WO2025200816A1 - 一种电解液、锂离子二次电池、电池模块、电池包及电子装置 - Google Patents

一种电解液、锂离子二次电池、电池模块、电池包及电子装置

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Publication number
WO2025200816A1
WO2025200816A1 PCT/CN2025/076932 CN2025076932W WO2025200816A1 WO 2025200816 A1 WO2025200816 A1 WO 2025200816A1 CN 2025076932 W CN2025076932 W CN 2025076932W WO 2025200816 A1 WO2025200816 A1 WO 2025200816A1
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WO
WIPO (PCT)
Prior art keywords
component
lithium
electrolyte
mass percentage
mass
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/CN2025/076932
Other languages
English (en)
French (fr)
Inventor
张丽兰
彭谢学
刘俊飞
唐超
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ningde Amperex Technology Ltd
Original Assignee
Ningde Amperex Technology Ltd
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Filing date
Publication date
Application filed by Ningde Amperex Technology Ltd filed Critical Ningde Amperex Technology Ltd
Publication of WO2025200816A1 publication Critical patent/WO2025200816A1/zh
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
    • H01M10/056—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
    • H01M10/05—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
    • H01M10/0568—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
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • H01M2300/0037—Mixture of 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

  • the first aspect of the present application provides an electrolyte comprising a first component and a second component.
  • the first component comprises ethyl methyl carbonate and ethylene carbonate. Based on the mass of the electrolyte, the mass percentage of ethyl methyl carbonate is W1 %, the mass percentage of ethylene carbonate is W2 %, and the mass percentage of the first component is W%, 60 ⁇ W ⁇ 88, 1.14 ⁇ W1 / W2 ⁇ 1.93 .
  • the second component comprises lithium tetrafluoroborate and lithium difluorophosphate.
  • the mass percentage of lithium tetrafluoroborate is m1 %
  • the mass percentage of lithium difluorophosphate is m2
  • the mass percentage of the second component is m%, 0.03 ⁇ m ⁇ 1.5, 0.1 ⁇ m1 / m2 ⁇ 25 .
  • 75 ⁇ W ⁇ 88 75 ⁇ W ⁇ 88.
  • the electrolyte further includes a third component, the third component including at least one of diethyl sulfate or triphenyl phosphate, and the mass percentage of the third component is a ppm based on the mass of the electrolyte, 10 ⁇ a ⁇ 1000.
  • the electrolyte includes the third component within the above range and regulates the mass percentage of the third component a ppm within the above range, which can further enrich the components of the solid electrolyte interface film (SEI film) at the negative electrode interface, enhance the stability of the negative electrode interface, and further improve the safety performance and high-temperature cycle performance of the lithium-ion secondary battery.
  • SEI film solid electrolyte interface film
  • the electrolyte further includes a fourth component, the fourth component including at least one of triphenyl phosphite, triethyl phosphate, trimethyl phosphate, or vinyl sulfate, and the mass percentage of the fourth component is b%, based on the mass of the electrolyte, 0.1 ⁇ b ⁇ 1.1.
  • the electrolyte includes the fourth component within the above range and regulates the mass percentage b% of the fourth component within the above range.
  • the fourth component can form a stable interface at the positive electrode, increase the proportion of sulfide and/or phosphide in the positive electrode electrolyte interface film (CEI film), enhance the oxidation resistance of the positive electrode interface, and further improve the safety performance and high temperature cycle performance of the lithium-ion secondary battery.
  • CEI film positive electrode electrolyte interface film
  • the electrolyte further includes a fifth component, the fifth component including a fluorine-containing inorganic salt; based on the mass of the electrolyte, the mass percentage content of the fifth component is c ppm, 2 ⁇ c ⁇ 500.
  • the electrolyte including the fifth component within the above range and regulating the mass percentage content of the fifth component c ppm within the above range facilitates timely repair of damaged SEI films, reduces the probability of thermal runaway, and further improves the safety performance and high-temperature cycling performance of lithium-ion secondary batteries.
  • the fifth component includes at least one of magnesium fluoride, potassium fluoride, calcium fluoride, lithium fluoride, sodium fluoride, silicon fluoride, iron fluoride, or zirconium fluoride.
  • the electrolyte including the fifth component within the above range facilitates timely repair of damaged SEI films, reduces the probability of thermal runaway, and further improves the safety and high-temperature cycling performance of lithium-ion secondary batteries.
  • the electrolyte further includes at least one of a third component, a fourth component, or a fifth component
  • the third component includes at least one of diethyl sulfate or triphenyl phosphate
  • the mass percentage of the third component based on the mass of the electrolyte is a ppm
  • the fourth component includes at least one of triphenyl phosphite, triethyl phosphate, trimethyl phosphate, or vinyl sulfate
  • the mass percentage of the fourth component based on the mass of the electrolyte is b%
  • the fifth component includes at least one of magnesium fluoride, potassium fluoride, calcium fluoride, lithium fluoride, sodium fluoride, silicon fluoride, iron fluoride, or zirconium fluoride
  • the mass percentage of the fifth component based on the mass of the electrolyte is c ppm
  • the electrolyte satisfies at least one of the following characteristics: (1) 50 ⁇ a
  • the second aspect of the present application provides a lithium-ion secondary battery comprising a positive electrode, a negative electrode, a separator disposed between the positive and negative electrodes, and the electrolyte provided by the first aspect of the present application.
  • the positive electrode comprises a lithium-cobalt composite oxide, wherein the lithium-cobalt composite oxide includes at least three doping elements selected from aluminum, magnesium, titanium, zirconium, lanthanum, iridium, cerium, tungsten, zinc, nickel, manganese, boron, phosphorus, silicon, gallium, indium, and cesium; and the mass percentage of any one of the doping elements is 0.01% to 1% based on the mass of the lithium-cobalt composite oxide.
  • the positive electrode comprising the lithium-cobalt composite oxide within the aforementioned range and regulating the mass percentage of any one of the doping elements within the aforementioned range is beneficial for improving the structural stability of the lithium-cobalt composite oxide in a highly delithiated state.
  • a third aspect of the present application provides a battery module, which includes the lithium-ion secondary battery provided in the second aspect of the present application.
  • a fourth aspect of the present application provides a battery pack, which includes the battery module provided in the third aspect of the present application.
  • the fifth aspect of the present application provides an electronic device, which includes the lithium-ion secondary battery provided by the second aspect of the present application, the battery module provided by the third aspect of the present application, or the battery pack provided by the fourth aspect of the present application.
  • the present application provides an electrolyte, a lithium-ion secondary battery, a battery module, a battery pack, and an electronic device.
  • the electrolyte includes a first component and a second component.
  • the first component includes ethyl methyl carbonate and ethylene carbonate. Based on the mass of the electrolyte, the mass percentage of ethyl methyl carbonate is W1 %, the mass percentage of ethylene carbonate is W2 %, and the mass percentage of the first component is W%, 60 ⁇ W ⁇ 88, 1.14 ⁇ W1 / W2 ⁇ 1.93 .
  • the second component includes lithium tetrafluoroborate and lithium difluorophosphate.
  • the mass percentage of lithium tetrafluoroborate is m1 %
  • the mass percentage of lithium difluorophosphate is m2 %
  • the mass percentage of the second component is m%, 0.03 ⁇ m ⁇ 1.5, 0.1 ⁇ m1 / m2 ⁇ 25 .
  • the present application provides an electrolyte comprising a first component and a second component.
  • the first component comprises ethyl methyl carbonate and ethylene carbonate.
  • the mass percentage of ethyl methyl carbonate is W 1 %
  • the mass percentage of ethylene carbonate is W 2 %
  • the mass percentage of the first component is W%, 60 ⁇ W ⁇ 88, 1.14 ⁇ W 1 /W 2 ⁇ 1.93.
  • the mass percentage W% of the first component can be 60%, 63%, 65%, 68%, 70%, 73%, 75%, 78%, 80%, 83%, 85%, 88% or a range consisting of any two of the values therein.
  • the value of W 1 /W 2 can be 1.14, 1.20, 1.30, 1.40, 1.50, 1.60, 1.70, 1.80, 1.90, 1.93 or a range consisting of any two of the values therein.
  • the second component includes lithium tetrafluoroborate and lithium difluorophosphate. Based on the mass of the electrolyte, the mass percentage of lithium tetrafluoroborate is m 1 , the mass percentage of lithium difluorophosphate is m 2 , and the mass percentage of the second component is m %, 0.03 ⁇ m ⁇ 1.5, and 0.1 ⁇ m 1 /m 2 ⁇ 25.
  • the mass percentage of the second component m % can be 0.03%, 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.3%, 1.5%, or a range consisting of any two thereof.
  • the mass percentage of m 1 /m 2 can be 0.1, 1, 3, 5, 8, 10, 13, 15, 18, 20, 23, 25, or a range consisting of any two thereof.
  • the highly stable negative electrode interface can inhibit the reaction of the electrolyte at the negative electrode, reduce the temperature rise inside the lithium-ion secondary battery, delay the failure time of the lithium-ion secondary battery, and improve the safety performance of the lithium-ion secondary battery.
  • lithium tetrafluoroborate and lithium difluorophosphate can be simultaneously introducing lithium tetrafluoroborate and lithium difluorophosphate into the electrolyte, lithium tetrafluoroborate can be reduced at the positive and negative electrode interfaces before the solvent, further improving the stability of the positive and negative electrode interfaces.
  • lithium tetrafluoroborate can increase the interfacial impedance.
  • the introduction of lithium difluorophosphate can weaken the effect of lithium tetrafluoroborate on the interfacial impedance of the positive and negative electrodes.
  • the two work synergistically to further improve the interfacial stability of the positive and negative electrodes while also reducing the effect of lithium tetrafluoroborate on the interfacial impedance, thereby further improving the safety and high-temperature cycling performance of the lithium-ion secondary battery.
  • the mass percentage W% of the first component is too low, for example, less than 60%, the content of ethyl methyl carbonate and ethylene carbonate is low, and the negative electrode interface stability cannot be effectively improved.
  • the film formation reaction of lithium tetrafluoroborate on the interface is too weak, failing to effectively improve interface stability.
  • the m 1 /m 2 ratio is too large, for example, greater than 25, the lithium difluorophosphate content is too low, failing to effectively alleviate the high interfacial impedance caused by lithium tetrafluoroborate, affecting the cycle performance of lithium-ion secondary batteries.
  • the electrolyte includes ethyl methyl carbonate and ethylene carbonate as first components, and lithium tetrafluoroborate and lithium difluorophosphate as second components, and the mass percentage W and W1 / W2 of the first component, and the mass percentage m and m1 / m2 of the second component are regulated within the ranges of this application, the safety performance and high-temperature cycle performance of the lithium-ion secondary battery can be improved.
  • high temperature generally refers to a temperature greater than or equal to 30°C.
  • the mass percentage content W 1 % of ethyl methyl carbonate may be 32%, 35%, 38%, 40%, 43%, 45%, 48%, 50%, 53%, 55%, 58%, or a range consisting of any two values thereof
  • the mass percentage content m 1 % of lithium tetrafluoroborate may be 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.8%, 1%, 1.2%, 1.4%, or a range consisting of any two values thereof.
  • the safety performance and high-temperature cycle performance of the lithium-ion secondary battery can be further improved.
  • 21 ⁇ W 2 ⁇ 41 the mass percentage content W 2 % of ethylene carbonate can be 21%, 25%, 28%, 30%, 32%, 35%, 38%, 41%, or a range consisting of any two of these values.
  • the safety performance and high-temperature cycle performance of the lithium-ion secondary battery can be further improved.
  • the mass percentage content m 2 of lithium difluorophosphate can be 0.01, 0.05, 0.1, 0.5, 0.8, 1, 1.3, or a range consisting of any two of these values.
  • the safety performance and high-temperature cycle performance of the lithium-ion secondary battery can be further improved.
  • the electrolyte further includes a third component
  • the third component includes at least one of diethyl sulfate or triphenyl phosphate
  • the mass percentage of the third component is a ppm based on the mass of the electrolyte, 10 ⁇ a ⁇ 1000.
  • 50 ⁇ a ⁇ 500 the mass percentage of the third component a ppm can be 10ppm, 50ppm, 100ppm, 200ppm, 300ppm, 400ppm, 500ppm, 600ppm, 700ppm, 800ppm, 900ppm, 1000ppm or a range consisting of any two values therein.
  • the electrolyte includes the third component within the above range and regulates the mass percentage of the third component a ppm within the above range, which can further enrich the components of the solid electrolyte interface film (SEI film) at the negative electrode interface, improve the stability of the negative electrode interface, and further improve the safety performance and high-temperature cycle performance of the lithium-ion secondary battery.
  • SEI film solid electrolyte interface film
  • the electrolyte further includes a fourth component, the fourth component including at least one of triphenyl phosphite, triethyl phosphate, trimethyl phosphate or vinyl sulfate, and the mass percentage of the fourth component is b%, 0.1 ⁇ b ⁇ 1.1 based on the mass of the electrolyte. In some embodiments of the present application, 0.21 ⁇ b ⁇ 0.55.
  • the mass percentage b% of the fourth component can be 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.1% or a range consisting of any two values therein.
  • the electrolyte includes the fourth component within the above range and regulates the mass percentage b% of the fourth component within the above range.
  • the electrolyte includes a first component, a second component, and at least one of a third component, a fourth component, and a fifth component.
  • the second aspect of the present application provides a lithium-ion secondary battery comprising a positive electrode, a negative electrode, a separator between the positive electrode and the negative electrode, and the electrolyte provided by the first aspect of the present application, wherein the positive electrode comprises a positive electrode active material, the positive electrode active material comprises a lithium cobalt composite oxide, the lithium cobalt composite oxide comprises at least three doping elements selected from aluminum, magnesium, titanium, zirconium, lanthanum, iridium, cerium, tungsten, zinc, nickel, manganese, boron, phosphorus, silicon, gallium, indium, and cesium; based on the mass of the lithium cobalt composite oxide, the mass percentage of any one of the doping elements is 0.01% to 1%.
  • the mass percentage of any one of the doping elements can be 0.01%, 0.05%, 0.1%, 0.3%, 0.5%, 0.8%, 1%, or a range consisting of any two of these values.
  • the positive electrode comprises a lithium cobalt composite oxide within the above range and the mass percentage of any one of the doping elements is regulated within the above range, which is beneficial for improving the structural stability of the lithium cobalt composite oxide in a highly delithiated state.
  • the present application does not particularly limit the preparation method of the above-mentioned lithium cobalt composite oxide positive electrode active material containing doping elements, as long as the purpose of the present application can be achieved.
  • the preparation method of the lithium cobalt composite oxide positive electrode active material containing doping elements may include but is not limited to the following steps: mixing the lithium cobalt composite oxide with a compound containing the doping element, and then heat-treating it in an oxygen atmosphere or air atmosphere to obtain a lithium cobalt composite oxide containing the doping element.
  • the lithium cobalt composite oxide may include but is not limited to at least one of lithium nickel cobalt manganese oxide (NCM811, NCM622, NCM523, NCM111), lithium nickel cobalt aluminum oxide, or lithium cobalt oxide ( LiCoO2 ).
  • the doping element is aluminum, magnesium, titanium, zirconium, lanthanum, iridium, cerium, tungsten, zinc, nickel, manganese, boron, phosphorus, silicon, gallium, indium, or cesium
  • the corresponding oxide containing the doping element, hydroxide containing the doping element, and carbonate compound containing the doping element may be added, and the selection can be based on actual needs, as long as the purpose of the present application can be achieved.
  • the positive electrode of the present application includes a positive electrode current collector and a positive electrode material layer arranged on at least one surface of the positive electrode current collector, and the positive electrode material layer includes the above-mentioned positive electrode active material.
  • the present application has no special restrictions on the positive electrode current collector, as long as the purpose of the present application can be achieved.
  • the positive electrode current collector may include aluminum foil, aluminum alloy foil or a composite current collector (such as an aluminum-carbon composite current collector), etc.
  • there is no special restriction on the thickness of the positive electrode current collector and the positive electrode material layer as long as the purpose of the present application can be achieved.
  • the thickness of the positive electrode current collector is 5 ⁇ m to 20 ⁇ m.
  • the thickness of the single-sided positive electrode material layer is 30 ⁇ m to 120 ⁇ m.
  • the positive electrode material layer can be arranged on one surface in the thickness direction of the positive electrode current collector, or on two surfaces in the thickness direction of the positive electrode current collector. It should be noted that the "surface" here can be the entire area of the positive electrode current collector or a partial area of the positive electrode current collector.
  • the positive electrode material may also include other positive electrode active materials, such as lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, etc.
  • the above-mentioned carbon fibers may include but are not limited to vapor-grown carbon fibers (VGCF) and/or nano-carbon fibers.
  • the above-mentioned metal materials may include but are not limited to metal powder and/or metal fibers. Specifically, the metal may include but is not limited to at least one of copper, nickel, aluminum or silver.
  • the above-mentioned conductive polymers may include but are not limited to at least one of polyphenylene derivatives, polyaniline, polythiophene, polyacetylene or polypyrrole.
  • the binder may include, but is not limited to, at least one of polyacrylic acid, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyimide, polyvinyl alcohol, carboxymethyl cellulose, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, polyimide, polyamideimide, styrene-butadiene rubber, or polyvinylidene fluoride.
  • the negative electrode includes a negative electrode current collector and a negative electrode material layer arranged on at least one surface of the negative electrode current collector.
  • the negative electrode material layer can be arranged on one surface in the thickness direction of the negative electrode current collector, or on two surfaces in the thickness direction of the negative electrode current collector.
  • the "surface" here can be the entire area of the negative electrode current collector, or it can be a partial area of the negative electrode current collector.
  • the present application has no special restrictions, as long as the purpose of the present application can be achieved.
  • the present application has no special restrictions on the negative electrode current collector, as long as the purpose of the present application can be achieved.
  • the negative electrode current collector can include but is not limited to copper foil, copper alloy foil, nickel foil, titanium foil, foam nickel, foam copper or composite current collector, etc.
  • the negative electrode material layer of the present application includes a negative electrode active material.
  • the present application has no special restrictions on the type of negative electrode active material, as long as the purpose of the present application can be achieved.
  • the negative electrode active material may include, but is not limited to, at least one of natural graphite, artificial graphite, mesophase microcarbon beads (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, SiO x (0 ⁇ x ⁇ 2) or metallic lithium.
  • the thickness of the negative electrode current collector and the negative electrode material layer there is no particular restriction on the thickness of the negative electrode current collector and the negative electrode material layer, as long as the purpose of the present application can be achieved.
  • the thickness of the negative electrode current collector is 4 ⁇ m to 15 ⁇ m
  • the thickness of the single-sided negative electrode material layer is 30 ⁇ m to 130 ⁇ m.
  • the negative electrode material layer of the present application may also include a conductive agent and a binder.
  • the present application has no particular restrictions on the conductive agent and the binder, as long as the purpose of the present application can be achieved.
  • the binder and the conductive agent may include, but are not limited to, at least one of the above-mentioned conductive agent and the above-mentioned binder.
  • the material of the isolation membrane may include but is not limited to polyethylene (PE), polypropylene (PP)-based polyolefins (PO), polyesters (such as polyethylene terephthalate (PET) film), cellulose, polyimide (PI), polyamide (PA), spandex or aramid.
  • the type of isolation membrane may include at least one of a woven membrane, a non-woven membrane (non-woven fabric), a microporous membrane, a composite membrane, a rolled membrane or a spun membrane.
  • the diaphragm of the present application may have a porous structure, and the porous layer is provided on at least one surface of the diaphragm, and the porous layer includes inorganic particles and a binder.
  • the inorganic particles may include at least one of aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide or barium sulfate.
  • the lithium-ion secondary battery of the present application further includes a housing, which may be a hard shell or a flexible shell.
  • the hard shell may be made of a metal.
  • the present application does not limit the type of metal; any metal hard shell known in the art may be used as long as the purpose of the present application is achieved.
  • the flexible shell may be a metal plastic film, such as an aluminum plastic film or a steel plastic film.
  • the preparation process of the lithium-ion secondary battery of the present application is well known to those skilled in the art and is not particularly limited in the present application.
  • the preparation process of the lithium-ion secondary battery may include but is not limited to the following steps: stacking the positive electrode sheet, the separator and the negative electrode sheet in order, and winding, folding and other operations as needed to obtain an electrode assembly with a wound structure, placing the electrode assembly in a shell, injecting the electrolyte into the shell and sealing it to obtain a lithium-ion secondary battery.
  • a third aspect of the present application provides a battery module comprising the lithium-ion secondary battery provided in the second aspect of the present application.
  • the lithium-ion secondary batteries can be assembled into a battery module, and the number of lithium-ion secondary batteries contained in the battery module can be one or more, with those skilled in the art selecting the specific number based on the application and capacity of the battery module.
  • a fourth aspect of the present application provides a battery pack comprising the battery modules provided in the third aspect of the present application.
  • the battery modules can be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, with those skilled in the art selecting the specific number based on the application and capacity of the battery pack.
  • a fifth aspect of the present application provides an electronic device comprising at least one of the lithium-ion secondary battery provided in the second aspect of the present application, the battery module provided in the third aspect, or the battery pack provided in the fourth aspect.
  • the lithium-ion secondary battery, battery module, or battery pack can be used as a power source for the electronic device or as an energy storage unit for the electronic device.
  • the electronic device can select a lithium-ion secondary battery, battery module, or battery pack based on its usage requirements.
  • the electronic device can include, but is not limited to, a laptop computer, a pen-type computer, a mobile computer, an e-book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a headset, a video recorder, an LCD television, a portable cleaner, a portable CD player, a mini-disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, an automobile, a motorcycle, a power-assisted bicycle, a bicycle, a lighting fixture, a toy, a game console, a clock, a power tool, a flashlight, a camera, a large household battery or a lithium-ion capacitor, etc.
  • a lithium-ion battery was placed in a 25°C environment and charged at a constant current of 0.5C to 4.3V. It was then charged at a constant voltage of 4.3V to 0.025C.
  • a temperature-sensing wire was attached to the surface of the lithium-ion battery near the positive electrode tab.
  • the lithium-ion battery was then placed in an oven with an initial temperature of 25°C and the oven temperature was increased at a rate of 1°C/second. When the oven temperature reached a certain level, the lithium-ion battery would experience thermal runaway. Thermal runaway was determined to occur if the surface temperature of the lithium-ion battery increased by 30°C within 3 seconds. The oven temperature, T0 , before thermal runaway occurred was recorded.
  • T0 represents the safety temperature of the lithium-ion battery. Five lithium-ion batteries were tested for each set of examples or comparative examples, and the average value was taken as the safety temperature for that example or comparative example. A higher safety temperature indicates better safety performance for the lithium-ion secondary battery.
  • the lithium-ion battery was placed in an environment of 45°C, charged to 4.3V at a constant current of 0.5C, allowed to stand for 30 minutes, and then discharged to 3.0V at a constant current of 0.5C.
  • the initial discharge capacity of the lithium-ion battery was recorded as C 1 .
  • the charge and discharge conditions were cycled 200 times under this condition.
  • the discharge capacity of the lithium-ion battery after 200 cycles was recorded as C 200 .
  • the capacity retention rate of the lithium-ion battery was calculated.
  • Capacity retention rate C 200 /C 1 ⁇ 100%.
  • the capacity retention rate is used to characterize the high-temperature cycle performance of the lithium-ion battery. A higher capacity retention rate indicates better high-temperature cycle performance of the lithium-ion secondary battery.
  • Lithium-ion batteries were disassembled, the positive electrode plates were separated, and a solid powder sample was scraped off the positive electrode plates using a knife. 0.2 g of the solid powder sample was weighed and dissolved in a 42% nitric acid solution. The nitric acid solution was then analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES) to determine the type and mass percentage of the doping element.
  • ICP-OES inductively coupled plasma optical emission spectrometry
  • ethyl methyl carbonate and ethylene carbonate were added at a mass ratio W 1 /W 2 of 1.14, and then an organic solvent, sulfolane, as well as lithium hexafluorophosphate, lithium tetrafluoroborate, and lithium difluorophosphate were added, and stirred uniformly to obtain an electrolyte.
  • the mass percentage W 1 % of ethyl methyl carbonate was 32%
  • the mass percentage W 2 % of ethylene carbonate was 28%
  • the mass percentage m 1 % of lithium tetrafluoroborate was 0.1%
  • the mass percentage m 2 % of lithium difluorophosphate was 0.1%
  • the mass percentage of lithium hexafluorophosphate was 11.5%
  • the balance was the organic solvent.
  • Aluminum oxide, a thickener (sodium carboxymethyl cellulose), and a wetting agent (dimethylsiloxane) were mixed in a mass ratio of 95:0.5:4.5.
  • Deionized water was added and the mixture was stirred thoroughly in a vacuum mixer to obtain a porous coating slurry with a viscosity of 40 mPa ⁇ s and a solids content of 5%.
  • the porous coating slurry was evenly coated on one surface of a 10 ⁇ m thick polyethylene porous substrate and dried in an 85°C oven for 4 hours to obtain a separator membrane coated on one side with the porous coating.
  • the coating weight was 1 mg/1000 mm2 .
  • the coating process was repeated on the other surface of the polyethylene porous substrate to obtain a separator membrane coated on both sides with the porous coating.
  • the positive electrode active material lithium nickel cobalt manganese oxide (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ) (NCM811), the positive electrode binder, polyvinylidene fluoride (PVDF), and the conductive agent, acetylene black, were mixed in a mass ratio of 96:2:2.
  • NMP N-methylpyrrolidone
  • the negative electrode active material, artificial graphite, sodium carboxymethyl cellulose (CMC), and the negative electrode binder, styrene-butadiene rubber, were mixed in a mass ratio of 85:2:13.
  • Deionized water was added and the mixture was stirred thoroughly in a vacuum mixer to produce a negative electrode slurry with a solid content of 28 wt%.
  • the negative electrode slurry was evenly coated on one surface of a 12 ⁇ m thick negative electrode current collector copper foil and baked at 120°C for 1 hour to produce a negative electrode sheet coated on one side with a 100 ⁇ m thick negative electrode material layer.
  • the above steps were repeated on the other surface of the negative electrode current collector copper foil to produce a negative electrode sheet coated on both sides with a negative electrode material layer.
  • the sheet After drying under vacuum conditions at 120°C for 1 hour, the sheet was cold pressed, cut, slit, and the tabs were welded to produce a negative electrode sheet measuring 76 mm x 875 mm.
  • the compacted density of the negative electrode material layer was 1.6 g/ cm3 .
  • the separator, positive electrode sheet, separator, and negative electrode sheet are stacked in sequence, with the separator positioned between the positive and negative electrode sheets, and then wound to form an electrode assembly.
  • the electrode assembly is placed in an aluminum foil bag, and the positive and negative tabs are led out of the bag's interior. After baking at 80°C for 12 hours to remove moisture, electrolyte is injected.
  • the battery undergoes vacuum packaging, resting, formation, degassing, trimming, and shaping to produce a lithium-ion secondary battery.
  • the upper formation voltage is 4.15V
  • the formation temperature is 70°C
  • the formation rest time is 2 hours.
  • the preparation of the electrolyte was the same as in Example 1-1 except that the mass percentages of ethyl methyl carbonate, ethylene carbonate, lithium tetrafluoroborate, and lithium difluorophosphate were adjusted according to Table 1, the mass percentages of the organic solvent were changed accordingly, and the mass percentage of lithium hexafluorophosphate remained unchanged.
  • the preparation of the electrolyte was the same as in Example 1-11, except that the third component was added and the mass percentage of the third component was adjusted as shown in Table 2, wherein the mass percentage of the organic solvent was changed accordingly, and the mass percentages of the first component, the second component, and the lithium salt lithium hexafluorophosphate remained unchanged.
  • the preparation of the electrolyte was the same as in Example 2-5, except that the fourth component was added and the mass percentage of the fourth component was adjusted as shown in Table 3, wherein the mass percentage of the organic solvent was changed accordingly, and the mass percentages of the first component, the second component, the third component and the lithium salt lithium hexafluorophosphate remained unchanged.
  • the preparation of the electrolyte was the same as in Examples 3-6, except that the fifth component was added and the mass percentage of the fifth component was adjusted as shown in Table 4, wherein the mass percentage of the organic solvent was changed accordingly, and the mass percentages of the first component, the second component, the third component, the fourth component and the lithium salt lithium hexafluorophosphate remained unchanged.
  • the preparation of the electrolyte was the same as in Example 1-11 except that the relevant parameters were adjusted as shown in Table 5, wherein the mass percentage of the organic solvent changed after the third component, the fourth component, and the fifth component were added, and the mass percentage of the first component, the second component, and the lithium salt lithium hexafluorophosphate remained unchanged.
  • Lithium nickel cobalt manganese oxide (NCM811), Al2O3 , MgO , and TiO2 were uniformly mixed in a mass ratio of 19700:1:100:200 and calcined at 800°C in an oxygen atmosphere to produce a lithium cobalt composite oxide positive electrode active material doped with aluminum, magnesium, and titanium.
  • the type of the fourth component usually affects the safety performance and high-temperature cycle performance of the lithium-ion secondary battery. It can be seen from Examples 3-2, 3-13, and 3-14 that when the type of the fourth component is within the scope of this application, the lithium-ion secondary battery can have a higher safety temperature and a higher capacity retention rate, indicating that the lithium-ion secondary battery has good safety performance and high-temperature cycle performance.
  • the type of positive electrode active material usually affects the safety performance and high-temperature cycle performance of lithium-ion secondary batteries. It can be seen from Examples 1-11 and Examples 6-1 to 6-4 that when the type and mass percentage of the doping elements in the positive electrode active material are within the scope of this application, the lithium-ion secondary battery can have a higher safety temperature and a higher capacity retention rate, indicating that the lithium-ion secondary battery has good safety performance and high-temperature cycle performance.

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Abstract

本申请提供了一种电解液、锂离子二次电池、电池模块、电池包及电子装置。电解液包括第一组分和第二组分。第一组分包括碳酸甲乙酯和碳酸乙烯酯，基于电解液的质量，碳酸甲乙酯的质量百分含量W1％，碳酸乙烯酯的质量百分含量为W2％，第一组分的质量百分含量为W％，60≤W≤88，1.14≤W1/W2≤1.93。第二组分包括四氟硼酸锂和二氟磷酸锂，基于电解液的质量，四氟硼酸锂的质量百分含量为m1％，二氟磷酸锂的质量百分含量为m2％，第二组分的质量百分含量为m％，0.03≤m≤1.5，0.1≤m1/m2≤25。通过上述设置，可以使电解液体系具有较好的动力学性能并提高正极和负极的界面稳定性，提高锂离子二次电池的安全性能和高温循环性能。

Description

一种电解液、锂离子二次电池、电池模块、电池包及电子装置
本申请要求于2024年3月28日提交中国专利局、申请号为202410369752.9、发明名称为“一种电解液、锂离子二次电池、电池模块、电池包及电子装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及电化学技术领域，特别是涉及一种电解液、锂离子二次电池、电池模块、电池包及电子装置。
背景技术
锂离子电池由于具备能量密度大、输出功率高、循环寿命长和环境污染小等优点而被广泛应用于电动汽车以及消费类电子产品中。随着锂离子电池的使用范围不断扩大，其使用场景更加多元，市场对锂离子电池电化学性能提出了更高的要求。锂离子电池目前广泛使用以六氟磷酸锂为导电锂盐的非水电解液体系。然而上述非水电解液尚存在诸多不足，例如在高电压体系中，上述非水电解液的安全性能有待提高，从而影响二次电池的安全性能和高温循环性能。
发明内容
本申请的目的在于提供一种电解液、锂离子二次电池、电池模块、电池包及电子装置，以提高锂离子二次电池的安全性能和高温循环性能。具体技术方案如下：
本申请的第一方面提供了一种电解液，其包括第一组分和第二组分。第一组分包括碳酸甲乙酯和碳酸乙烯酯，基于电解液的质量，碳酸甲乙酯的质量百分含量W1％，碳酸乙烯酯的质量百分含量为W2％，第一组分的质量百分含量为W％，60≤W≤88，1.14≤W1/W2≤1.93。第二组分包括四氟硼酸锂和二氟磷酸锂，基于电解液的质量，四氟硼酸锂的质量百分含量为m1％，二氟磷酸锂的质量百分含量为m2％，第二组分的质量百分含量为m％，0.03≤m≤1.5，0.1≤m1/m2≤25。通过调控第一组分的质量百分含量W％和W1/W2的比值在本申请的范围内，可以使电解液体系具有较好的动力学性能并减少负极界面的副反应，提高负极界面的稳定性，提高锂离子二次电池的安全性能和高温循环性能。通过调控第二组分的质量百分含量m％和m1/m2的值在本申请的范围内，可进一步提高正极和负极的界面稳定性，从而进一步提高锂离子二次电池的安全性能和高温循环性能。
在本申请的一些实施方案中，75≤W≤88。通过调控第一组分的质量百分含量W％的值在上述范围内，可有利于提高电解液体系的动力学性能并减少负极界面的副反应，提高负极界面的稳定性，提高锂离子二次电池的安全性能和高温循环性能。
在本申请的一些实施方案中，32≤W1≤58，0.01≤m1≤1.4。通过调控碳酸甲乙酯的质量百分含量W1％和四氟硼酸锂的质量百分含量m1％在上述范围内，可进一步提高锂离子二次电池的安全性能和高温循环性能。
在本申请的一些实施方案中，电解液还包括第三组分，第三组分包括硫酸二乙酯或磷酸三苯酯中的至少一种，基于电解液的质量，第三组分的质量百分含量为a ppm，10≤a≤1000。电解液包括上述范围内的第三组分并调控第三组分的质量百分含量a ppm在上述范围内，可进一步丰富负极界面的固体电解质界面膜(SEI膜)的组分，提升负极界面的稳定性，进一步提高锂离子二次电池的安全性能和高温循环性能。
在本申请的一些实施方案中，电解液还包括第四组分，第四组分包括亚磷酸三苯酯、磷酸三乙酯、磷酸三甲酯或硫酸乙烯酯中的至少一种，基于电解液的质量，第四组分的质量百分含量为b％，0.1≤b≤1.1。电解液包括上述范围内的第四组分并调控第四组分的质量百分含量b％在上述范围内，第四组分可以在正极形成稳定的界面，提高正极电解质界面膜(CEI膜)中硫化物和/或磷化物的比例，增强正极界面的耐氧化性，进一步提高锂离子二次电池的安全性能和高温循环性能。
在本申请的一些实施方案中，电解液还包括第五组分，第五组分包括含氟无机盐；基于电解液的质量，第五组分的质量百分含量为c ppm，2≤c≤500。电解液包括上述范围内的第五组分并调控第五组分的质量百分含量c ppm在上述范围内，有利于及时修复破损的SEI膜，降低热失控的发生概率，进一步提高锂离子二次电池的安全性能和高温循环性能。
在本申请的一些实施方案中，第五组分包括氟化镁、氟化钾、氟化钙、氟化锂、氟化钠、氟化硅、氟化铁或氟化锆中的至少一种。电解液包括上述范围内的第五组分，有利于及时修复破损的SEI膜，降低热失控的发生概率，进一步提高锂离子二次电池的安全性能和高温循环性能。
在本申请的一些实施方案中，电解液还包括第三组分、第四组分或第五组分中的至少一种，第三组分包括硫酸二乙酯或磷酸三苯酯中的至少一种，基于电解液的质量，第三组分的质量百分含量为a ppm，第四组分包括亚磷酸三苯酯、磷酸三乙酯、磷酸三甲酯或硫酸乙烯酯中的至少一种，基于电解液的质量，第四组分的质量百分含量为b％，第五组分包括氟化镁、氟化钾、氟化钙、氟化锂、氟化钠、氟化硅、氟化铁或氟化锆中的至少一种，基于电解液的质量，第五组分的质量百分含量为c ppm，电解液满足以下特征中的至少一者:(1)50≤a≤500；(2)0.21≤b≤0.55；(3)5≤c≤300。电解液满足上述特征中的至少一者，可进一步提高锂离子二次电池的安全性能和高温循环性能。
本申请的第二方面提供了一种锂离子二次电池，其包括正极、负极、间隔于正极和负极之间的隔离膜、本申请第一方面提供的电解液，其中正极包括锂钴复合氧化物，锂钴复合氧化物包括铝、镁、钛、锆、镧、铱、铈、钨、锌、镍、锰、硼、磷、硅、镓、铟、铯中至少三种掺杂元素；基于锂钴复合氧化物的质量，掺杂元素中任一种的质量百分含量为0.01％至1％。正极包括上述范围内的锂钴复合氧化物并调控掺杂元素中任一种的质量百分含量在上述范围内，有利于提升锂钴复合氧化物在高脱锂态下的结构稳定性。
本申请的第三方面提供了一种电池模块，其包括本申请第二方面提供的锂离子二次电池。
本申请的第四方面提供了一种电池包，其包括本申请第三方面提供的电池模块。
本申请的第五方面提供了一种电子装置，其包括本申请第二方面提供的锂离子二次电池、本申请第三方面提供的电池模块或本申请第四方面提供的电池包。
本申请的有益效果：
本申请提供了一种电解液、锂离子二次电池、电池模块、电池包及电子装置。电解液包括第一组分和第二组分。第一组分包括碳酸甲乙酯和碳酸乙烯酯，基于电解液的质量，碳酸甲乙酯的质量百分含量W1％，碳酸乙烯酯的质量百分含量为W2％，第一组分的质量百分含量为W％，60≤W≤88，1.14≤W1/W2≤1.93。第二组分包括四氟硼酸锂和二氟磷酸锂，基于电解液的质量，四氟硼酸锂的质量百分含量为m1％，二氟磷酸锂的质量百分含量为m2％，第二组分的质量百分含量为m％，0.03≤m≤1.5，0.1≤m1/m2≤25。具有上述特征的电解液应用于锂离子二次电池，可以使电解液体系具有较好的动力学性能，并提高正极和负极的界面稳定性，从而提高锂离子二次电池的安全性能和高温循环性能。
当然，实施本申请的任一产品或方法并不一定需要同时达到以上所述的所有优点。
具体实施方式
下面将对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。本领域技术人员基于本申请所获得的所有其他实施例，都属于本申请保护的范围。
本申请提供了一种电解液，其包括第一组分和第二组分。第一组分包括碳酸甲乙酯和碳酸乙烯酯，基于电解液的质量，碳酸甲乙酯的质量百分含量W1％，碳酸乙烯酯的质量百分含量为W2％，第一组分的质量百分含量为W％，60≤W≤88，1.14≤W1/W2≤1.93。在本申请的一些实施方案中，75≤W≤88。例如，第一组分的质量百分含量W％的值可以为60％、63％、65％、68％、70％、73％、75％、78％、80％、83％、85％、88％或为其中任意两个数值组成的范围。W1/W2的值可以为1.14、1.20、1.30、1.40、1.50、1.60、1.70、1.80、1.90、1.93或为其中任意两个数值组成的范围。第二组分包括四氟硼酸锂和二氟磷酸锂，基于电解液的质量，四氟硼酸锂的质量百分含量为m1％，二氟磷酸锂的质量百分含量为m2％，第二组分的质量百分含量为m％，0.03≤m≤1.5，0.1≤m1/m2≤25。例如，第二组分的质量百分含量m％的值可以为0.03％、0.1％、0.3％、0.5％、0.8％、1％、1.3％、1.5％或为其中任意两个数值组成的范围。m1/m2的值可以为0.1、1、3、5、8、10、13、15、18、20、23、25或为其中任意两个数值组成的范围。
发明人研究发现，电解液包括第一组分碳酸甲乙酯和碳酸乙烯酯，一方面，可使电解液体系具有较好的动力学性能；另一方面，使用在负极的耐还原性较好的碳酸甲乙酯作为主溶剂，同时搭配负极成膜效果较好的碳酸乙烯酯作为辅溶剂，控制二者的比值W1/W2在本申请范围内，可减少负极的副反应，提高负极界面的稳定性，当外界的温度升高时，高稳定的负极界面可抑制电解液在负极的反应，降低锂离子二次电池内部的温升，延后锂离子二次电池的失效时间，提高锂离子二次电池的安全性能。另外，通过在电解液中同时引入第二组分四氟硼酸锂和二氟磷酸锂，四氟硼酸锂可优先于溶剂在正负极界面被还原，可进一步提高正极和负极界面的稳定性，但是四氟硼酸锂会导致界面阻抗增大，二氟磷酸锂的引入可削弱四氟硼酸锂对正极和负极界面阻抗的影响，两者协同作用，进一步提高正极和负极界面稳定性的同时，还可降低四氟硼酸锂对界面阻抗的影响，从而进一步提高锂离子二次电池的安全性能和高温循环性能。当第一组分的质量百分含量W％的值过小时，例如小于60％，碳酸甲乙酯和碳酸乙烯酯含量较少，无法有效提高负极界面稳定性；当第一组分的质量百分含量过大，例如大于88％，会导致锂盐的质量百分含量过低，影响锂离子二次电池的循环性能。当W1/W2的值过小时，例如小于1.14，碳酸乙烯酯含量偏高，过量的碳酸乙烯酯将在正极被氧化，导致安全温度下降；当W1/W2的值过大时，例如大于1.93，碳酸乙烯酯含量偏低，负极成膜稳定性下降，导致安全温度下降。当m1/m2的值过小时，例如小于0.1，四氟硼酸锂对界面的成膜反应太弱，无法有效提升界面稳定性；而当m1/m2的值过大时，例如大于25，二氟磷酸锂的含量太少，无法有效缓解四氟硼酸锂带来的高界面阻抗问题，影响锂离子二次电池的循环性能。当电解液包括第一组分碳酸甲乙酯和碳酸乙烯酯、第二组分四氟硼酸锂和二氟磷酸锂，并调控第一组分的质量百分含量W、W1/W2的值、第二组分的质量百分含量m和m1/m2的值在本申请的范围，可改善锂离子二次电池的安全性能和高温循环性能。在本申请中，高温通常是指温度大于或等于30℃。
本申请的一些实施方案中，32≤W1≤58，0.01≤m1≤1.4。例如，碳酸甲乙酯的质量百分含量W1％的值可以为32％、35％、38％、40％、43％、45％、48％、50％、53％、55％、58％或为其中任意两个数值组成的范围，四氟硼酸锂的质量百分含量m1％的值可以为0.01％、0.05％、0.1％、0.15％、0.2％、0.25％、0.3％、0.35％、0.4％、0.45％、0.5％、0.8％、1％、1.2％、1.4％或为其中任意两个数值组成的范围。通过调控碳酸甲乙酯的质量百分含量W1％和四氟硼酸锂的质量百分含量为m1％在上述范围内，可进一步提高锂离子二次电池的安全性能和高温循环性能。
在本申请的一些实施方案中，21≤W2≤41。例如，碳酸乙烯酯的质量百分含量W2％的值可以为21％、25％、28％、30％、32％、35％、38％、41％或为其中任意两个数值组成的范围，通过调控碳酸乙烯酯的质量百分含量W2％的值在上述范围内，可进一步提高锂离子二次电池的安全性能和高温循环性能。
在本申请的一些实施方案中，0.01≤m2≤1.3。例如，二氟磷酸锂的质量百分含量m2的值可以为0.01、0.05、0.1、0.5、0.8、1、1.3或为其中任意两个数值组成的范围，通过调控二氟磷酸锂的质量百分含量m2的值在上述范围内，可进一步提高锂离子二次电池的安全性能和高温循环性能。
在本申请的一些实施方案中，电解液还包括第三组分，第三组分包括硫酸二乙酯或磷酸三苯酯中的至少一种，基于电解液的质量，第三组分的质量百分含量为a ppm，10≤a≤1000。在本申请的一些实施方案中，50≤a≤500。例如，第三组分的质量百分含量a ppm可以为10ppm、50ppm、100ppm、200ppm、300ppm、400ppm、500ppm、600ppm、700ppm、800ppm、900ppm、1000ppm或为其中任意两个数值组成的范围。电解液包括上述范围内的第三组分并调控第三组分的质量百分含量a ppm在上述范围内，可进一步丰富负极界面的固体电解质界面膜(SEI膜)的组分，提升负极界面的稳定性，进一步提高锂离子二次电池的安全性能和高温循环性能。
在本申请的一些实施方案中，电解液还包括第四组分，第四组分包括亚磷酸三苯酯、磷酸三乙酯、磷酸三甲酯或硫酸乙烯酯中的至少一种，基于电解液的质量，第四组分的质量百分含量为b％，0.1≤b≤1.1。在本申请的一些实施方案中，0.21≤b≤0.55。例如，第四组分的质量百分含量b％可以为0.1％、0.3％、0.5％、0.8％、1％、1.1％或为其中任意两个数值组成的范围。电解液包括上述范围内的第四组分并调控第四组分的质量百分含量b％在上述范围内，第四组分可以在正极形成稳定的界面，提高正极电解质界面膜(CEI膜)中硫化物和/或磷化物的比例，增强正极界面的耐氧化性，进一步提高锂离子二次电池的安全性能和高温循环性能。
在本申请的一些实施方案中，电解液还包括第五组分，第五组分包括含氟无机盐；基于电解液的质量，第五组分的质量百分含量为c ppm，2≤c≤500。在本申请的一些实施方案中，5≤c≤300。例如，第五组分的质量百分含量c ppm的值可以为2ppm、5ppm、10ppm、50ppm、100ppm、150ppm、200ppm、250ppm、300ppm、350ppm、400ppm、450ppm、500ppm或为其中任意两个数值组成的范围。电解液包括上述范围内的第五组分并调控第五组分的质量百分含量c ppm在上述范围内，有利于及时修复破损的SEI膜，降低热失控的发生概率，进一步提高锂离子二次电池的安全性能和高温循环性能。
在本申请的一些实施方案中，第五组分包括氟化镁、氟化钾、氟化钙、氟化锂、氟化钠、氟化硅、氟化铁或氟化锆中的至少一种。电解液包括上述范围内的第五组分，有利于及时修复破损的SEI膜，降低热失控的发生概率，进一步提高锂离子二次电池的安全性能和高温循环性能。
在本申请的一些实施方案中，本申请的电解液还包括电解质盐。电解质盐包括有机锂盐或无机锂盐中的至少一种。在一些实施例中，电解质盐可以包括但不限于六氟磷酸锂(LiPF6)、双三氟甲烷磺酰亚胺锂LiN(CF3SO2)2(LiTFSI)、双(氟磺酰)亚胺锂Li(N(SO2F)2)(LiFSI)、六氟铯酸锂(LiCsF6)、高氯酸锂(LiClO4)或三氟甲磺酸锂(LiCF3SO3)中的至少一种。本申请对电解质盐的含量没有特别限制，只要能实现本申请的目的即可。例如，基于电解液的质量，电解质盐的质量百分含量为10％至15％。
在本申请的一些实施方案中，电解液还可以包括非水有机溶剂。例如非水溶剂可以包括但不限于碳酸酯化合物、羧酸酯化合物、醚化合物或其它有机溶剂中的至少一种。
上述碳酸酯化合物可以包括但不限于链状碳酸酯化合物、环状碳酸酯化合物或氟代碳酸酯化合物中的至少一种。上述链状碳酸酯化合物可以包括但不限于碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)或碳酸乙丙酯(EPC)中的至少一种。上述环状碳酸酯可以包括但不限于碳酸亚丙酯(PC)、碳酸亚丁酯(BC)或碳酸乙烯基亚乙酯(VEC)中的至少一种。氟代碳酸酯化合物可以包括但不限于氟代碳酸乙烯酯(FEC)、碳酸1,2-二氟亚乙酯、碳酸1,1-二氟亚乙酯、碳酸1,1,2-三氟亚乙酯、碳酸1,1,2,2-四氟亚乙酯、碳酸1-氟-2-甲基亚乙酯、碳酸1-氟-1-甲基亚乙酯、碳酸1,2-二氟-1-甲基亚乙酯、碳酸1,1,2-三氟-2-甲基亚乙酯或碳酸三氟甲基亚乙酯中的至少一种。上述羧酸酯化合物可以包括但不限于甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸正丙酯、乙酸叔丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、γ-丁内酯、癸内酯、戊内酯或己内酯中的至少一种。上述醚化合物可以包括但不限于二丁醚、四甘醇二甲醚、二甘醇二甲醚、1,2-二甲氧基乙烷、1,2-二乙氧基乙烷、1-乙氧基-1-甲氧基乙烷、2-甲基四氢呋喃或四氢呋喃中的至少一种。上述其它有机溶剂可以包括但不限于二甲亚砜、1,2-二氧戊环、环丁砜、甲基环丁砜、1,3-二甲基-2-咪唑烷酮、N-甲基-2-吡咯烷酮、二甲基甲酰胺、乙腈或磷酸三辛酯中的至少一种。本申请对非水溶剂在电解液中的含量没有特别限制，只要能实现本申请的目的即可。例如，基于电解液的质量，非水有机溶剂的质量百分含量为0％至25％。
在本申请的一些实施方案中，电解液包括第一组分、第二组分以及第三组分、第四组分、第五组分中的至少一种。电解液包括第一组分、第二组分以及第三组分、第四组分、第五组分中的至少一种，并调控其质量百分含量在本申请的范围内，可进一步提高锂离子二次电池的安全性能和高温循环性能。
本申请的第二方面提供了一种锂离子二次电池，其包括正极、负极、间隔于正极和负极之间的隔离膜、本申请第一方面提供的电解液，其中正极包括正极活性材料，正极活性材料包括锂钴复合氧化物，锂钴复合氧化物包括铝、镁、钛、锆、镧、铱、铈、钨、锌、镍、锰、硼、磷、硅、镓、铟、铯中至少三种掺杂元素；基于锂钴复合氧化物的质量，掺杂元素中任一种的质量百分含量为0.01％至1％。例如，掺杂元素中任一种的质量百分含量可以为0.01％、0.05％、0.1％、0.3％、0.5％、0.8％、1％或为其中任意两个数值组成的范围。正极包括上述范围内的锂钴复合氧化物并调控掺杂元素中任一种的质量百分含量在上述范围内，有利于提升锂钴复合氧化物在高脱锂态下的结构稳定性。
本申请对上述含掺杂元素的锂钴复合氧化物正极活性材料的制备方法没有特别限定，只要能实现本申请的目的即可，例如含掺杂元素的锂钴复合氧化物正极活性材料的制备方法可以包括但不限于以下步骤：将锂钴复合氧化物与含掺杂元素的化合物混合均匀后在氧气气氛或空气气氛中热处理后得到含掺杂元素的锂钴复合氧化物。所述锂钴复合氧化物可以包括但不限于镍钴锰酸锂(NCM811、NCM622、NCM523、NCM111)、镍钴铝酸锂或钴酸锂(LiCoO2)中的至少一种。当掺杂元素为铝、镁、钛、锆、镧、铱、铈、钨、锌、镍、锰、硼、磷、硅、镓、铟、铯时，可对应加入含掺杂元素的氧化物、含掺杂元素的氢氧化物和含掺杂元素的碳酸盐化合物，可根据实际需要进行选择，只要能实现本申请的目的即可。本申请对上述热处理温度或时间没有特别限制，只要能实现本申请的目的即可，例如，热处理温度为650℃至1100℃，时间为22h至26h。包括掺杂元素的锂钴复合氧化物正极活性材料中掺杂元素的质量百分含量可以通过调控含掺杂元素的化合物的加入量来调控。
本申请的正极包括正极集流体和设置在正极集流体至少一个表面上的正极材料层，正极材料层包括上述正极活性材料。本申请对正极集流体没有特别限制，只要能够实现本申请目的即可。例如，正极集流体可以包含铝箔、铝合金箔或复合集流体(例如铝碳复合集流体)等。在本申请中，对正极集流体和正极材料层的厚度没有特别限制，只要能够实现本申请目的即可。例如，正极集流体的厚度为5μm至20μm。单面正极材料层的厚度为30μm至120μm。在本申请中，正极材料层可以设置于正极集流体厚度方向上的一个表面上，也可以设置于正极集流体厚度方向上的两个表面上。需要说明，这里的“表面”可以是正极集流体的全部区域，也可以是正极集流体的部分区域，本申请没有特别限制，只要能实现本申请目的即可。在本申请中，所述正极材料还可以包括其他正极活性材料，例如钴酸锂、锰酸锂、磷酸铁锂等。
本申请的正极材料层还可以包括导电剂和粘结剂，本申请对导电剂和粘结剂的种类没有特别限制，只要能够实现本申请目的即可。例如，导电剂可以包括但不限于导电炭黑(Super P)、碳纳米管(CNTs)、碳纤维、鳞片石墨、科琴黑、石墨烯、金属材料或导电聚合物中的至少一种。上述碳纳米管可以包括但不限于单壁碳纳米管和/或多壁碳纳米管。上述碳纤维可以包括但不限于气相生长碳纤维(VGCF)和/或纳米碳纤维。上述金属材料可以包括但不限于金属粉和/或金属纤维，具体地，金属可以包括但不限于铜、镍、铝或银中的至少一种。上述导电聚合物可以包括但不限于聚亚苯基衍生物、聚苯胺、聚噻吩、聚乙炔或聚吡咯中的至少一种。例如，粘结剂可以包括但不限于聚丙烯酸、聚丙烯酸钠、聚丙烯酸钾、聚丙烯酸锂、聚酰亚胺、聚乙烯醇、羧甲基纤维素、羧甲基纤维素钠、羧甲基纤维素锂、聚酰亚胺、聚酰胺酰亚胺、丁苯橡胶或聚偏氟乙烯中的至少一种。
本申请对负极没有特别限制，只要能够实现本申请目的即可。例如，负极包含负极集流体和设置在负极集流体至少一个表面上的负极材料层。在本申请中，负极材料层可以设置于负极集流体厚度方向上的一个表面上，也可以设置于负极集流体厚度方向上的两个表面上。需要说明，这里的“表面”可以是负极集流体的全部区域，也可以是负极集流体的部分区域，本申请没有特别限制，只要能实现本申请目的即可。本申请对负极集流体没有特别限制，只要能够实现本申请目的即可。例如，负极集流体可以包括但不限于铜箔、铜合金箔、镍箔、钛箔、泡沫镍、泡沫铜或复合集流体等。本申请的负极材料层包含负极活性材料。本申请对负极活性材料的种类没有特别限制，只要能够实现本申请目的即可。例如，负极活性材料可以包括但不限于天然石墨、人造石墨、中间相微碳球(MCMB)、硬碳、软碳、硅、硅-碳复合物、SiOx(0<x≤2)或金属锂等中的至少一种。在本申请中，对负极集流体和负极材料层的厚度没有特别限制，只要能够实现本申请目的即可。例如，负极集流体的厚度为4μm至15μm，单面负极材料层的厚度为30μm至130μm。本申请的负极材料层还可以包含导电剂和粘结剂。本申请对导电剂和粘结剂没有特别限制，只要能够实现本申请目的即可。例如，粘接剂和导电剂可以包括但不限于上述导电剂和上述粘结剂中的至少一种。
本申请对隔离膜没有特别限制，只要能够实现本申请目的即可。例如，隔离膜的材料可以包括但不限于聚乙烯(PE)、聚丙烯(PP)为主的聚烯烃(PO)类、聚酯(例如聚对苯二甲酸二乙酯(PET)膜)、纤维素、聚酰亚胺(PI)、聚酰胺(PA)、氨纶或芳纶中的至少一种。隔离膜的类型可以包括织造膜、非织造膜(无纺布)、微孔膜、复合膜、碾压膜或纺丝膜中的至少一种。本申请的隔膜可以具有多孔结构，多孔层设置在隔膜的至少一个表面上，多孔层包括无机颗粒和粘结剂，无机颗粒可以包括氧化铝、氧化硅、氧化镁、氧化钛、二氧化铪、氧化锡、二氧化铈、氧化镍、氧化锌、氧化钙、氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙或硫酸钡中的至少一种。粘结剂可以包括聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸甲酯、聚丙烯酸乙酯、聚丙烯酸丁酯、聚丙烯酸、聚丙烯酸盐、羧甲基纤维素纳、聚乙烯吡咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯或聚六氟丙烯中的至少一种。本申请对多孔结构的孔径的尺寸没有特别限制，只要能实现本申请的目的即可，例如，孔径的尺寸可以为0.01μm至1μm。在本申请中，隔膜的厚度没有特别限制，只要能实现本申请的目的即可，例如厚度可以为3μm至30μm。
本申请的锂离子二次电池还包括壳体，壳体可以为硬壳壳体或柔性壳体。硬壳壳体的材料可以为金属，本申请对金属的种类不做限定，可以采用本领域已知的金属硬壳壳体，只要能实现本申请的目的即可。柔性壳体可以为金属塑膜，例如铝塑膜、钢塑膜等。
本申请的锂离子二次电池的制备过程为本领域技术人员所熟知的，本申请没有特别的限制，例如，锂离子二次电池的制备过程可以包括但不限于以下步骤：将正极极片、隔离膜和负极极片按顺序堆叠，并根据需要将其卷绕、折叠等操作得到卷绕结构的电极组件，将电极组件放入壳体内，将电解液注入壳体并封口，得到锂离子二次电池。或者，将正极极片、隔离膜和负极极片按顺序堆叠，然后用胶带将整个叠片结构的四个角固定好得到叠片结构的电极组件，将电极组件置入壳体内，将电解液注入壳体并封口，得到锂离子二次电池。此外，也可以根据需要将防过电流元件、导板等置于壳体中，从而防止锂离子二次电池内部的压力上升、过充放电。
本申请的第三方面提供了一种电池模块，其包括本申请第二方面提供的锂离子二次电池。锂离子二次电池可以组装成电池模块，电池模块所含锂离子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。
本申请的第四方面提供了一种电池包，其包括本申请第三方面提供的电池模块。电池模块可以组装成电池包，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。
本申请的第五方面提供了一种电子装置，其包括本申请第二方面提供的锂离子二次电池、第三方面提供的电池模块、或第四方面提供的电池包中的至少一种。锂离子二次电池、电池模块、或电池包可以用作电子装置的电源，也可以用作电子装置的能量存储单元。电子装置可以根据其使用需求来选择锂离子二次电池、电池模块或电池包。
本申请对电子装置没有特别限定，其可以是用于现有技术中已知的任何电子装置。在一些实施例中，电子装置可以包括但不限于笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池或锂离子电容器等。
实施例
以下，举出实施例及对比例来对本申请的实施方式进行更具体地说明。各种的试验及评价按照下述的方法进行。另外，只要无特别说明，“份”、“％”为质量基准。
测试方法和设备：
安全性能测试
将锂离子电池置于25℃的环境下，以0.5C恒定电流充电至4.3V，再以4.3V恒压充电至0.025C，在锂离子电池表面贴上感温线，贴线位置在正极极耳附近，然后将锂离子电池放置在烘箱中，初始温度为25℃，烘箱以1℃/秒的速度升温，当烘箱升温至一定温度时，锂离子电池会发生热失控，锂离子电池表面的温度在3秒内升高30℃则判定该锂离子电池发生热失控，记录锂离子电池发生热失控前烘箱内的温度T0，T0为锂离子电池的安全温度。每组实施例或对比例测试5颗锂离子电池，取平均值作为该实施例或对比例的安全温度。安全温度越高，表示锂离子二次电池的安全性能越好。
高温循环性能的测试
将锂离子电池置于45℃的环境下，以0.5C恒定电流充电至4.3V，静置30min，然后再以0.5C恒定电流放电至3.0V，记录锂离子电池的初始放电容量为C1，以此充放电条件循环200次，记录循环200次后锂离子电池的放电容量为C200，计算锂离子电池的容量保持率。
容量保持率＝C200/C1×100％，以容量保持率表征锂离子电池的高温循环性能，容量保持率越高表明锂离子二次电池的高温循环性能越好。
正极活性材料中掺杂元素含量的测试
取锂离子电池进行拆解，分离正极极片，使用小刀刮取正极极片上的固体粉末样品。称量0.2g上述固体粉末样品，溶解于浓度为42％的硝酸溶液，然后对溶解固体粉末样品的硝酸溶液进行电感耦合等离子体发射光谱仪(ICP-OES)检测，得到掺杂元素的种类及质量百分含量。
实施例1-1
<电解液的制备>
在含水量＜10ppm的氩气气氛手套箱中，按照质量比W1/W2为1.14加入碳酸甲乙酯和碳酸乙烯酯，再加入有机溶剂环丁砜，以及六氟磷酸锂、四氟硼酸锂和二氟磷酸锂，搅拌均匀得到电解液。其中，基于电解液的质量，碳酸甲乙酯的质量百分含量W1％为32％，碳酸乙烯酯的质量百分含量W2％为28％，四氟硼酸锂的质量百分含量m1％为0.1％，二氟磷酸锂的质量百分含量m2％为0.1％，六氟磷酸锂的质量百分含量为11.5％，余量为有机溶剂。
<隔离膜的制备>
将三氧化二铝、增稠剂羧甲基纤维素钠和润湿剂二甲基硅氧烷按照质量比95:0.5:4.5进行混合，加入去离子水，在真空搅拌机作用下搅拌均匀，获得粘度为40mPa·s、固含量为5％的多孔涂层浆料。将多孔涂层浆料均匀涂覆在厚度为10μm的聚乙烯多孔基材的一个表面上，放于85℃烘箱中烘干处理4h，得到单面涂布多孔涂层的隔离膜，涂层重量为1mg/1000mm2。在聚乙烯多孔基材的另一个表面上重复上述涂覆过程，得到双面涂布多孔涂层的隔离膜。
<正极极片的制备>
将正极活性材料镍钴锰酸锂LiNi0.8Co0.1Mn0.1O2(NCM811)、正极粘结剂聚偏二氟乙烯(PVDF)、导电剂乙炔黑按照质量比为96:2:2进行混合，加入N-甲基吡咯烷酮(NMP)，在真空搅拌机作用下搅拌均匀，得到固含量为70wt％的正极浆料。将正极浆料均匀涂覆于厚度为14μm的正极集流体铝箔的一个表面上，120℃下烘烤处理1小时，得到涂层厚度为110μm的单面涂覆正极材料层的正极极片。在正极集流体铝箔的另一个表面上重复以上步骤，即得到双面涂覆正极材料层的正极极片。然后在120℃的真空条件下干燥1小时后，经过冷压、裁片、分切、焊接极耳得到规格为74mm×867mm的正极极片。其中，正极材料层的压实密度为3.4g/cm3。
<负极极片的制备>
将负极活性材料人造石墨、羧甲基纤维素钠(CMC)、负极粘结剂丁苯橡胶按照质量比为85:2:13进行混合，加入去离子水，在真空搅拌机作用下搅拌均匀，得到固含量为28wt％的负极浆料。将负极浆料均匀涂覆于厚度为12μm的负极集流体铜箔的一个表面上，120℃下烘烤处理1小时，得到涂层厚度为100μm的单面涂覆负极材料层的负极极片。在负极集流体铜箔的另一个表面上重复以上步骤，即得到双面涂覆负极材料层的负极极片。然后在120℃的真空条件下干燥1小时后，经过冷压、裁片、分切、焊接极耳得到规格为76mm×875mm的负极极片。其中，负极材料层的压实密度为1.6g/cm3。
<锂离子二次电池的制备>
将隔膜、正极极片、隔膜以及负极极片按顺序依次层叠，使隔膜处于正极极片和负极极片之间，然后卷绕获得电极组件。将电极组件装入铝箔包装袋中，并将正极耳和负极耳自包装袋的内部空间引出至包装袋的外部空间，在80℃烘烤12小时脱去水分后，注入电解液，经过真空封装、静置、化成、脱气、切边、整形工序，即制得锂离子二次电池。其中，化成上限电压为4.15V，化成温度为70℃，化成静置时间为2h。
实施例1-2至实施例1-16
除了<电解液的制备>按表1调整碳酸甲乙酯、碳酸乙烯酯、四氟硼酸锂、二氟磷酸锂的质量百分含量，有机溶剂的质量百分含量随之变化，六氟磷酸锂的质量百分含量不变以外，其余与实施例1-1相同。
实施例2-1至实施例2-11
除了<电解液的制备>按表2所示加入第三组分并调整第三组分的质量百分含量，其中，有机溶剂的质量百分含量随之改变，第一组分、第二组分、锂盐六氟磷酸锂的质量百分含量不变以外，其余与实施例1-11相同。
实施例3-1至实施例3-14
除了<电解液的制备>按表3所示加入第四组分并调整第四组分的质量百分含量，其中，有机溶剂的质量百分含量随之改变，第一组分、第二组分、第三组分和锂盐六氟磷酸锂的质量百分含量不变以外，其余与实施例2-5相同。
实施例4-1至实施例4-11
除了<电解液的制备>按表4所示加入第五组分并调整第五组分的质量百分含量，其中，有机溶剂的质量百分含量随之改变，第一组分、第二组分、第三组分、第四组分和锂盐六氟磷酸锂的质量百分含量不变以外，其余与实施例3-6相同。
实施例5-1至实施例5-4
除了<电解液的制备>按表5所示调整相关参数，其中，第三组分、第四组分和第五组分加入后，有机溶剂的质量百分含量随之改变，第一组分、第二组分、锂盐六氟磷酸锂的质量百分含量不变以外，其余与实施例1-11相同。
实施例6-1
<正极活性材料的制备>
将镍钴锰酸锂NCM811、Al2O3、MgO、TiO2以质量比19700：1：100：200混合均匀，并在氧气气氛下800℃煅烧，得到含铝元素、镁元素、钛元素掺杂的锂钴复合氧化物正极活性材料。其中，基于正极活性材料的质量，铝元素的质量百分含量为0.01％，镁元素的质量百分含量为0.5％，钛元素的质量百分含量为1％。
除了<正极活性材料的制备>按上述步骤制备以外，其余与实施例1-11相同。
实施例6-2
除了在<正极活性材料的制备>中，调整镍钴锰酸锂NCM811、Al2O3、MgO、TiO2的质量比，使得铝元素、镁元素、钛元素掺杂元素的质量百分含量如表6所示以外，其余与实施例6-1相同。
实施例6-3、实施例6-4
除了在<正极活性材料的制备>中，调整掺杂元素的种类及镍钴锰酸锂NCM811与含掺杂元素的化合物的质量比以外，使得掺杂元素的种类及质量百分含量如表6所示以外，其余与实施例6-1相同。其中，含锌元素的化合物为氧化锌、含硼元素的化合物为氧化硼、含磷元素的化合物为磷酸锂、含镓元素的化合物为氧化镓、含铟元素的化合物为氧化铟。
对比例1至对比例7
除了<电解液的制备>按表1调整碳酸甲乙酯、碳酸乙烯酯、四氟硼酸锂、二氟磷酸锂的质量百分含量。其中，对比例1、对比例3至对比例7的有机溶剂的质量百分含量随之改变，锂盐六氟磷酸锂的质量百分含量不变以外，其余与实施例1-2相同；对比例2的有机溶剂环丁砜的质量百分含量为0，锂盐六氟磷酸锂的质量百分含量为10.8％以外，其余与实施例1-2相同。
对比例8
除了<电解液的制备>不添加四氟硼酸锂和二氟磷酸锂，碳酸甲乙酯和碳酸乙烯酯的质量百分含量不变，锂盐六氟磷酸锂的质量百分含量不变，有机溶剂的质量百分含量随之改变以外，其余与实施例1-9相同。
对比例9
除了<电解液的制备>不添加二氟磷酸锂，碳酸甲乙酯和碳酸乙烯酯的质量百分含量不变，锂盐六氟磷酸锂的质量百分含量不变，有机溶剂的质量百分含量随之改变以外，其余与实施例1-9相同。
对比例10
除了<电解液的制备>不添加四氟硼酸锂，碳酸甲乙酯和碳酸乙烯酯的质量百分含量不变，锂盐六氟磷酸锂的质量百分含量不变，有机溶剂的质量百分含量随之改变以外，其余与实施例1-9相同。
各实施例和对比例的制备参数及性能参数如表1至表6所示。
表1


注：表1中的“/”表示无相关参数。
从实施例1-1至实施例1-16、对比例1至对比例10可以看出，本申请各实施例的锂离子二次电池的电解液包括第一组分碳酸甲乙酯和碳酸乙烯酯、第二组分四氟硼酸锂和二氟磷酸锂，并调控第一组分的质量百分含量W、W1/W2的值、第二组分的质量百分含量m和m1/m2的值在本申请的范围内，而对比例中的锂离子二电池并未同时满足上述特征，各实施例中的锂离子电池具有更高的安全温度和更高的容量保持率，说明锂离子二次电池的安全性能和高温循环性能得到改善。
碳酸甲乙酯的质量百分含量W1％通常会影响锂离子二次电池的安全性能和高温循环性能，从实施例1-1至实施例1-8可以看出，通过调控W1％的值在本申请的范围内，可使锂离子二次电池具有较高的安全温度和较高的容量保持率，说明锂离子二次电池具有良好的安全性能和高温循环性能。
四氟硼酸锂的质量百分含量m1％通常会影响锂离子二次电池的安全性能和高温循环性能，从实施例1-9至实施例1-16可以看出，通过调控m1％的值在本申请的范围内，可使锂离子二次电池具有较高的安全温度和较高的容量保持率，说明锂离子二次电池具有良好的安全性能和高温循环性能。
表2

注：表2中的“/”表示无相关参数。
从实施例1-11、实施例2-1至实施例2-11可以看出，在电解液包括第一组分碳酸甲乙酯和碳酸乙烯酯、第二组分四氟硼酸锂和二氟磷酸锂的基础上，进一步引入第三组分，可以进一步提高锂离子二次电池的安全温度和容量保持率，说明锂离子二次电池的安全性能和高温循环性能得到进一步的改善。
第三组分的种类通常会影响锂离子二次电池的安全性能和高温循环性能，从实施例2-7、实施例2-10、实施例2-11可以看出，当第三组分的种类在本申请的范围内时，可使锂离子二次电池具有较高的安全温度和较高的容量保持率，说明锂离子二次电池具有良好的安全性能和高温循环性能。
第三组分的质量百分含量a ppm通常会影响锂离子二次电池的安全性能和高温循环性能，从实施例2-1至实施例2-9可以看出，当第三组分的质量百分含量a ppm在本申请的范围内时，可使锂离子二次电池具有较高的安全温度和较高的容量保持率，说明锂离子二次电池具有良好的安全性能和高温循环性能。
表3

注：表3中的“/”表示无相关参数。
从实施例2-5、实施例3-1至实施例3-14可以看出，在电解液包括第一组分碳酸甲乙酯和碳酸乙烯酯、第二组分四氟硼酸锂和二氟磷酸锂、第三组分的基础上，进一步引入第四组分，可以进一步提高锂离子二次电池的安全温度和容量保持率，说明锂离子二次电池的安全性能和高温循环性能得到进一步的改善。
第四组分的种类通常会影响锂离子二次电池的安全性能和高温循环性能，从实施例3-2、实施例3-13、实施例3-14可以看出，当第四组分的种类在本申请的范围内时，可使锂离子二次电池具有较高的安全温度和较高的容量保持率，说明锂离子二次电池具有良好的安全性能和高温循环性能。
第四组分的质量百分含量b％通常会影响锂离子二次电池的安全性能和高温循环性能，从实施例3-1至实施例3-11可以看出，当第四组分的质量百分含量b％在本申请的范围内时，可使锂离子二次电池具有较高的安全温度和较高的容量保持率，说明锂离子二次电池具有良好的安全性能和高温循环性能。
表4

注：表4中的“/”表示无相关参数。
从实施例3-6、实施例4-1至实施例4-11可以看出，在电解液包括第一组分碳酸甲乙酯和碳酸乙烯酯、第二组分四氟硼酸锂和二氟磷酸锂、第三组分、第四组分的基础上，进一步引入第五组分，可以进一步提高锂离子二次电池的安全温度和容量保持率，说明锂离子二次电池的安全性能和高温循环性能得到进一步的改善。
本申请研究人员发现，第五组分的种类通常会影响锂离子二次电池的安全性能和高温循环性能，从实施例4-6、实施例4-11可以看出，当第五组分的种类在本申请的范围内时，可使锂离子二次电池具有较高的安全温度和较高的容量保持率，说明锂离子二次电池具有良好的安全性能和高温循环性能。
本申请研究人员发现，第五组分的质量百分含量c ppm通常会影响锂离子二次电池的安全性能和高温循环性能，从实施例4-1至实施例4-10可以看出，当第五组分的质量百分含量c ppm在本申请的范围内时，可使锂离子二次电池具有较高的安全温度和较高的容量保持率，说明锂离子二次电池具有良好的安全性能和高温循环性能。
表5


注：表5中的“/”表示无相关参数。
从实施例1-11、实施例2-5、实施例3-6、实施例4-5和实施例5-1至实施例5-4可以看出，第一组分、第二组分与第三组分、第四组分、第五组分中的至少一种均具有良好的叠加性，当电解液在包括第一组分、第二组分的基础上进一步包括第三组分、第四组分、第五组分中的至少一种，锂离子二次电池的安全温度和容量保持率得到进一步提高，说明锂离子二次电池的安全性能和高温循环性能得到进一步提高。
表6

注：表6中的“/”表示无相关参数。
正极活性材料的种类通常会影响锂离子二次电池的安全性能和高温循环性能，从实施例1-11、实施例6-1至实施例6-4可以看出，当正极活性材料中掺杂元素的种类和质量百分含量在本申请的范围内时，可使锂离子二次电池具有较高的安全温度和较高的容量保持率，说明锂离子二次电池具有良好的安全性能和高温循环性能。
以上所述仅为本申请的较佳实施例，并不用以限制本申请，凡在本申请的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本申请保护的范围之内。

Claims (12)

  1. 一种用于锂离子二次电池的电解液，其包括第一组分和第二组分，所述第一组分包括碳酸甲乙酯和碳酸乙烯酯，基于所述电解液的质量，所述碳酸甲乙酯的质量百分含量W1％，所述碳酸乙烯酯的质量百分含量为W2％，所述第一组分的质量百分含量为W％，60≤W≤88，1.14≤W1/W2≤1.93；
    所述第二组分包括四氟硼酸锂和二氟磷酸锂，基于所述电解液的质量，所述四氟硼酸锂的质量百分含量为m1％，所述二氟磷酸锂的质量百分含量为m2％，所述第二组分的质量百分含量为m％，0.03≤m≤1.5，0.1≤m1/m2≤25。
  2. 根据权利要求1所述的电解液，其中，75≤W≤88。
  3. 根据权利要求1所述的电解液，其中，32≤W1≤58，0.01≤m1≤1.4。
  4. 根据权利要求1至3中任一项所述的电解液，其中，所述电解液还包括第三组分，所述第三组分包括硫酸二乙酯或磷酸三苯酯中的至少一种；基于所述电解液的质量，所述第三组分的质量百分含量为a ppm，10≤a≤1000。
  5. 根据权利要求1至3中任一项所述的电解液，其中，所述电解液还包括第四组分，所述第四组分包括亚磷酸三苯酯、磷酸三乙酯、磷酸三甲酯或硫酸乙烯酯中的至少一种；基于所述电解液的质量，所述第四组分的质量百分含量为b％，0.1≤b≤1.1。
  6. 根据权利要求1至3中任一项所述的电解液，其中，所述电解液还包括第五组分，所述第五组分包括含氟无机盐；基于所述电解液的质量，所述第五组分的质量百分含量为c ppm，2≤c≤500。
  7. 根据权利要求6所述的电解液，其中，所述第五组分包括氟化镁、氟化钾、氟化钙、氟化锂、氟化钠、氟化硅、氟化铁或氟化锆中的至少一种。
  8. 根据权利要求1至3中任一项所述的电解液，其还包括第三组分、第四组分或第五组分中的至少一种；所述第三组分包括硫酸二乙酯或磷酸三苯酯中的至少一种，基于所述电解液的质量，所述第三组分的质量百分含量为a ppm；所述第四组分包括亚磷酸三苯酯、磷酸三乙酯、磷酸三甲酯或硫酸乙烯酯中的至少一种，基于所述电解液的质量，所述第四组分的质量百分含量为b％；所述第五组分包括氟化镁、氟化钾、氟化钙、氟化锂、氟化钠、氟化硅、氟化铁或氟化锆中的至少一种，基于所述电解液的质量，所述第五组分的质量百分含量为c ppm；所述电解液满足以下特征中的至少一者:
    (1)50≤a≤500；
    (2)0.21≤b≤0.55；
    (3)5≤c≤300。
  9. 一种锂离子二次电池，其包括正极、负极、间隔于所述正极和负极之间的隔离膜、权利要求1至8中任一项所述的电解液，其中所述正极包括锂钴复合氧化物，所述锂钴复合氧化物包括铝、镁、钛、锆、镧、铱、铈、钨、锌、镍、锰、硼、磷、硅、镓、铟、铯中至少三种掺杂元素；基于所述锂钴复合氧化物的质量，所述掺杂元素中任一种的质量百分含量为0.01％至1％。
  10. 一种电池模块，其包括权利要求9所述的锂离子二次电池。
  11. 一种电池包，其包括权利要求10所述的电池模块。
  12. 一种电子装置，其包括权利要求9所述的锂离子二次电池、权利要求10所述的电池模块或权利要求11所述的电池包。
PCT/CN2025/076932 2024-03-28 2025-02-12 一种电解液、锂离子二次电池、电池模块、电池包及电子装置 Pending WO2025200816A1 (zh)

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