WO2023123673A1 - 一种非水电解液及含有该非水电解液的锂离子电池 - Google Patents

一种非水电解液及含有该非水电解液的锂离子电池 Download PDF

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WO2023123673A1
WO2023123673A1 PCT/CN2022/079923 CN2022079923W WO2023123673A1 WO 2023123673 A1 WO2023123673 A1 WO 2023123673A1 CN 2022079923 W CN2022079923 W CN 2022079923W WO 2023123673 A1 WO2023123673 A1 WO 2023123673A1
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lithium
electrolyte
electrolytic solution
prepare
aqueous electrolytic
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French (fr)
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余林颇
赵鑫涛
徐凯辰
王志涛
刘春彦
甘朝伦
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Zhangjiagang Guotai Huarong New Chemical Materials Co Ltd
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Zhangjiagang Guotai Huarong New Chemical Materials Co Ltd
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Priority claimed from CN202111628953.9A external-priority patent/CN116365026A/zh
Priority claimed from CN202111626579.9A external-priority patent/CN116404248B/zh
Application filed by Zhangjiagang Guotai Huarong New Chemical Materials Co Ltd filed Critical Zhangjiagang Guotai Huarong New Chemical Materials Co Ltd
Priority to EP22912979.6A priority Critical patent/EP4459732A4/en
Priority to US18/555,953 priority patent/US20240213538A1/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0568—Liquid materials characterised by the solutes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0569—Liquid materials characterised by the solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • H01M2300/0037—Mixture of solvents
    • H01M2300/004—Three solvents
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the invention belongs to the technical field of lithium batteries, and in particular relates to a nonaqueous electrolytic solution and a lithium ion battery containing the nonaqueous electrolytic solution.
  • Lithium-ion batteries have the highest energy density among the currently commercially used secondary batteries, so they are widely used in mobile electronics, green transportation, large-scale energy storage and other scenarios. Since the first commercial application in 1990, the lithium-ion battery industry has maintained rapid growth. With its high energy density, lithium-ion batteries have rapidly occupied the market of mobile electronic energy storage products since the emergence of commercial products. In the past ten years, with the emphasis on energy security and sustainable energy development around the world, lithium-ion batteries, as an important electrochemical energy storage device, have been pushed onto the fast track of scientific research and industrialization.
  • the electrolyte used in commercial lithium-ion batteries is composed of organic solvents and lithium salts such as LiPF 6 dissolved therein.
  • the organic solvent is usually a binary or ternary mixed solvent based on ethylene carbonate (EC) with a large dielectric constant.
  • chain carbonate dimethyl carbonate (DMC); diethyl carbonate (DEC) ); Ethyl methyl carbonate (EMC), carboxylate or ethers are co-solvents.
  • Lithium-ion battery anti-overcharge is mainly to prevent the battery from decomposing and heating the electrolyte due to overcharging, triggering a chain reaction and then burning.
  • the commonly used anti-overcharge additives mainly include biphenyl, 2-fluorobiphenyl and cyclohexylbenzene, etc., which have certain anti-overcharge performance, but will cause the temperature of the battery to rise and have a certain impact on the cycle performance of the battery. Therefore, the market urgently needs to develop a new electrolyte solution with anti-overcharge performance and less impact on the cycle performance of the battery.
  • the object of the present invention is to provide a non-aqueous electrolytic solution which has anti-overcharge characteristics and can improve the room temperature cycle performance of lithium-ion batteries.
  • Another object of the present invention is to provide a lithium-ion battery that has good cycle performance at room temperature, does not rise significantly in temperature when overcharged, and can effectively prevent overcharge to a certain extent.
  • One aspect of the present invention provides a nonaqueous electrolytic solution, which includes a lithium salt, an organic solvent and an additive, and the additive includes 2-phenyl-benzothiazole and derivatives thereof having a structure shown in general formula (1),
  • R 1 , R 2 and R 3 are independently H, a halogen atom or an alkyl group.
  • R 1 , R 2 and R 3 are independently H, Cl, F, C 1 -C 4 linear alkyl or tert-butyl.
  • R 1 , R 2 and R 3 are independently H, Cl or F.
  • the additive includes one or more of the following compounds:
  • the 2-phenyl-benzothiazole and its derivatives represented by the general formula (1) account for 0.1-10 wt% of the total mass of the non-aqueous electrolyte.
  • the 2-phenyl-benzothiazole and its derivatives represented by the general formula (1) account for 0.1-5 wt% of the total mass of the non-aqueous electrolyte.
  • the dosage of the additive is within an appropriate range, overcharging can be effectively prevented, and the room temperature cycle performance of the battery is less affected.
  • the additive also includes 3-phenyl-1,4,2-dioxazol-5-one (PDO) and optionally other additives, and the other additives are vinylene carbonate Ester (VC), 1,3-propane sultone (PS), propenyl-1,3-sultone (PST), vinyl sulfate (DTD), lithium difluorophosphate (LiPO 2 F 2 ) one or more.
  • PDO 3-phenyl-1,4,2-dioxazol-5-one
  • the other additives are vinylene carbonate Ester (VC), 1,3-propane sultone (PS), propenyl-1,3-sultone (PST), vinyl sulfate (DTD), lithium difluorophosphate (LiPO 2 F 2 ) one or more.
  • the additives include 3-phenyl-1,4,2-dioxazol-5-one, 2-phenyl-benzothiazole having a structure represented by general formula (1) and derivatives and other additives.
  • the composition of 3-phenyl-1,4,2-dioxazol-5-one, other additives and 2-phenyl-benzothiazole and its derivatives of the structure shown in general formula (1) Combined use, while ensuring the anti-overcharge performance, further improves the high-temperature cycle performance of the lithium-ion battery, effectively prevents the combustion or explosion of the lithium-ion battery due to overcharge, and expands the operating temperature range of the lithium-ion battery
  • the other additives are vinyl sulfate DTD and/or lithium difluorophosphate (LiPO 2 F 2 ).
  • the feeding mass of the 3-phenyl-1,4,2-dioxazol-5-one is 0.1-10 wt% of the total mass of the non-aqueous electrolytic solution.
  • the feeding mass of the 3-phenyl-1,4,2-dioxazol-5-one is 0.1-5 wt% of the total mass of the non-aqueous electrolyte.
  • the mass of the 3-phenyl-1,4,2-dioxazol-5-one fed is 0.1-3 wt% of the total mass of the non-aqueous electrolytic solution.
  • An appropriate amount of 3-phenyl-1,4,2-dioxazol-5-one can alleviate the cycle capacity at high temperature caused by 2-phenyl-benzothiazole and its derivatives with the structure shown in general formula (1) The problem of rapid descent.
  • the feeding mass of the other additives is 0.1-10 wt% of the total mass of the non-aqueous electrolyte.
  • the feeding mass of the other additives is 0.1-5 wt% of the total mass of the non-aqueous electrolyte.
  • the organic solvent includes cyclic esters and/or chain esters, and the cyclic esters are one of ⁇ -butyrolactone, ethylene carbonate, propylene carbonate, fluoroethylene carbonate or several kinds; the chain esters are dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl propionate, ethyl propionate, propyl propionate, methyl acetate, acetic acid One or more of ethyl ester, propyl acetate, methyl butyrate, ethyl butyrate, propyl butyrate, methyl fluoropropionate, ethyl fluoropropionate, and ethyl fluoroacetate.
  • the cyclic esters are one of ⁇ -butyrolactone, ethylene carbonate, propylene carbonate, fluoroethylene carbonate or several kinds
  • the chain esters are dimethyl carbonate, ethyl
  • the organic solvent is a mixture of cyclic esters and chain esters, wherein the mass ratio of the cyclic esters and the chain esters is 1: (1-2.5).
  • the cyclic ester is mixed with the chain ester at a mass ratio of 1:(1.5-2).
  • the lithium salt is lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, anhydrous lithium perchlorate, lithium bis(trifluoromethylsulfonyl)imide, lithium difluorodioxalate phosphate, Lithium difluorophosphate (LiPO 2 F 2 ), lithium trifluoromethanesulfonate, lithium difluorodioxalate phosphate, lithium dioxalate borate, monooxalate lithium difluoroborate, lithium difluorosulfonimide, or Several kinds.
  • the concentration of the lithium salt is 0.6-1.5 mol/L.
  • the concentration of the lithium salt is 0.8-1.3 mol/L.
  • Another aspect of the present invention provides a lithium ion battery, which includes a positive electrode, a negative electrode and an electrolyte, and the electrolyte is the non-aqueous electrolyte.
  • the positive electrode is a lithium cobalt oxide material or a lithium nickel cobalt manganese oxide material.
  • the negative electrode is graphite material.
  • the present invention has the following advantages compared with the prior art:
  • 2-phenyl-benzothiazole and derivatives thereof having a structure shown in general formula (1) can form a passivation film on the surface of the positive electrode when the lithium-ion battery is overcharged, preventing the battery voltage from being overcharged.
  • the additive also makes the temperature of the electrolyte rise slowly when overcharged, and the addition of the additive not only does not affect the room temperature cycle performance of the lithium-ion battery, but can even improve the room temperature cycle performance of the lithium-ion battery, thus effectively The potential safety hazard caused by battery overcharging is avoided.
  • Fig. 1 is the cyclic voltammogram of the non-aqueous electrolyte solution of Example 1 under the three-electrode system, and the scanning speed is 5 mV/s.
  • the present invention mainly proceeds from the perspective of preventing battery overcharge, conducts a lot of research and test verification on the additives of lithium battery electrolyte, and finally provides a non-aqueous electrolyte and a related lithium ion battery.
  • the non-aqueous point solution includes a lithium salt, a solvent and an additive
  • the additive includes 2-phenyl-benzothiazole and derivatives thereof having a structure shown in general formula (1),
  • R 1 , R 2 and R 3 are independently H, a halogen atom or an alkyl group.
  • R 1 , R 2 and R 3 are independently H, Cl, F, C 1 -C 4 linear alkyl or tert-butyl.
  • R 1 , R 2 and R 3 are independently H, Cl or F.
  • the amount of 2-phenyl-benzothiazole and its derivatives is 0.1-10wt%, such as 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 8.5wt%, 9wt%, 9.5wt%, 10wt%.
  • An appropriate amount of 2-phenyl-benzothiazole and its derivatives can effectively prevent overcharge, and have little effect on the room temperature cycle performance of lithium-ion batteries.
  • the inventors believe that it may be because 2-phenyl-benzothiazole and its derivatives react slowly with the positive electrode of the battery under high temperature conditions, gradually forming a non-conductive polymer film, which affects the cycle performance.
  • the inventors introduced 3-phenyl-1,4,2-dioxazol-5-one, which can be preferentially used in the battery
  • the positive and negative electrodes form a protective film, and inhibit the interaction of 2-phenyl-benzothiazole and its derivatives with battery electrode materials within the working voltage range of the battery.
  • other conventional auxiliary additives that is, other additives
  • the amount of 3-phenyl-1,4,2-dioxazol-5-one is 0.1-10wt%, such as 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt% %, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 8.5wt%, 9wt%, 9.5wt%, 10wt% , preferably 0.1 to 5 wt%, more preferably 0.1 to 3 wt%.
  • 3-phenyl-1,4,2-dioxazol-5-one can effectively alleviate the problem of high-temperature performance degradation caused by 2-phenyl-benzothiazole and its derivatives, so that the electrolyte remains stable at high temperatures. Has a high cycle capacity.
  • the dosage of other additives is 0.1 ⁇ 10wt%, such as 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 8.5wt%, 9wt%, 9.5wt%, 10wt%, preferably 0.1-5wt%.
  • An appropriate amount of other additives can assist 3-phenyl-1,4,2-dioxazol-5-one, 2-phenyl-benzothiazole and its derivatives, so as to improve the comprehensive performance of lithium-ion batteries.
  • the organic solvent is a cyclic ester and/or a chain ester
  • the cyclic ester is one of ⁇ -butyrolactone, ethylene carbonate, propylene carbonate, and fluoroethylene carbonate Or several
  • Described chain ester is dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl propyl carbonate, methyl propionate, ethyl propionate, propyl propionate, methyl acetate, One or more of ethyl acetate, propyl acetate, methyl butyrate, ethyl butyrate, propyl butyrate, methyl fluoropropionate, ethyl fluoropropionate, and ethyl fluoroacetate.
  • the organic solvent is a mixture of cyclic esters and chain esters, wherein the mass ratio of the cyclic esters to the chain esters is 1: (1-2.5), such as 1:1, 1 :1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, 1:2.2, 1:2.4, 1:2.5.
  • the lithium salt is lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium perchlorate anhydrous, lithium bis(trifluoromethylsulfonyl)imide, lithium difluorodioxalate phosphate , lithium difluorophosphate, lithium trifluoromethanesulfonate, lithium difluorodioxalate phosphate, lithium dioxalate borate, monooxalate lithium difluoroborate, and lithium bisfluorosulfonyl imide.
  • the concentration of the lithium salt is 0.6-1.5 mol/L, such as 0.6 mol/L, 0.8 mol/L, 1 mol/L, 1.2 mol/L, 1.4 mol/L, 1.5 mol/L.
  • the performance of the lithium-ion battery can be improved by selecting an organic solvent with a special formula and cooperating with the 2-phenyl-benzothiazole and its derivatives and lithium salt.
  • the lithium-ion battery includes a positive electrode, a negative electrode and an electrolyte, wherein the electrolyte is the above-mentioned non-aqueous electrolyte, and the positive electrode is lithium cobaltate positive electrode material or lithium nickel cobalt manganate material, and the negative electrode is graphite material.
  • the non-aqueous electrolytic solution provided by the invention has anti-overcharge characteristics in lithium ion batteries, the temperature of the battery does not increase significantly when overcharged to 130% SOC, and has the advantages of improving the room temperature cycle performance of the battery. Furthermore, by compounding other specific additives in the electrolyte, the high-temperature cycle performance of the battery can be further improved.
  • DMC, EC and EMC were uniformly mixed at a mass ratio of 1:1:1 to prepare a mixed solvent. Then, weigh 1 equivalent of LiPF 6 and dissolve it in the aforementioned mixed solvent to prepare a target electrolyte solution containing 1 mol/L LiPF 6 .
  • FIG. 1 shows the cyclic voltammogram of Example 1 under test conditions, in which the initial oxidative polymerization potential of the additive and the oxidative decomposition potential of the electrolyte are marked.
  • the test results of Examples 1-6 are shown in Table 1. Experimental results show that compounds 1-6 used in Examples 1-6 all undergo oxidative polymerization above 4.5V (vs. Li/Li + ). After the three-electrode test, the surface of the working electrode will be covered with a layer of dark polymer. The polymer can inhibit the battery voltage from further increasing when the lithium-ion battery is overcharged.
  • Example 20 4.79 27 Example 21 4.88 28 Example 22 4.62 30 Example 23 4.79 28 Example 24 4.88 28 Example 25 4.62 29 Example 26 4.62 29 Example 27 4.62 28 Example 28 4.62 29 Example 29 4.79 30 Example 30 4.79 29 Example 31 4.79 30 Example 32 4.79 29 Example 33 4.88 28 Example 34 4.88 29 Example 35 4.88 31 Example 36 4.88 30 Comparative example 1 5.45 30 Example 1 4.62 29 Example 2 4.79 27 Example 4 4.88 28
  • Comparative Example 1 has no anti-overcharge effect because it does not contain 2-phenyl-benzothiazole and its derivatives, its overcharge plateau is greater than 5V.
  • Other examples and comparative examples containing 2-phenyl-benzothiazole and its derivatives all showed an overcharge plateau voltage below 5V, showing obvious overcharge prevention performance.
  • the battery was overcharged to 130% SOC, none of the examples showed significant temperature rise.
  • Example 21 90 84 60
  • Example 22 87 79 60
  • Example 23 90 86 70
  • Example 24 90 84 71
  • Example 25 95 89 82
  • Example 26 96 90 84
  • Example 27 95 90 85
  • Example 28 95 89 82
  • Example 29 95 90 83
  • Example 30 96 90 84
  • Example 31 95 90 85
  • Example 32 95 90 86
  • Example 33 95 90 85
  • Example 34 96 90 84
  • Example 35 96 90 86
  • Example 36 96 90 87 Comparative example 1 95 88 75
  • Example 1 85 70 40
  • Example 2 90 85 55
  • Example 1 has been lower than 80% of the initial capacity
  • Examples 2 and 4 have been close to 80% of the initial capacity
  • the capacity retention rate of Comparative Example 1 without adding any additives is close to 90%.
  • Example 25-36 After introducing the third additive (Example 25-36), the high-temperature cycle performance of some examples is significantly improved, mainly the examples containing DTD and LiPO 2 F 2 .
  • the combination of PDO and DTD or LiPO 2 F 2 can effectively improve the high-temperature cycle capacity fading caused by the addition of 2-phenyl-benzothiazole and its derivatives, and its anti-overcharge performance will not be affected .

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Abstract

本发明涉及一种非水电解液及含有该非水电解液的锂离子电池。为了解决现有技术中电池过充所带来的安全隐患的技术问题，本发明提供一种非水电解液，其包括锂盐、有机溶剂和添加剂，所述的添加剂包括2-苯基-苯并噻唑及其衍生物，其在锂离子电池过充时能够在正极表面形成钝化膜，防止电池电压在过充过程中进一步升高，该添加剂使电解液在过充时温度升高较慢，而且该添加剂的加入不仅不会影响锂离子电池的室温循环性能，甚至可以提升锂离子电池的室温循环性能，从而有效避免了电池过充所带来的安全隐患。

Description

一种非水电解液及含有该非水电解液的锂离子电池 技术领域
本发明属于锂电池技术领域，具体涉及一种非水电解液及含有该非水电解液的锂离子电池。
背景技术
锂离子电池在目前商业化应用的二次电池中，具有最高的能量密度，因而被广泛地应用于移动电子、绿色交通、大型能源存储等场景。从1990年第一次商业化应用至今，锂离子电池产业保持了快速增长。锂离子电池凭借其能量密度高的特点，自其商业化产品出现起，迅速占领了移动电子储能产品的市场。近十年来，伴随着世界各国对能源安全和可持续能源发展的重视，锂离子电池作为一种重要的电化学储能器件被推上了科研和产业化发展的快车道。
目前，商品化锂离子电池所采用的电解液由有机溶剂以及溶于其中的LiPF 6等锂盐所组成。其中，有机溶剂通常是以介电常数大的碳酸乙烯酯(EC)为基础的二元或三元混合溶剂，其中，链状碳酸酯(碳酸二甲酯(DMC)；碳酸二乙酯(DEC)；碳酸甲乙酯(EMC)、羧酸酯或醚类为共溶剂。这些常用溶剂具有与锂盐的溶解性好、所组成的电解液电导率高、且能够在正负极形成稳定的SEI膜等特点，因而被认为是电解液体系，特别是电动汽车电池电解液溶剂的最佳选择。不过这些溶剂的易燃特性，使得在电池的日常使用中，必须对电池的滥用加以限制。
当前，随着锂离子电池的应用越来越广泛，由于各种原因造成的电池滥用所导致的安全事故不时发生，使得公众对锂离子电池的应用产生了极大的安全焦虑。
锂离子电池防过充主要是防止电池因过充而导致电解液分解发热引发链式反应进而燃烧。目前常用的防过充添加剂主要有联苯、2-氟联苯和环己基苯等，其具有一定的防过充性能，但是会导致电池温度升高，并对电池的循环性能有一定影响。因此，市场亟待开发新的具有防过充性能且对电池的循环性能影响较小的电解液。
发明内容
本发明的目的在于提供一种具有防过充特性且能够提高锂离子电池的室温循环性能的非水电解液。
本发明的另一目的在于提供一种常温循环性能好，过充时温度升高不明显且一定程度上能够有效防过充的锂离子电池。
为实现上述目的，本发明采取的技术方案如下：
本发明一方面提供一种非水电解液，其包括锂盐、有机溶剂和添加剂，所述的添加剂包括具有通式(1)所示结构的2-苯基-苯并噻唑及其衍生物，
Figure PCTCN2022079923-appb-000001
其中，R 1、R 2和R 3独立地为H、卤素原子或烷基。
优选地，R 1、R 2和R 3独立地为H、Cl、F、C 1～C 4直链烷基或叔丁基。
优选地，R 1、R 2和R 3独立地为H、Cl或F。
优选地，所述的添加剂包括以下化合物中的一种或多种：
Figure PCTCN2022079923-appb-000002
优选地，所述的通式(1)所示结构的2-苯基-苯并噻唑及其衍生物占所述的非水电解液的总质量的0.1～10wt％。
进一步优选地，所述的通式(1)所示结构的2-苯基-苯并噻唑及其衍生物占所述的非水电解液的总质量的0.1～5wt％。当添加剂的投料量在适宜的范围内时，能够有效防过充，并且对电池的室温循环性能影响较小。
根据一种实施方式，所述添加剂还包括3-苯基-1,4,2-二噁唑-5-酮(PDO)以及可选择性地包括其他添加剂，所述的其他添加剂为碳酸亚乙烯酯(VC)、1,3-丙烷磺内酯(PS)、丙烯基-1,3-磺内酯(PST)、硫酸乙烯酯(DTD)、二氟磷酸锂(LiPO 2F 2)中的一种或多种。通过将3-苯基-1,4,2-二噁唑-5-酮与具有通式(1)所示结构的2-苯基-苯并噻唑及其衍生物联用，缓解了由通式(1)所示结构的2-苯基-苯并噻唑及其衍生物带来的高温下锂离子电池的循环性能下降的问题，同时也不会影响锂离子电池的常温循环性能。
根据一些实施例，优选所述的添加剂包括3-苯基-1,4,2-二噁唑-5-酮、具有通式(1)所示结构的2-苯基-苯并噻唑及其衍生物以及其他添加剂。进一步地，将3-苯基-1,4,2-二噁唑-5-酮、其他添加剂的组合物与通式(1)所示结构的2-苯基-苯并噻唑及其衍生物联用，在保证防过充性能的同时，进一步提升了锂离子 电池的高温循环性能，有效防止锂电池由于过充导致的燃烧或爆炸现象，并扩大了锂离子电池的使用温度范围
进一步优选地，所述的其他添加剂为硫酸乙烯酯DTD和/或二氟磷酸锂(LiPO 2F 2)。
进一步优选地，所述的3-苯基-1,4,2-二噁唑-5-酮的投料质量为所述的非水电解液的总质量的0.1～10wt％。
更为优选地，所述的3-苯基-1,4,2-二噁唑-5-酮的投料质量为所述的非水电解液的总质量的0.1～5wt％。
更进一步优选地，所述的3-苯基-1,4,2-二噁唑-5-酮的投料质量为所述的非水电解液的总质量的0.1～3wt％。适量的3-苯基-1,4,2-二噁唑-5-酮可以缓解具有通式(1)所示结构的2-苯基-苯并噻唑及其衍生物导致的高温下循环容量快速下降的问题。
进一步优选地，所述的其他添加剂的投料质量为所述的非水电解液的总质量的0.1～10wt％。
更为优选地，所述的其他添加剂的投料质量为所述的非水电解液的总质量的0.1～5wt％。
当适量3-苯基-1,4,2-二噁唑-5-酮和适量其他添加剂联用时，能够完全克服具有通式(1)所示结构的2-苯基-苯并噻唑及其衍生物导致的高温下循环容量快速下降的问题，甚至可以提高锂电池高温循环性能。
优选地，所述的有机溶剂包括环状酯和/或链状酯，所述的环状酯为γ-丁内酯、碳酸乙烯酯、碳酸丙烯酯、氟代碳酸乙烯酯中的一种或几种；所述的链状酯为碳酸二甲酯、碳酸甲乙酯、碳酸二乙酯、碳酸甲丙酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、丁酸甲酯、丁酸乙酯、丁酸丙酯、氟代丙酸甲酯、氟代丙酸乙酯、氟代乙酸乙酯中的一种或几种。
进一步优选地，所述的有机溶剂为环状酯和链状酯的混合，其中，所述的环状酯与所述的链状酯以质量比为1：(1～2.5)进行混合。
更进一步优选地，所述的环状酯与所述的链状酯以质量比为1：(1.5～2)进行混合。
优选地，所述的锂盐为六氟磷酸锂、四氟硼酸锂、六氟砷酸锂、无水高氯酸锂、二(三氟甲基磺酸酰)亚胺锂、二氟二草酸磷酸锂、二氟磷酸锂(LiPO 2F 2)、三氟甲基磺酸锂、二氟二草酸磷酸锂、二草酸硼酸锂、单草酸双氟硼酸锂、双氟磺酰亚胺锂中的一种或者几种。
优选地，所述的锂盐的浓度为0.6～1.5mol/L。
进一步优选地，所述的锂盐的浓度为0.8～1.3mol/L。
本发明另一方面提供一种锂离子电池，其包括正极、负极和电解液，所述的电解液为所述的非水电解液。
优选地，所述的正极为钴酸锂材料或镍钴锰酸锂材料。
优选地，所述的负极为石墨材料。
由于上述技术方案运用，本发明与现有技术相比具有下列优点：
本发明中的具有通式(1)所示结构的2-苯基-苯并噻唑及其衍生物在锂离子电池过充时能够在正极表面形成钝化膜，防止电池电压在过充过程中进一步升高，该添加剂还使电解液在过充时温度升高较慢，而且该添加剂的加入不仅不会影响锂离子电池的室温循环性能，甚至可以提升锂离子电池的室温循环性能，从而有效避免了电池过充所带来的安全隐患。
附图说明
图1为实施例1的非水电解液在三电极体系下的循环伏安图，扫描速度：5mV/s。
具体实施方式
下面结合实施例对本发明作进一步描述。但本发明并不限于以下实施例。实施例中采用的实施条件可以根据具体使用的不同要求做进一步调整，未注明的实施条件为本行业中的常规条件。本发明各个实施方式中所涉及到的技术特征只要彼此之间未构成冲突就可以相互组合。
本发明主要从防止电池过充的角度出发，对锂电池电解液的添加剂进行了大量研究和试验验证，最终提供一种非水电解液和与之相关的锂离子电池。
根据本发明，所述的非水点解液包括锂盐、溶剂和添加剂，所述的添加剂包括具有通式(1)所示结构的2-苯基-苯并噻唑及其衍生物，
Figure PCTCN2022079923-appb-000003
其中，R 1、R 2和R 3独立地为H、卤素原子或烷基。
优选地，R 1、R 2和R 3独立地为H、Cl、F、C 1～C 4直链烷基或叔丁基。
优选地，R 1、R 2和R 3独立地为H、Cl或F。
根据本发明，优选地选用化合物1-6，分子结构如下：
Figure PCTCN2022079923-appb-000004
根据本发明，所述的2-苯基-苯并噻唑及其衍生物的用量为0.1～10wt％，例如0.1wt％、0.5wt％、1wt％、1.5wt％、2wt％、2.5wt％、3wt％、3.5wt％、4wt％、4.5wt％、5wt％、5.5wt％、6wt％、6.5wt％、7wt％、8.5wt％、9wt％、9.5wt％、10wt％。适量的2-苯基-苯并噻唑及其衍生物能有效防过充，并且对锂离子电池的室温循环性能影响较小。
但是，随着研究的深入，发明人发现，添加2-苯基-苯并噻唑及其衍生物的电解液在高温条件下的循环容量衰减极大。
发明人认为可能是因为高温条件下2-苯基-苯并噻唑及其衍生物与电池正极缓慢反应，逐渐形成不导电的高分子薄膜，影响循环性能。为了解决该问题，在添加2-苯基-苯并噻唑及其衍生物的基础上，发明人引入3-苯基-1,4,2-二噁唑-5-酮，可优先在电池的正、负极形成保护膜，并且在电池的工作电压范围内抑制2-苯基-苯并噻唑及其衍生物与电池电极材料的相互作用。进一步地，同时引入其他常规的辅助性添加剂(即其他添加剂)，进一步保证防过充电解液的综合性能。
根据本发明，所述的3-苯基-1,4,2-二噁唑-5-酮的用量为0.1～10wt％，例如0.1wt％、0.5wt％、1wt％、1.5wt％、2wt％、2.5wt％、3wt％、3.5wt％、4wt％、4.5wt％、5wt％、5.5wt％、6wt％、6.5wt％、7wt％、8.5wt％、9wt％、9.5wt％、10wt％，优选为0.1～5wt％，进一步优选为0.1～3wt％。适量的3-苯基-1,4,2-二噁唑-5-酮可以有效缓解2-苯基-苯并噻唑及其衍生物导致的高温性能下降的问题，使电解液在高温下仍然具有较高循环容量。
根据本发明，所述的其他添加剂的用量为0.1～10wt％，例如0.1wt％、0.5wt％、1wt％、1.5wt％、2wt％、2.5wt％、3wt％、3.5wt％、4wt％、4.5wt％、5wt％、5.5wt％、6wt％、6.5wt％、7wt％、8.5wt％、9wt％、9.5wt％、10wt％，优选为0.1～5wt％。适量的其他添加剂可以辅助3-苯基-1,4,2-二噁唑-5-酮和2-苯基-苯并噻唑及其衍生物，使锂离子电池的综合性能提升。
根据本发明，所述的有机溶剂为环状酯和/或链状酯，所述的环状酯为γ-丁内酯、碳酸乙烯酯、碳酸丙烯酯、氟代碳酸乙烯酯中的一种或几种；所述的链状酯为碳酸二甲酯、碳酸甲乙酯、碳酸二乙酯、碳酸甲丙酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、丁酸甲酯、丁酸乙酯、丁酸 丙酯、氟代丙酸甲酯、氟代丙酸乙酯、氟代乙酸乙酯中的一种或几种。
优选地，所述的有机溶剂为环状酯和链状酯的混合，其中，所述环状酯与所述链状酯以质量比为1：(1～2.5)，例如1:1、1:1.2、1:1.4、1:1.6、1:1.8、1:2、1:2.2、1:2.4、1:2.5。
根据本发明，所述的锂盐为六氟磷酸锂、四氟硼酸锂、六氟砷酸锂、无水高氯酸锂、二(三氟甲基磺酸酰)亚胺锂、二氟二草酸磷酸锂、二氟磷酸锂、三氟甲基磺酸锂、二氟二草酸磷酸锂、二草酸硼酸锂、单草酸双氟硼酸锂、双氟磺酰亚胺锂中的一种或者几种。
根据本发明，所述的锂盐的浓度为0.6～1.5mol/L，例如0.6mol/L、0.8mol/L、1mol/L、1.2mol/L、1.4mol/L、1.5mol/L。
通过选取特殊配方的有机溶剂，与所述的2-苯基-苯并噻唑及其衍生物及锂盐配合，可使锂离子电池的性能提升。
根据本发明，所述的锂离子电池，包括正极、负极和电解液，其中，所述的电解液为上述的非水电解液，所述的正极为钴酸锂正极材料或镍钴锰酸锂材料，所述负极为石墨材料。
本发明提供的非水电解液在锂离子电池中具有防过充特性，过充到130％SOC时的电池温度提高不显著，并且提高电池的室温循环性能的优点。进一步地，通过在电解液中复配其他特定添加剂，可以进一步提高电池的高温循环性能。
下面通过实施例和对比例进一步阐述本发明的技术方案和技术效果。
以下实施例和对比例中，若无特征说明，所使用的原料均通过市售获得。
实施例1
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物1，配制得到目标电解液。
实施例2
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物2，配制得到目标电解液。
实施例3
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物3，配制得到目标电解液。
实施例4
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物4，配制得到目标电解液。
实施例5
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物5，配制得到目标电解液。
实施例6
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物6，配制得到目标电解液。
实施例7
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加3wt％的化合物1，配制得到目标电解液。
实施例8
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加3wt％的化合物2，配制得到目标电解液。
实施例9
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加3wt％的化合物3，配制得到目标电解液。
实施例10
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加3wt％的化合物4，配制得到目标电解液。
实施例11
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加3wt％的化合物5，配制得到目标电解液。
实施例12
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加3wt％的化合物6，配制得到目标电解液。
实施例13
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加5wt％的化合物1，配制得到目标电解液。
实施例14
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加5wt％的化合物2，配制得到目标电解液。
实施例15
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加5wt％的化合物3，配制得到目标电解液。
实施例16
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加5wt％的化合物4，配制得到目标电解液。
实施例17
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加5wt％的化合物5，配制得到目标电解液。
实施例18
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加5wt％的化合物6，配制得到目标电解液。
对比例1
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的目标电解液。
对比例2
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的2-氟联苯，配制得到目标电解液。
对比例3
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加3wt％的2-氟联苯，配制得到目标电解液。
对比例4
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加5wt％的2-氟联苯，配制得到目标电解液。
性能比较：
(1)添加剂氧化聚合电势测试：
使用三电极测试体系，其中3mm直径铂盘电极作为工作电极，两片金属锂片分别作为参比电极和对电极，表征各个电解液中电极的钝化起始电势和电解液的氧化分解电势。图1显示了实施例1在测试条件下的循环伏安图，图中标注了添加剂的起始氧化聚合电势和电解液的氧化分解电势。实施例1-6的测试结果如表1所示。实验结果显示实施列1-6所采用的化合物1-6均在4.5V(vs.Li/Li +)以上发生氧化聚合反应。三电极测试后，工作电极表面均会覆盖一层深色聚合物。该聚合物在锂离子电池过充时能起到抑制电池电压进一步升高的作用。
表1
Figure PCTCN2022079923-appb-000005
Figure PCTCN2022079923-appb-000006
(2)室温4.2V钴酸锂/石墨电池1C倍率循环测试，充放电截止电压分别是2.75V和4.2V。200周、400周及600周1C倍率循环后的电池容量保持率如表2所示。从对比例1-4的实验结果可以看出，传统防过充添加剂2-氟联苯的加入，会严重影响电池的循环性能。对比例2-4在200周、400周和600周的电池容量保持率明显低于对比例1，即不添加任何过充保护剂的电池。而在实施例中，除了实施例11、12、17和18以外，其它实施例在200周、400周和600周的电池容量保持率相比于对比例1均没有劣化，甚至优于对比例1。
表2
Figure PCTCN2022079923-appb-000007
Figure PCTCN2022079923-appb-000008
(3)室温4.2V钴酸锂/石墨电池在满电状态后进行1C倍率过充至10V，记录过充过程中的平台电压和电池达到130％SOC条件下的电池表面温度(热电偶测量)。结果如表3所示。结果显示，除了对比例1以外，其它实施例和对比例均能在电池过充时保持5V以下的过充平台电压，显示出明显的防过充性能。并且，在电池过充到130％SOC时，实施例1-18均比对比例2-4的电池温度要低，说明化合物1-6相比于2-氟联苯，表现出更优的防过充性能，它们的氧化聚合过程所放出的热量明显低于2-氟联苯。
表3
Figure PCTCN2022079923-appb-000009
Figure PCTCN2022079923-appb-000010
综合考虑电池的循环容量保持率和防过充性能，化合物4>化合物2>化合物3>化合物1>其它，其质量分数为3％最优，1％次之。
实施例19
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物1和1wt％PDO，配制得到目标电解液。
实施例20
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物2和1wt％PDO，配制得到目标电解液。
实施例21
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物4和1wt％PDO，配制得到目标电解液。
实施例22
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物1和2wt％PDO，配制得到目标电解液。
实施例23
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀， 配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物2和2wt％PDO，配制得到目标电解液。
实施例24
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物4和2wt％PDO，配制得到目标电解液。
实施例25
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物1，2wt％PDO和1wt％VC，配制得到目标电解液。
实施例26
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物1，2wt％PDO和1wt％PS，配制得到目标电解液。
实施例27
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物1，2wt％PDO和1wt％DTD，配制得到目标电解液。
实施例28
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物1，2wt％PDO和1wt％LiPO 2F 2，配制得到目标电解液。
实施例29
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物2，2wt％PDO和1wt％VC，配制得到目标电解液。
实施例30
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物2，2wt％PDO和1wt％PS，配制得到目标电解液。
实施例31
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物2，2wt％PDO和1wt％DTD，配制得到目标电解液。
实施例32
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物2，2wt％PDO和1wt％LiPO 2F 2，配制得到目标电解液。
实施例33
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物4，2wt％PDO和1wt％VC，配制得到目标电解液。
实施例34
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物4，2wt％PDO和1wt％PS，配制得到目标电解液。
实施例35
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物4，2wt％PDO和1wt％DTD，配制得到目标电解液。
实施例36
在充氮气的手套箱中(H 2O<10ppm，O 2<10ppm)，将DMC、EC和EMC按质量比1:1:1混合均匀，配制成混合溶剂。然后，称取1当量的LiPF 6溶解在前述混合溶剂中配制成含有1mol/L LiPF 6的电解液。最后，向该电解液中添加1wt％的化合物4，2wt％PDO和1wt％LiPO 2F 2，配制得到目标电解液。
性能比较：
(1)室温4.2V钴酸锂/石墨电池在满电状态后进行1C倍率过充至10V，记录过充过程中的平台电压和电池达到130％SOC条件下的电池表面温度(热电偶测量)。结果如表4所示。
表4
电解液 过充平台电压(V) 温度@130％SOC(℃)
实施例19 4.62 29
实施例20 4.79 27
实施例21 4.88 28
实施例22 4.62 30
实施例23 4.79 28
实施例24 4.88 28
实施例25 4.62 29
实施例26 4.62 29
实施例27 4.62 28
实施例28 4.62 29
实施例29 4.79 30
实施例30 4.79 29
实施例31 4.79 30
实施例32 4.79 29
实施例33 4.88 28
实施例34 4.88 29
实施例35 4.88 31
实施例36 4.88 30
对比例1 5.45 30
实施例1 4.62 29
实施例2 4.79 27
实施例4 4.88 28
结果显示，只有对比例1由于不含有2-苯基-苯并噻唑及其衍生物，其过充平台大于5V，没有防过充效果。其它含有2-苯基-苯并噻唑及其衍生物的实施例和对比例，均表现出5V以下的过充平台电压，显示出明显的防过充性能。并且，在电池过充到130％SOC时，所有实施例均未表现出明显的温度升高。
(2)在45℃条件下，4.2V镍钴锰酸锂(NMC532)/石墨电池1C倍率循环测试。充、放电截止电压分别是4.2V和3.0V。200周、400周及600周1C倍率循环后的电池容量保持率如表5所示。
表5
电解液 200周容量保持率(％) 400周容量保持率(％) 600周容量保持率(％)
实施例19 86 76 55
实施例20 90 85 60
实施例21 90 84 60
实施例22 87 79 60
实施例23 90 86 70
实施例24 90 84 71
实施例25 95 89 82
实施例26 96 90 84
实施例27 95 90 85
实施例28 95 89 82
实施例29 95 90 83
实施例30 96 90 84
实施例31 95 90 85
实施例32 95 90 86
实施例33 95 90 85
实施例34 96 90 84
实施例35 96 90 86
实施例36 96 90 87
对比例1 95 88 75
实施例1 85 70 40
实施例2 90 85 55
实施例4 89 83 50
从对比例1，以及实施例1，2和4的实验结果可以看出，含有2-苯基-苯并噻唑及其衍生物的NMC532电池高温循环后电池容量保持率劣化十分严重。400周时，实施例1已经低于初始容量的80％，实施例2和4已经接近初始容量的80％，而未加入任何添加剂的对比例1的容量保持率接近90％。
加入PDO后(实施例19-24)，对添加2-苯基-苯并噻唑及其衍生物的电池的高温循环性能稍有改善，但是高温循环性能仍然劣于对比例1。其中，含有2％PDO的实施例优于1％PDO的实施例。
引入第三种添加剂后(实施例25-36)，部分实施例的高温循环性能明显改善，主要是含有DTD和LiPO 2F 2的实施例。
综上，通过添加PDO与DTD或者LiPO 2F 2的组合能够有效改善因为加入2-苯基-苯并噻唑及其衍生物而造成的高温循环容量衰减，并且其防过充的性能不受影响。

Claims (15)

  1. 一种非水电解液，其包括锂盐、有机溶剂和添加剂，其特征在于，所述的添加剂包括具有通式(1)所示结构的2-苯基-苯并噻唑及其衍生物，
    Figure PCTCN2022079923-appb-100001
    其中，R 1、R 2和R 3独立地为H、卤素原子或烷基。
  2. 根据权利要求1所述的非水电解液，其特征在于，R 1、R 2和R 3独立地为H、Cl、F、C 1～C 4直链烷基或叔丁基。
  3. 根据权利要求2所述的非水电解液，其特征在于，R 1、R 2和R 3独立地为H、Cl或F。
  4. 根据权利要求1所述的非水电解液，其特征在于，所述的添加剂包括以下化合物中的一种或多种：
    Figure PCTCN2022079923-appb-100002
  5. 根据权利要求1所述的非水电解液，其特征在于，所述的通式(1)所示结构的2-苯基-苯并噻唑及其衍生物占所述的非水电解液的总质量的0.1～10wt％。
  6. 根据权利要求5所述的非水电解液，其特征在于，所述的通式(1)所示结构的2-苯基-苯并噻唑及其衍生物占所述的非水电解液的总质量的0.1～5wt％。
  7. 根据权利要求1所述的非水电解液，其特征在于，所述添加剂还包括3-苯基-1,4,2-二噁唑-5-酮以及可选择性地包括其他添加剂，所述的其他添加剂为碳酸亚乙烯酯、1,3-丙烷磺内酯、丙烯基-1,3-磺内酯、硫酸乙烯酯、二氟磷酸锂中的一种或多种。
  8. 根据权利要求7所述的非水电解液，其特征在于，所述的其他添加剂为硫酸乙烯酯和/或二氟磷酸锂。
  9. 根据权利要求7所述的非水电解液，其特征在于，所述的3-苯基-1,4,2-二噁唑-5-酮和所述的其他添加剂的投料质量分别独立地为所述的非水电解液的总质量的0.1～10wt％。
  10. 根据权利要求7所述的非水电解液，其特征在于，所述的3-苯基-1,4,2-二噁唑-5-酮和所述的其他添加剂的投料质量分别独立地为所述的非水电解液的总质量的0.1～5wt％。
  11. 根据权利要求1所述的非水电解液，其特征在于，所述的有机溶剂包括环状酯和/或链状酯，所述的环状酯为γ-丁内酯、碳酸乙烯酯、碳酸丙烯酯、氟代碳酸乙烯酯中的一种或几种；所述的链状酯为碳酸二甲酯、碳酸甲乙酯、碳酸二乙酯、碳酸甲丙酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、丁酸甲酯、丁酸乙酯、丁酸丙酯、氟代丙酸甲酯、氟代丙酸乙酯、氟代乙酸乙酯中的一种或几种。
  12. 根据权利要求1所述的非水电解液，其特征在于，所述的锂盐为六氟磷酸锂、四氟硼酸锂、六氟砷酸锂、无水高氯酸锂、二(三氟甲基磺酸酰)亚胺锂、二氟二草酸磷酸锂、二氟磷酸锂、三氟甲基磺酸锂、二氟二草酸磷酸锂、二草酸硼酸锂、单草酸双氟硼酸锂、双氟磺酰亚胺锂中的一种或者几种。
  13. 根据权利要求1所述的非水电解液，其特征在于，所述的锂盐的浓度为0.6～1.5mol/L。
  14. 一种锂离子电池，其包括正极、负极和电解液，其特征在于，所述的电解液为权利要求1至13中任一项所述的非水电解液。
  15. 根据权利要求14所述的锂离子电池，其特征在于，所述的正极为钴酸锂材料或镍钴锰酸锂材料，所述的负极为石墨材料。
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