore, competitive chemical/electrochemical reactions exist between different additives, reducing the stability of the interfacial film. Therefore, the batteries corresponding to Comparative Examples 1-3 exhibit poor high-temperature storage performance and cycle performance.
  • the lithium secondary batteries in Examples 3-10 of this application exhibit a 25°C cycle capacity retention rate of 84.1%-85.9% and a 60°C storage capacity retention rate of 87.2%-91.1%. Both are higher than the 25°C cycle capacity retention rate (79.9%-82.1%) and 60°C storage capacity retention rate (81.9%-84.7%) of the lithium secondary batteries in Comparative Examples 4-7. This indicates that the electrolyte additive of this application can significantly improve the battery's cycle performance and high-temperature storage performance.
  • the electrolyte additive F has a fluorine-substituted group at one end.
  • This group can form a film on the surface of the positive electrode material LCO and the silicon-carbon negative electrode, creating a stable interfacial film containing compounds such as lithium fluoride, lithium nitride, and sulfides. This reduces side reactions between the electrolyte and the positive and negative electrodes, improving the battery's coulombic efficiency and cycle performance.
  • the electrolyte additive F includes a nitrile group, which can complex with Co ions in the positive electrode material LCO, inhibiting the dissolution of transition metal ions and further oxidative decomposition of the electrolyte, thus improving the high-voltage stability of the electrolyte and enhancing the battery's high-temperature storage and cycle performance.
  • the lithium secondary battery in Example 4 of this application has a cycle capacity retention rate of 85.6% at 25°C and a storage capacity retention rate of 90.8% at 60°C. Both are higher than the cycle capacity retention rate (82.1%) and storage capacity retention rate (84.2%) of the lithium secondary battery in Comparative Example 6.
  • Example 4 is the same as Example 3 above, except that the electrolyte additive F has a fluorine-substituted group at one end and a cyano group at the other end. This improves the high-voltage stability of the electrolyte and forms a highly stable interfacial film on the positive and negative electrode surfaces, thereby improving the battery's high-temperature storage performance and cycle performance.
  • Comparative Example 6 uses N,N-dimethyl-fluorosulfonamide and 1,2-di(2-cyanoethoxy)ethane. The combination of multiple additives increases battery impedance. Furthermore, competitive chemical/electrochemical reactions occur between different additives, reducing the stability of the interfacial film. Therefore, the battery in Comparative Example 6 exhibits poor high-temperature storage performance and cycle performance.
  • the lithium secondary battery in Example 7 of this application has a cycle capacity retention rate of 85.9% at 25°C and a storage capacity retention rate of 91.1% at 60°C. Both are higher than the cycle capacity retention rate (81.8%) and storage capacity retention rate (84.7%) of the lithium secondary battery in Comparative Example 7.
  • electrolyte additive A and electrolyte additive F are combined. These two additives do not react chemically, do not increase battery impedance, and simultaneously improve the high-voltage stability of the electrolyte, forming a highly stable interface film on the positive and negative electrode surfaces. This improves the battery's high-temperature storage performance and cycle performance.
  • Comparative Example 7 uses succinate (SN) and 1,2-bis(2-cyanoethoxy)ethane, which can complex with Co ions in the cathode material LCO to inhibit the dissolution of transition metal ions, but cannot form a highly stable solid electrolyte interface film.
  • the lithium secondary battery in Example 9 of this application has a cycle capacity retention rate of 84.1% at 25°C and a storage capacity retention rate of 87.2% at 60°C. Both are higher than the cycle capacity retention rate (83.6%) and storage capacity retention rate (86.8%) of the lithium secondary battery in Example 11.
  • the mass ratio of electrolyte additive G to cyclic carbonate (EC+PC) is 0.01:1, which falls within the suitable range of 0.01:1 to 0.5:1, preventing the generation of large amounts of gas through reactions between the electrolyte and the positive and negative electrodes. Simultaneously, it can interact with complexed Co ions, effectively inhibiting the dissolution of transition metal ions and forming a highly stable, highly conductive interfacial film at the positive and negative electrodes. This improves the battery's high-temperature storage performance and cycle performance.
  • the lithium secondary battery in Example 10 of this application has a cycle capacity retention rate of 84.8% at 25°C and a storage capacity retention rate of 88.7% at 60°C. Both are higher than the lithium secondary battery in Example 12, which has a cycle capacity retention rate of 83.9% at 25°C and a storage capacity retention rate of 87.1% at 60°C.
  • the mass ratio of electrolyte additive G to cyclic carbonate is 0.5:1, which falls within the suitable range of 0.01:1 to 0.5:1. This ensures an appropriate content of cyclic carbonate in the electrolyte, preventing excessive electrolyte viscosity. Simultaneously, it facilitates the formation of a highly stable interfacial film on the electrode surface by the electrolyte additive, thereby improving the battery's cycle performance and high-temperature storage performance.
  • the lithium secondary battery in Example 13 of this application has a cycle capacity retention rate of 84.9% at 25°C and a storage capacity retention rate of 89.5% at 60°C. Both are higher than the cycle capacity retention rate (78.8%) and storage capacity retention rate (81.1%) of the lithium secondary battery in Comparative Example 8.
  • the electrolyte additive F has a fluorine-substituted group at one end. This group can form a stable interfacial film on the surfaces of the positive electrode material LCO and the silicon-carbon negative electrode, reducing side reactions between the electrolyte and the positive and negative electrodes, and improving the battery's coulombic efficiency and cycle performance.
  • the electrolyte additive F includes a nitrile group, which can complex with Co ions in the positive electrode material LCO, inhibiting the dissolution of transition metal ions and further oxidative decomposition of the electrolyte, thus improving the high-voltage stability of the electrolyte and enhancing the battery's high-temperature storage and cycle performance.
  • Comparative Example 8 uses N,N-dimethyl-fluorosulfonamide (J), which, although able to form an interfacial film on the positive and negative electrode surfaces, does not contain a nitrile group and cannot complex with Co ions in the positive electrode material LCO. Therefore, it cannot effectively inhibit the dissolution of transition metal ions and reduces the stability of the interfacial film.
  • J N,N-dimethyl-fluorosulfonamide
  • the electrolyte additives used in Example 3 were electrolyte additive F, fluoroethylene carbonate (FEC), and 1,3-propanesulfonic acid lactone (PS).
  • the electrolyte additives used in Example 13 were electrolyte additive F, vinylene carbonate (VC), and ethylene sulfate (DTD).
  • the lithium secondary batteries corresponding to Examples 3 and 13 both exhibited high 25°C cycle capacity retention and 60°C storage capacity retention.
  • the first and/or second additives proposed in this application can be combined with other types of electrolyte additives to improve the high-temperature storage performance and cycle performance of the battery.
  • This application also provides a secondary battery, including a positive electrode, a negative electrode, a separator located between the positive electrode and the negative electrode, and the electrolyte described above, with the electrolyte filling the space between the positive electrode and the negative electrode.
  • secondary batteries may include lithium secondary batteries, potassium secondary batteries, sodium secondary batteries, magnesium secondary batteries, zinc secondary batteries, or aluminum secondary batteries.
  • This application also provides an electronic device, which includes a housing, electronic components and a battery housed within the housing, wherein the battery powers the electronic components and includes the aforementioned secondary battery.
  • the electronic device can be, for example, a mobile phone 1100, and may also include a smart screen, tablet computer, personal computer (PC), personal digital assistant (PDA), smartwatch, power bank, netbook, wearable device, augmented reality (AR) device, virtual reality (VR) device, in-vehicle device, energy storage device, base station, and automobile, etc.
  • a smart screen tablet computer
  • PC personal computer
  • PDA personal digital assistant
  • smartwatch smartwatch
  • power bank netbook
  • wearable device augmented reality (AR) device
  • VR virtual reality
  • in-vehicle device energy storage device
  • base station and automobile, etc.
  • AR augmented reality
  • VR virtual reality
  • multiple embodiments of this application can be combined, and the combined solution can be implemented.
  • some operations in the processes of each method embodiment may be combined, and/or the order of some operations may be changed.
  • the execution order between the steps of each process is merely exemplary and does not constitute a limitation on the execution order between steps; other execution orders are also possible. It is not intended to indicate that the execution order is the only possible order in which these operations can be performed.
  • steps in the method embodiments can be equivalently replaced with other possible steps.
  • some steps in the method embodiments may be optional and can be deleted in certain use cases.
  • other possible steps may be added to the method embodiments.

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Abstract

Des modes de réalisation de la présente demande se rapportent au domaine technique des batteries. L'invention concerne un additif électrolytique et son procédé de préparation, une batterie secondaire et un dispositif électronique. L'additif électrolytique comprend non seulement des atomes de fluor ou un substituant contenant du fluor, mais également un groupe cyano, et peut être utilisé pour générer un film d'interface d'électrolyte solide ayant des composants inorganiques riches. La conductivité ionique et la stabilité du film d'interface d'électrolyte solide sont améliorées. Ainsi, les performances de cycle et les performances de stockage à haute température de batteries peuvent être améliorées en conséquence.
PCT/CN2025/098149 2024-06-07 2025-05-29 Additif électrolytique et son procédé de préparation, batterie secondaire et dispositif électronique Pending WO2025252004A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101997139A (zh) * 2009-08-21 2011-03-30 索尼公司 电解质和电池
CN103996871A (zh) * 2013-02-15 2014-08-20 索尼公司 电解液、非水二次电池、电池组、电动车辆、蓄电系统
KR20210074150A (ko) * 2019-12-11 2021-06-21 주식회사 앤아이씨연구소 이미노디아세토니트릴 첨가제, 이를 포함하는 리튬 이차전지 전해액 및 리튬 이차전지
CN114639873A (zh) * 2020-12-16 2022-06-17 华为技术有限公司 电池电解液、二次电池和终端
CN119153793A (zh) * 2024-11-14 2024-12-17 烟台力华电源科技有限公司 一种含有氰基磺酰胺化合物的锂离子电池电解液和锂离子二次电池

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101997139A (zh) * 2009-08-21 2011-03-30 索尼公司 电解质和电池
CN103996871A (zh) * 2013-02-15 2014-08-20 索尼公司 电解液、非水二次电池、电池组、电动车辆、蓄电系统
KR20210074150A (ko) * 2019-12-11 2021-06-21 주식회사 앤아이씨연구소 이미노디아세토니트릴 첨가제, 이를 포함하는 리튬 이차전지 전해액 및 리튬 이차전지
CN114639873A (zh) * 2020-12-16 2022-06-17 华为技术有限公司 电池电解液、二次电池和终端
CN119153793A (zh) * 2024-11-14 2024-12-17 烟台力华电源科技有限公司 一种含有氰基磺酰胺化合物的锂离子电池电解液和锂离子二次电池

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