WO2023098477A1 - 一种锂离子电池 - Google Patents

一种锂离子电池 Download PDF

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Publication number
WO2023098477A1
WO2023098477A1 PCT/CN2022/132198 CN2022132198W WO2023098477A1 WO 2023098477 A1 WO2023098477 A1 WO 2023098477A1 CN 2022132198 W CN2022132198 W CN 2022132198W WO 2023098477 A1 WO2023098477 A1 WO 2023098477A1
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negative electrode
ion battery
lithium ion
material layer
structural formula
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PCT/CN2022/132198
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English (en)
French (fr)
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邓永红
刘中波
钱韫娴
王勇
黄雄
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深圳新宙邦科技股份有限公司
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Priority to EP22900282.9A priority Critical patent/EP4443588A1/en
Publication of WO2023098477A1 publication Critical patent/WO2023098477A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • H01M10/052—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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0569—Liquid materials characterised by the solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/483—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides for non-aqueous cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • 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
    • 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 invention belongs to the technical field of energy storage battery devices, and in particular relates to a lithium ion battery.
  • lithium-ion batteries Due to the advantages of high working voltage, wide working temperature range, high energy density and power density, no memory effect and long cycle life, lithium-ion batteries have been widely used in the field of 3C digital products such as mobile phones and notebook computers, as well as in the field of new energy vehicles. Applications.
  • 3C digital products such as mobile phones and notebook computers, as well as in the field of new energy vehicles.
  • Applications In recent years, with the continuous development of thinner and thinner 3C digital products, the battery industry has higher and higher requirements for high energy density of lithium-ion batteries. At the same time, for the consideration of users, fast charging has become a basic requirement for batteries. Therefore, there is an urgent need to increase the energy density of lithium-ion batteries and improve the fast charging performance.
  • the main methods to increase the energy density of batteries are: 1. Increase the cut-off voltage of the positive electrode charge. 2. A method of reducing the volume occupied by the active material inside the battery as much as possible by pressurizing the active material layer of the electrode to increase the density. However, increasing the charging cut-off voltage of the positive electrode will further increase the activity of the positive electrode, intensify the side reaction between the positive electrode and the electrolyte, and the transition metal ions of the positive electrode will dissolve, resulting in excessive loss of high-temperature storage capacity and performance degradation of the battery.
  • carboxylate solvents can also be used.
  • Carboxylate solvents have the advantages of wide liquid range, low viscosity, and high conductivity. , can greatly improve the fast charging performance of the battery, but the stability of the carboxylate is poorer than that of the linear carbonate, and it is easy to have a side reaction with the positive electrode during the cycle, so that the side reaction product migrates to the negative electrode and is reduced at the negative electrode, resulting in an increase in cycle impedance Fast, and carboxylate esters can cause gas production problems during high temperature storage. Therefore, how to ensure the long-term fast charging cycle performance of the battery while taking into account the high-temperature storage performance of the battery is a major topic in the research of high-voltage and high-pressure lithium-ion batteries.
  • the present invention provides a lithium-ion battery.
  • the invention provides a lithium-ion battery, comprising a positive electrode containing a positive electrode material layer, a negative electrode containing a negative electrode material layer, and a non-aqueous electrolyte, wherein the positive electrode material layer includes a magnesium-containing lithium transition metal oxide as a positive electrode active material.
  • the negative electrode material layer includes a negative electrode active material and a magnesium-containing compound, and the nonaqueous electrolyte includes a carboxylate solvent, an electrolyte salt and a compound shown in structural formula 1:
  • R1 is selected from unsaturated hydrocarbon groups with 3-6 carbon atoms
  • R2 is selected from alkylene groups with 2-5 carbon atoms
  • n is 1 or 2;
  • the lithium ion battery meets the following conditions:
  • x is the mass percentage content of carboxylic acid ester in the non-aqueous electrolytic solution, and the unit is %;
  • m is the mass percentage of the compound shown in structural formula 1 in the non-aqueous electrolyte, in %;
  • z is the mass content of Mg element relative to the negative electrode material layer, and the unit is ppm.
  • the lithium-ion battery meets the following conditions:
  • the compound represented by the structural formula 1 is selected from one or more of the following compounds:
  • the mass percentage m of the compound represented by structural formula 1 in the non-aqueous electrolyte is 0.1-5%;
  • the mass percent content m of the compound represented by structural formula 1 in the non-aqueous electrolyte is 0.1-2%.
  • the mass content z of the Mg element relative to the negative electrode material layer is 5-500 ppm;
  • the mass content z of the Mg element relative to the negative electrode material layer is 50-500 ppm.
  • the mass percentage x of carboxylic acid ester in the non-aqueous electrolyte is 5-55%;
  • the mass percentage content x of carboxylic acid ester in the non-aqueous electrolytic solution is 10-40%.
  • the carboxylic acid ester is selected from methyl acetate, ethyl acetate, ethyl propionate, butyl acetate, propyl propionate, butyl propionate, ⁇ -butyrolactone, ⁇ -valerolactone, At least one of ⁇ -valerolactones.
  • the compacted density of the negative electrode material layer is greater than or equal to 1.5 g/cm 3 ; preferably, the compacted density of the negative electrode material layer is 1.55 ⁇ 1.9 g/cm 3 .
  • the non-aqueous electrolyte also includes auxiliary additives, the auxiliary additives include cyclic sulfate ester compounds, sultone compounds, cyclic carbonate compounds, unsaturated phosphoric acid ester compounds and nitrile at least one of the class of compounds;
  • the amount of the auxiliary additive added is 0.01%-30%.
  • the cyclic sulfate ester compound is selected from at least one of vinyl sulfate, propylene sulfate or vinyl methyl sulfate;
  • the sultone compound is selected from at least one of 1,3-propane sultone, 1,4-butane sultone or 1,3-propene sultone;
  • the cyclic carbonate compound is selected from at least one of vinylene carbonate, ethylene carbonate, fluoroethylene carbonate or the compound shown in structural formula 2,
  • R 21 , R 22 , R 23 , R 24 , R 25 , and R 26 are each independently selected from a hydrogen atom, a halogen atom, and a C1-C5 group;
  • the unsaturated phosphate compound is selected from at least one of the compounds shown in structural formula 3:
  • R 31 , R 32 , and R 33 are each independently selected from C1-C5 saturated hydrocarbon groups, unsaturated hydrocarbon groups, halogenated hydrocarbon groups, -Si(C m H 2m+1 ) 3 , m is 1 to A natural number of 3, and at least one of R 31 , R 32 , and R 33 is an unsaturated hydrocarbon group;
  • nitrile compound comprises succinonitrile, glutaronitrile, ethylene glycol two (propionitrile) ether, hexanetrinitrile, adiponitrile, pimelonitrile, suberonitrile, azelanitrile, sebaconitrile one or more.
  • the inventors of the present application have found through painstaking research that: in terms of electrolyte, the compound shown in structural formula 1 is used in conjunction with a carboxylate solvent, and the compound shown in structural formula 1 can effectively protect the positive electrode and ease the oxidation reaction between the carboxylate solvent and the positive electrode , to ensure the fast charge cycle performance of the battery; on the negative electrode, Mg in the negative electrode can regulate the formation of the SEI film formed by the compound shown in structural formula 1 on the negative electrode.
  • Mg participates in the formation of the SEI film, and the thickness of the obtained SEI film is reduced, avoid Due to the problem of excessive impedance caused by too thick SEI film thickness, on the other hand, the formed Mg-containing SEI film has high conductivity, which can reduce the charge transfer resistance of the negative electrode, so that the Li + intercalation and The overpotential of the extraction reaction is reduced, so the impedance growth rate during the cycle process can be effectively suppressed, thereby improving the high-temperature cycle performance and storage performance of the battery.
  • the mass content z of the Mg element in the negative electrode material layer and the mass content m of the compound shown in Structural Formula 1 and the carboxylate content x satisfy 0.002 ⁇ m/x ⁇ 0.25 and 0.001 ⁇ m/z ⁇ 0.1, it can Under the premise of maintaining the battery's excellent high-temperature storage performance, it is guaranteed that the battery has good fast charge cycle performance.
  • An embodiment of the present invention provides a lithium ion battery, including a positive electrode, a negative electrode and a non-aqueous electrolyte.
  • the positive electrode is composed of a positive electrode collector and a positive electrode material layer formed on the positive electrode collector.
  • the positive electrode current collector is selected from metal materials that can conduct electrons.
  • the positive electrode current collector includes one or more of Al, Ni, tin, copper, and stainless steel.
  • the positive electrode The current collector is selected from aluminum foil.
  • the anode material layer includes magnesium-containing lithium transition metal oxide as an anode active material, an anode binder and an anode conductor.
  • the positive active material includes magnesium-containing lithium transition metal oxide.
  • the positive electrode active material may be selected from one of LiFe 1-x' Mg x' PO 4 , LiMn 2-y' Mg y' O 4 and LiNi x Co y Mn z Mg 1-xyz O 2 or Various, among them, 0 ⁇ x' ⁇ 1, 0 ⁇ y' ⁇ 1, 0 ⁇ y ⁇ 1, 0 ⁇ x ⁇ 1, 0 ⁇ z ⁇ 1, x+y+z ⁇ 1.
  • the positive electrode active material contains magnesium, which can improve the stability of the positive electrode active material, and at the same time, the Mg element of the positive electrode active material will dissolve in a small amount during the charge and discharge cycle and migrate into the negative electrode material layer, so that the Mg element containing element described in the present invention can be obtained. negative electrode material layer.
  • the positive electrode binder can be selected from polyvinylidene fluoride, copolymers of vinylidene fluoride, polytetrafluoroethylene, copolymers of vinylidene fluoride-hexafluoropropylene, copolymers of tetrafluoroethylene-hexafluoropropylene, tetrafluoroethylene Ethylene-perfluoroalkyl vinyl ether copolymer, ethylene-tetrafluoroethylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-trichloro Copolymers of ethylene, copolymers of vinylidene fluoride-ethylene fluoride, copolymers of vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene, thermoplastic polyimide, thermoplastic resins such as polyethylene and poly
  • the positive electrode conductive agent can be selected from one or more of metal conductive agents, carbon-based materials, metal oxide-based conductive agents, and composite conductive agents.
  • the metal conductive agent can be copper powder, nickel powder, silver powder and other metals
  • the carbon-based material can be carbon-based materials such as conductive graphite, conductive carbon black, conductive carbon fiber or graphene
  • the metal oxide-based conductive agent can be tin oxide , iron oxide, zinc oxide, etc.
  • the composite conductive agent can be composite powder, composite fiber, etc.
  • the conductive carbon black can be one or more of acetylene black, 350G, Ketjen black, carbon fiber (VGCF), and carbon nanotubes (CNTs).
  • the negative electrode includes a negative electrode current collector and a negative electrode material layer formed on the negative electrode current collector.
  • the negative electrode current collector is selected from metal materials that can conduct electrons.
  • the negative electrode current collector includes one or more of Al, Ni, tin, copper, and stainless steel.
  • the negative electrode The current collector is selected from aluminum foil.
  • the negative electrode material layer includes negative electrode active material, magnesium-containing compound, negative electrode binder and negative electrode conductive agent.
  • the negative electrode active material includes one or more of silicon-based negative electrodes and carbon-based negative electrodes.
  • the carbon-based negative electrode may include graphite, hard carbon, soft carbon, graphene, mesocarbon microspheres, and the like.
  • the graphite includes but not limited to one or more of natural graphite, artificial graphite, amorphous carbon, carbon-coated graphite, graphite-coated graphite, and resin-coated graphite.
  • the silicon-based negative electrode may include silicon materials, silicon oxides, silicon-carbon composite materials, silicon alloy materials, and the like. The added amount of the silicon-based material is greater than 0 and less than 30%.
  • the upper limit of the added amount of the silicon-based material is 10%, 15%, 20% or 25%; the lower limit of the added amount of the silicon-based material is 5%, 10% or 15%.
  • the silicon material is one or more of silicon nanoparticles, silicon nanowires, silicon nanotubes, silicon films, 3D porous silicon, and hollow porous silicon.
  • the negative electrode binder is selected from polyvinylidene fluoride, copolymers of vinylidene fluoride, polytetrafluoroethylene, copolymers of vinylidene fluoride-hexafluoropropylene, copolymers of tetrafluoroethylene-hexafluoropropylene, tetrafluoroethylene -Copolymers of perfluoroalkyl vinyl ethers, ethylene-tetrafluoroethylene copolymers, vinylidene fluoride-tetrafluoroethylene copolymers, vinylidene fluoride-trifluoroethylene copolymers, vinylidene fluoride-trichloroethylene copolymers Copolymers of vinylidene fluoride-ethylene fluoride, copolymers of vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene, thermoplastic polyimide, thermoplastic resins such as polyethylene and polypropylene; acrylic
  • the negative electrode conductive agent is selected from one or more of conductive carbon black, conductive carbon spheres, conductive graphite, conductive carbon fibers, carbon nanotubes, graphene or reduced graphene oxide.
  • Described non-aqueous electrolytic solution comprises carboxylate solvent, electrolyte salt and the compound shown in structural formula 1:
  • R1 is selected from unsaturated hydrocarbon groups with 3-6 carbon atoms
  • R2 is selected from alkylene groups with 2-5 carbon atoms
  • n is 1 or 2;
  • the lithium ion battery meets the following conditions:
  • x is the mass percentage content of carboxylic acid ester in the non-aqueous electrolytic solution, and the unit is %;
  • m is the mass percentage of the compound shown in structural formula 1 in the non-aqueous electrolyte, in %;
  • z is the mass content of Mg element relative to the negative electrode material layer, and the unit is ppm.
  • the inventors of the present application have found through painstaking research that: in terms of electrolyte, the compound shown in structural formula 1 is used in conjunction with a carboxylate solvent, and the compound shown in structural formula 1 can effectively protect the positive electrode and ease the oxidation reaction between the carboxylate solvent and the positive electrode , to ensure the fast charge cycle performance of the battery; on the negative electrode, Mg in the negative electrode can regulate the formation of the SEI film formed by the compound shown in structural formula 1 on the negative electrode.
  • Mg participates in the formation of the SEI film, and the thickness of the obtained SEI film is reduced, avoid Due to the problem of excessive impedance caused by too thick SEI film thickness, on the other hand, the formed Mg-containing SEI film has high conductivity, which can reduce the charge transfer resistance of the negative electrode, so that the Li + intercalation and The overpotential of the extraction reaction is reduced, so the impedance growth rate during the cycle process can be effectively suppressed, thereby improving the high-temperature cycle performance and storage performance of the battery.
  • the mass content z of the Mg element in the negative electrode material layer and the mass content m of the compound shown in Structural Formula 1 and the carboxylate content x satisfy 0.002 ⁇ m/x ⁇ 0.25 and 0.001 ⁇ m/z ⁇ 0.1, it can Under the premise of maintaining the battery's excellent high-temperature performance, it is guaranteed that the battery has good fast charge cycle performance.
  • the lithium-ion battery meets the following conditions:
  • the compound shown in structural formula 1 is correlated with the mass content z of the Mg element in the negative electrode material layer and the mass percentage content of the carboxylate in the non-aqueous electrolyte, which can be integrated to a certain extent
  • Negative electrode, carboxylic acid ester and compound represented by structural formula 1 have influence on battery performance, and obtain a kind of lithium-ion battery that not only has better fast charging cycle performance, but also has better high temperature performance.
  • the compound represented by the structural formula 1 is selected from one or more of the following compounds:
  • the mass percentage m of the compound represented by structural formula 1 in the non-aqueous electrolyte is 0.1-5%.
  • the mass percentage m of the compound represented by structural formula 1 in the non-aqueous electrolyte is 0.1-2%.
  • the positive electrode is in a state of strong oxidation, which is easy to oxidize the electrolyte, causing the electrolyte to decompose, and the oxidation products produced will migrate to the negative electrode interface, reduce on the negative electrode surface, and consume active Li.
  • the compound shown can effectively inhibit the reaction between the non-aqueous electrolyte and the positive electrode active material, and inhibit the migration of the positive electrode reaction product to the negative electrode for reaction, thereby reducing the loss of active lithium in the battery.
  • the addition amount of the compound shown in Structural Formula 1 should not be too large.
  • the initial impedance of the SEI film formed on the negative electrode of the battery is relatively large, which will cause an increase in battery impedance, and excessive addition of the compound shown in Structural Formula 1 will increase the viscosity of the electrolyte. , reduce the conductance, which is not conducive to the cycle performance of the battery.
  • the mass content z of the Mg element relative to the negative electrode material layer is 5-500 ppm.
  • the mass content z of the Mg element relative to the negative electrode material layer is 50-500 ppm.
  • the negative electrode material layer refers to the part of the negative electrode other than the negative electrode current collector, and the parameter z defines the content of Mg element in the negative electrode material layer.
  • the Mg element in the negative electrode material layer can come from the additional addition when preparing the negative electrode material layer, or from the dissolution of Mg metal ions from the positive electrode active material, for example, by doping Mg in the positive electrode active material element, the Mg element in the positive electrode active material is partially ionized by charge and discharge, and migrates to the negative electrode material layer for precipitation.
  • the Mg element in the negative electrode material layer exists in the form of simple substance or compound.
  • the Mg element in the negative electrode material layer is beneficial to solve the problem that the initial impedance of the SEI film formed by the compound shown in structural formula 1 is relatively large.
  • the mass content z of the Mg element in the negative electrode material layer is too low, it is difficult to reduce the thickness of the SEI film; when the negative electrode If the mass content z of the Mg element in the material layer is too high, the energy density of the negative electrode will decrease, which will affect the intercalation and removal of electrolyte ions.
  • the mass percentage x of carboxylic acid ester in the non-aqueous electrolyte is 5-55%
  • the mass percentage x of carboxylic acid ester in the non-aqueous electrolyte is 10-40%.
  • the fast charging performance of the battery can be improved, but adding too much carboxylate will reduce the stability of the non-aqueous electrolyte, thereby affecting the cycle performance of the battery .
  • the carboxylic acid ester is selected from methyl acetate, ethyl acetate, ethyl propionate, butyl acetate, propyl propionate, butyl propionate, ⁇ -butyrolactone, ⁇ -valerolactone At least one of esters and ⁇ -valerolactone.
  • the non-aqueous electrolyte also includes auxiliary additives, and the auxiliary additives include cyclic sulfate compounds, sultone compounds, cyclic carbonate compounds, unsaturated phosphate compounds and at least one of nitrile compounds.
  • the cyclic sulfate ester compound is selected from at least one of vinyl sulfate, propylene sulfate or vinyl methyl sulfate;
  • the sultone compound is selected from at least one of 1,3-propane sultone, 1,4-butane sultone or 1,3-propene sultone;
  • the cyclic carbonate compound is selected from at least one of vinylene carbonate, ethylene carbonate, fluoroethylene carbonate or the compound shown in structural formula 2,
  • R 21 , R 22 , R 23 , R 24 , R 25 , and R 26 are each independently selected from a hydrogen atom, a halogen atom, and a C1-C5 group.
  • the unsaturated phosphate compound is selected from at least one of the compounds shown in structural formula 3:
  • R 31 , R 32 , and R 33 are each independently selected from C1-C5 saturated hydrocarbon groups, unsaturated hydrocarbon groups, halogenated hydrocarbon groups, -Si(C m H 2m+1 ) 3 , m is 1 to 3, and at least one of R 31 , R 32 , and R 33 is an unsaturated hydrocarbon group.
  • the unsaturated phosphoric acid ester compound may be tripropargyl phosphate, dipropargyl methyl phosphate, dipropargyl ethyl phosphate, dipropargyl propyl phosphate, Dipropargyl trifluoromethyl phosphate, Dipropargyl-2,2,2-trifluoroethyl phosphate, Dipropargyl-3,3,3-trifluoropropyl phosphate, Dipropargyl Hexafluoroisopropyl phosphate, triallyl phosphate, diallyl methyl phosphate, diallyl ethyl phosphate, diallyl propyl phosphate, diallyl trifluoromethyl Phosphate, diallyl-2,2,2-trifluoroethyl phosphate, diallyl-3,3,3-trifluoropropyl phosphate, diallyl hexafluoroisopropyl phosphate at least one of the
  • nitrile compound comprises succinonitrile, glutaronitrile, ethylene glycol two (propionitrile) ether, hexanetrinitrile, adiponitrile, pimelonitrile, suberonitrile, azelanitrile, sebaconitrile one or more.
  • the auxiliary additives may also include other additives that can improve battery performance: for example, additives that improve battery safety performance, specifically flame retardant additives such as fluorophosphate esters and cyclophosphazene, or tert-amyl Benzene, tert-butylbenzene and other anti-overcharge additives.
  • additives that improve battery safety performance specifically flame retardant additives such as fluorophosphate esters and cyclophosphazene, or tert-amyl Benzene, tert-butylbenzene and other anti-overcharge additives.
  • the amount of the auxiliary additive is 0.01%-30%.
  • the addition amount of any optional substance in the auxiliary additive in the non-aqueous electrolyte is less than 10%, preferably, the addition amount is 0.1-5%, more Preferably, the added amount is 0.1%-2%.
  • the addition amount of any optional substance in the auxiliary additive can be 0.05%, 0.08%, 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2% %, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 7.8%, 8%, 8.5%, 9%, 9.5%, 10%.
  • the auxiliary additive is selected from fluoroethylene carbonate, based on 100% of the total mass of the non-aqueous electrolyte, the added amount of the fluoroethylene carbonate is 0.05%-30%.
  • the electrolyte salt is selected from the group consisting of LiPF 6 , LiPO 2 F 2 , LiBF 4 , LiBOB, LiSbF 6 , LiAsF 6 , LiCF 3 SO 3 , LiDFOB, LiN(SO 2 CF 3 ) 2 , LiC(SO 2 CF 3 ) 3 , LiN(SO 2 C 2 F 5 ) 2 , LiN(SO 2 F) 2 , LiCl, LiBr, LiI, LiClO 4 , LiBF 4 , LiB 10 Cl 10 , LiAlCl 4 At least one of lithium chloroborane, lower aliphatic lithium carboxylate having 4 or less carbon atoms, lithium tetraphenylborate, and lithium imide.
  • the electrolyte salt can be inorganic electrolyte salts such as LiBF 4 , LiClO 4 , LiAlF 4 , LiSbF 6 , LiTaF 6 , LiWF 7 ; fluorophosphate electrolyte salts such as LiPF 6 ; tungstate electrolyte salts such as LiWOF 5 ; HCO 2 Li , CH 3 CO 2 Li, CH 2 FCO 2 Li, CHF 2 CO 2 Li, CF 3 CO 2 Li, CF 3 CH 2 CO 2 Li, CF 3 CF 2 CO 2 Li, CF 3 CF 2 CO 2 Li, CF 3 CF 2 CF 2 CO 2 Li , CF 3 CF 2 CF 2 CO 2 Li , CF 3 CF 2 CF 2 CO 2 Li and other carboxylic acid electrolyte salts; CH 3 SO 3 Li and other sulfonic acid electrolyte salts; LiN(FCO 2 ) 2 , LiN(FCO)(FSO 2 ), LiN(
  • the electrolyte salt in the electrolyte is the transfer unit of lithium ions.
  • concentration of the electrolyte salt directly affects the transfer speed of lithium ions, and the transfer speed of lithium ions will affect the potential change of the negative electrode.
  • the total concentration of the electrolyte salt in the electrolyte can be 0.5mol/L-2.0mol/L, 0.5mol/L-0.6mol/L, 0.6mol/L-0.7mol/L, 0.7mol/L ⁇ 0.8mol/L, 0.8mol/L ⁇ 0.9mol/L, 0.9mol/L ⁇ 1.0mol/L, 1.0mol/L ⁇ 1.1mol/L, 1.1mol/L ⁇ 1.2mol/L, 1.2mol/L ⁇ 1.3mol/L, 1.3mol/L ⁇ 1.4mol/L, 1.4mol/L ⁇ 1.5mol/L, 1.5mol/L ⁇ 1.6mol/L, 1.6mol/L ⁇ 1.7mol/L, 1.7mol/L ⁇ 1.8mol/L, 1.8mol/L ⁇ 1.9mol/L, or 1.9mol/L ⁇ 2.0mol/L, more preferably 0.6mol/L ⁇ 1.8mol/L, 0.7mol/L ⁇ 1.7mol/L L, or 0.8mol/L ⁇ 1.5mol/L.
  • the non-aqueous electrolyte solution further includes other solvents, such as ether solvents, nitrile solvents, carbonate solvents, and the like.
  • ether solvents include cyclic ethers or chain ethers, preferably chain ethers with 3 to 10 carbon atoms and cyclic ethers with 3 to 6 carbon atoms.
  • the cyclic ethers can specifically be but not limited to It is 1,3-dioxolane (DOL), 1,4-dioxane (DX), crown ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-CH 3 -THF), 2-tri One or more of fluoromethyltetrahydrofuran (2-CF 3 -THF);
  • the chain ether can be, but not limited to, dimethoxymethane, diethoxymethane, ethoxymethoxymethane , Ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether.
  • Dimethoxymethane, diethoxymethane, and ethoxymethoxymethane which are low in viscosity and impart high ion conductivity, are particularly preferred because the solvation ability of chain ethers with lithium ions is high and ion dissociation can be improved.
  • methyl methane One kind of ether compound may be used alone, or two or more kinds may be used in any combination and ratio.
  • the addition amount of the ether compound is not particularly limited, and it is arbitrary within the scope of not significantly destroying the effect of the high-compression lithium-ion battery of the present invention.
  • the volume ratio of the non-aqueous solvent is 100%, the volume ratio is usually more than 1%, preferably 1% by volume.
  • the ratio is 2% or more, more preferably 3% or more by volume, and usually 30% or less by volume, preferably 25% or less by volume, more preferably 20% or less by volume.
  • the total amount of the ether compounds may satisfy the above range.
  • the addition amount of the ether compound is within the above-mentioned preferred range, it is easy to ensure the effect of improving the ion conductivity by increasing the lithium ion dissociation degree of the chain ether and reducing the viscosity.
  • the negative electrode active material is a carbon material, it is possible to suppress the co-intercalation phenomenon of the chain ether and lithium ions, so that the input-output characteristics and the charge-discharge rate characteristics can be brought into appropriate ranges.
  • the nitrile solvent may specifically be, but not limited to, one or more of acetonitrile, glutaronitrile, and malononitrile.
  • the carbonate solvents include cyclic carbonates or chain carbonates
  • the cyclic carbonates can specifically be, but not limited to, ethylene carbonate (EC), propylene carbonate (PC), gamma-butyrolactone One or more of (GBL), butylene carbonate (BC);
  • the chain carbonate can specifically be, but not limited to, dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC ), one or more of dipropyl carbonate (DPC).
  • the content of the cyclic carbonate is not particularly limited, and it is arbitrary within the scope of not significantly destroying the effect of the lithium-ion battery of the present invention, but the lower limit of its content is relative to the total amount of solvent in the non-aqueous electrolyte when one is used alone.
  • the volume ratio is 3% or more, preferably 5% or more.
  • the upper limit is usually 90% or less by volume, preferably 85% or less by volume, and more preferably 80% or less by volume.
  • the content of the chain carbonate is not particularly limited, but is usually 15% or more by volume, preferably 20% or more by volume, and more preferably 25% or more by volume relative to the total amount of solvent in the nonaqueous electrolyte.
  • the volume ratio is 90% or less, preferably 85% or less, more preferably 80% or less.
  • the content of the chain carbonate within the above range, it is easy to make the viscosity of the non-aqueous electrolytic solution in an appropriate range, suppress the decrease in ion conductivity, and contribute to making the output characteristics of the non-aqueous electrolyte battery a good range.
  • the total amount of the chain carbonates may satisfy the above-mentioned range.
  • chain carbonates having fluorine atoms may also be preferably used.
  • the number of fluorine atoms in the fluorinated chain carbonate is not particularly limited as long as it is 1 or more, but is usually 6 or less, preferably 4 or less.
  • these fluorine atoms may be bonded to the same carbon or to different carbons.
  • the fluorinated chain carbonate include fluorinated dimethyl carbonate derivatives, fluorinated ethyl methyl carbonate derivatives, and fluorinated diethyl carbonate derivatives.
  • Carboxylate solvents include cyclic carboxylates and/or chain carbonates.
  • cyclic carboxylic acid esters include one or more of ⁇ -butyrolactone, ⁇ -valerolactone, and ⁇ -valerolactone.
  • chain carbonates include: methyl acetate (MA), ethyl acetate (EA), propyl acetate (EP), butyl acetate, propyl propionate (PP), butyl propionate one or more of .
  • the sulfone solvent includes cyclic sulfone and chain sulfone.
  • cyclic sulfone it usually has 3 to 6 carbon atoms, preferably 3 to 5 carbon atoms.
  • a sulfone it is usually a compound having 2 to 6 carbon atoms, preferably a compound having 2 to 5 carbon atoms.
  • the amount of sulfone solvent added is not particularly limited, and it is arbitrary within the scope of not significantly destroying the effect of the lithium ion battery of the present invention.
  • the volume ratio is usually more than 0.3%, preferably 0.3% by volume.
  • the total amount of the sulfone-based solvent may satisfy the above range.
  • the added amount of the sulfone solvent is within the above range, an electrolytic solution having excellent high-temperature storage stability tends to be obtained.
  • the battery further includes a separator, and the separator is located between the positive electrode and the negative electrode.
  • the diaphragm can be an existing conventional diaphragm, which can be a polymer diaphragm, non-woven fabric, etc., including but not limited to single-layer PP (polypropylene), single-layer PE (polyethylene), double-layer PP/PE, double-layer PP /PP and three-layer PP/PE/PP separators.
  • This embodiment is used to illustrate the battery disclosed in the present invention and its preparation method, including the following steps:
  • the positive pole piece, the separator and the negative pole piece are stacked in sequence, and then after the top and side sealing, injecting a certain amount of electrolyte and other processes, the soft pack battery is made, and the prepared soft pack battery is formed. , Divide the volume, then disassemble, take out the negative electrode sheet separately, scrape 1g of negative electrode powder with a blade, send the sample for ICP elemental analysis and determination, test the Mg content, and the results are listed in Table 1 in ppm.
  • Examples 2-31 are used to illustrate the battery disclosed in the present invention and its preparation method, including most of the operation steps in Example 1, the differences are:
  • Comparative Examples 1-9 are used to illustrate the battery disclosed in the present invention and its preparation method, including most of the operation steps in Example 1, the difference being:
  • Battery capacity retention rate (%) retention capacity D2/initial discharge capacity D1 ⁇ 100%.
  • Growth rate of battery impedance after cycle (%) [(internal resistance after the corresponding number of cycles-internal resistance after the first cycle)/internal resistance after the first cycle] ⁇ 100%.
  • the formed battery was charged to the cut-off voltage with 2C constant current and constant voltage, then charged at constant voltage until the current dropped to 0.05C, and then discharged to 3.0V with a constant current of 2C, and cycled for 500 cycles.
  • Capacity retention ratio last discharge capacity / first discharge capacity ⁇ 100%.
  • PS (1,3-propane sultone), DTD (ethylene sulfate), VC (ethylene carbonate ) or tripropargyl phosphate as an auxiliary additive can further improve the high-temperature storage performance and fast charge cycle performance of the battery.
  • ester DTD (vinyl sulfate), VC (ethylene carbonate) or tripropargyl phosphate
  • there is a certain common decomposition reaction which can participate in the formation of a passivation film on the electrode surface, and the obtained passivation film can improve
  • the stability of the electrode material maintains the stability of the battery cycle and the performance of high current resistance.

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Abstract

为克服现有锂离子电池存在的快充性能不足，高温存储性能不足和高温循环阻抗增长的问题，本发明提供了一种锂离子电池，包括含正极材料层的正极、含负极材料层的负极以及非水电解液，所述正极材料层包括含镁的锂过渡金属氧化物作为正极活性物质，所述负极材料层包括负极活性物质和含镁化合物，所述非水电解液包括羧酸酯溶剂、电解质盐和结构式1所示的化合物：其中，R1选自碳原子数为3-6的不饱和烃基，R2选自碳原子数为2-5的亚烃基，n＝1或2；所述锂离子电池满足以下条件： 0.002≤m/x≤0.25且0.001≤m/z≤0.1。本发明在保持电池具有优异的高温性能的前提下，保证电池具有较低的阻抗增长率，提高电池长期循环的可靠性。

Description

一种锂离子电池 技术领域
本发明属于储能电池器件技术领域，具体涉及一种锂离子电池。
背景技术
锂离子电池因具有工作电压高、工作温度范围广、能量密度和功率密度大、无记忆效应和循环寿命长等优点，在手机、笔记本电脑等3C数码产品领域以及新能源汽车领域都得到了广泛的应用。近年来，随着3C数码产品轻薄化的不断发展，电池行业对锂离子电池高能量密度化的要求也越来越高，同时出于用户端考虑，快充已成为电池的基本要求。因此亟需提升锂离子电池的能量密度并提高快充性能。
目前提高电池能量密度的方法主要有：1.提高正极充电截止电压。2.通过对电极的活性物质层进行加压来进行高密度化，从而使电池内部的活性物质以外所占的体积尽可能减少的方法。但是，提高正极充电截止电压，正极的活性进一步提高，正极和电解液之间的副反应加剧，正极过渡金属离子溶出，造成电池高温存储容量损失过度，性能劣化。另外，使用高压实的电极，由于高压实电极孔隙率低，电池的保液量也会降低，电解液在低孔隙率极片界面渗透难，使得电解液与电极之间的接触内阻增大，在长循环过程中，充放电极化变大，存在因出现析锂而造成突然跳水的情况。因此，在改善高压实，高电压锂离子电池的高温性能的同时抑制循环过程的阻抗增长是一项难题。
电解液方面目前常用的方法有两种，一种是使用腈类或其他高电压添加剂，加强对高电压下正极的保护，但腈类添加剂在循环过程中会劣化电池阻抗，造成电池快充性能差，且循环后期极化增大，造成电池长循环性能差；另一种是添加促进循环、降低阻抗的添加剂，如FEC等，这些添加剂会降低电池阻抗，有利于电池的循环寿命的提高，但会降低电池高温稳定性，导致电解液的高温性能变差，高温存储容易气胀等，此外，还可使用羧酸酯溶剂，羧酸酯溶剂具有宽液程、低粘度、高电导的优点，可大幅提升电池的快充性能，但是羧酸酯稳定性差于线性碳酸酯，其在循环过程中易与正极发生副反应，从而副反应产 物迁移到负极，并在负极还原，造成循环阻抗增长快，而且羧酸酯在高温存储过程中会带来产气问题。因此，如何保证电池长期快充循环性能，又兼顾电池的高温存储性能，是高电压高压实锂离子电池研究的一大课题。
发明内容
针对现有锂离子电池存在的快充循环性能不足、高温循环阻抗增长及高温存储性能不佳的问题，本发明提供了一种锂离子电池。
本发明解决上述技术问题所采用的技术方案如下：
本发明提供了一种锂离子电池，包括含正极材料层的正极、含负极材料层的负极以及非水电解液，所述正极材料层包括含镁的锂过渡金属氧化物作为正极活性物质，所述负极材料层包括负极活性物质和含镁化合物，所述非水电解液包括羧酸酯溶剂、电解质盐和结构式1所示的化合物：
Figure PCTCN2022132198-appb-000001
其中，R1选自碳原子数为3-6的不饱和烃基，R2选自碳原子数为2-5的亚烃基，n为1或2；
所述锂离子电池满足以下条件：
0.002≤m/x≤0.25且0.001≤m/z≤0.1；
其中，x为非水电解液中羧酸酯的质量百分含量，单位为％；
m为非水电解液中结构式1所示的化合物的质量百分含量，单位为％；
z为Mg元素相对负极材料层的质量含量，单位为ppm。
可选的，所述锂离子电池满足以下条件：
0.005≤m/x≤0.1且0.001≤m/z≤0.02。
可选的，所述结构式1所示的化合物选自以下化合物中的一种或多种：
Figure PCTCN2022132198-appb-000002
Figure PCTCN2022132198-appb-000003
可选的，所述非水电解液中结构式1所示的化合物的质量百分含量m为0.1～5％；
优选的，所述非水电解液中结构式1所示的化合物的质量百分含量m为0.1～2％。
可选的，所述Mg元素相对负极材料层的质量含量z为5～500ppm；
优选的，所述Mg元素相对负极材料层的质量含量z为50～500ppm。
可选的，所述非水电解液中羧酸酯的质量百分含量x为5～55％；
优选的，所述非水电解液中羧酸酯的质量百分含量x为10～40％。
可选的，所述羧酸酯选自乙酸甲酯、乙酸乙酯、丙酸乙酯、乙酸丁酯、丙酸丙酯、丙酸丁酯、γ-丁内酯、γ-戊内酯、δ-戊内酯中的至少一种。
可选的，负极材料层的压实密度大于等于1.5g/cm 3；优选的，负极材料层的压实密度为1.55～1.9g/cm 3。
可选的，所述非水电解液中还包括辅助添加剂，所述辅助添加剂包括环状硫酸酯类化合物、磺酸内酯类化合物、环状碳酸酯类化合物、不饱和磷酸酯类化合物和腈类化合物中的至少一种；
优选的，以所述非水电解液的总质量为100％计，所述辅助添加剂的添加量为0.01％～30％。
可选的，所述环状硫酸酯类化合物选自硫酸乙烯酯、硫酸丙烯酯或甲基硫酸乙烯酯中的至少一种；
所述磺酸内酯类化合物选自1,3-丙烷磺酸内酯、1,4-丁烷磺酸内酯或1,3-丙烯磺酸内酯中的至少一种；
所述环状碳酸酯类化合物选自碳酸亚乙烯酯、碳酸乙烯亚乙酯、氟代碳酸乙烯酯或结构式2所示化合物中的至少一种，
Figure PCTCN2022132198-appb-000004
所述结构式2中，R 21、R 22、R 23、R 24、R 25、R 26各自独立地选自氢原子、卤素原子、C1-C5基团中的一种；
所述不饱和磷酸酯类化合物选自结构式3所示化合物中的至少一种：
Figure PCTCN2022132198-appb-000005
所述结构式3中，R 31、R 32、R 33各自独立的选自C1-C5的饱和烃基、不饱和烃基、卤代烃基、-Si(C mH 2m+1) 3，m为1～3的自然数，且R 31、R 32、R 33中至少有一个为不饱和烃基；
所述腈类化合物包括丁二腈、戊二腈、乙二醇双(丙腈)醚、己烷三腈、己二腈、庚二腈、辛二腈、壬二腈、癸二腈中的一种或多种。
本申请发明人经过潜心研究发现：在电解液方面，将结构式1所示的化合物与羧酸酯溶剂配合使用，结构式1所示的化合物能够有效保护正极，缓和羧酸酯溶剂与正极的氧化反应，保证电池的快充循环性能；在负极方面，负极中Mg可以调控结构式1所示的化合物在负极生成的SEI膜的形成方式，一方面Mg参与SEI膜形成，得到的SEI膜厚度降低，避免由于SEI膜厚度过厚导致的阻抗过大的问题，另一方面，形成的含Mg的SEI膜具有较高的电导率，能够降 低负极的电荷转移阻抗，从而使充放电过程的Li +嵌入和脱出反应的过电位降低，因此能够能有效抑制循环过程的阻抗增长率，从而提高电池的高温循环性能和存储性能。尤其是，当负极材料层中Mg元素的质量含量z和结构式1所示的化合物的质量含量m以及羧酸酯含量x满足0.002≤m/x≤0.25且0.001≤m/z≤0.1时，能够在保持电池具有优异的高温存储性能的前提下，保证电池具有良好的快充循环性能。
具体实施方式
为了使本发明所解决的技术问题、技术方案及有益效果更加清楚明白，以下结合实施例，对本发明进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本发明，并不用于限定本发明。
本发明实施例提供了一种锂离子电池，包括正极、负极和非水电解液。
所述正极由正极集流体和形成于正极集流体上的正极材料层构成。所述正极集流体选自可传导电子的金属材料，优选的，所述正极集流体包括Al、Ni、锡、铜、不锈钢的一种或多种，在更优选的实施例中，所述正极集流体选自铝箔。所述正极材料层包括含镁的锂过渡金属氧化物作为正极活性物质、正极粘结剂和正极导电剂。
所述正极活性物质包括含镁的锂过渡金属氧化物。具体地，所述正极活性物质可选自LiFe 1-x’Mg x’PO 4、LiMn 2-y’Mg y’O 4和LiNi xCo yMn zMg 1-x-y-zO 2中的一种或多种，其中，0≤x’＜1，0≤y’≤1，0≤y≤1，0≤x≤1，0≤z≤1，x+y+z≤1。所述正极活性物质中含有镁，能够提高正极活性物质的稳定性，同时正极活性物质的Mg元素在充放电循环中会少量溶出并迁移至负极材料层中，得到本发明所述的含有Mg元素的负极材料层。
所述正极粘结剂可选自聚偏氟乙烯、偏氟乙烯的共聚物、聚四氟乙烯、偏氟乙烯-六氟丙烯的共聚物、四氟乙烯-六氟丙烯的共聚物、四氟乙烯-全氟烷基乙烯基醚的共聚物、乙烯-四氟乙烯的共聚物、偏氟乙烯-四氟乙烯的共聚物、偏氟乙烯-三氟乙烯的共聚物、偏氟乙烯-三氯乙烯的共聚物、偏氟乙烯-氟代乙烯的共聚物、偏氟乙烯-六氟丙烯-四氟乙烯的共聚物、热塑性聚酰亚胺、聚乙烯及聚丙烯等热塑性树脂；丙烯酸类树脂；以及苯乙烯丁二烯橡胶中的一种或多种。
所述正极导电剂可选自金属导电剂、碳系材料、金属氧化物系导电剂、复 合导电剂中的一种或多种。具体的，金属导电剂可以为铜粉、镍粉、银粉等金属；碳系材料可为导电石墨、导电炭黑、导电碳纤维或石墨烯等碳系材料；金属氧化物系导电剂可为氧化锡、氧化铁、氧化锌等；复合导电剂可以为复合粉、复合纤维等。更具体的，导电炭黑可以为乙炔黑、350G、科琴黑、碳纤维(VGCF)、碳纳米管(CNTs)中的一种或几种。
所述负极包括负极集流体和形成于所述负极集流体上的负极材料层。
所述负极集流体选自可传导电子的金属材料，优选的，所述负极集流体包括Al、Ni、锡、铜、不锈钢的一种或多种，在更优选的实施例中，所述负极集流体选自铝箔。
所述负极材料层包括负极活性物质、含镁化合物、负极粘结剂和负极导电剂。
所述负极活性物质包括硅基负极和碳基负极中的一种或多种。所述碳基负极可包括石墨、硬碳、软碳、石墨烯、中间相碳微球等。所述石墨包括但不限于天然石墨、人造石墨、非晶碳、碳包覆石墨、石墨包覆石墨、树脂包覆石墨中的一种或几种。所述硅基负极可包括硅材料、硅的氧化物、硅碳复合材料以及硅合金材料等。所述硅基材料的添加量大于0小于30％。优选地，所述硅基材料的添加量的上限值为10％、15％、20％或25％；所述硅基材料的添加量的下限值为5％、10％或15％。所述硅材料为硅纳米颗粒、硅纳米线、硅纳米管、硅薄膜、3D多孔硅、中空多孔硅中的一种或几种。
所述负极粘结剂选自聚偏氟乙烯、偏氟乙烯的共聚物、聚四氟乙烯、偏氟乙烯-六氟丙烯的共聚物、四氟乙烯-六氟丙烯的共聚物、四氟乙烯-全氟烷基乙烯基醚的共聚物、乙烯-四氟乙烯的共聚物、偏氟乙烯-四氟乙烯的共聚物、偏氟乙烯-三氟乙烯的共聚物、偏氟乙烯-三氯乙烯的共聚物、偏氟乙烯-氟代乙烯的共聚物、偏氟乙烯-六氟丙烯-四氟乙烯的共聚物、热塑性聚酰亚胺、聚乙烯及聚丙烯等热塑性树脂；丙烯酸类树脂；羟甲基纤维素钠；以及苯乙烯丁二烯橡胶中的一种或多种。
所述负极导电剂选自导电炭黑、导电碳球、导电石墨、导电碳纤维、碳纳米管、石墨烯或还原氧化石墨烯中的一种或多种。
所述非水电解液包括羧酸酯溶剂、电解质盐和结构式1所示的化合物：
Figure PCTCN2022132198-appb-000006
Figure PCTCN2022132198-appb-000007
其中，R1选自碳原子数为3-6的不饱和烃基，R2选自碳原子数为2-5的亚烃基，n为1或2；
所述锂离子电池满足以下条件：
0.002≤m/x≤0.25且0.001≤m/z≤0.1；
其中，x为非水电解液中羧酸酯的质量百分含量，单位为％；
m为非水电解液中结构式1所示的化合物的质量百分含量，单位为％；
z为Mg元素相对负极材料层的质量含量，单位为ppm。
本申请发明人经过潜心研究发现：在电解液方面，将结构式1所示的化合物与羧酸酯溶剂配合使用，结构式1所示的化合物能够有效保护正极，缓和羧酸酯溶剂与正极的氧化反应，保证电池的快充循环性能；在负极方面，负极中Mg可以调控结构式1所示的化合物在负极生成的SEI膜的形成方式，一方面Mg参与SEI膜形成，得到的SEI膜厚度降低，避免由于SEI膜厚度过厚导致的阻抗过大的问题，另一方面，形成的含Mg的SEI膜具有较高的电导率，能够降低负极的电荷转移阻抗，从而使充放电过程的Li +嵌入和脱出反应的过电位降低，因此能够能有效抑制循环过程的阻抗增长率，从而提高电池的高温循环性能和存储性能。
尤其是，当负极材料层中Mg元素的质量含量z和结构式1所示的化合物的质量含量m以及羧酸酯含量x满足0.002≤m/x≤0.25且0.001≤m/z≤0.1时，能够在保持电池具有优异的高温性能的前提下，保证电池具有良好的快充循环性能。
在优选的实施例中，所述锂离子电池满足以下条件：
0.005≤m/x≤0.1且0.001≤m/z≤0.02。
在本发明提供的锂离子电池中，将结构式1所示的化合物与负极材料层中Mg元素的质量含量z以及非水电解液中羧酸酯的质量百分含量相关联，能够一定程度上综合负极、羧酸酯和结构式1所示化合物对于电池性能的影响，而获得一种即具有较好快充循环性能，又具有较优高温性能的锂离子电池。
在一些实施例中，所述结构式1所示的化合物选自以下化合物中的一种或多种：
Figure PCTCN2022132198-appb-000008
Figure PCTCN2022132198-appb-000009
在一些实施例中，所述非水电解液中结构式1所示的化合物的质量百分含量m为0.1～5％。
在优选的实施例中，所述非水电解液中结构式1所示的化合物的质量百分含量m为0.1～2％。
电池在循环过程中，正极处于氧化性较强的状态，易于电解液发生氧化反应，造成电解液分解，产生的氧化产物会迁移至负极界面，在负极表面还原，消耗活性Li，通过添加结构式1所示的化合物，能够有效抑制非水电解液与正极活性物质之间的反应，抑制正极反应产物迁移至负极发生反应，从而降低电池的活性锂损失。但结构式1所示的化合物的添加量也不宜过大，其在电池负极所成SEI膜的初期阻抗较大，会造成电池阻抗增加，且过量添加结构式1所示的化合物会增大电解液粘度，降低电导，从而不利于电池的循环性能。
在一些实施例中，所述Mg元素相对负极材料层的质量含量z为5～500ppm。
在优选的实施例中，所述Mg元素相对负极材料层的质量含量z为50～500ppm。
需要说明的是，本申请中负极材料层是指负极除负极集流体以外的部分，参数z限定的是负极材料层中Mg元素的含量。所述负极材料层中的Mg元素可来自于制备所述负极材料层时的额外添加，或是来自于所述正极活性物质的Mg金属离子溶出，例如，可通过在正极活性物质中掺杂Mg元素，通过充放电使正极活性物质中的Mg元素部分离子化，并迁移至负极材料层中析出。具体的，所述负极材料层中的Mg元素以单质或化合物形式存在。
负极材料层中Mg元素有利于解决结构式1所示的化合物形成的SEI膜初期阻抗较大的问题，当负极材料层中Mg元素的质量含量z过低，则难以降低SEI膜的厚度；当负极材料层中Mg元素的质量含量z过高，则会导致负极的能量密 度降低，影响电解质离子的嵌入和脱除。
在一些实施例中，所述非水电解液中羧酸酯的质量百分含量x为5～55％；
在优选的实施例中，所述非水电解液中羧酸酯的质量百分含量x为10～40％。
通过在所述非水电解液中加入羧酸酯作为溶剂，能够提高电池的快充性能，但过多地添加羧酸酯则会使非水电解液的稳定性降低，进而影响电池的循环性能。
在一些实施例中，所述羧酸酯选自乙酸甲酯、乙酸乙酯、丙酸乙酯、乙酸丁酯、丙酸丙酯、丙酸丁酯、γ-丁内酯、γ-戊内酯、δ-戊内酯中的至少一种。
在一些实施例中，所述非水电解液中还包括辅助添加剂，所述辅助添加剂包括环状硫酸酯类化合物、磺酸内酯类化合物、环状碳酸酯类化合物、不饱和磷酸酯类化合物和腈类化合物中的至少一种。
优选的，所述环状硫酸酯类化合物选自硫酸乙烯酯、硫酸丙烯酯或甲基硫酸乙烯酯中的至少一种；
所述磺酸内酯类化合物选自1,3-丙烷磺酸内酯、1,4-丁烷磺酸内酯或1,3-丙烯磺酸内酯中的至少一种；
所述环状碳酸酯类化合物选自碳酸亚乙烯酯、碳酸乙烯亚乙酯、氟代碳酸乙烯酯或结构式2所示化合物中的至少一种，
Figure PCTCN2022132198-appb-000010
所述结构式2中，R 21、R 22、R 23、R 24、R 25、R 26各自独立地选自氢原子、卤素原子、C1-C5基团中的一种。
所述不饱和磷酸酯类化合物选自结构式3所示化合物中的至少一种：
Figure PCTCN2022132198-appb-000011
所述结构式3中，R 31、R 32、R 33各自独立的选自C1-C5的饱和烃基、不饱和烃基、卤代烃基、-Si(C mH 2m+1) 3，m为1～3的自然数，且R 31、R 32、R 33中至少有一个为不饱和烃基。
在优选的实施例中，所述不饱和磷酸酯类化合物可为磷酸三炔丙酯、二炔丙基甲基磷酸酯、二炔丙基乙基磷酸酯、二炔丙基丙基磷酸酯、二炔丙基三氟甲基磷酸酯、二炔丙基-2,2,2-三氟乙基磷酸酯、二炔丙基-3,3,3-三氟丙基磷酸酯、二炔丙基六氟异丙基磷酸酯、磷酸三烯丙酯、二烯丙基甲基磷酸酯、二烯丙基乙基磷酸酯、二烯丙基丙基磷酸酯、二烯丙基三氟甲基磷酸酯、二烯丙基-2,2,2-三氟乙基磷酸酯、二烯丙基-3,3,3-三氟丙基磷酸酯、二烯丙基六氟异丙基磷酸酯中的至少一种。
所述腈类化合物包括丁二腈、戊二腈、乙二醇双(丙腈)醚、己烷三腈、己二腈、庚二腈、辛二腈、壬二腈、癸二腈中的一种或多种。
在另一些实施例中，所述辅助添加剂还可包括其它能改善电池性能的添加剂：例如，提升电池安全性能的添加剂，具体如氟代磷酸酯、环磷腈等阻燃添加剂，或叔戊基苯、叔丁基苯等防过充添加剂。
在一些实施例中，以所述非水电解液的总质量为100％计，所述辅助添加剂的添加量为0.01％～30％。
需要说明的是，除非特殊说明，一般情况下，所述辅助添加剂中任意一种可选物质在非水电解液中的添加量为10％以下，优选的，添加量为0.1-5％，更优选的，添加量为0.1％～2％。具体的，所述辅助添加剂中任意一种可选物质的添加量可以为0.05％、0.08％、0.1％、0.5％、0.8％、1％、1.2％、1.5％、1.8％、2％、2.2％、2.5％、2.8％、3％、3.2％、3.5％、3.8％、4％、4.5％、5％、5.5％、6％、6.5％、7％、7.5％、7.8％、8％、8.5％、9％、9.5％、10％。
在一些实施例中，当辅助添加剂选自氟代碳酸乙烯酯时，以所述非水电解液的总质量为100％计，所述氟代碳酸乙烯酯的添加量为0.05％～30％。
在一些实施例中，所述电解质盐选自所述电解质盐选自LiPF 6、LiPO 2F 2、LiBF 4、LiBOB、LiSbF 6、LiAsF 6、LiCF 3SO 3、LiDFOB、LiN(SO 2CF 3) 2、LiC(SO 2CF 3) 3、LiN(SO 2C 2F 5) 2、LiN(SO 2F) 2、LiCl、LiBr、LiI、LiClO 4、LiBF 4、LiB 10Cl 10、LiAlCl 4、氯硼烷锂、具有4个以下的碳原子的低级脂族羧酸锂、四苯基硼酸锂以及亚氨基锂中的至少一种。具体的，电解质盐可以为LiBF 4、LiClO 4、LiAlF 4、LiSbF 6、LiTaF 6、LiWF 7等无机电解质盐；LiPF 6等氟磷酸电解质盐类；LiWOF 5等钨酸电解质盐类；HCO 2Li、CH 3CO 2Li、CH 2FCO 2Li、CHF 2CO 2Li、CF 3CO 2Li、CF 3CH 2CO 2Li、CF 3CF 2CO 2Li、CF 3CF 2CF 2CO 2Li、CF 3CF 2CF 2CF 2CO 2Li等羧酸电解质盐类；CH 3SO 3Li等磺酸电解质盐类；LiN(FCO 2) 2、LiN(FCO)(FSO 2)、LiN(FSO 2) 2、LiN(FSO 2)(CF 3SO 2)、LiN(CF 3SO 2) 2、LiN(C 2F 5SO 2) 2、环状1,2-全氟乙二磺酰亚胺锂、环状1,3-全氟丙二磺酰亚胺锂、LiN(CF 3SO 2)(C 4F 9SO 2)等酰亚胺电解质盐类；LiC(FSO 2) 3、LiC(CF 3SO 2) 3、LiC(C 2F 5SO 2) 3等甲基电解质盐类；二氟草酸根合硼酸锂、二(草酸根合)硼酸锂、四氟草酸根合磷酸锂、二氟二(草酸根合)磷酸锂、三(草酸根合)磷酸锂等草酸电解质盐类；以及LiPF 4(CF 3) 2、LiPF 4(C 2F 5) 2、LiPF 4(CF 3SO 2) 2、LiPF 4(C 2F 5SO 2) 2、LiBF 3CF 3、LiBF 3C 2F 5、LiBF 3C 3F 7、LiBF 2(CF 3) 2、LiBF 2(C 2F 5) 2、LiBF 2(CF 3SO 2) 2、LiBF 2(C 2F 5SO 2) 2等含氟有机电解质盐类等。
通常，电解液中的电解质盐是锂离子的传递单元，电解质盐的浓度大小直接影响锂离子的传递速度，而锂离子的传递速度会影响负极的电位变化。在电池快速充电过程中，需要尽量提高锂离子的移动速度，防止负极电位下降过快导致锂枝晶的形成，给电池带来安全隐患，同时还能防止电池的循环容量过快衰减。优选的，所述电解质盐在电解液中的总浓度可以为0.5mol/L～2.0mol/L、0.5mol/L～0.6mol/L、0.6mol/L～0.7mol/L、0.7mol/L～0.8mol/L、0.8mol/L～0.9mol/L、0.9mol/L～1.0mol/L、1.0mol/L～1.1mol/L、1.1mol/L～1.2mol/L、1.2mol/L～1.3mol/L、1.3mol/L～1.4mol/L、1.4mol/L～1.5mol/L、1.5mol/L～1.6mol/L、1.6mol/L～1.7mol/L、1.7mol/L～1.8mol/L、1.8mol/L～1.9mol/L、或1.9mol/L～2.0mol/L，进一步优选的可以为0.6mol/L～1.8mol/L、0.7mol/L～1.7mol/L、或0.8mol/L～1.5mol/L。
在一些实施例中，所述非水电解液还包括其它溶剂，比如醚类溶剂、腈类溶剂、碳酸酯类溶剂等。
在一些实施例中，醚类溶剂包括环状醚或链状醚，优选为碳原子数3～10的链状醚及碳原子数3～6的环状醚，环状醚具体可以但不限于是1,3-二氧戊烷(DOL)、1,4-二氧惡烷(DX)、冠醚、四氢呋喃(THF)、2-甲基四氢呋喃(2-CH 3-THF)，2-三氟甲基四氢呋喃(2-CF 3-THF)中的一种或多种；所述链状醚具体可以但不限于是二甲氧基甲烷、二乙氧基甲烷、乙氧基甲氧基甲烷、乙二醇二正丙基醚、乙二醇二正丁基醚、二乙二醇二甲基醚。由于链状醚与锂离子的溶剂化能力高、可提高离子解离性，因此特别优选粘性低、可赋予高离子电导率的二甲氧基甲烷、二乙氧基甲烷、乙氧基甲氧基甲烷。醚类化合物可以单独使用一种，也可以以任意的组合及比率组合使用两种以上。醚类化合物的添加量没有特殊限制，在不显著破坏本发明高压实锂离子电池效果的范围内是任意的，在非水溶剂体积比为100％中通常体积比为1％以上、优选体积比为2％以上、更优选体积比为3％以上，另外，通常体积比为30％以下、优选体积比为25％以下、更优选体积比为20％以下。在将两种以上醚类化合物组合使用的情况下，使醚类化合物的总量满足上述范围即可。醚类化合物的添加量在上述的优选范围内时，易于确保由链状醚的锂离子离解度的提高和粘度降低所带来的离子电导率的改善效果。另外，负极活性物质为碳素材料的情况下，可抑制因链状醚与锂离子共同发生共嵌入的现象，因此能够使输入输出特性、充放电速率特性达到适当的范围。
在一些实施例中，腈类溶剂具体可以但不限于是乙腈、戊二腈、丙二腈中的一种或多种。
在一些实施例中，碳酸酯类溶剂包括环状碳酸酯或链状碳酸酯，环状碳酸酯具体可以但不限于是碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、γ-丁内酯(GBL)、碳酸亚丁酯(BC)中的一种或多种；链状碳酸酯具体可以但不限于是碳酸二甲酯(DMC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)、碳酸二丙酯(DPC)中的一种或多种。环状碳酸酯的含量没有特殊限制，在不显著破坏本发明锂离子电池效果的范围内是任意的，但在单独使用一种的情况下其含量的下限相对于非水电解液的溶剂总量来说，通常体积比为3％以上、优选体积比为5％以上。通过设定该范围，可避免由于非水电解液的介电常数降低而导致电导率降低，易于使非水电解质电池的大电流放电特性、相对于负极的稳定性、循环特性达到良好的范围。另外，上限通常体积比为90％以下、优选体积比为85％以下、更优选体积比为80％以下。通过设定该范围，可提高非水电解液的氧化/还原耐性，从而有助于提高高温保存时的稳定性。链状碳酸酯的含量没有特殊限定，相对于非水电解液的溶剂总量，通常为体积比为15％以上、优选体积比为20％以上、更优选体积比为25％以上。另外，通常体积比为90％以下、优选体积比 为85％以下、更优选体积比为80％以下。通过使链状碳酸酯的含量在上述范围，容易使非水电解液的粘度达到适当范围，抑制离子电导率的降低，进而有助于使非水电解质电池的输出特性达到良好的范围。在组合使用两种以上链状碳酸酯的情况下，使链状碳酸酯的总量满足上述范围即可。
在一些实施例中，还可优选使用具有氟原子的链状碳酸酯类(以下简称为“氟化链状碳酸酯”)。氟化链状碳酸酯所具有的氟原子的个数只要为1以上则没有特殊限制，但通常为6以下、优选4以下。氟化链状碳酸酯具有多个氟原子的情况下，这些氟原子相互可以键合于同一个碳上，也可以键合于不同的碳上。作为氟化链状碳酸酯，可列举，氟化碳酸二甲酯衍生物、氟化碳酸甲乙酯衍生物、氟化碳酸二乙酯衍生物等。
羧酸酯类溶剂包括环状羧酸酯和/或链状碳酸酯。作为环状羧酸酯的例子，可以列举如：γ-丁内酯、γ-戊内酯、δ-戊内酯中的一种或多种。作为链状碳酸酯的例子，可以列举如：乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(EP)、乙酸丁酯、丙酸丙酯(PP)、丙酸丁酯中的一种或多种。
在一些实施例中，砜类溶剂包括环状砜和链状砜，优选地，在为环状砜的情况下，通常为碳原子数3～6、优选碳原子数3～5，在为链状砜的情况下，通常为碳原子数2～6、优选碳原子数2～5的化合物。砜类溶剂的添加量没有特殊限制，在不显著破坏本发明锂离子电池效果的范围内是任意的，相对于非水电解液的溶剂总量，通常体积比为0.3％以上、优选体积比为0.5％以上、更优选体积比为1％以上，另外，通常体积比为40％以下、优选体积比为35％以下、更优选体积比为30％以下。在组合使用两种以上砜类溶剂的情况下，使砜类溶剂的总量满足上述范围即可。砜类溶剂的添加量在上述范围内时，倾向于获得高温保存稳定性优异的电解液。
在一些实施例中，所述电池中还包括有隔膜，所述隔膜位于所述正极和所述负极之间。
所述隔膜可为现有常规隔膜，可以是聚合物隔膜、无纺布等，包括但不限于单层PP(聚丙烯)、单层PE(聚乙烯)、双层PP/PE、双层PP/PP和三层PP/PE/PP等隔膜。
以下通过实施例对本发明进行进一步的说明。
以下实施例中所采用的结构式1所示的化合物如下表：
Figure PCTCN2022132198-appb-000012
Figure PCTCN2022132198-appb-000013
表1 实施例和对比例各参数设计
Figure PCTCN2022132198-appb-000014
Figure PCTCN2022132198-appb-000015
实施例1
本实施例用于说明本发明公开的电池及其制备方法，包括以下操作步骤：
(1)正极极片的制备
将含Mg正极活性物质、导电剂及粘结剂PVDF分散至溶剂NMP中进行混合均匀，得到正极浆料；将正极浆料均匀涂布于正极集流体铝箔上，经烘干、辊压、裁片后，得到正极极片，正极活性物质、导电炭黑及粘结剂PVDF的质量比为96:2:2。
(2)负极极片的制备
将负极活性物质石墨、导电剂、粘结剂CMC及SBR按照质量比96:1:1:2分散于去离子水中进行搅拌，得到负极浆料；将负极浆料均匀涂布于负极集流体铜箔上，烘干、辊压、裁片后，得到压实密度为1.6g/cm 3的负极极片。
(3)电解液的制备
将丙酸乙酯、碳酸乙烯酯(EC)和碳酸二乙酯(DEC)以质量比20:30:50混合均匀，将1mol/L的LiPF 6和占电解液的质量百分含量为0.1wt％的结构式1所示化合物溶解于上述非水有机溶剂中，得到电解液。
(4)锂离子电池的制备
采用叠片工艺，将正极极片、隔离膜及负极极片依次层叠，再经顶侧封、注入一定量的电解液等工序后，制成软包电池，将制作好的软包电池进行化成、分容，然后进行拆解，单独取出负极片，用刀片刮取1g负极粉料，送样ICP元素分析测定，测试Mg含量，结果以ppm计入表1中。
实施例2～31
实施例2～31用于说明本发明公开的电池及其制备方法，包括实施例1中大部分操作步骤，其不同之处在于：
采用表1所示的电解液添加组分。
对比例1～9
对比例1～9用于说明本发明公开的电池及其制备方法，包括实施例1中大部分操作步骤，其不同之处在于：
采用表1所示的电解液添加组分。
性能测试
对上述制备得到的锂离子电池进行如下性能测试：
1、将化成后的电池在常温下以1C的电流恒流充电至截止电压，再恒流恒压充电至电流下降至0.05C，然后以1C的电流恒流放电至3.0V，测量电池初始放电容量D1，然后充至满电在85℃环境中储存48h后，以1C放电至3V，测量电池的保持容量D2。计算公式如下：
电池容量保持率(％)＝保持容量D2/初始放电容量D1×100％。
2、将电池置于恒温45℃的高温烘箱中，以0.5C的电流恒流充电至截止电压，再恒压充电至电流下降至0.02C，搁置5分钟后，以1C的电流恒流放电至3.0V，此为首次循环，按照上述条件分别进行500次循环充电/放电，计算得出电池在45℃下循环500次后的阻抗增长率。
循环后的电池阻抗增长率(％)＝[(对应循环次数后的内阻-首次循环后的内阻)/首次循环后的内阻]×100％。
3、高温快充循环性能测试：
在45℃下，将化成后的电池用2C恒流恒压充至截止电压，再恒压充电至电流下降至0.05C，然后以2C的电流恒流放电至3.0V，如此循环500周，记录第 1次的放电容量和最后1次的放电容量。
按下式计算高温循环的容量保持率：
容量保持率＝最后1次的放电容量/第1次的放电容量×100％。
(1)实施例1～24和对比例1～9得到的测试结果填入表2。
表2
Figure PCTCN2022132198-appb-000016
Figure PCTCN2022132198-appb-000017
由实施例1～24和对比例1～9的测试结果可知，采用本发明提供的锂离子电池，当负极材料层中Mg元素的质量含量z和结构式1所示的化合物的质量含量m以及羧酸酯含量x满足关系式0.002≤m/x≤0.25且0.001≤m/z≤0.1时，锂离子电池能够同时具有较好的高温存储性能和快充循环性能，而m/x及m/z值过大或过小均不利于锂离子电池高温存储性能的提升和快充循环阻抗的降低。
对比实施例1～24的测试结果可知，当关系式满足0.005≤m/x≤0.1且0.001≤m/z≤0.02时，锂离子电池具有最佳的电池综合性能。
(3)实施例8、25～28得到的测试结果填入表3。
表3
Figure PCTCN2022132198-appb-000018
由实施例8和对比例25～28的测试结果可知，在本发明提供的电池的基础上，加入PS(1,3-丙烷磺内酯)、DTD(硫酸乙烯酯)、VC(碳酸乙烯酯)或磷酸三炔丙酯作为辅助添加剂，能够进一步提高电池的高温存储性能和快充循环性能，推测是由于结构式1所示的化合物、羧酸酯和加入的PS(1,3-丙烷磺内酯)、DTD(硫酸乙烯酯)、VC(碳酸乙烯酯)或磷酸三炔丙酯之间存在一 定的共同分解反应，能够共同参与电极表面钝化膜的形成，且得到的钝化膜能够提高电极材料的稳定性，保持电池循环的稳定性和耐大电流的性能。
(3)实施例8、29～31得到的测试结果填入表4。
表4
Figure PCTCN2022132198-appb-000019
由实施例8和对比例29～31的测试结果可知，当采用化合物2、化合物5、化合物6等其他结构式1所示化合物作为非水电解液的添加剂时，同样满足关系式0.002≤m/x≤0.25且0.001≤m/z≤0.1的限定，说明本发明提供的关系限定对于不同的结构式1所示的化合物具有普适性，对于锂离子电池的高温存储性能和快充循环性能均具有提升效果。
以上所述仅为本发明的较佳实施例而已，并不用以限制本发明，凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本发明的保护范围之内。

Claims (15)

  1. 一种锂离子电池，其特征在于，包括含正极材料层的正极、含负极材料层的负极以及非水电解液，所述正极材料层包括含镁的锂过渡金属氧化物作为正极活性物质，所述负极材料层包括负极活性物质和含镁化合物，所述非水电解液包括羧酸酯溶剂、电解质盐和结构式1所示的化合物：
    Figure PCTCN2022132198-appb-100001
    其中，R1选自碳原子数为3-6的不饱和烃基，R2选自碳原子数为2-5的亚烃基，n为1或2；
    所述锂离子电池满足以下条件：
    0.002≤m/x≤0.25且0.001≤m/z≤0.1；
    其中，x为非水电解液中羧酸酯的质量百分含量，单位为％；
    m为非水电解液中结构式1所示的化合物的质量百分含量，单位为％；
    z为Mg元素相对负极材料层的质量含量，单位为ppm。
  2. 根据权利要求1所述的锂离子电池，其特征在于，所述锂离子电池满足以下条件：
    0.005≤m/x≤0.1且0.001≤m/z≤0.02。
  3. 根据权利要求1所述的锂离子电池，其特征在于，所述结构式1所示的化合物选自以下化合物中的一种或多种：
    Figure PCTCN2022132198-appb-100002
    Figure PCTCN2022132198-appb-100003
  4. 根据权利要求1所述的锂离子电池，其特征在于，所述非水电解液中结构式1所示的化合物的质量百分含量m为0.1～5％。
  5. 根据权利要求4所述的锂离子电池，其特征在于，所述非水电解液中结构式1所示的化合物的质量百分含量m为0.1～2％。
  6. 根据权利要求1所述的锂离子电池，其特征在于，所述Mg元素相对负极材料层的质量含量z为5～500ppm。
  7. 根据权利要求6所述的锂离子电池，其特征在于，所述Mg元素相对负极材料层的质量含量z为50～500ppm。
  8. 根据权利要求1所述的锂离子电池，其特征在于，所述非水电解液中羧酸酯的质量百分含量x为5～55％。
  9. 根据权利要求8所述的锂离子电池，其特征在于，所述非水电解液中羧酸酯的质量百分含量x为10～40％。
  10. 根据权利要求1所述的锂离子电池，其特征在于，所述羧酸酯选自乙酸甲酯、乙酸乙酯、丙酸乙酯、乙酸丁酯、丙酸丙酯、丙酸丁酯、γ-丁内酯、γ-戊内酯、δ-戊内酯中的至少一种。
  11. 根据权利要求1所述的锂离子电池，其特征在于，所述负极材料层的压实密度大于等于1.5g/cm 3。
  12. 根据权利要求11所述的锂离子电池，其特征在于，所述负极材料层的压实密度为1.55～1.9g/cm 3。
  13. 根据权利要求1所述的锂离子电池，其特征在于，所述非水电解液中还包括辅助添加剂，所述辅助添加剂包括环状硫酸酯类化合物、磺酸内酯类化 合物、环状碳酸酯类化合物、不饱和磷酸酯类化合物和腈类化合物中的至少一种。
  14. 根据权利要求13所述的锂离子电池，其特征在于，以所述非水电解液的总质量为100％计，所述辅助添加剂的添加量为0.01％～30％。
  15. 根据权利要求13所述的锂离子电池，其特征在于，所述环状硫酸酯类化合物选自硫酸乙烯酯、硫酸丙烯酯或甲基硫酸乙烯酯中的至少一种；
    所述磺酸内酯类化合物选自1,3-丙烷磺酸内酯、1,4-丁烷磺酸内酯或1,3-丙烯磺酸内酯中的至少一种；
    所述环状碳酸酯类化合物选自碳酸亚乙烯酯、碳酸乙烯亚乙酯、氟代碳酸乙烯酯或结构式2所示化合物中的至少一种，
    Figure PCTCN2022132198-appb-100004
    所述结构式2中，R 21、R 22、R 23、R 24、R 25、R 26各自独立地选自氢原子、卤素原子、C1-C5基团中的一种；
    所述不饱和磷酸酯类化合物选自结构式3所示化合物中的至少一种：
    Figure PCTCN2022132198-appb-100005
    所述结构式3中，R 31、R 32、R 33各自独立的选自C1-C5的饱和烃基、不饱 和烃基、卤代烃基、-Si(C mH 2m+1) 3，m为1～3的自然数，且R 31、R 32、R 33中至少有一个为不饱和烃基；
    所述腈类化合物包括丁二腈、戊二腈、乙二醇双(丙腈)醚、己烷三腈、己二腈、庚二腈、辛二腈、壬二腈、癸二腈中的一种或多种。
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