WO2023087536A1 - 电解液添加剂组合物、电解液及锂二次电池 - Google Patents

电解液添加剂组合物、电解液及锂二次电池 Download PDF

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WO2023087536A1
WO2023087536A1 PCT/CN2022/073094 CN2022073094W WO2023087536A1 WO 2023087536 A1 WO2023087536 A1 WO 2023087536A1 CN 2022073094 W CN2022073094 W CN 2022073094W WO 2023087536 A1 WO2023087536 A1 WO 2023087536A1
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electrolyte
lithium
total mass
fluorine
compound
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PCT/CN2022/073094
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English (en)
French (fr)
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刘念滔
范伟贞
信勇
赵经纬
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九江天赐高新材料有限公司
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Publication of WO2023087536A1 publication Critical patent/WO2023087536A1/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
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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 relates to the technical field of batteries, in particular to an electrolyte additive composition, an electrolyte and a lithium secondary battery.
  • lithium secondary batteries Compared with other secondary batteries, lithium secondary batteries have the advantages of high working voltage, long cycle life, low self-discharge rate, environmental friendliness, and no memory effect.
  • Lithium transition metal oxides have broad application prospects as positive electrode active materials for practical lithium secondary batteries.
  • lithium transition metal oxides lithium cobalt oxide, lithium nickel oxide, and lithium manganese oxide are known to exhibit high battery performance. Therefore, a large number of research institutions and enterprises have conducted active research and development mainly on these compounds to put them into practical use. However, even in the case of using these materials, various problems must be overcome to bring the battery to a practical level.
  • DTD as a low-impedance and high-performance electrolyte functional additive commonly used in electrolytes, has become an indispensable substance in electrolytes, but electrolytes containing DTD are easily hydrolyzed, causing the acidity and chroma of the electrolyte to increase. High, so that DTD needs to be used under harsh conditions, and the cost of low-temperature storage and refrigerated transportation is high. In addition, the increase in acidity will also cause damage to the positive electrode interface, and at the same time cause the dissolution of transition metal ions. The transition metal ions migrate to the negative electrode, which will destroy the interface film on the surface of the negative electrode, which will cause the deterioration of the electrochemical performance of the battery, especially at high temperature. , the cycle performance is poor.
  • a halogenated pyridine is used as a flame retardant additive for the electrolyte of lithium-ion batteries, which improves the safety of the battery through the flame-retardant and inhibitory effect of halogen and nitrogen atoms on hydroxyl radicals, but this product is only used as a flame retardant It is not used for DTD stability, nor can it prevent the corrosion damage of HF to the electrode interface. Therefore, it is of great significance to develop new electrolyte additives that can improve the high-temperature performance of batteries and suppress the increase of electrolyte acidity and chroma.
  • the present invention provides an electrolyte additive composition, an electrolyte and an energy storage device.
  • the electrolyte additive composition can improve the high-temperature performance of the battery and suppress the increase of the acidity and chromaticity of the electrolyte.
  • An electrolyte additive composition comprising a fluorine-containing pyridine compound having a structure represented by formula (I) and a phosphite compound having a structure represented by formula (II);
  • the mass ratio of the fluorine-containing pyridine compound to the phosphite compound is (3-10):1;
  • R 1 , R 2 , R 3 and R 4 are independently selected from hydrogen, halogen, C 1 -C 20 alkyl, halogenated C 1 -C 20 alkyl, C 6 -C 26 aryl, halogenated C 6 ⁇ C 26 aryl, amino, isocyano or alkoxy;
  • R 5 , R 6 and R 7 are independently selected from C 1 -C 20 alkyl, halogenated C 1 -C 20 alkyl, C 6 -C 26 aryl, and halogenated C 6 -C 26 aryl.
  • R 1 , R 2 , R 3 and R 4 are independently selected from hydrogen, halogen, C 1 -C 10 alkyl, C 6 -C 10 aryl, amino, isocyano or C 1 ⁇ C 10 alkoxy.
  • R 1 , R 2 , R 3 and R 4 are independently selected from hydrogen, halogen, methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl 1-pentyl, 2-pentyl, 3-pentyl, 1-hexyl, 2-hexyl, 3-hexyl, octyl, phenyl, naphthyl, biphenyl, methoxy or ethoxy.
  • the fluorine-containing pyridine compound has the structure shown in any one of the following (F1)-(F9):
  • R 5 , R 6 and R 7 are independently selected from C 1 -C 10 alkyl, phenyl, naphthyl or biphenyl.
  • R 5 , R 6 and R 7 are independently selected from methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, 1-pentyl, 2-pentyl, 3-pentyl, 1-hexyl, 2-hexyl, 3-hexyl, octyl, phenyl, naphthyl or biphenyl.
  • the phosphite compound has the structure shown in any of the following (P1)-(P9):
  • the present invention also provides an electrolyte, including the above-mentioned electrolyte additive composition.
  • the electrolyte solution further includes electrolyte lithium salt, organic solvent and vinyl sulfate.
  • the organic solvent is selected from a mixture of at least two of ethylene carbonate, propylene carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl acetate and propyl acetate;
  • the electrolyte lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bisoxalate borate, lithium difluorophosphate, lithium difluorooxalate phosphate and lithium bisfluorosulfonyl imide.
  • the concentration of the electrolyte lithium salt in the organic solvent is 0.8mol/L-1.5mol/L;
  • the addition amount of the electrolyte additive composition is 0.05% to 1.5% of the total mass of the electrolyte
  • the added amount of the vinyl sulfate is 0.5%-3% of the total mass of the electrolytic solution.
  • the added amount of the fluorine-containing pyridine compound having the structure represented by formula (I) is 0.03% to 1% of the total mass of the electrolyte solution;
  • the added amount of the phosphite compound having the structure represented by formula (II) is 0.01%-0.1% of the total mass of the electrolyte solution.
  • the electrolyte solution also includes a functional additive selected from the group consisting of tris(trimethylsilyl) phosphate, tris(trimethylsilyl) borate, lithium difluorooxalate borate, vinylene carbonate, At least one of ethylene carbonate, fluoroethylene carbonate, and 1,3-propane sultone; and/or
  • the added amount of the functional additive is 0.5%-5% of the total mass of the electrolyte solution.
  • the present invention also provides a lithium secondary battery, comprising the above-mentioned electrolyte additive composition or electrolyte.
  • the lithium secondary battery includes a lithium-ion battery, a lithium-sulfur battery or a lithium-air battery.
  • the electrolyte additive composition provided by the present invention comprises a specific mass ratio of a fluorine-containing pyridine compound having a structure shown in formula (I) and a phosphite compound having a structure shown in formula (II). It can significantly inhibit the increase of acidity and chroma of the electrolyte (especially the electrolyte containing vinyl sulfate, which can significantly reduce the decomposition of vinyl sulfate and inhibit the increase of acidity and chroma of the electrolyte), and it can also be used in A stable passivation film is formed on the surface of the electrode, which inhibits the decomposition of the electrolyte and the dissolution of transition metal ions, and improves the cycle performance and high temperature performance of the battery.
  • the electrolyte additive composition provided by the invention can also effectively inhibit The acidity and color of the electrolyte system increase.
  • a stable passivation film can also be formed on the surface of the electrode, which can inhibit the decomposition of the electrolyte and the dissolution of transition metal ions, improve the cycle performance and high temperature performance of the battery, and has broad application prospects.
  • alkyl refers to a saturated hydrocarbon comprising primary (normal) carbon atoms, or secondary carbon atoms, or tertiary carbon atoms, or quaternary carbon atoms, or combinations thereof. Phrases containing this term, eg, "C 1-16 alkyl” means an alkyl group containing 1 to 16 carbon atoms.
  • Suitable examples include, but are not limited to: methyl (Me, -CH 3 ), ethyl (Et, -CH 2 CH 3 ), 1-propyl (n-Pr, n-propyl, -CH 2 CH 2 CH 3 ), 2-propyl (i-Pr, i-propyl, -CH(CH 3 ) 2 ), 1-butyl (n-Bu, n-butyl, -CH 2 CH 2 CH 2 CH 3 ) , 2-methyl-1-propyl (i-Bu, i-butyl, -CH 2 CH(CH 3 ) 2 ), 2-butyl (s-Bu, s-butyl, -CH(CH 3 )CH 2 CH 3 ), 2-methyl-2-propyl (t-Bu, t-butyl, -C(CH 3 ) 3 ), 1-pentyl (n-pentyl, -CH 2 CH 2 CH 2 CH 3 ), 2-pentyl (-CH(CH3)
  • alkoxy refers to a group having an -O-alkyl group, ie an alkyl group as defined above attached to a parent core structure via an oxygen atom. Suitable examples include, but are not limited to: methoxy (-O-CH 3 or -OMe), ethoxy (-O-CH 2 CH 3 or -OEt), and tert-butoxy (-OC(CH 3 ) 3 or -OtBu).
  • Aryl refers to an aromatic hydrocarbon group derived from an aromatic ring compound by removing a hydrogen atom. It can be a single-ring aryl, or a fused-ring aryl, or a polycyclic aryl. For polycyclic ring species, at least One is an aromatic ring system.
  • C 6 -C 26 aryl refers to an aryl group containing 6-26 carbon atoms, suitable examples include but not limited to: benzene, biphenyl, naphthalene, anthracene, phenanthrene.
  • Halogen or halo means F, Cl, Br or I.
  • the present invention provides an electrolyte additive composition, comprising a fluorine-containing pyridine compound having a structure represented by formula (I) and a phosphite compound having a structure represented by formula (II);
  • the mass ratio of the fluorine-containing pyridine compound to the phosphite compound is (3-10):1;
  • R 1 , R 2 , R 3 and R 4 are independently selected from hydrogen, halogen, C 1 -C 20 alkyl, halogenated C 1 -C 20 alkyl, C 6 -C 26 aryl, halogenated C 6 ⁇ C 26 aryl, amino, isocyano or alkoxy;
  • R 5 , R 6 and R 7 are independently selected from C 1 -C 20 alkyl, halogenated C 1 -C 20 alkyl, C 6 -C 26 aryl, and halogenated C 6 -C 26 aryl.
  • the electrolyte additive composition provided by the present invention comprises a specific weight ratio of a fluorine-containing pyridine compound having a structure shown in formula (I) and a phosphite compound having a structure shown in formula (II). It can significantly inhibit the acidity and color of the electrolyte from increasing, and can also form a stable passivation film on the surface of the electrode, inhibit the decomposition of the electrolyte and the dissolution of transition metal ions, and improve the cycle performance and high temperature performance of the battery.
  • R 1 , R 2 , R 3 and R 4 are independently selected from hydrogen, halogen, C 1 -C 10 alkyl, C 6 -C 10 aryl, amino, isocyano or C 1 ⁇ C 10 alkoxy.
  • R 1 , R 2 , R 3 and R 4 are independently selected from hydrogen, halogen, methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, 1- Pentyl, 2-pentyl, 3-pentyl, 1-hexyl, 2-hexyl, 3-hexyl, octyl, phenyl, naphthyl, biphenyl, methoxy or ethoxy.
  • fluorine-containing pyridine compound has the structure shown in any of the following (F1)-(F9):
  • R 5 , R 6 and R 7 are independently selected from C 1 -C 10 alkyl, phenyl, naphthyl or biphenyl.
  • R 5 , R 6 and R 7 are independently selected from methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, 1-pentyl, 2-pentyl , 3-pentyl, 1-hexyl, 2-hexyl, 3-hexyl, octyl, phenyl, naphthyl or biphenyl.
  • the phosphite compound has a structure shown in any of the following (P1)-(P9):
  • the present invention also provides an electrolyte, including the above-mentioned electrolyte additive composition.
  • the electrolyte solution further includes electrolyte lithium salt, organic solvent and vinyl sulfate.
  • Adding the electrolyte additive composition provided by the invention in the electrolyte containing vinyl sulfate can significantly reduce the decomposition of vinyl sulfate, suppress the increase of acidity and chromaticity of the electrolyte, and also form a stable passivation on the surface of the electrode.
  • the film can inhibit the decomposition of electrolyte and the dissolution of transition metal ions, and improve the cycle performance and high temperature performance of the battery.
  • the organic solvent is selected from a mixture of at least two of ethylene carbonate, propylene carbonate, diethyl carbonate, ethyl methyl carbonate, ethyl acetate and propyl acetate;
  • the electrolyte lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bisoxalate borate, lithium difluorophosphate, lithium difluorooxalate phosphate and lithium bisfluorosulfonyl imide.
  • the concentration of the electrolyte lithium salt in the organic solvent is 0.8mol/L-1.5mol/L;
  • the addition amount of the electrolyte additive composition is 0.05% to 1.5% of the total mass of the electrolyte
  • the added amount of the vinyl sulfate is 0.5%-3% of the total mass of the electrolytic solution.
  • the added amount of the fluorine-containing pyridine compound having the structure represented by formula (I) is 0.03% to 1% of the total mass of the electrolyte solution;
  • the added amount of the phosphite compound having the structure represented by formula (II) is 0.01%-0.1% of the total mass of the electrolyte solution.
  • the electrolyte solution also includes a functional additive selected from the group consisting of tris(trimethylsilyl) phosphate, tris(trimethylsilyl) borate, lithium difluorooxalate borate, vinylene carbonate, At least one of ethylene carbonate, fluoroethylene carbonate, and 1,3-propane sultone; and/or
  • the added amount of the functional additive is 0.5%-5% of the total mass of the electrolyte solution.
  • the present invention also provides the preparation method of above-mentioned electrolytic solution, comprises the following steps:
  • the preparation method of the electrolyte comprises the following steps:
  • step (2) at room temperature, adding electrolyte lithium salt to the purified organic solvent obtained in step (1), stirring evenly to obtain a mixed solution;
  • step (3) in the mixed liquor that step (2) obtains, add the fluorine-containing pyridine compound with the structure shown in formula (I) and the phosphite compound with the structure shown in formula (II), vinyl sulfate (functional Additives then also add functional additives), stir evenly.
  • the purification and removal of impurities and water described in step (1) are preferably carried out through molecular sieves, activated carbon, calcium hydride, lithium hydride, anhydrous calcium oxide, calcium chloride, phosphorus pentoxide, alkali metal or Any one or several kinds of alkaline earth metals.
  • the present invention also provides a lithium secondary battery, comprising the above-mentioned electrolyte additive composition or electrolyte.
  • the lithium secondary battery includes a lithium-ion battery, a lithium-sulfur battery or a lithium-air battery.
  • the lithium-ion battery includes a positive electrode sheet, a negative electrode sheet, a separator, and the electrolyte containing fluorinated pyridine, phosphite and its derivatives;
  • the positive electrode sheet includes lithium intercalation or deintercalation
  • the positive electrode material of the lithium ion battery includes Li 1+a ( Nix Co y M 1-xy )O 2 , Li( Nip Mn q Co 2-pq )O 4 and LiM h (PO 4 ) m One or more of them; where 0 ⁇ a ⁇ 0.3, 0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 1, 0 ⁇ x+y ⁇ 1; 0 ⁇ p ⁇ 2, 0 ⁇ q ⁇ 2, 0 ⁇ p +q ⁇ 2; 0 ⁇ h ⁇ 5, 0 ⁇ m ⁇ 5; M is Fe, Ni, Co, Mn, Al or V.
  • the negative electrode material of the lithium ion battery includes at least one of lithium metal, lithium alloy, carbon, silicon-based negative electrode material and tin-based negative electrode material.
  • Above-mentioned lithium-ion battery adopts the electrolytic solution that comprises above-mentioned fluorine-containing pyridine compound with the structure shown in formula (I) and the phosphite compound with the structure shown in formula (II), through fluorine-containing pyridine compound and phosphite
  • the complex effect of the compound can significantly inhibit the increase of the acidity and chroma of the electrolyte, and can form a stable passivation film on the surface of the electrode, thereby inhibiting the decomposition of the electrolyte and the dissolution of transition metal ions, improving the cycle performance and high temperature performance of the battery. It has good capacity retention rate when stored or used under high temperature conditions.
  • an electrolyte additive composition in this embodiment, electrolyte and lithium ion battery are provided.
  • the electrolyte additive composition consists of Composition according to the mass ratio of 10:1.
  • Electrolyte and preparation method thereof are as follows:
  • Example 2 Compared with Example 1, the difference of Example 2 is that the fluorine-containing pyridine compound added in the basic electrolyte prepared in step (2) is 2-fluoro-6-picoline (F2), and its dosage is 0.3% of the total mass of liquid.
  • F2 2-fluoro-6-picoline
  • Example 3 Compared with Example 1, the difference of Example 3 is that the fluorine-containing pyridine compound added to the basic electrolyte prepared in step (2) is 6-fluoro-2,3-lutidine (F3), which The dosage is 0.3% of the total mass of the electrolyte.
  • F3 6-fluoro-2,3-lutidine
  • Example 4 Compared with Example 1, the difference of Example 4 is that the fluorine-containing pyridine compound added to the basic electrolyte prepared in step (2) is 6-fluoro-2,3,4-collidine (F4) , and its consumption is 0.3% of the total mass of the electrolyte.
  • F4 6-fluoro-2,3,4-collidine
  • Example 5 Compared with Example 1, the difference of Example 5 is that the fluorine-containing pyridine compound added in the basic electrolyte prepared in step (2) is 2-fluoro-3,4,5,6-tetramethylpyridine ( F5), its consumption is 0.3% of the total mass of electrolyte.
  • F5 2-fluoro-3,4,5,6-tetramethylpyridine
  • Example 6 Compared with Example 1, the difference of Example 6 is that the fluorine-containing pyridine compound added to the basic electrolyte prepared in step (2) is 2,6-difluoropyridine (F6), and its dosage is 0.3% of mass.
  • F6 2,6-difluoropyridine
  • Example 7 Compared with Example 1, the difference of Example 7 is that the fluorine-containing pyridine compound added to the basic electrolyte prepared in step (2) is 2,6-difluoro-3-methylpyridine (F7), which The dosage is 0.3% of the total mass of the electrolyte.
  • F7 2,6-difluoro-3-methylpyridine
  • Example 8 Compared with Example 1, the difference of Example 8 is that the fluorine-containing pyridine compound added in the basic electrolyte prepared in step (2) is 2,6-difluoro-3,4-lutidine (F8 ), its consumption is 0.3% of the total mass of the electrolyte.
  • Example 9 Compared with Example 1, the difference of Example 9 is that the fluorine-containing pyridine compound added to the basic electrolyte prepared in step (2) is 2,6-difluoro-3,4,5-collidine (F9), its consumption is 0.3% of the total mass of electrolyte.
  • Example 10 Compared with Example 1, the difference of Example 10 is that the phosphite compound added in the basic electrolyte prepared in step (2) is triethyl phosphite (P2), and its consumption is 0.03% of the total mass of the electrolyte. %.
  • P2 triethyl phosphite
  • Example 11 Compared with Example 1, the difference of Example 11 is that the phosphite compound is triphenyl phosphite (P6) added to the basic electrolyte prepared in step (2), and its consumption is 0.03% of the total mass of the electrolyte .
  • P6 triphenyl phosphite
  • Example 12 Compared with Example 1, the difference of Example 12 is that the fluorine-containing pyridine compound added to the basic electrolyte prepared in step (2) is 2-fluoro-6-methylpyridine (F2), and its dosage is 0.15% of the total mass, the phosphite compound is triethyl phosphite (P2), and its consumption is 0.03% of the total mass of the electrolyte.
  • F2 2-fluoro-6-methylpyridine
  • P2 triethyl phosphite
  • Comparative Example 1 Compared with Example 1, the difference of Comparative Example 1 is that the basic electrolyte prepared in step (2) does not contain the fluorine-containing pyridine compounds with the structure shown in formula (I) described in the present invention and the formula ( II) Phosphite compounds of the shown structure.
  • Example 2 Compared with Example 1, the difference of Comparative Example 2 is that the phosphite compound P1 of Example 1 is replaced by three (trimethylsilyl) phosphite
  • Example 3 Compared with Example 1, the difference of Comparative Example 3 is that the addition of the phosphite compound P1 of Example 1 is omitted, and in the electrolyte, the amount of 2-fluoropyridine (F1) added is the total mass of the electrolyte 0.33%.
  • Example 4 Compared with Example 1, the difference of Comparative Example 4 is that the addition of the phosphite compound P1 of Example 2 is omitted, and in the electrolyte, the addition amount of the fluorine-containing pyridine compound F2 is 1% of the total mass of the electrolyte. 0.33%.
  • Example 1 Compared with Example 1, the difference of Comparative Example 5 is that the addition of the phosphite compound P1 of Example 1 is omitted, and in the electrolyte, the addition amount of the fluorine-containing pyridine compound F3 is 1% of the total mass of the electrolyte. 0.33%.
  • Example 1 Compared with Example 1, the difference of Comparative Example 6 is that the addition of the phosphite compound P1 of Example 1 is omitted, and in the electrolyte, the addition amount of the fluorine-containing pyridine compound F4 is 1% of the total mass of the electrolyte. 0.33%.
  • Comparative Example 7 Compared with Example 1, the difference of Comparative Example 7 is that the addition of the phosphite compound P1 of Example 1 is omitted, and in the electrolyte, the addition amount of the fluorine-containing pyridine compound F5 is 1% of the total mass of the electrolyte. 0.33%.
  • Comparative Example 8 Compared with Example 1, the difference of Comparative Example 8 is that the addition of the phosphite compound P1 of Example 1 is omitted, and in the electrolyte, the addition amount of the fluorine-containing pyridine compound F6 is 1% of the total mass of the electrolyte. 0.33%.
  • Example 9 Compared with Example 1, the difference of Comparative Example 9 is that the addition of the phosphite compound P1 of Example 1 is omitted, and in the electrolyte, the addition amount of the fluorine-containing pyridine compound F7 is 1% of the total mass of the electrolyte. 0.33%.
  • Comparative Example 10 Compared with Example 1, the difference of Comparative Example 10 is that the addition of the phosphite compound P1 of Example 1 is omitted, and in the electrolyte, the addition amount of the fluorine-containing pyridine compound F8 is 1% of the total mass of the electrolyte. 0.33%.
  • Example 11 Compared with Example 1, the difference of Comparative Example 11 is that the addition of the phosphite compound P1 of Example 1 is omitted, and in the electrolyte, the addition amount of the fluorine-containing pyridine compound F9 is 1% of the total mass of the electrolyte. 0.33%.
  • Comparative Example 12 Compared with Example 1, the difference of Comparative Example 12 is that the addition of the fluorine-containing pyridine compound F1 in Example 1 is omitted, and in the electrolyte, the amount of the phosphite compound P1 added is 1% of the total mass of the electrolyte. 0.33%.
  • Example 13 Compared with Example 1, the difference of Comparative Example 13 is that the addition of the fluorine-containing pyridine compound F1 of Example 1 is omitted, and the phosphite compound P1 of Example 1 is replaced by tris(trimethylsilyl) Phosphite And in the electrolytic solution, the addition amount of tris(trimethylsilyl) phosphite is 0.33% of the total mass of the electrolytic solution.
  • the lithium secondary battery electrolytes in Examples 1 to 12 and Comparative Examples 1 to 13 are all soft-pack batteries for the corresponding battery system.
  • the test of these soft-pack batteries is 3.0-4.2V in a high temperature environment of 45°C , 1C rate charge-discharge cycle performance and 30-day high-temperature storage performance at 60°C.
  • the test method is as follows:
  • Battery high-temperature storage experiment The batteries obtained in Examples 1 to 12 and Comparative Examples 1 to 13 were subjected to 5 charge-discharge cycle tests at a charge-discharge rate of 1C at room temperature, and finally charged to a fully charged state at a rate of 1C . Record 1C capacity Q and battery internal resistance T respectively. Store the fully charged battery at 60°C for 30 days, record the battery internal resistance T0 and 1C discharge capacity Q1, then charge and discharge the battery at room temperature at a rate of 1C for 5 weeks, select the time with the highest discharge capacity and record it as the discharge capacity Q2. Calculate and obtain the experimental data such as battery high-temperature storage capacity retention rate, capacity recovery rate, and internal resistance change rate. The recorded results are shown in Table 1.
  • the difference from the basic electrolyte comparative example G0 is that the fluorine-containing pyridine compound 2-fluoropyridine (F1) is also added in step (2), and its dosage is 0.3% of the total mass of the electrolyte to obtain lithium secondary for storage.
  • the electrolyte of the battery is also added in step (2), and its dosage is 0.3% of the total mass of the electrolyte to obtain lithium secondary for storage.
  • the difference from the basic electrolyte comparative example G0 is that the fluorine-containing pyridine compound 2-fluoro-6-picoline (F2) is also added in step (2), and its consumption is 0.3% of the total mass of the electrolyte to obtain Stored electrolyte of lithium secondary batteries.
  • F2 fluorine-containing pyridine compound 2-fluoro-6-picoline
  • the difference from the basic electrolyte comparative example G0 is that the fluorine-containing pyridine compound 6-fluoro-2,3-lutidine (F3) is also added in step (2), and its consumption is 0.3% of the total mass of the electrolyte, An electrolyte solution for a lithium secondary battery for storage is obtained.
  • F3 fluorine-containing pyridine compound 6-fluoro-2,3-lutidine
  • the difference from the basic electrolyte comparative example G0 is that the fluorine-containing pyridine compound 6-fluoro-2,3,4-collidine (F4) is added in step (2), and the amount is 0.3% of the total mass of the electrolyte. %, to obtain the electrolyte solution of the lithium secondary battery for storage.
  • F4 fluorine-containing pyridine compound 6-fluoro-2,3,4-collidine
  • the difference from the basic electrolyte comparative example G0 is that the fluorine-containing pyridine compound 2-fluoro-3,4,5,6-tetramethylpyridine (F5) is added in step (2), and the amount is the total mass of the electrolyte 0.3% to obtain an electrolyte solution for storing lithium secondary batteries.
  • F5 fluorine-containing pyridine compound 2-fluoro-3,4,5,6-tetramethylpyridine
  • the difference from the basic electrolyte comparative example G0 is that a fluorine-containing pyridine compound 2,6-difluoropyridine (F6) is also added in step (2), and its dosage is 0.3% of the total mass of the electrolyte to obtain a Electrolyte for lithium secondary batteries.
  • F6 fluorine-containing pyridine compound 2,6-difluoropyridine
  • the difference from the basic electrolyte comparative example G0 is that a fluorine-containing pyridine compound 2,6-difluoro-3-methylpyridine (F7) is also added in step (2), and its consumption is 0.3% of the total mass of the electrolyte, An electrolyte solution for a lithium secondary battery for storage is obtained.
  • a fluorine-containing pyridine compound 2,6-difluoro-3-methylpyridine (F7) is also added in step (2), and its consumption is 0.3% of the total mass of the electrolyte, An electrolyte solution for a lithium secondary battery for storage is obtained.
  • the difference with the basic electrolyte comparative example G0 is that the fluorine-containing pyridine compound 2,6-difluoro-3,4-lutidine (F8) is also added in step (2), and its consumption is 1% of the total mass of the electrolyte 0.3%, to obtain an electrolyte solution for storing lithium secondary batteries.
  • F8 fluorine-containing pyridine compound 2,6-difluoro-3,4-lutidine
  • the difference from the basic electrolyte comparative example G0 is that the fluorine-containing pyridine compound 2,6-difluoro-3,4,5-collidine (F9) is also added in step (2), and its consumption is the total amount of the electrolyte. 0.3% by mass to obtain an electrolyte solution for storing lithium secondary batteries.
  • F9 fluorine-containing pyridine compound 2,6-difluoro-3,4,5-collidine
  • the difference from the basic electrolyte comparative example G0 is that the phosphite compound trimethyl phosphite (P1) is also added in the step (2), and its dosage is 0.03% of the total mass of the electrolyte to obtain lithium di electrolyte of the secondary battery.
  • P1 phosphite compound trimethyl phosphite
  • the difference from the basic electrolyte comparative example G0 is that the phosphite compound tris(trimethylsilyl)phosphite is also added in step (2)
  • the amount used is 0.03% of the total mass of the electrolyte to obtain the electrolyte for a lithium secondary battery used for storage.
  • the difference from the basic electrolyte comparative example G0 is that the fluorine-containing pyridine compound 2-fluoropyridine (F1) is also added in step (2), and its dosage is 0.3% of the total mass of the electrolyte; in addition, phosphite Compound tris (trimethylsilyl) phosphite, its dosage is 0.03% of the total mass of the electrolyte, to obtain the electrolyte of the lithium secondary battery used for storage;
  • the difference from the basic electrolyte comparative example G0 is that the fluorine-containing pyridine compound 2-fluoropyridine (F1) is also added in step (2), and its dosage is 0.3% of the total mass of the electrolyte; in addition, phosphite
  • the compound trimethyl phosphite (P1) is used in an amount of 0.03% of the total mass of the electrolyte to obtain an electrolyte for a lithium secondary battery for storage.
  • the difference with the basic electrolyte comparative example G0 is that the fluorine-containing pyridine compound 2-fluoro-6-picoline (F2) is also added in step (2), and its consumption is 0.3% of the total mass of the electrolyte; in addition, The phosphite compound trimethyl phosphite (P1) is added in an amount of 0.03% of the total mass of the electrolyte to obtain an electrolyte for a lithium secondary battery for storage.
  • F2 fluorine-containing pyridine compound 2-fluoro-6-picoline
  • P1 phosphite compound trimethyl phosphite
  • the difference from the basic electrolyte comparative example G0 is that a fluorine-containing pyridine compound 6-fluoro-2,3-lutidine (F3) is also added in step (2), and its consumption is 0.3% of the total mass of the electrolyte;
  • F3 fluorine-containing pyridine compound 6-fluoro-2,3-lutidine
  • P1 trimethyl phosphite
  • P1 a phosphite compound
  • the difference from the basic electrolyte comparative example G0 is that the fluorine-containing pyridine compound 6-fluoro-2,3,4-collidine (F4) is added in step (2), and the amount is 0.3% of the total mass of the electrolyte. %;
  • F4 fluorine-containing pyridine compound 6-fluoro-2,3,4-collidine
  • P1 phosphite compound trimethyl phosphite
  • the difference from the basic electrolyte comparative example G0 is that the fluorine-containing pyridine compound 2-fluoro-3,4,5,6-tetramethylpyridine (F5) is added in step (2), and the amount is the total mass of the electrolyte.
  • a phosphite compound, trimethyl phosphite (P1) was added in an amount of 0.03% of the total mass of the electrolyte to obtain an electrolyte for a lithium secondary battery for storage.
  • the difference from the basic electrolyte comparative example G0 is that the fluorine-containing pyridine compound 2,6-difluoropyridine (F6) is also added in step (2), and its consumption is 0.3% of the total mass of the electrolyte;
  • the phosphoric acid ester compound trimethyl phosphite (P1) is used in an amount of 0.03% of the total mass of the electrolyte to obtain an electrolyte for a lithium secondary battery for storage.
  • the difference from the basic electrolyte comparative example G0 is that a fluorine-containing pyridine compound 2,6-difluoro-3-methylpyridine (F7) is also added in step (2), and its consumption is 0.3% of the total mass of the electrolyte;
  • trimethyl phosphite (P1) a phosphite compound, is added in an amount of 0.03% of the total mass of the electrolyte to obtain an electrolyte for a lithium secondary battery for storage.
  • the difference with the basic electrolyte comparative example G0 is that the fluorine-containing pyridine compound 2,6-difluoro-3,4-lutidine (F8) is also added in step (2), and its consumption is 1% of the total mass of the electrolyte 0.3%; in addition, also add phosphite compound trimethyl phosphite (P1), its consumption is 0.03% of the total mass of electrolyte, obtain the electrolyte of the lithium secondary battery that is used for storage.
  • F8 fluorine-containing pyridine compound 2,6-difluoro-3,4-lutidine
  • P1 phosphite compound trimethyl phosphite
  • the difference from the basic electrolyte comparative example G0 is that the fluorine-containing pyridine compound 2,6-difluoro-3,4,5-collidine (F9) is also added in step (2), and its consumption is the total amount of the electrolyte. 0.3% of the mass; in addition, a phosphite compound trimethyl phosphite (P1) was added in an amount of 0.03% of the total mass of the electrolyte to obtain an electrolyte for a lithium secondary battery for storage.
  • F9 fluorine-containing pyridine compound 2,6-difluoro-3,4,5-collidine
  • P1 phosphite compound trimethyl phosphite
  • the difference from the basic electrolyte comparative example G0 is that the fluorine-containing pyridine compound 2-fluoropyridine (F1) is also added in step (2), and its dosage is 0.3% of the total mass of the electrolyte; in addition, phosphite The amount of compound P2 is 0.03% of the total mass of the electrolyte to obtain the electrolyte of the lithium secondary battery used for storage.
  • F1 fluorine-containing pyridine compound 2-fluoropyridine
  • the difference from the basic electrolyte comparative example G0 is that the fluorine-containing pyridine compound 2-fluoropyridine (F1) is also added in step (2), and its dosage is 0.3% of the total mass of the electrolyte; in addition, phosphite
  • the compound P6 is used in an amount of 0.03% of the total mass of the electrolyte to obtain an electrolyte for a lithium secondary battery for storage.
  • Lithium secondary battery electrolytes from G0 to G23 are used for storage at room temperature and 45°C, and test the acidity and color of the electrolyte for 7 days, 15 days, 30 days, and 60 days of storage;
  • the acidity test instrument is a potentiometer Titrator, the acidity test method is the triethylamine potentiometric titration method, and the chromaticity is tested with a colorimeter; the chromaticity record results are shown in Table 2; the acidity record results are shown in Table 3.
  • the combination of fluorine-containing pyridine compounds and phosphite compounds can effectively inhibit the acidity and chromaticity of the electrolyte containing vinyl sulfate (DTD).
  • DTD electrolyte containing vinyl sulfate
  • its application in the electrolyte of lithium secondary batteries can improve the high-temperature cycle performance and high-temperature storage performance of lithium secondary batteries, and at the same time form a stable SEI layer on the negative surface, improving the negative electrode/electrolyte interface It reduces the irreversible capacity of the lithium secondary battery in the first charge and discharge, improves the stability of the interface, and helps to improve the cycle stability and high temperature storage performance of the lithium secondary battery.

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Abstract

本发明涉及电解液添加剂组合物、电解液及锂二次电池。该电解液添加剂组合物包括具有式(I)所示结构的含氟吡啶类化合物和具有式(II)所示结构的亚磷酸酯类化合物，R 1、R 2、R 3和R 4分别独立选自氢、卤素、C 1～C 20烷基、卤代的C 1～C 20烷基、C 6～C 26芳基、卤代的C 6～C 26芳基、氨基、异氰基或烷氧基；R 5、R 6和R 7分别独立选自C 1～C 20烷基、卤代的C 1～C 20烷基、C 6～C 26芳基、卤代的C 6～C 26芳基；所述含氟吡啶类化合物和所述亚磷酸酯类化合物的质量比为(3～10):1。该电解液添加剂组合物能够提高电池的高温性能、抑制电解液酸度和色度升高。

Description

电解液添加剂组合物、电解液及锂二次电池 技术领域
本发明涉及电池技术领域，特别涉及电解液添加剂组合物、电解液及锂二次电池。
背景技术
与其他二次电池相比，锂二次电池具有工作电压高、循环寿命长、自放电率低、环境友好、无记忆效应等优点。锂过渡金属氧化物作为提供可实际使用的锂二次电池的正极活性材料,具有广阔的应用前景。在锂过渡金属氧化物中，锂钴氧化物，锂镍氧化物和锂锰氧化物已知表现出高的电池性能。因此，大量的研究机构和企业主要针对这些化合物进行了积极的研究和开发，使其投入实际使用。然而，即使在使用这些材料的情况下，也必须克服各种问题以使电池达到实用水平。
目前亟需解决的是高温环境下电池性能劣化和硫酸乙烯酯(DTD)在电解液中不稳定的问题。具体如下：
(1)锂二次电池在高温环境下的性能劣化是由多种因素引起的，例如，锂过渡金属氧化物在高温环境下金属离子的溶出，电解液的分解以及在负极上形成的固体电解质膜(SEI)的破裂，这些因素均能导致电池性能严重下降。
(2)DTD作为电解液中常用的低阻抗且高性能的电解液功能添加剂，已成为电解液中不可或缺的物质，但含DTD的电解液极易水解，引起电解液酸度、色度升高，从而使得DTD需在苛刻的条件下使用，低温存储和冷藏运输成本高。此外，酸度的升高也会对正极界面造成破坏，同时引起过渡金属离子的溶解，过渡金属离子迁移至负极，会破坏负极表面的界面膜，这些均会引起电池电化学性能恶化，尤其是高温下，循环性能较差。
目前，已报道一种以卤代吡啶作为锂离子电池电解液的阻燃添加剂，通过卤和氮原子对氢氧自由基的阻燃抑制作用提高电池的安全性，但该产品仅作为阻燃剂使用，并未将其用于DTD稳定性方面，也无法阻止HF对电极界面的腐蚀破坏。因此，开发新型的、能够提高电池高温性能、抑制电解液酸度和色度升高的电解液添加剂具有重要意义。
发明内容
基于此，本发明提供了一种电解液添加剂组合物、电解液及储能装置，该电解液添加剂组合物能够提高电池高温性能、抑制电解液酸度和色度升高。
技术方案如下：
一种电解液添加剂组合物，包括具有式(I)所示结构的含氟吡啶类化合物和具有式(II)所示结构的亚磷酸酯类化合物；
所述含氟吡啶类化合物和所述亚磷酸酯类化合物的质量比为(3～10):1；
Figure PCTCN2022073094-appb-000001
其中：
R 1、R 2、R 3和R 4分别独立选自氢、卤素、C 1～C 20烷基、卤代的C 1～C 20烷基、C 6～C 26芳基、卤代的C 6～C 26芳基、氨基、异氰基或烷氧基；
R 5、R 6和R 7分别独立选自C 1～C 20烷基、卤代的C 1～C 20烷基、C 6～C 26芳基、卤代的C 6～C 26芳基。
在其中一个实施例中，R 1、R 2、R 3和R 4分别独立选自氢、卤素、C 1～C 10烷基、C 6～C 10芳基、氨基、异氰基或C 1～C 10烷氧基。
在其中一个实施例中，R 1、R 2、R 3和R 4分别独立选自氢、卤素、甲基、乙基、1-丙基、2-丙基、1-丁基、2-丁基、1-戊基、2-戊基、3-戊基、1-己基、2-己基、3-己基、辛基、苯基、萘基、联苯基、甲氧基或乙氧基。
在其中一个实施例中，所述含氟吡啶类化合物具有如下(F1)-(F9)任一所示的结构：
Figure PCTCN2022073094-appb-000002
在其中一个实施例中，R 5、R 6和R 7分别独立选自C 1～C 10烷基、苯基、萘基或联苯基。
在其中一个实施例中，R 5、R 6和R 7分别独立选自甲基、乙基、1-丙基、2-丙基、1-丁基、2-丁基、1-戊基、2-戊基、3-戊基、1-己基、2-己基、3-己基、辛基、苯基、萘基或联苯基。
在其中一个实施例中，所述亚磷酸酯类化合物具有如下(P1)-(P9)任一所示的结构：
Figure PCTCN2022073094-appb-000003
Figure PCTCN2022073094-appb-000004
本发明还提供一种电解液，包括如上所述的电解液添加剂组合物。
在其中一个实施例中，所述电解液还包括电解质锂盐、有机溶剂和硫酸乙烯酯。
在其中一个实施例中，所述有机溶剂选自碳酸乙烯酯、碳酸丙烯酯、碳酸二乙酯、碳酸甲乙酯、乙酸乙酯和乙酸丙酯中至少两种的混合物；
所述电解质锂盐选自六氟磷酸锂、四氟硼酸锂、双草酸硼酸锂、二氟磷酸锂、二氟草酸磷酸锂和双氟磺酰亚胺锂中的至少一种。
在其中一个实施例中，所述电解质锂盐在所述有机溶剂中的浓度为0.8mol/L～1.5mol/L；
所述电解液添加剂组合物的加入量为所述电解液的总质量的0.05％～1.5％；
所述硫酸乙烯酯的加入量为所述电解液的总质量的0.5％～3％。
在其中一个实施例中，所述具有式(I)所示结构的含氟吡啶类化合物的加入量为所述电解液的总质量的0.03％～1％；
所述具有式(II)所示结构的亚磷酸酯类化合物的加入量为所述电解液的总质量的0.01％～0.1％。
在其中一个实施例中，所述电解液还包括功能添加剂，所述功能添加剂选自三(三甲硅烷)磷酸酯、三(三甲硅烷)硼酸酯、二氟草酸硼酸锂、碳酸亚乙烯酯、碳酸乙烯亚乙酯、氟代碳酸乙烯酯和1,3-丙磺酸内酯中的至少一种；和/或
所述功能添加剂的加入量为所述电解液的总质量的0.5％～5％。
本发明还提供一种锂二次电池，包括如上所述的电解液添加剂组合物或电解液。
在其中一个实施例中，所述锂二次电池包括锂离子电池、锂硫电池或锂空气电池。
本发明具有如下有益效果：
本发明提供的电解液添加剂组合物，包括特定质量比的具有式(I)所示结构的含氟吡啶类化合物和具有式(II)所示结构的亚磷酸酯类化合物，通过二者的协同作用，能显著抑制电解液酸度和色度的升高(尤其是含有硫酸乙烯酯的电解液，能显著降低硫酸乙烯酯的分解，抑制电解液酸度和色度的升高)，并且还能在电极表面形成稳定的钝化膜，抑制电解液分解和过渡金属离子溶出，改善电池循环性能以及高温性能。
此外，对于含有其他不稳定添加剂如三(三甲硅烷)磷酸酯、三(三甲硅烷)硼酸酯、二氟草酸硼酸锂的电解液体系，本发明提供的电解液添加剂组合物也能有效的抑制该电解液体系酸度和色度的升高。同样地，也能在电极表面形成稳定的钝化膜，抑制电解液分解和过渡金属离子溶出，改善电池循环性能以及高温性能，具有广阔的应用前景。
具体实施方式
为了便于理解本发明，下面将对本发明进行更全面的描述，并给出了本发明的较佳实施例。但是，本发明可以以许多不同的形式来实现，并不限于本文所描述的实施例。相反地，提供这些实施例的目的是使对本发明的公开内容的理解更加透彻全面。
除非另有定义，本文所使用的所有的技术和科学术语与属于本发明的技术领域的技术人员通常理解的含义相同。本文中在本发明的说明书中所使用的术语只是为了描述具体的实施例的目的，不是旨在于限制本发明。本文所使用的术语“和/或”包括一个或多个相关的所列项目的任意的和所有的组合。
术语
除非另外说明或存在矛盾之处，本文中使用的术语或短语具有以下含义：
术语“烷基”是指包含伯(正)碳原子、或仲碳原子、或叔碳原子、或季碳原子、或其组合的饱和烃。包含该术语的短语，例如，“C 1-16烷基”是指包含1～16个碳原子的烷基。合适的实例包括但不限于：甲基(Me、-CH 3)、乙基(Et、-CH 2CH 3)、1-丙基(n-Pr、n-丙基、-CH 2CH 2CH 3)、2-丙基(i-Pr、i-丙基、-CH(CH 3) 2)、1-丁基(n-Bu、n-丁基、-CH 2CH 2CH 2CH 3)、2-甲基-1-丙基(i-Bu、i-丁基、-CH 2CH(CH 3) 2)、2-丁基(s-Bu、s-丁基、-CH(CH 3)CH 2CH 3)、2-甲基-2-丙基(t-Bu、t-丁基、-C(CH 3) 3)、1-戊基(n-戊基、-CH 2CH 2CH 2CH 2CH 3)、2-戊基(-CH(CH3)CH2CH2CH3)、3-戊基(-CH(CH 2CH 3) 2)、2-甲基-2-丁基(-C(CH 3) 2CH 2CH 3)、3-甲基-2-丁基(-CH(CH 3)CH(CH 3) 2)、3-甲基-1-丁基(-CH 2CH 2CH(CH 3) 2)、2-甲基-1-丁基(-CH 2CH(CH 3)CH 2CH 3)、1-己基(-CH 2CH 2CH 2CH 2CH 2CH 3)、2-己基(-CH(CH 3)CH 2CH 2CH 2CH 3)、3-己基(-CH(CH 2CH 3)(CH 2CH 2CH 3))、2-甲基-2-戊基(-C(CH 3) 2CH 2CH 2CH 3)、3-甲基-2-戊基(-CH(CH 3)CH(CH 3)CH 2CH 3)、4-甲基-2-戊基(-CH(CH 3)CH 2CH(CH 3) 2)、3-甲基-3-戊基(-C(CH 3)(CH 2CH 3) 2)、2-甲基-3-戊基(-CH(CH 2CH 3)CH(CH 3) 2)、2,3-二甲基-2-丁基(-C(CH 3) 2CH(CH 3) 2)、3,3-二甲基-2-丁基(-CH(CH 3)C(CH 3) 3和辛基(-(CH 2) 7CH 3)。
术语“烷氧基”是指具有-O-烷基的基团，即如上所定义的烷基经由氧原子连接至母核结构。合适的实例包括但不限于：甲氧基(-O-CH 3或-OMe)、乙氧基(-O-CH 2CH 3或-OEt)和叔丁氧基(-O-C(CH 3) 3或-OtBu)。
“芳基”是指在芳香环化合物的基础上除去一个氢原子衍生的芳族烃基，可以为单环芳基、或稠环芳基、或多环芳基，对于多环的环种，至少一个是芳族环系。例如，“C 6～C 26芳基”是指包含6～26个碳原子的芳基，合适的实例包括但不限于：苯、联苯、萘、蒽、菲。
“卤素”或“卤基”是指F、Cl、Br或I。
本发明提供了一种电解液添加剂组合物，包括具有式(I)所示结构的含氟吡啶类化合物和具有式(II)所示结构的亚磷酸酯类化合物；
所述含氟吡啶类化合物和所述亚磷酸酯类化合物的质量比为(3～10):1；
Figure PCTCN2022073094-appb-000005
其中：
R 1、R 2、R 3和R 4分别独立选自氢、卤素、C 1～C 20烷基、卤代的C 1～C 20烷基、C 6～C 26芳基、卤代的C 6～C 26芳基、氨基、异氰基或烷氧基；
R 5、R 6和R 7分别独立选自C 1～C 20烷基、卤代的C 1～C 20烷基、C 6～C 26芳基、卤代的C 6～C 26芳基。
本发明提供的电解液添加剂组合物，包括特定重量比的具有式(I)所示结构的含氟吡啶类化合物和具有式(II)所示结构的亚磷酸酯类化合物，通过二者的协同作用，能显著抑制电解液酸度和色度的升高，并且还能在电极表面形成稳定的钝化膜，抑制电解液分解和过渡金属离子溶出，改善电池循环性能以及高温性能。
在其中一个实施方式中，R 1、R 2、R 3和R 4分别独立选自氢、卤素、C 1～C 10烷基、C 6～C 10芳基、氨基、异氰基或C 1～C 10烷氧基。
进一步地，R 1、R 2、R 3和R 4分别独立选自氢、卤素、甲基、乙基、1-丙基、2-丙基、1-丁基、2-丁基、1-戊基、2-戊基、3-戊基、1-己基、2-己基、3-己基、辛基、苯基、萘基、联苯基、甲氧基或乙氧基。
进一步地，所述含氟吡啶类化合物具有如下(F1)-(F9)任一所示的结构：
Figure PCTCN2022073094-appb-000006
在其中一个实施方式中，R 5、R 6和R 7分别独立选自C 1～C 10烷基、苯基、萘基或联苯基。
进一步地，R 5、R 6和R 7分别独立选自甲基、乙基、1-丙基、2-丙基、1-丁基、2-丁基、1-戊基、2-戊基、3-戊基、1-己基、2-己基、3-己基、辛基、苯基、萘基或联苯基。
进一步地，所述亚磷酸酯类化合物具有如下(P1)-(P9)任一所示的结构：
Figure PCTCN2022073094-appb-000007
Figure PCTCN2022073094-appb-000008
本发明还提供一种电解液，包括如上所述的电解液添加剂组合物。
在其中一个实施例中，所述电解液还包括电解质锂盐、有机溶剂和硫酸乙烯酯。
在含硫酸乙烯酯的电解液中加入本发明提供的电解液添加剂组合物，能显著降低硫酸乙烯酯的分解，抑制电解液酸度和色度的升高，并且还能在电极表面形成稳定的钝化膜，抑制电解液分解和过渡金属离子溶出，改善电池循环性能以及高温性能。
在其中一个实施例中，所述有机溶剂选自碳酸乙烯酯、碳酸丙烯酯、碳酸二乙酯、碳酸甲乙酯、乙酸乙酯和乙酸丙酯中至少两种的混合物；
所述电解质锂盐选自六氟磷酸锂、四氟硼酸锂、双草酸硼酸锂、二氟磷酸锂、二氟草酸磷酸锂和双氟磺酰亚胺锂中的至少一种。
在其中一个实施例中，所述电解质锂盐在所述有机溶剂中的浓度为0.8mol/L～1.5mol/L；
所述电解液添加剂组合物的加入量为所述电解液的总质量的0.05％～1.5％；
所述硫酸乙烯酯的加入量为所述电解液的总质量的0.5％～3％。
在其中一个实施例中，所述具有式(I)所示结构的含氟吡啶类化合物的加入量为所述电解液的总质量的0.03％～1％；
所述具有式(II)所示结构的亚磷酸酯类化合物的加入量为所述电解质液的总质量的0.01％～0.1％。
在其中一个实施例中，所述电解液还包括功能添加剂，所述功能添加剂选自三(三甲硅烷)磷酸酯、三(三甲硅烷)硼酸酯、二氟草酸硼酸锂、碳酸亚乙烯酯、碳酸乙烯亚乙酯、氟代碳酸乙烯酯和1,3-丙磺酸内酯中的至少一种；和/或
所述功能添加剂的加入量为所述电解液的总质量的0.5％～5％。
本发明还提供了上述电解液的制备方法，包括以下步骤：
将用于制备所述电解液的各原料混合，搅拌均匀。
在其中一个实施例中，所述电解液的制备方法，包括以下步骤：
(1)对有机溶剂进行纯化除杂、除水处理；
(2)在室温条件下，将电解质锂盐加入步骤(1)所得纯化后的有机溶剂中，搅拌均匀，制得混合液；
(3)向步骤(2)得到的混合液中加入具有式(I)所示结构的含氟吡啶类化合物和具有式(II)所示结构的亚磷酸酯类化合物、硫酸乙烯酯(有功能添加剂则还加入功能添加剂)，搅拌均匀。
在其中一个实施例中，步骤(1)中所述的纯化除杂、除水优选通过分子筛、活性炭、氢化钙、氢化锂、无水氧化钙、氯化钙、五氧化二磷、碱金属或碱土金属中的任意一种或几种进行处理。
本发明还提供一种锂二次电池，包括如上所述的电解液添加剂组合物或电解液。
在其中一个实施例中，所述锂二次电池包括锂离子电池、锂硫电池或锂空气电池。
在其中一个实施例中，所述锂离子电池包括正极片、负极片、隔膜以及所述含氟代吡啶、含亚磷酸酯及其衍生物的电解液；所述正极片包括嵌入或者脱嵌锂离子的正极活性材料、导电剂、集流体和将正极活性材料和导电剂与所述集流体结合的结合剂；所述负极片包括可嵌入或者脱嵌锂离子的负极活性材料、导电剂、集流体和将负极活性材料和导电剂与所述集流体结合的结合剂。
在一实施例中锂离子电池的正极材料包括Li 1+a(Ni xCo yM 1-x-y)O 2、Li(Ni pMn qCo 2-p-q)O 4及LiM h(PO 4) m中的一种或几种；其中0≤a≤0.3，0≤x≤1，0≤y≤1，0＜x+y≤1；0≤p≤2，0≤q≤2，0＜p+q≤2；0＜h＜5，0＜m＜5；M为Fe、Ni、Co、Mn、Al或V。
在一实施例中，锂离子电池的负极材料包括金属锂、锂合金、碳、硅基负极材料及锡基负极材料中的至少一种。
上述锂离子电池采用包含上述具有式(I)所示结构的含氟吡啶类化合物和具有式(II所示结构的亚磷酸酯类化合物的电解液，通过含氟吡啶类化合物和亚磷酸酯类化合物的复配作用，能显著抑制电解液酸度和色度的升高，并且能在电极表面形成稳定的钝化膜，从而抑制电解液分解和过渡金属离子溶出，改善电池循环性能以及高温性能，在高温条件下存储或使用，均具有良好的容量保持率。
下面列举具体实施例来对本发明进行说明。
1、考察含有本发明电解液的电池的高温循环和高温存储性能
实施例1
本实施中提供一种电解液添加剂组合物、电解液和锂离子电池。
(1)电解液添加剂组合物由
Figure PCTCN2022073094-appb-000009
按照质量比10:1组成。
(2)电解液及其制备方法如下：
1)将碳酸乙烯酯(EC)和碳酸甲乙酯(EMC)以及碳酸二乙酯(DEC)按质量比EC：EMC：DEC＝3：5：2混合，并采用分子筛纯化除杂、除水；
2)在室温条件下，以占电解液总质量百分比计，将12.5wt％的导电锂盐六氟磷酸锂(约1mol/L，LiPF 6)、1wt％硫酸乙烯酯、0.3wt％的2-氟吡啶(F1)和0.03wt％亚磷酸三甲酯(P1)溶解在步骤1)得到的有机溶剂中，再添加1wt％加碳酸亚乙烯酯和1.5wt％1,3-丙磺酸内酯作为功能添加剂，搅拌均匀，得到基础电解液。
(3)将本实施例所得电解液用于LiNi 0.8Co 0.1Mn 0.1O 2/石墨软包装电池，测试LiNi 0.8Co 0.1Mn 0.1O 2/石墨软包装电池在常温环境下3.0～4.2V，1C倍率充放电的循环性能和60℃30天高温存储。
实施例2
与实施例1相比，实施例2的不同之处在于步骤(2)制备的基础电解液中添加的含氟吡啶类化合物为2-氟-6-甲基吡啶(F2)，其用量为电解液总质量的0.3％。
实施例3
与实施例1相比，实施例3的不同之处在于步骤(2)制备的基础电解液中添加的含氟吡啶类化合物为6-氟-2,3-二甲基吡啶(F3)，其用量为电解液总质量的0.3％。
实施例4
与实施例1相比，实施例4的不同之处在于步骤(2)制备的基础电解液中添加的含氟吡啶 类化合物为6-氟-2,3,4-三甲基吡啶(F4)，其用量为电解液总质量的0.3％。
实施例5
与实施例1相比，实施例5的不同之处在于步骤(2)制备的基础电解液中添加的含氟吡啶类化合物为2-氟-3,4,5,6-四甲基吡啶(F5)，其用量为电解液总质量的0.3％。
实施例6
与实施例1相比，实施例6的不同之处在于步骤(2)制备的基础电解液中添加的含氟吡啶类化合物为2,6-二氟吡啶(F6)，其用量为电解液总质量的0.3％。
实施例7
与实施例1相比，实施例7的不同之处在于步骤(2)制备的基础电解液中添加的含氟吡啶类化合物为2,6-二氟-3-甲基吡啶(F7)，其用量为电解液总质量的0.3％。
实施例8
与实施例1相比，实施例8的不同之处在于步骤(2)制备的基础电解液中添加的含氟吡啶类化合物为2,6-二氟-3,4-二甲基吡啶(F8)，其用量为电解液总质量的0.3％。
实施例9
与实施例1相比，实施例9的不同之处在于步骤(2)制备的基础电解液中添加的含氟吡啶类化合物为2,6-二氟-3,4,5-三甲基吡啶(F9)，其用量为电解液总质量的0.3％。
实施例10
与实施例1相比，实施例10的不同之处在于步骤(2)制备的基础电解液中添加亚磷酸酯类化合物为亚磷酸三乙酯(P2)，其用量为电解液总质量的0.03％。
实施例11
与实施例1相比，实施例11不同之处在于步骤(2)制备的基础电解液中添加亚磷酸酯类化合物为亚磷酸三苯酯(P6)，其用量为电解液总质量的0.03％。
实施例12
与实施例1相比，实施例12不同之处在于步骤(2)制备的基础电解液中添加的含氟吡啶类化合物为2-氟-6-甲基吡啶(F2)，其用量为电解液总质量的0.15％，亚磷酸酯类化合物为亚磷酸三乙酯(P2)，其用量为电解液总质量的0.03％。
对比例1
与实施例1相比，对比例1的不同之处在于步骤(2)制备的基础电解液中不含本发明所述的具有式(I)所示结构的含氟吡啶类化合物和具有式(II)所示结构的亚磷酸酯类化合物。
对比例2
与实施例1相比，对比例2的不同之处在于，将实施例1的亚磷酸酯类化合物P1替换为三(三甲基硅基)亚磷酸酯
Figure PCTCN2022073094-appb-000010
对比例3
与实施例1相比，对比例3的不同之处在于，省略添加实施例1的亚磷酸酯类化合物P1，且在电解液中，2-氟吡啶(F1)的加入量为电解液总质量的0.33％。
对比例4
与实施例1相比，对比例4的不同之处在于，省略添加实施例2的亚磷酸酯类化合物P1，且在电解液中，含氟吡啶类化合物F2的加入量为电解液总质量的0.33％。
对比例5
与实施例1相比，对比例5的不同之处在于，省略添加实施例1的亚磷酸酯类化合物P1，且在电解液中，含氟吡啶类化合物F3的加入量为电解液总质量的0.33％。
对比例6
与实施例1相比，对比例6的不同之处在于，省略添加实施例1的亚磷酸酯类化合物P1，且在电解液中，含氟吡啶类化合物F4的加入量为电解液总质量的0.33％。
对比例7
与实施例1相比，对比例7的不同之处在于，省略添加实施例1的亚磷酸酯类化合物P1，且在电解液中，含氟吡啶类化合物F5的加入量为电解液总质量的0.33％。
对比例8
与实施例1相比，对比例8的不同之处在于，省略添加实施例1的亚磷酸酯类化合物P1，且在电解液中，含氟吡啶类化合物F6的加入量为电解液总质量的0.33％。
对比例9
与实施例1相比，对比例9的不同之处在于，省略添加实施例1的亚磷酸酯类化合物P1，且在电解液中，含氟吡啶类化合物F7的加入量为电解液总质量的0.33％。
对比例10
与实施例1相比，对比例10的不同之处在于，省略添加实施例1的亚磷酸酯类化合物P1，且在电解液中，含氟吡啶类化合物F8的加入量为电解液总质量的0.33％。
对比例11
与实施例1相比，对比例11的不同之处在于，省略添加实施例1的亚磷酸酯类化合物P1，且在电解液中，含氟吡啶类化合物F9的加入量为电解液总质量的0.33％。
对比例12
与实施例1相比，对比例12的不同之处在于，省略添加实施例1的含氟吡啶类化合物F1，且在电解液中，亚磷酸酯类化合物P1的加入量为电解液总质量的0.33％。
对比例13
与实施例1相比，对比例13的不同之处在于，省略添加实施例1的含氟吡啶类化合物F1，将实施例1的亚磷酸酯类化合物P1替换为三(三甲基硅基)亚磷酸酯
Figure PCTCN2022073094-appb-000011
且在电解液中，三(三甲基硅基)亚磷酸酯的加入量为电解液总质量的0.33％。
实施例1至实施例12和对比例1至对比例13中的锂二次电池电解液都是用于对应电池体系的软包电池，测试这些软包电池在45℃高温环境下3.0～4.2V，1C倍率充放电的循环性 能和60℃30天高温存储性能。测试方法如下：
电池高温存储实验：将实施例1至实施例12和对比例1至对比例13中所得电池在室温下以1C的充放电倍率进行5次充放电循环测试，最后以1C倍率充到满电状态。分别记录1C容量Q和电池内阻T。将满电状态的电池在60℃下存储30天，记录电池内阻T0和1C放电容量Q1，再将电池在室温下以1C的倍率充放5周，选放电容量最高的一次记录为放电容量Q2，计算得到电池高温存储容量保持率，容量恢复率，内阻变化率等实验数据，记录结果如表1。
Figure PCTCN2022073094-appb-000012
Figure PCTCN2022073094-appb-000013
Figure PCTCN2022073094-appb-000014
表1实施例1至实施例12和对比例1至对比例13的电池高温循环和高温存储实验结果对比
Figure PCTCN2022073094-appb-000015
Figure PCTCN2022073094-appb-000016
由表1可知，本发明含氟吡啶类物化合物和亚磷酸酯化合物复配使用能提升电池的高温循环和高温存储性能。另外，在其他条件相同的情况下，将2-氟吡啶(F1)与亚磷酸三甲酯(P1)、或亚磷酸三乙酯(P2)、或亚磷酸三苯酯(P6)联用，其高温循环、高温存储以及内阻变化率均优于2-氟吡啶(F1)与三(三甲基硅基)亚磷酸酯联用的性能，说明本发明采用的复配体系更优。
2、考察含硫酸乙烯酯(DTD)的电解液的存储实施如下：
基础电解液对比例G0
(1)将环状的碳酸酯溶剂碳酸乙烯酯(EC)和线性碳酸酯溶剂碳酸甲乙酯(EMC)按质量比EC：EMC＝3：7混合，并采用分子筛纯化除杂、除水；
(2)在室温条件下，将质量分数为15％导电锂盐六氟磷酸锂(LiPF 6)、2％硫酸乙烯酯(DTD)溶解在步骤(1)得到的溶剂中，搅拌均匀，得到基础电解液；
(3)将本对比例所得电解液分别进行45℃存储和室温存储，分别取存储7天、15天、30天、60天的电解液进行酸度、色度测试。
对比例G1
与基础电解液对比例G0的区别在于还在步骤(2)中添加含氟吡啶类化合物2-氟吡啶(F1)，其用量为电解液总质量的0.3％，得到用于存储的锂二次电池的电解液。
对比例G2
与基础电解液对比例G0的区别在于还在步骤(2)中添加含氟吡啶类化合物2-氟-6-甲基吡啶(F2)，其用量为电解液总质量的0.3％，得到用于存储的锂二次电池的电解液。
对比例G3
与基础电解液对比例G0的区别在于还在步骤(2)中添加含氟吡啶类化合物6-氟-2,3-二甲基吡啶(F3)，其用量为电解液总质量的0.3％，得到用于存储的锂二次电池的电解液。
对比例G4
与基础电解液对比例G0的区别在于还在步骤(2)中添加含氟吡啶类化合物6-氟-2,3,4-三甲基吡啶(F4)，其用量为电解液总质量的0.3％，得到用于存储的锂二次电池的电解液。
对比例G5
与基础电解液对比例G0的区别在于还在步骤(2)中添加含氟吡啶类化合物2-氟-3,4,5,6-四甲基吡啶(F5)，其用量为电解液总质量的0.3％，得到用于存储的锂二次电池的电解液。
对比例G6
与基础电解液对比例G0的区别在于还在步骤(2)中添加含氟吡啶类化合物2,6-二氟吡啶(F6)，其用量为电解液总质量的0.3％，得到用于存储的锂二次电池的电解液。
对比例G7
与基础电解液对比例G0的区别在于还在步骤(2)中添加含氟吡啶类化合物2,6-二氟-3- 甲基吡啶(F7)，其用量为电解液总质量的0.3％，得到用于存储的锂二次电池的电解液。
对比例G8
与基础电解液对比例G0的区别在于还在步骤(2)中添加含氟吡啶类化合物2,6-二氟-3,4-二甲基吡啶(F8)，其用量为电解液总质量的0.3％，得到用于存储的锂二次电池的电解液。
对比例G9
与基础电解液对比例G0的区别在于还在步骤(2)中添加含氟吡啶类化合物2,6-二氟-3,4,5-三甲基吡啶(F9)，其用量为电解液总质量的0.3％，得到用于存储的锂二次电池的电解液。
对比例G10
与基础电解液对比例G0的区别在于还在步骤(2)中添加亚磷酸酯类化合物亚磷酸三甲酯(P1)，其用量为电解液总质量的0.03％，得到用于存储的锂二次电池的电解液。
对比例G11
与基础电解液对比例G0的区别在于还在步骤(2)中添加亚磷酸酯类化合物三(三甲基硅基)亚磷酸酯
Figure PCTCN2022073094-appb-000017
其用量为电解液总质量的0.03％，得到用于存储的锂二次电池的电解液。
对比例G12
与基础电解液对比例G0的区别在于还在步骤(2)中添加含氟吡啶类化合物2-氟吡啶(F1)，其用量为电解液总质量的0.3％；另外，还添加亚磷酸酯类化合物三(三甲基硅基)亚磷酸酯，其用量为电解液总质量的0.03％，得到用于存储的锂二次电池的电解液；
实施例G13
与基础电解液对比例G0的区别在于还在步骤(2)中添加含氟吡啶类化合物2-氟吡啶(F1)，其用量为电解液总质量的0.3％；另外，还添加亚磷酸酯类化合物亚磷酸三甲酯(P1)，其用量为电解液总质量的0.03％，得到用于存储的锂二次电池的电解液。
实施例G14
与基础电解液对比例G0的区别在于还在步骤(2)中添加含氟吡啶类化合物2-氟-6-甲基吡啶(F2)，其用量为电解液总质量的0.3％；另外，还添加亚磷酸酯类化合物亚磷酸三甲酯(P1)，其用量为电解液总质量的0.03％，得到用于存储的锂二次电池的电解液。
实施例G15
与基础电解液对比例G0的区别在于还在步骤(2)中添加含氟吡啶类化合物6-氟-2,3-二甲基吡啶(F3)，其用量为电解液总质量的0.3％；另外，还添加亚磷酸酯类化合物亚磷酸三甲酯(P1)，其用量为电解液总质量的0.03％，得到用于存储的锂二次电池的电解液。
实施例G16
与基础电解液对比例G0的区别在于还在步骤(2)中添加含氟吡啶类化合物6-氟-2,3,4-三甲基吡啶(F4)，其用量为电解液总质量的0.3％；另外，还添加亚磷酸酯类化合物亚磷酸三甲酯(P1)，其用量为电解液总质量的0.03％，得到用于存储的锂二次电池的电解液。
实施例G17
与基础电解液对比例G0的区别在于还在步骤(2)中添加含氟吡啶类化合物2-氟-3,4,5,6- 四甲基吡啶(F5)，其用量为电解液总质量的0.3％；另外，还添加亚磷酸酯类化合物亚磷酸三甲酯(P1)，其用量为电解液总质量的0.03％，得到用于存储的锂二次电池的电解液。
实施例G18
与基础电解液对比例G0的区别在于还在步骤(2)中添加含氟吡啶类化合物2,6-二氟吡啶(F6)，其用量为电解液总质量的0.3％；另外，还添加亚磷酸酯类化合物亚磷酸三甲酯(P1)，其用量为电解液总质量的0.03％，得到用于存储的锂二次电池的电解液。
实施例G19
与基础电解液对比例G0的区别在于还在步骤(2)中添加含氟吡啶类化合物2,6-二氟-3-甲基吡啶(F7)，其用量为电解液总质量的0.3％；另外，还添加亚磷酸酯类化合物亚磷酸三甲酯(P1)，其用量为电解液总质量的0.03％，得到用于存储的锂二次电池的电解液。
实施例G20
与基础电解液对比例G0的区别在于还在步骤(2)中添加含氟吡啶类化合物2,6-二氟-3,4-二甲基吡啶(F8)，其用量为电解液总质量的0.3％；另外，还添加亚磷酸酯类化合物亚磷酸三甲酯(P1)，其用量为电解液总质量的0.03％，得到用于存储的锂二次电池的电解液。
实施例G21
与基础电解液对比例G0的区别在于还在步骤(2)中添加含氟吡啶类化合物2,6-二氟-3,4,5-三甲基吡啶(F9)，其用量为电解液总质量的0.3％；另外，还添加亚磷酸酯类化合物亚磷酸三甲酯(P1)，其用量为电解液总质量的0.03％，得到用于存储的锂二次电池的电解液。
实施例G22
与基础电解液对比例G0的区别在于还在步骤(2)中添加含氟吡啶类化合物2-氟吡啶(F1)，其用量为电解液总质量的0.3％；另外，还添加亚磷酸酯类化合物P2，其用量为电解液总质量的0.03％，得到用于存储的锂二次电池的电解液。
实施例G23
与基础电解液对比例G0的区别在于还在步骤(2)中添加含氟吡啶类化合物2-氟吡啶(F1)，其用量为电解液总质量的0.3％；另外，还添加亚磷酸酯类化合物P6，其用量为电解液总质量的0.03％，得到用于存储的锂二次电池的电解液。
G0至G23的锂二次电池电解液都是用于常温存储和45℃存储，并分别测试存储7天、15天、30天、60天电解液的酸度、色度；酸度测试的仪器为电位滴定仪，酸度测试方法为三乙胺电位滴定法，色度用比色计进行测试；色度记录结果如表2；酸度记录结果如表3。
表2 G0至G23的锂二次电池电解液存储色度实验结果对比
Figure PCTCN2022073094-appb-000018
Figure PCTCN2022073094-appb-000019
由表2可知，本发明含氟代吡啶类化合物和亚磷酸酯类化合物复配使用能显著抑制电解液色度的上升。另外，在其他条件相同的情况下，添加亚磷酸三甲酯(P1)、亚磷酸三乙酯(P2)或亚磷酸三苯酯(P6)对色度的抑制效果均远优于三(三甲基硅基)亚磷酸酯。
表3 G0至G23的锂二次电池电解液存储酸度实验结果对比
Figure PCTCN2022073094-appb-000020
Figure PCTCN2022073094-appb-000021
由表3可知，本发明含氟代吡啶类化合物和亚磷酸酯类化合物复配使用能显著抑制酸度的上升。另外，在其他条件相同的情况下，添加0.03wt％的亚磷酸三甲酯(P1)对酸度具有一定的抑制作用，但效果欠佳；而添加0.03wt％三(三甲基硅基)亚磷酸酯不但无法抑制酸度的增加，反而会促进电解液酸度的上升。
综上可知，含氟吡啶类化合物、亚磷酸酯类化合物的联用，尤其是2-氟吡啶与亚磷酸三甲酯联用能有效的抑制含硫酸乙烯酯(DTD)电解液酸度和色度的升高；此外，将其应用在锂二次电池电解液中能改善锂二次电池的高温循环性能以及高温存储性能，同时在负面表面形成稳定的SEI层，改善了负极电极/电解液界面性质，减少了锂二次电池在首次充放电的不可逆容量，提高了界面的稳定性，有助于提升锂二次电池在循环稳定性和高温存储性能。
以上所述实施例的各技术特征可以进行任意的组合，为使描述简洁，未对上述实施例中的各个技术特征所有可能的组合都进行描述，然而，只要这些技术特征的组合不存在矛盾，都应当认为是本说明书记载的范围。
以上所述实施例仅表达了本发明的几种实施方式，其描述较为具体和详细，但并不能因此而理解为对发明专利范围的限制。应当指出的是，对于本领域的普通技术人员来说，在不脱离本发明构思的前提下，还可以做出若干变形和改进，这些都属于本发明的保护范围。因此，本发明专利的保护范围应以所附权利要求为准。

Claims (10)

  1. 一种电解液添加剂组合物，其特征在于，包括具有式(I)所示结构的含氟吡啶类化合物和具有式(II)所示结构的亚磷酸酯类化合物；
    所述含氟吡啶类化合物和所述亚磷酸酯类化合物的质量比为(3～10):1；
    Figure PCTCN2022073094-appb-100001
    其中：
    R 1、R 2、R 3和R 4分别独立选自氢、卤素、C 1～C 20烷基、卤代的C 1～C 20烷基、C 6～C 26芳基、卤代的C 6～C 26芳基、氨基、异氰基或烷氧基；
    R 5、R 6和R 7分别独立选自C 1～C 20烷基、卤代的C 1～C 20烷基、C 6～C 26芳基、卤代的C 6～C 26芳基。
  2. 根据权利要求1所述的电解液添加剂组合物，其特征在于，所述含氟吡啶类化合物具有如下(F1)-(F9)任一所示的结构：
    Figure PCTCN2022073094-appb-100002
  3. 根据权利要求1所述的电解液添加剂组合物，其特征在于，所述亚磷酸酯类化合物具有如下(P1)-(P9)任一所示的结构：
    Figure PCTCN2022073094-appb-100003
    Figure PCTCN2022073094-appb-100004
  4. 一种电解液，其特征在于，包括权利要求1-3任一项所述的电解液添加剂组合物。
  5. 根据权利要求4所述的电解液，其特征在于，所述电解液还包括电解质锂盐、有机溶剂和硫酸乙烯酯。
  6. 根据权利要求5所述的电解液，其特征在于，所述有机溶剂选自碳酸乙烯酯、碳酸丙烯酯、碳酸二乙酯、碳酸甲乙酯、乙酸乙酯和乙酸丙酯中至少两种的混合物；
    所述电解质锂盐选自六氟磷酸锂、四氟硼酸锂、双草酸硼酸锂、二氟磷酸锂、二氟草酸磷酸锂和双氟磺酰亚胺锂中的至少一种。
  7. 根据权利要求4至6任一项所述的电解液，其特征在于，所述电解质锂盐在所述有机溶剂中的浓度为0.8mol/L～1.5mol/L；
    所述电解液添加剂组合物的加入量为所述电解质锂盐和所述有机溶剂的总质量的0.05％～1.5％；
    所述硫酸乙烯酯的加入量为所述电解液的总质量的0.5％～3％。
  8. 根据权利要求7所述的电解液，其特征在于，所述具有式(I)所示结构的含氟吡啶类化合物的加入量为所述电解液总质量的0.03％～1％；
    所述具有式(II)所示结构的亚磷酸酯类化合物的加入量为所述电解质液的总质量的0.01％～0.1％。
  9. 根据权利要求4至6任一项所述的电解液，其特征在于，所述电解液还包括功能添加剂，所述功能添加剂选自三(三甲硅烷)磷酸酯、三(三甲硅烷)硼酸酯、二氟草酸硼酸锂、碳酸亚乙烯酯、碳酸乙烯亚乙酯、氟代碳酸乙烯酯和1,3-丙磺酸内酯中的至少一种；和/或
    所述功能添加剂的加入量为所述电解液的总质量的0.5％～5％。
  10. 一种锂二次电池，其特征在于，包括权利要求1至3任一项所述的电解液添加剂组合物，或权利要求4至9任一项所述的电解液。
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