WO2022095772A1 - 一种锂离子电池非水电解液及锂离子电池 - Google Patents

一种锂离子电池非水电解液及锂离子电池 Download PDF

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WO2022095772A1
WO2022095772A1 PCT/CN2021/126864 CN2021126864W WO2022095772A1 WO 2022095772 A1 WO2022095772 A1 WO 2022095772A1 CN 2021126864 W CN2021126864 W CN 2021126864W WO 2022095772 A1 WO2022095772 A1 WO 2022095772A1
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group
lithium ion
aqueous electrolyte
carbonate
unsubstituted
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PCT/CN2021/126864
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English (en)
French (fr)
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曹朝伟
王驰
陈群
胡时光
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深圳新宙邦科技股份有限公司
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Priority to EP21888469.0A priority Critical patent/EP4243146A4/en
Priority to US18/034,377 priority patent/US20230411689A1/en
Publication of WO2022095772A1 publication Critical patent/WO2022095772A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F5/00—Compounds containing elements of Groups 3 or 13 of the Periodic Table
    • C07F5/02—Boron compounds
    • C07F5/04—Esters of boric acids
    • 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
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F9/00—Compounds containing elements of Groups 5 or 15 of the Periodic Table
    • C07F9/02—Phosphorus compounds
    • C07F9/547—Heterocyclic compounds, e.g. containing phosphorus as a ring hetero atom
    • C07F9/6564—Heterocyclic compounds, e.g. containing phosphorus as a ring hetero atom having phosphorus atoms, with or without nitrogen, oxygen, sulfur, selenium or tellurium atoms, as ring hetero atoms
    • C07F9/6571—Heterocyclic compounds, e.g. containing phosphorus as a ring hetero atom having phosphorus atoms, with or without nitrogen, oxygen, sulfur, selenium or tellurium atoms, as ring hetero atoms having phosphorus and oxygen atoms as the only ring hetero atoms
    • C07F9/6574—Esters of oxyacids of phosphorus
    • C07F9/65744—Esters of oxyacids of phosphorus condensed with carbocyclic or heterocyclic rings or ring systems
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D497/00—Heterocyclic compounds containing in the condensed system at least one hetero ring having oxygen and sulfur atoms as the only ring hetero atoms
    • C07D497/02—Heterocyclic compounds containing in the condensed system at least one hetero ring having oxygen and sulfur atoms as the only ring hetero atoms in which the condensed system contains two hetero rings
    • C07D497/10—Spiro-condensed systems
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/30—Batteries in portable systems, e.g. mobile phone, laptop
    • 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 new energy, and in particular relates to a lithium ion battery non-aqueous electrolyte and a lithium ion battery.
  • lithium-ion batteries have been widely used in various portable electronic communication devices due to their high operating voltage, no memory effect, long life, wide operating temperature range and high safety.
  • lithium-ion batteries as a power source for new energy electric vehicles will usher in a period of explosive growth in demand.
  • non-aqueous electrolyte lithium-ion batteries non-aqueous electrolyte, as a medium for lithium ion transport and current conduction between positive and negative electrodes, is a key factor determining battery performance.
  • the compounds of the non-aqueous electrolyte first undergo a reduction and decomposition reaction on the surface of the negative electrode, producing compounds such as lithium alkoxides, Li 2 CO 3 , and lithium sulfonates, which form a passivation film on the surface of the negative electrode. It is called solid electrolyte interface film (SEI).
  • SEI solid electrolyte interface film
  • a good passivation SEI film has thermal and chemical stability, which not only prevents further decomposition of the electrolyte on the surface of the carbon anode, but also allows lithium ions to freely enter and exit the electrode while preventing solvent molecules from passing through, thereby inhibiting the co-insertion of solvent molecules into the counter electrode. destroy. Therefore, the quality of SEI film formation determines the performance of Li-ion batteries.
  • Vinyl sulfite can also play a role in inhibiting the decrease of the initial capacity of the battery, increasing the initial discharge capacity, reducing the swelling of the battery after being placed at a high temperature, and improving the charge-discharge performance and cycle times of the battery, but these compounds form on the graphite negative electrode interface.
  • the stability of the SEI film is poor. With the increase of the number of cycles, the interfacial resistance of the electrode gradually increases, and the electronic polarization of the battery becomes more and more serious, resulting in a rapid decrease in the reversible capacity of the electrode.
  • the high-voltage additive represented by 1,3-propane sultone additive is through preferential oxidation reaction on the surface of the positive electrode and forming a dense passivation film on the surface of the positive electrode, so that the positive electrode active material and the electrolyte are in contact with each other. , Inhibit the oxidative decomposition of the electrolyte under high voltage.
  • the current market places higher requirements on the high-temperature storage and cycle performance of lithium-ion batteries.
  • the technical problem to be solved by the present invention is to provide a non-aqueous electrolyte for a lithium ion battery and a lithium ion battery, which can improve the high temperature cycle and high temperature storage performance of the high voltage lithium ion battery, and suppress the gas swelling phenomenon.
  • an embodiment of the present invention provides a non-aqueous electrolyte for a lithium ion battery, comprising a non-aqueous organic solvent, a lithium salt, and a spiro compound shown in structural formula 1,
  • X represents an oxygen atom, a carboxylate group, a sulfite group, a sulfate group, a carbonate group, a substituted or unsubstituted phosphate group, and a substituted or unsubstituted boronate ester group;
  • R 1 , R 2 , R 3 , R 4 are each independently selected from substituted or unsubstituted C1-C5 hydrocarbylene.
  • R 1 , R 2 , R 3 and R 4 is a substituted or unsubstituted C1-C5 alkylene group
  • the substituents of the C1-C5 alkylene group include halogen-substituted or unsubstituted C1-C20 Alkyl, halogen substituted or unsubstituted C2-C20 alkenyl, halogen substituted or unsubstituted C2-C20 alkynyl, halogen substituted or unsubstituted C3-C20 cycloalkenyl, halogen substituted or unsubstituted C3-C20 hetero
  • R 1 , R 2 , R 3 and R 4 is a substituted or unsubstituted C1-C5 alkylene group, and the substituent of the C1-C5 alkylene group is selected from halogen, methyl, ethyl, Propyl, isopropyl, butyl, tert-butyl, alkenyl, alkynyl, phenyl, trimethylsilyl, cyano, trifluoromethyl, tetrafluoroethyl, naphthyl, tetrafluorophenyl, One or more of pyrrolyl or pyridyl.
  • the cyclic spiro compound shown in structural formula 1 includes at least one of the compounds shown in formulas 1 to 7,
  • R 5 and R 6 are each independently selected from a hydrogen atom, a halogen, a hydrocarbon group, a halogenated hydrocarbon group, an oxygen-containing hydrocarbon group, a silicon-containing hydrocarbon group, a cyano-containing hydrocarbon group or a nitrogen-containing hydrocarbon group.
  • R 5 and R 6 are each independently selected from hydrogen atom, fluorine atom, methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, alkenyl, alkynyl, phenyl, tri Methylsilyl, cyano, trifluoromethyl, tetrafluoroethyl, naphthyl, tetrafluorophenyl, pyrrolyl or pyridyl.
  • the mass percentage of the compound represented by the structural formula 1 in the non-aqueous electrolyte of the lithium ion battery is 0.05% to 10%.
  • the non-aqueous electrolyte also includes 1,3-propane sultone, 1,4-butane sultone, 1,3-propene sultone, vinylene carbonate, ethylene ethylene carbonate , one or more of fluoroethylene carbonate and vinyl sulfate.
  • the lithium salt is selected from LiPF 6 , LiBF 4 , LiBOB, LiPO 2 F 2 , LiDFOB, LiSbF 6 , LiAsF 6 , LiN(SO 2 CF 3 ) 2 , LiN(SO 2 C 2 F 5 ) 2 , one or more of LiC(SO 2 CF 3 ) 3 or LiN(SO 2 F) 2 ;
  • the non-aqueous organic solvent is a mixture of a cyclic carbonate and a chain carbonate, the cyclic carbonate is selected from one or more of ethylene carbonate, propylene carbonate or butylene carbonate, and the chain
  • the carbonic acid ester is selected from one or more of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate or propyl methyl carbonate.
  • an embodiment of the present invention provides a lithium ion battery, which includes a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and an electrolyte, wherein the electrolyte is selected from the above-mentioned lithium ions Battery non-aqueous electrolyte.
  • the positive electrode includes a positive electrode active material
  • the positive electrode active material includes LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , LiCo 1-y My O 2 , LiNi 1-y My O 2 , LiMn 2- One or more of y My O 4 , LiCo x M (1-x) O 2 or LiNi x Co y M z M 1-xyz O 2 , wherein M is selected from Al, Sr, Mg, Ti, One or more of Ca, Zr, Zn, Si, Cu, V or Fe, and 0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1, 0 ⁇ z ⁇ 1, and x+y+z ⁇ 1.
  • the non-aqueous electrolyte provided by the present invention contains the compound represented by the structural formula 1, which not only has the performance characteristics of the sulfonic acid ester additive to improve the high temperature storage of the battery, but also has the sulfate ester additive to improve the performance of the high temperature cycle of the battery.
  • the sulfonate structure in structural formula 1 can take precedence over the solvent molecule to undergo a reduction and decomposition reaction at the positive electrode, and the reaction product forms a passivation film on the surface of the positive electrode, which can inhibit the The solvent molecules are further broken down.
  • the strong coordination between the O atom of the sulfonate structure and Li + leads to the breaking of the five-membered ring of the 1,3-PS (1,3-propane sultone) molecule in structural formula 1, and after Li + gains an electron Anion free radicals are formed. Since the anion free radicals are very active and have a particularly high reactivity, lithium sulfonate is further generated, thereby depositing a passivation film on the surface of the positive electrode, and the X functional group is further cross-linked to make the passivation film denser and more stable, which can effectively improve the electrode electrical conductivity. Chemical properties, battery storage properties and self-discharge properties.
  • a non-aqueous electrolyte for a lithium ion battery provided by an embodiment of the present invention includes a solvent, a lithium salt, and a spiro compound as shown in Structural Formula 1,
  • X represents an oxygen atom, a carboxylate group, a sulfite group, a sulfate group, a carbonate group, a substituted or unsubstituted phosphate group, and a substituted or unsubstituted boronate group.
  • R 1 , R 2 , R 3 , and R 4 are each independently selected from substituted or unsubstituted C1-C5 hydrocarbylene.
  • the non-aqueous electrolyte of the lithium ion battery of the present invention contains the compound shown in the structural formula 1 as an additive.
  • This asymmetric spiro ring structure compound has the performance characteristics of a sulfonate additive to improve the high temperature storage of the battery, and also has a sulfate ester Such additives improve the performance of high temperature cycling of batteries.
  • the sulfonate structure in structural formula 1 can take precedence over the solvent molecule to undergo a reduction and decomposition reaction at the positive electrode, and the reaction product forms a passivation film on the surface of the positive electrode. Suppresses further decomposition of solvent molecules in the electrolyte.
  • the strong coordination between the O atom of the sulfonate structure and Li + leads to the breaking of the five-membered ring of the 1,3-PS (1,3-propane sultone) molecule in structural formula 1, and after Li + gains an electron Anion free radicals are formed.
  • the anion radical is very active, the reactivity is particularly high, and further lithium sulfonate is formed, thereby depositing a passivation film on the surface of the positive electrode.
  • the sulfate structure in structural formula 1 can improve the composition of the SEI film, delay the exothermic decomposition of the SEI film under high temperature conditions, and synergistically improve the high temperature cycle performance of the battery.
  • the X functional group can be selected from oxygen atoms, carboxylate groups, sulfite groups, sulfate groups, carbonate groups, substituted or unsubstituted phosphate groups, substituted or unsubstituted boronate groups, all of which have Cross-linking activity, further cross-linking reaction with solvent molecules in the electrolyte, making the passive film coated on the surface of the positive electrode more dense and stable, which can effectively improve the electrochemical performance of the electrode, the storage performance of the battery and the self-discharge performance.
  • the spiro compound shown in the structural formula 1 is an asymmetric structure
  • the asymmetric structure shown in the structural formula 1 includes a five-membered ring structure similar to 1,3-PS and a cyclic lactone.
  • the multi-ring structure can synergistically improve the high temperature cycling performance of the battery.
  • At least one of R 1 , R 2 , R 3 and R 4 is a substituted or unsubstituted C1-C5 alkylene group
  • the substituents of the C1-C5 alkylene group include halogen-substituted or unsubstituted C1 -C20 alkyl, halogen substituted or unsubstituted C2-C20 alkenyl, halogen substituted or unsubstituted C2-C20 alkynyl, halogen substituted or unsubstituted C3-C20 cycloalkenyl, halogen substituted or unsubstituted C3- One or more of a C20 heterocyclic group, a halogen-substituted or unsubstituted C6-C40 aryl group, a halogen-substituted or unsubstituted C2-C40 heteroaryl group, or a polar functional group having at least one heteroatom.
  • R 1 , R 2 , R 3 , and R 4 are each independently selected from an alkylene group, preferably, the number of carbon atoms is controlled to be 5 or less (including 5). When the number of carbon atoms is controlled to be 5 or less, high temperature performance can be taken into consideration. However, when the number of carbon atoms in the alkyl group is more than 6, the relative density of the alkyl group increases gradually as the number of carbon atoms increases, which adversely affects the high temperature performance of the battery and the inhibition of gas swelling.
  • R 1 , R 2 , R 3 , and R 4 are independent of each other.
  • the number of carbon atoms in the alkylene group is preferably controlled to be less than 5.
  • C1-C5 alkylene substituents include halogen, methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, alkenyl, alkynyl, phenyl, trimethyl
  • silyl, cyano, trifluoromethyl, tetrafluoroethyl, naphthyl, tetrafluorophenyl, pyrrolyl or pyridyl One or more of silyl, cyano, trifluoromethyl, tetrafluoroethyl, naphthyl, tetrafluorophenyl, pyrrolyl or pyridyl.
  • the cyclic spiro compound represented by structural formula 1 includes at least one of formulas 1 to 7,
  • R 5 and R 6 are each independently selected from a hydrogen atom, a halogen, a hydrocarbon group, a halogenated hydrocarbon group, an oxygen-containing hydrocarbon group, a silicon-containing hydrocarbon group, a cyano-containing hydrocarbon group or a nitrogen-containing hydrocarbon group.
  • R 5 and R 6 are each independently selected from hydrogen atom, fluorine atom, methyl group, ethyl group, propyl group, isopropyl group, butyl group, tert-butyl group, alkenyl group, alkynyl group, phenyl group , trimethylsilyl, cyano, trifluoromethyl, tetrafluoroethyl, naphthyl, tetrafluorophenyl, pyrrolyl or pyridyl.
  • the compound represented by structural formula 1 can be any organic compound represented by structural formula 1
  • the addition amount of the compound represented by Structural Formula 1 is not intended to limit the present invention.
  • controlling the content of the compound represented by Structural Formula 1 in the non-aqueous electrolyte has a beneficial effect on further optimizing the high temperature performance.
  • the mass percentage of the compound represented by the structural formula 1 in the non-aqueous electrolyte of the lithium-ion battery is 0.05% to 10% .
  • the mass percentage of the compound represented by the structural formula 1 may 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 compound represented by Structural Formula 1 can significantly improve the high-temperature storage performance and high-temperature cycle performance of the battery, and take into account no gas swelling.
  • the mass percentage of the compound represented by structural formula 1 is less than 0.05%, the content of structural formula 1 in the electrolyte is too low to form a complete passivation film on the surface of the positive electrode, so that it is difficult to significantly improve the high temperature performance of the non-aqueous electrolyte battery. And the internal resistance of the battery is not significantly reduced.
  • the mass percentage of the compound represented by Structural Formula 1 exceeds 10.0%, an excessively thick passivation film is easily formed on the surface of the positive electrode, which increases the internal resistance of the battery, and the battery capacity retention rate is significantly deteriorated.
  • the additives in the non-aqueous electrolyte further include 1,3-propane sultone (1,3-PS), 1,4-butane sultone (BS), 1,3- One or more of propene sultone (PST), vinylene carbonate (VC), ethylene ethylene carbonate (VEC), fluoroethylene carbonate (FEC), and vinyl sulfate (DTD).
  • PST propene sultone
  • VEC vinylene carbonate
  • VEC ethylene ethylene carbonate
  • FEC fluoroethylene carbonate
  • DTD vinyl sulfate
  • the mass percentage of the above additives in the lithium-ion battery non-aqueous electrolyte is 0.05% to 10%, preferably, in the lithium-ion battery non-aqueous electrolyte
  • the mass percentage in the lithium ion battery is 0.2% to 5%, and more preferably, the mass percentage in the non-aqueous electrolyte of the lithium ion battery is 0.5% to 2%.
  • the mass percentage of the above additives 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 non-aqueous organic solvent is a mixture of cyclic carbonate and chain carbonate.
  • the cyclic carbonate includes one or more of ethylene carbonate, propylene carbonate and butylene carbonate.
  • the chain carbonate includes one or more of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate and propyl methyl carbonate.
  • lithium salt there is no special restriction on the lithium salt in the scheme of the present invention, and various existing substances can be used.
  • the lithium salt is selected from LiPF 6 , LiBF 4 , LiBOB, LiPO 2 F 2 , LiDFOB, LiSbF 6 , LiAsF 6 , LiN(SO 2 CF 3 ) 2 , LiN(SO 2 C 2 F 5 ) ) 2 , LiC(SO 2 CF 3 ) 3 or LiN(SO 2 F) 2 , preferably, the lithium salt is LiPF 6 or a mixture of LiPF 6 and other lithium salts.
  • the mass percentage of the lithium salt in the non-aqueous electrolyte of the lithium ion battery is 0.1-15% based on the total mass of the non-aqueous electrolyte of the lithium ion battery as 100%.
  • a lithium-ion battery which includes a positive electrode, a negative electrode, a separator, and an electrolyte, and the electrolyte is the above-mentioned non-aqueous electrolyte for the lithium-ion battery.
  • the non-aqueous electrolyte of lithium ion batteries contains non-aqueous organic solvents and lithium salts.
  • the type and content of solvents there are no special restrictions on lithium salts.
  • Various existing substance there are no special restrictions on the type and content of solvents, and there are no special restrictions on lithium salts.
  • the positive electrode includes a positive electrode active material
  • the positive electrode active material includes LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , LiCo 1-y My O 2 , LiNi 1-y My O 2 , LiMn One or more of 2-y My O 4 , LiCo x M (1-x) O 2 or LiNi x Co y M z M 1-xyz O 2 , wherein M is selected from Al, Sr, Mg, One or more of Ti, Ca, Zr, Zn, Si, Cu, V or Fe, and 0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1, 0 ⁇ z ⁇ 1, and x+y+z ⁇ 1.
  • the positive electrode further includes a positive electrode current collector for drawing current, and the positive electrode active material covers the positive electrode current collector.
  • the negative electrode includes a negative electrode active material, and the negative electrode active material includes graphite, a conductive agent, SBR (styrene butadiene rubber), CMC (sodium carboxymethyl cellulose), and NMP (N-methylpyrrolidone).
  • the negative electrode active material includes graphite, a conductive agent, SBR (styrene butadiene rubber), CMC (sodium carboxymethyl cellulose), and NMP (N-methylpyrrolidone).
  • the negative electrode further includes a negative electrode current collector for drawing current, and the negative electrode active material is covered on the negative electrode current collector.
  • a separator is spaced between the positive electrode of the battery and the negative electrode of the battery, and the separator is a conventional separator in the field of lithium ion batteries, which will not be repeated here.
  • This embodiment is used to illustrate the non-aqueous electrolyte for lithium ion battery, lithium ion battery and preparation method thereof disclosed in the present invention, including the following steps:
  • LiPF6 lithium hexafluorophosphate
  • the cathode active material lithium nickel cobalt manganese oxide LiNi 0.5 Co 0.2 Mn 0.3 O 2 , conductive carbon black Super-P and binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 93:4:3, and then they were mixed Disperse in N-methyl-2-pyrrolidone (NMP), and mix uniformly to prepare a lithium ion battery to obtain a positive electrode slurry.
  • NMP N-methyl-2-pyrrolidone
  • the positive electrode is uniformly coated on both sides of the positive electrode current collector aluminum foil. After drying, calendering and vacuum drying, the positive electrode is obtained by trimming, cutting and slitting. Pole piece, the thickness of the positive pole piece is between 120-150 ⁇ m.
  • the negative electrode active material artificial graphite Mix the negative electrode active material artificial graphite, the conductive agent conductive carbon black Super-P, the binder styrene-butadiene rubber (SBR) and the thickener carboxymethyl cellulose (CMC) in a mass ratio of 94:1:2.5:2.5, and then They were dispersed in deionized water to obtain negative electrode slurry. Coating the slurry on both sides of the copper foil, drying, calendering and vacuum drying, then trimming, cutting, and slitting, and welding nickel lead wires with an ultrasonic welder to obtain a negative pole piece, a negative pole piece, and a negative pole piece. The thickness of the pole pieces is between 120-150 ⁇ m.
  • a lithium battery three-layer separator with a thickness of 20 ⁇ m is placed between the above-prepared positive electrode sheet and negative electrode sheet, and the sandwich structure composed of the positive electrode sheet, the negative electrode sheet and the separator is wound, and then the rolled body is flattened and placed Put it into an aluminum foil packaging bag, and bake it in a vacuum at 75°C for 48 hours to obtain the cell to be injected.
  • the electrolyte prepared above was injected into the dried cells, vacuum-sealed, and allowed to stand for 24 hours, and then the conventional formation of the first charge was carried out according to the following steps: 0.05C constant current Charge for 180min, 0.2C constant current charge to 3.95V, secondary vacuum sealing, then further charge to 4.2V with 0.2C current constant current, after 24hrs at room temperature, discharge to 3.0V with 0.2C current constant current, get a LiNi 0.5 Co 0.2 Mn 0.3 O 2 /artificial graphite lithium-ion battery.
  • the battery was prepared according to the method described in Example 1, except that the types and contents of the compound additives added in the preparation step of the non-aqueous electrolyte were different. Please refer to Table 1 for details.
  • the battery was prepared as described in Example 1, except that:
  • the battery was prepared according to the method described in Example 1, except that the types and contents of the compound additives added in the preparation step of the non-aqueous electrolyte were different. Please refer to Table 1 for details.
  • the formed battery was charged with 1C constant current and constant voltage to 4.2V (LiNi 0.5 Co 0.2 Mn 0.3 O 2 /artificial graphite battery), and then charged with constant voltage until the current dropped to 0.02C, and then charged with 1C constant voltage.
  • the current was discharged to 3.0V at a constant current, and N cycles of charge/discharge were performed in this way, and the capacity retention rate after the 500th cycle was calculated to evaluate its high-temperature cycle performance.
  • the 500th cycle capacity retention rate (%) 500th cycle discharge capacity/1st cycle discharge capacity ⁇ 100%.
  • the formed lithium-ion battery was charged to 4.2V with 1C constant current and constant voltage (LiNi 0.5 Co 0.2 Mn 0.3 O 2 /artificial graphite battery) at room temperature, and the initial discharge capacity and thickness of the battery were measured, and then the battery was stored at 60°C. After 30 days of storage, the battery was discharged at 1C to 3V, and the retention capacity and recovery capacity of the battery and the thickness of the battery after storage were measured.
  • 1C constant current and constant voltage LiNi 0.5 Co 0.2 Mn 0.3 O 2 /artificial graphite battery
  • Battery capacity retention rate (%) retained capacity / initial capacity ⁇ 100%;
  • Thickness expansion ratio (%) (battery thickness after storage ⁇ initial battery thickness)/initial battery thickness ⁇ 100%.
  • Example 9-Example 12 in Table 2 adding 0.1% or 5% of Compound 5 to the non-aqueous electrolyte solution can be prepared compared to adding 1%, 2% or 3% of Compound 5
  • the high-temperature performance of the lithium-ion battery is slightly degraded, indicating that the addition of too little or too much will lead to the deterioration of the high-temperature performance of the lithium-ion battery.
  • Example 13-Example 15 in Table 2 compared to adding the compound represented by Structural Formula 1 alone in Example 10, when the compound represented by Structural Formula 1 and FEC (or VEC) were simultaneously added to the non-aqueous electrolyte , VC), FEC can be used in combination with the compound shown in structural formula 1, and synergistically forms a more stable SEI film on the surface of the graphite negative electrode, which makes the lithium-ion battery have good high-temperature performance and high-temperature storage performance, and significantly improves the lithium-ion battery. cycle performance.
  • Comparative Example 1 no additives were added. According to the experimental data, it can be seen that when no additives are added, the density and stability of the SEI film will be affected, and the charge-discharge performance and cycle performance of the lithium-ion battery will be affected. The high temperature storage performance is not ideal, and the battery produces a lot of gas.
  • the reductive decomposition reaction of solvent molecules occurs on the surface of the negative electrode to generate a polyalkoxy lithium carbonate compound, which forms a passivation film on the surface of the negative electrode, preventing the electrolyte from further decomposing on the surface of the electrode, and improving the cycle performance of the battery performance.
  • the battery is likely to generate gas during high temperature storage, resulting in serious battery swelling.
  • the stability is poor. As the number of cycles increases, the interface resistance of the electrode gradually increases, and the electronic polarization of the battery becomes more and more serious, which leads to a rapid decrease in the reversible capacity of the electrode and reduces the high-temperature cycle performance of the battery.

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Abstract

本发明属于新能源技术领域，特别是涉及一种锂离子电池非水电解液及锂离子电池。锂离子电池非水电解液包括非水有机溶剂、锂盐、如结构式(1)所示的螺环化合物，结构式(1)所示的化合物具有磺酸酯类添加剂改善电池高温存储的性能特征，而且还具有硫酸酯类添加剂改善电池高温循环的性能，在正电极表面沉积成钝化膜，X官能团进一步发生交联使这层包覆的钝化膜更加致密、稳定，能够有效地提高电极电化学性能、电池的储存性能及自放电性能。

Description

一种锂离子电池非水电解液及锂离子电池 技术领域
本发明属于新能源技术领域，特别是涉及一种锂离子电池非水电解液及锂离子电池。
背景技术
近年来，由于锂离子电池具有工作电压高、无记忆效应、长寿命、较宽的工作温度范围及安全性高等特点已经广泛应用于各种便携式电子通讯设备。在国家出台相关新能源汽车产业规划政策背景下，作为新能源电动汽车电源的锂离子电池将迎来需求爆发增长时期。
在非水电解液锂离子电池中，非水电解液作为正负极之间锂离子输送和传导电流的介质，是决定电池性能的关键因素。在首次充电过程中，非水电解液的化合物首先在负极表面发生还原分解反应，产生烷氧基锂、Li 2CO 3、磺酸锂等化合物，使负极表面形成钝化膜，该钝化膜称为固体电解液界面膜(SEI)。良好的钝化SEI膜具有热稳定性和化学稳定性，不仅阻止电解液进一步在碳负极表面分解，并且能够允许锂离子自由进出电极的同时阻止溶剂分子穿越，从而抑制溶剂分子共插入对电极的破坏。因此，SEI膜成膜质量决定了锂离子电池的性能。
随着锂离子电池在不同领域的广泛应用，市场对锂离子电池各项性能提出更高的要求。科研工作者通过在电解液中添加不同的负极成膜添加剂(如碳酸亚乙烯酯、亚硫酸乙烯酯、1,3-丙烷磺酸内酯)改善SEI膜的质量，从而提高电池的循环寿命和可逆容量等性能。例如，在日本特开2000-123867号公报中提出在电解液中添加碳酸亚乙烯酯能够优先于溶剂分子在负极表面发生还原分解反 应，生成聚烷氧基碳酸锂化合物，在负极表面形成钝化膜，阻止电解液在电极表面进一步分解，改善电池性能的循环性能。但添加碳酸亚乙烯酯后，电池在高温储存中过程中容易产生气体，导致电池发生鼓胀。亚硫酸乙烯酯也能起作用，抑制电池初始容量的下降，增大初始放电容量，减少高温放置后的电池膨胀，提高电池的充放电性能及循环次数，但这类化合物在石墨负极界面形成的SEI膜稳定性差，随着循环次数的增加，电极界面电阻逐渐升高，电池的电子极化现象愈来愈严重，从而导致电极的可逆容量迅速降低。以1,3-丙烷磺酸内酯添加剂为代表的高电压添加剂，则是通过在正极表面优先发生氧化反应并在正极表面形成一层致密的钝化膜，从而使正极活性物质和电解液接触、抑制电解液在高电压下发生氧化分解。但目前市场上对锂离子电池的高温存储和循环性能提出更高的要求。
发明内容
本发明所要解决的技术问题是：提供一种锂离子电池非水电解液及锂离子电池，能够改善高电压锂离子电池的高温循环和高温存储性能，并抑制气胀现象。
为解决上述技术问题，一方面，本发明实施例提供一种锂离子电池非水电解液，包括非水有机溶剂、锂盐、如结构式1所示的螺环化合物，
Figure PCTCN2021126864-appb-000001
其中，结构式1中，X表示氧原子、羧酸酯基、亚硫酸酯基、硫酸酯基、碳酸酯基、取代或无取代的磷酸酯基、取代或无取代的硼酸酯基；
R 1、R 2、R 3、R 4各自独立地选自取代或无取代的C1-C5亚烃基。
可选地，R 1、R 2、R 3、R 4中至少一个为取代或无取代的C1-C5亚烷基，C1-C5 亚烷基的取代基包括卤素取代或无取代的C1-C20烷基、卤素取代或无取代的C2-C20烯基、卤素取代或无取代的C2-C20炔基、卤素取代或无取代的C3-C20环烯基、卤素取代或无取代的C3-C20杂环基、卤素取代或无取代的C6-C40芳基、卤素取代或无取代的C2-C40杂芳基或者具有至少一个杂原子的极性官能团中的一种或多种。
可选地，R 1、R 2、R 3、R 4中至少一个为取代或无取代的C1-C5亚烷基，C1-C5亚烷基的取代基选自卤素、甲基、乙基、丙基、异丙基、丁基、叔丁基、烯烃基、炔烃基、苯基、三甲基硅基、氰基、三氟甲基、四氟乙基、萘基、四氟苯基、吡咯基或吡啶基的一种或多种。
可选地，所述如结构式1所示的环螺环化合物至少包括式1～7所示化合物中的一种，
Figure PCTCN2021126864-appb-000002
其中，R 5、R 6各自独立地选自氢原子、卤素、烃基、卤代烃基、含氧烃基、含硅烃基、含氰烃基或含氮烃基。
可选地，R 5、R 6各自独立地选自氢原子、氟原子、甲基、乙基、丙基、异丙基、丁基、叔丁基、烯烃基、炔烃基、苯基、三甲基硅基、氰基、三氟甲基、四氟乙基、萘基、四氟苯基、吡咯基或吡啶基。
可选地，所述结构式1所示的化合物在锂离子电池非水电解液中的质量百分比为0.05％～10％。
可选地，所述非水电解液还包括1,3-丙烷磺内酯、1,4-丁烷磺内酯、1,3-丙烯磺内酯、碳酸亚乙烯酯、碳酸乙烯亚乙酯、氟代碳酸乙烯酯、硫酸乙烯酯中的一种或多种。
可选地，所述锂盐选自LiPF 6、LiBF 4、LiBOB、LiPO 2F 2、LiDFOB、LiSbF 6、LiAsF 6、LiN(SO 2CF 3) 2、LiN(SO 2C 2F 5) 2、LiC(SO 2CF 3) 3或LiN(SO 2F) 2中的一种或多种；
所述非水有机溶剂为环状碳酸酯和链状碳酸酯的混合物，所述环状碳酸酯选自碳酸乙烯酯、碳酸丙烯酯或碳酸丁烯酯中的一种或多种，所述链状碳酸酯选自碳酸二甲酯、碳酸二乙酯、碳酸甲乙酯或碳酸甲丙酯中的一种或多种。
另一方面，本发明实施例提供一种锂离子电池，其包括正极、负极、设置在所述正极和所述负极之间的隔膜以及电解液，其中，所述电解液选自上述的锂离子电池非水电解液。
可选地，所述正极包括正极活性材料，所述正极活性材料包括LiCoO 2、LiNiO 2、LiMn 2O 4、LiCo 1-yM yO 2、LiNi 1-yM yO 2、LiMn 2-yM yO 4、LiCo xM (1-x)O 2或LiNi xCo yMn zM 1-x-y-zO 2中的一种或多种，其中，M选自Al、Sr、Mg、Ti、Ca、Zr、Zn、Si、Cu、V或Fe中的一种或多种，且0≤x≤1，0≤y≤1，0≤z≤1，x+y+z≤1。
本发明提供的非水电解液中含有结构式1所示的化合物，不仅具有磺酸酯类添加剂改善电池高温存储的性能特征，而且还具有硫酸酯类添加剂改善电池高温循环的性能。在首次充电过程中，结构式1中的磺酸酯结构能够优先于溶剂分子在正极发生还原分解反应，其反应产物在正极电极表面形成一层钝化膜，该钝化膜能够抑制电解液中的溶剂分子进一步分解。磺酸酯结构的O原子与Li + 间的强烈的配位作用导致结构式1中的1,3-PS(1,3-丙烷磺内酯)分子五元环断开，Li +得到一个电子后形成阴离子自由基。由于阴离子自由基非常活泼，反应活性特别高，进一步生成磺酸锂，从而在正电极表面沉积成钝化膜，X官能团进一步发生交联使钝化膜更加致密、稳定，能够有效地提高电极电化学性能、电池的储存性能及自放电性能。
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的详细说明。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。
本发明实施例提供的一种锂离子电池非水电解液，包括溶剂、锂盐、如结构式1所示的螺环化合物，
Figure PCTCN2021126864-appb-000003
其中，结构式1中，X表示氧原子、羧酸酯基、亚硫酸酯基、硫酸酯基、碳酸酯基、取代或无取代的磷酸酯基、取代或无取代的硼酸酯基。
R 1、R2、R 3、R 4各自独立地选自取代或无取代的C1-C5亚烃基。
本发明的锂离子电池非水电解液中含有如结构式1所示的化合物作为添加剂，这种非对称的螺环结构化合物具有磺酸酯类添加剂改善电池高温存储的性能特征，而且还具有硫酸酯类添加剂改善电池高温循环的性能。
其作用机理为：在首次充电过程中，结构式1中的磺酸酯结构能够优先于溶剂分子在正极发生还原分解反应，其反应产物在正极电极表面形成一层钝化膜，该钝化膜能够抑制电解液中的溶剂分子进一步分解。磺酸酯结构的O原子与Li +间的强烈的配位作用导致结构式1中的1,3-PS(1,3-丙烷磺内酯)分子五 元环断开，Li +得到一个电子后形成阴离子自由基。由于阴离子自由基非常活泼，反应活性特别高，进一步生成磺酸锂，从而在正电极表面沉积成钝化膜。在首次充电过程中，结构式1中的硫酸酯结构可以改善SEI膜的组成成分，延缓SEI膜在高温条件下的放热分解，能协同改善电池的高温循环性能。
X官能团可选自氧原子、羧酸酯基、亚硫酸酯基、硫酸酯基、碳酸酯基、取代或无取代的磷酸酯基、取代或无取代的硼酸酯基，这些基团都具有交联活性，与电解液中的溶剂分子进一步发生交联反应，使正极电极表面包覆的钝化膜更加致密、稳定，能够有效地提高电极电化学性能、电池的储存性能及自放电性能。
在一实施例中，所述结构式1所示的螺环化合物为非对称结构，结构式1所示的非对称结构中包含有类似于1,3-PS的五元环结构和环状内脂的多元环结构，能协同改善电池高温循环的性能。
在一实施例中，R 1、R 2、R 3、R 4中至少一个为取代或无取代的C1-C5亚烷基，C1-C5亚烷基的取代基包括卤素取代或无取代的C1-C20烷基、卤素取代或无取代的C2-C20烯基、卤素取代或无取代的C2-C20炔基、卤素取代或无取代的C3-C20环烯基、卤素取代或无取代的C3-C20杂环基、卤素取代或无取代的C6-C40芳基、卤素取代或无取代的C2-C40杂芳基或者至少有一个杂原子的极性官能团中的一种或多种。
需要说明的是，R 1、R 2、R 3、R 4各自独立地选取亚烷基时，优选的，碳原子的数目控制在5个以下(包括5个)。碳原子的数目控制在5个以下时能够兼顾高温性能。然而在烷基的碳原子数为6个以上时，碳原子数越多，烷基的相对密度逐渐增大，对电池的高温性能和抑制气胀产生不利影响。
根据本发明，碳原子的数目在5个以下和6个以上时，都能实现改善SEI膜，改善电池的高温循环性能的效果，优选的，R 1、R 2、R 3、R 4各自独立地选取亚烷基的碳原子的数目控制在5个以下。
在一实施例中，C1-C5亚烷基的取代基包括卤素、甲基、乙基、丙基、异丙 基、丁基、叔丁基、烯烃基、炔烃基、苯基、三甲基硅基、氰基、三氟甲基、四氟乙基、萘基、四氟苯基、吡咯基或吡啶基的一种或多种。
在一实施例中，所述如结构式1所示的环螺环化合物至少包括式1～7中的一种，
Figure PCTCN2021126864-appb-000004
其中，R 5、R 6各自独立地选自氢原子、卤素、烃基、卤代烃基、含氧烃基、含硅烃基、含氰烃基或含氮烃基。
在一实施例中，R 5、R 6各自独立地选自氢原子、氟原子、甲基、乙基、丙基、异丙基、丁基、叔丁基、烯烃基、炔烃基、苯基、三甲基硅基、氰基、三氟甲基、四氟乙基、萘基、四氟苯基、吡咯基或吡啶基。
在一实施例中，结构式1所示的化合物可以为
Figure PCTCN2021126864-appb-000005
需要说明的是，以上化合物是本发明所要求保护的部分化合物，但不仅限于此，不应理解为对本发明的限制。
在本发明中结构式1所示的化合物的添加量并不用于限定本发明。但控制结构式1所示的化合物在非水电解液中的含量对于高温性能进一步优化具有有利影响。
在一实施例中，以所述锂离子电池非水电解液的总质量为100％计，所述结构式1所示的化合物在锂离子电池非水电解液中的质量百分比为0.05％～10％。具体的，所述结构式1所示的化合物的质量百分比可以为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％。
在上述范围内，结构式1所示的化合物能够明显改善电池的高温存储性能和高温循环性能，并兼顾无气胀。当结构式1所示的化合物的质量百分比低于0.05％时，电解液中的结构式1含量过低无法在正极电极表面形成完整的钝化膜， 从而难以明显改善非水电解液电池的高温性能，且电池内阻无明显降低。而结构式1所示的化合物的质量百分比超过10.0％时，正极电极表面容易形成过厚的钝化膜，反而增加电池内阻，而且电池容量保持率明显劣化。
在一实施例中，所述非水电解液中的添加剂还包括1,3-丙烷磺内酯(1,3-PS)、1,4-丁烷磺内酯(BS)、1,3-丙烯磺内酯(PST)、碳酸亚乙烯酯(VC)、碳酸乙烯亚乙酯(VEC)、氟代碳酸乙烯酯(FEC)、硫酸乙烯酯(DTD)中的一种或多种。这些添加剂能够和结构式1所示的化合物联合使用，协同作用，在石墨负极表面形成更稳定的SEI膜，从而显著提高锂离子电池的循环性能，相对于单独添加结构式1所示的化合物能够得到更优异的效果。
以所述锂离子电池非水电解液的总质量为100％计，上述添加剂在锂离子电池非水电解液中的质量百分比为0.05％～10％，优选地，在锂离子电池非水电解液中的质量百分比为0.2％～5％，更优选地，在锂离子电池非水电解液中的质量百分比为0.5％～2％。具体的，上述添加剂的质量百分比可以为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％。
在一实施例中，所述非水有机溶剂为环状碳酸酯和链状碳酸酯的混合物。所述环状碳酸酯包括碳酸乙烯酯、碳酸丙烯酯和碳酸丁烯酯中的一种或几种。所述链状碳酸酯包括碳酸二甲酯、碳酸二乙酯、碳酸甲乙酯和碳酸甲丙酯中的一种或几种。
本发明方案中对于锂盐没有特殊限制，可采用现有的各种物质。
在一实施例中，所述锂盐选自LiPF 6、LiBF 4、LiBOB、LiPO 2F 2、LiDFOB、LiSbF 6、LiAsF 6、LiN(SO 2CF 3) 2、LiN(SO 2C 2F 5) 2、LiC(SO 2CF 3) 3或LiN(SO 2F) 2中的一种或多种，优选地，所述锂盐为LiPF 6或LiPF 6与其他锂盐的混合物。
以所述锂离子电池非水电解液的总质量为100％计，所述锂盐在锂离子电池非水电解液中的质量百分比为0.1～15％。
本发明另一实施例公开了一种锂离子电池，其包括正极、负极、隔膜以及电解液，所述电解液是如上所述的锂离子电池非水电解液。
如现有的，锂离子电池非水电解液中均含有非水有机溶剂以及锂盐，本发明方案中对于溶剂种类和含量没有特殊限制，对于锂盐没有特殊限制，可采用现有的各种物质。
在一实施例中，所述正极包括正极活性材料，所述正极活性材料包括LiCoO 2、LiNiO 2、LiMn 2O 4、LiCo 1-yM yO 2、LiNi 1-yM yO 2、LiMn 2-yM yO 4、LiCo xM (1-x)O 2或LiNi xCo yMn zM 1-x-y-zO 2中的一种或多种，其中，M选自Al、Sr、Mg、Ti、Ca、Zr、Zn、Si、Cu、V或Fe中的一种或多种，且0≤x≤1，0≤y≤1，0≤z≤1，x+y+z≤1。
所述正极还包括有用于引出电流的正极集流体，所述正极活性材料覆盖于所述正极集流体上。
所述负极包括负极活性材料，所述负极活性材料中包括石墨、导电剂、SBR(丁苯橡胶)、CMC(羧甲基纤维素钠)、NMP(N-甲基吡咯烷酮)。
所述负极还包括有用于引出电流的负极集流体，所述负极活性材料覆盖于所述负极集流体上。
在一些实施例中，所述电池正极和所述电池负极之间隔有隔膜，所述隔膜为锂离子电池领域的常规隔膜，这里不再赘述。
以下通过实施例对本发明进行进一步的说明。
实施例1
本实施例用于说明本发明公开的锂离子电池非水电解液、锂离子电池及其制备方法，包括以下步骤：
1)非水电解液的制备
将碳酸乙烯酯(EC)、碳酸二乙酯(DEC)和碳酸甲乙酯(EMC)按质量比为EC:DEC:EMC＝1:1:1进行混合，然后加入六氟磷酸锂(LiPF6)至摩尔浓度为1mol/L，以所述非水电解液的总重量为100％计，加入1.0％的化合物1。
2)正极极片的制备
按93:4:3的质量比混合正极活性材料锂镍钴锰氧化物LiNi 0.5Co 0.2Mn 0.3O 2、导电碳黑Super-P和粘结剂聚偏二氟乙烯(PVDF)，然后将它们分散在N-甲基-2-吡咯烷酮(NMP)中，混和均匀制备得到锂离子电池得到正极浆料。正极将浆料均匀涂布在正极集流体铝箔的两面上，经过烘干、压延和真空干燥，然后进行切边、裁片、分条后，用超声波焊机焊上铝制引出线后得到正极极片，正极极片的厚度在120-150μm之间。
3)负极极片的制备
按94:1:2.5:2.5的质量比混合负极活性材料人造石墨，导电剂导电碳黑Super-P，粘结剂丁苯橡胶(SBR)和增稠剂羧甲基纤维素(CMC)，然后将它们分散在去离子水中，得到负极浆料。将浆料涂布在铜箔的两面上，经过烘干、压延和真空干燥，然后进行切边、裁片、分条后，用超声波焊机焊上镍制引出线后得到负极极片，负极极片的厚度在120-150μm之间。
4)电芯的制备
在上述制备得到的正极片和负极片之间放置厚度为20μm的锂电池三层隔膜，将正极极片、负极极片和隔膜组成的三明治结构进行卷绕，再将卷绕体压扁后放入铝箔包装袋，在75℃下真空烘烤48h，得到待注液的电芯。
5)电芯的注液和化成
在露点控制在-40℃以下的手套箱中，将上述制备的电解液注入到干燥后的电芯中，真空封装、静置24h，然后按照以下步骤进行首次充电的常规化成：0.05C恒流充电180min，0.2C恒流充电至3.95V，二次真空封口，然后进一步以0.2C的电流恒流充电至4.2V，常温搁置24hr后，以0.2C的电流恒流放电至3.0V，得到一种LiNi 0.5Co 0.2Mn 0.3O 2/人造石墨锂离子电池。
实施例2～15
按实施例1中所描述的方法制备电池，其不同之处在于：所述非水电解液的制备步骤中加入的化合物添加剂种类及含量不同，具体请参见表1。
对比例1
按实施例1中所描述的方法制备电池，其不同之处在于：
所述非水电解液的制备步骤中未加入1.0％的化合物1。
对比例2～7
按实施例1中所描述的方法制备电池，其不同之处在于：所述非水电解液的制备步骤中加入的化合物添加剂种类及含量不同，具体请参见表1。
表1
Figure PCTCN2021126864-appb-000006
性能测试
为了验证本发明的锂离子电池电极的性能，下面对上述实施例1～15和对比 例1～7制备的锂离子电池进行相关的性能测试。具体测试方法如下：
1)高温循环性能测试：
在45℃下，将化成后的电池用1C恒流恒压充至4.2V(LiNi 0.5Co 0.2Mn 0.3O 2/人造石墨电池)，再恒压充电至电流下降至0.02C，然后以1C的电流恒流放电至3.0V，如此充/放电N次循环，计算第500次循环后容量的保持率，以评估其高温循环性能。
45℃1C循环500次容量保持率计算公式如下：
第500次循环容量保持率(％)＝第500次循环放电容量/第1次循环放电容量×100％。
2)高温储存性能测试
将化成后的锂离子电池在常温下用1C恒流恒压充至4.2V(LiNi 0.5Co 0.2Mn 0.3O 2/人造石墨电池)，测量电池初始放电容量及初始电池厚度，然后在60℃环境中储存30天后，以1C放电至3V，测量电池的保持容量和恢复容量及储存后电池厚度。
计算公式如下：
电池容量保持率(％)＝保持容量/初始容量×100％；
电池容量恢复率(％)＝恢复容量/初始容量×100％；
厚度膨胀率(％)＝(储存后电池厚度-初始电池厚度)/初始电池厚度×100％。
实施例1-15及对比例1-7的性能测试结果如表2所示。
表2
Figure PCTCN2021126864-appb-000007
Figure PCTCN2021126864-appb-000008
根据表2中实施例1～实施例12的数据可知，相比于对比例1-7，实施例1～实施例12中加入了结构式1所示的化合物，得到的锂电池具有较好的高温循环和高温存储性能，且根据厚度膨胀率数据可以看出，加入了结构式1所示的化合物后产气少，改善了电池的高温性能，减少了在高温放置后的电池鼓胀，提高电池的充放电性能及循环次数。
根据表2中实施例5、实施例9-实施例12的数据可知，在非水电解液中添加0.1％或5％的化合物5相比添加1％、2％或3％的化合物5制备得到的锂离子电池，其高温性能略有劣化，说明添加量过少或过多都会导致锂离子电池的高温性能有劣化趋势。
根据表2中实施例13～实施例15中数据可知，相比于实施例10中单独加入结构式1所示的化合物，当非水电解液中同时加入结构式1所示的化合物和FEC(或VEC、VC)时，FEC能够和结构式1所示的化合物联合使用，协同作用，在石墨负极表面形成更稳定的SEI膜，使得锂离子电池具有良好的高温性能和 高温存储性能，显著提高锂离子电池的循环性能。
对比例1中没有加入任何添加剂，结合实验数据可以看到，不加入任何添加剂时，会影响SEI膜的致密程度和稳定性，会影响锂离子电池的充放电性能及循环性能，其高温循环和高温存储性能不理想，且电池产气较多。
对比分析对比例2～对比例4的实验数据，可以看出，对比例2～对比例4的锂离子电池虽然具有较好的高温循环性能，但是其高温存储性能较差，电池产气严重，电池鼓胀严重。对比例2中加入了氟代碳酸乙烯酯(FEC)，对比例3中加入了碳酸乙烯亚乙酯(VEC)，对比例4中加入了碳酸亚乙烯酯(VC)，这些物质作为添加剂能够优先于溶剂分子在负极表面发生还原分解反应，生成聚烷氧基碳酸锂化合物，在负极表面形成钝化膜，阻止电解液在电极表面进一步分解，改善电池性能的循环性能。但是添加FEC、VEC或VC后，电池在高温储存中过程中容易产生气体，导致电池鼓胀严重。
对比分析对比例5～对比例7的实验数据，可以看出，对比例5～对比例7中的锂离子电池具有较好的高温存储性能，且产气少，电池鼓胀不严重，但是其高温循环性能较差。这是由于对比例5中加入的1,3-丙烷磺内酯(1,3-PS)，对比例6中加入的1,3-丙烯磺内酯(PST)和对比例7中加入的硫酸乙烯酯(DTD)作为添加剂时，能够抑制电池初始容量的下降，增大初始放电容量，减少高温存储后的电池膨胀，提高电池的充放电性能及循环次数，但是在石墨负极界面形成的SEI膜稳定性差，随着循环次数的增加，电极界面电阻逐渐升高，电池的电子极化现象愈来愈严重，从而导致电极的可逆容量迅速降低，降低电池的高温循环性能。
通过实施例与对比例的对比发现，电解液中添加结构式1，或同时添加结构式1和本申请其他的添加剂时，电池的高温循环性能和高温存储性能均表现优异。
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 (10)

  1. 一种锂离子电池非水电解液，其特征在于，包括非水有机溶剂、锂盐、如结构式1所示的螺环化合物，
    Figure PCTCN2021126864-appb-100001
    其中，结构式1中，X表示氧原子、羧酸酯基、亚硫酸酯基、硫酸酯基、碳酸酯基、取代或无取代的磷酸酯基、取代或无取代的硼酸酯基；
    R 1、R 2、R 3、R 4各自独立地选自取代或无取代的C1-C5亚烃基。
  2. 如权利要求1所述的锂离子电池非水电解液，其特征在于，R 1、R 2、R 3、R 4中至少一个为取代或无取代的C1-C5亚烷基，C1-C5亚烷基的取代基包括卤素取代或无取代的C1-C20烷基、卤素取代或无取代的C2-C20烯基、卤素取代或无取代的C2-C20炔基、卤素取代或无取代的C3-C20环烯基、卤素取代或无取代的C3-C20杂环基、卤素取代或无取代的C6-C40芳基、卤素取代或无取代的C2-C40杂芳基或者具有至少一个杂原子的极性官能团中的一种或多种。
  3. 如权利要求2所述的锂离子电池非水电解液，其特征在于，C1-C5亚烷基的取代基选自卤素、甲基、乙基、丙基、异丙基、丁基、叔丁基、烯烃基、炔烃基、苯基、三甲基硅基、氰基、三氟甲基、四氟乙基、萘基、四氟苯基、吡咯基或吡啶基的一种或多种。
  4. 如权利要求1所述的锂离子电池非水电解液，其特征在于，所述如结构式1所示的螺环化合物至少包括式1～7中的一种，
    Figure PCTCN2021126864-appb-100002
    其中，R 5、R 6各自独立地选自氢原子、卤素、烃基、卤代烃基、含氧烃基、含硅烃基、含氰烃基或含氮烃基。
  5. 如权利要求4所述的锂离子电池非水电解液，其特征在于，R 5、R 6各自独立地选自氢原子、氟原子、甲基、乙基、丙基、异丙基、丁基、叔丁基、烯烃基、炔烃基、苯基、三甲基硅基、氰基、三氟甲基、四氟乙基、萘基、四氟苯基、吡咯基或吡啶基。
  6. 如权利要求1所述的锂离子电池非水电解液，其特征在于，所述结构式1所示的化合物在锂离子电池非水电解液中的质量百分比为0.05％～10％。
  7. 如权利要求1所述的锂离子电池非水电解液，其特征在于，所述非水电解液还包括1,3-丙烷磺内酯、1,4-丁烷磺内酯、1,3-丙烯磺内酯、碳酸亚乙烯酯、碳酸乙烯亚乙酯、氟代碳酸乙烯酯、硫酸乙烯酯中的一种或多种。
  8. 如权利要求1所述的锂离子电池非水电解液，其特征在于，所述锂盐选自LiPF 6、LiBF 4、LiBOB、LiPO 2F 2、LiDFOB、LiSbF 6、LiAsF 6、LiN(SO 2CF 3) 2、 LiN(SO 2C 2F 5) 2、LiC(SO 2CF 3) 3或LiN(SO 2F) 2中的一种或多种；
    所述非水有机溶剂为环状碳酸酯和链状碳酸酯的混合物，所述环状碳酸酯选自碳酸乙烯酯、碳酸丙烯酯或碳酸丁烯酯中的一种或多种，所述链状碳酸酯选自碳酸二甲酯、碳酸二乙酯、碳酸甲乙酯或碳酸甲丙酯中的一种或多种。
  9. 一种锂离子电池，其包括正极、负极、设置在所述正极和所述负极之间的隔膜以及电解液，其特征在于，所述电解液是如权利要求1～8中任一项所述的锂离子电池非水电解液。
  10. 如权利要求9所述的锂离子电池，其特征在于，所述正极包括正极活性材料，所述正极活性材料包括LiCoO 2、LiNiO 2、LiMn 2O 4、LiCo 1-yM yO 2、LiNi 1-yM yO 2、LiMn 2-yM yO 4、LiCo xM (1-x)O 2或LiNi xCo yMn zM 1-x-y-zO 2中的一种或多种，其中，M选自Al、Sr、Mg、Ti、Ca、Zr、Zn、Si、Cu、V或Fe中的一种或多种，且0≤x≤1，0≤y≤1，0≤z≤1，x+y+z≤1。
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