WO2024124903A1 - 一种锂离子电池的电解液添加剂组合物及含该添加剂组合物的电解液及电解液的应用 - Google Patents

一种锂离子电池的电解液添加剂组合物及含该添加剂组合物的电解液及电解液的应用 Download PDF

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WO2024124903A1
WO2024124903A1 PCT/CN2023/108148 CN2023108148W WO2024124903A1 WO 2024124903 A1 WO2024124903 A1 WO 2024124903A1 CN 2023108148 W CN2023108148 W CN 2023108148W WO 2024124903 A1 WO2024124903 A1 WO 2024124903A1
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lithium
electrolyte
carbonate
ion battery
additive composition
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PCT/CN2023/108148
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English (en)
French (fr)
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傅人俊
董斌
郁冬青
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苏州祺添新材料股份有限公司
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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
    • 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 present application relates to the field of lithium-ion batteries, and more specifically, to an electrolyte additive composition for lithium-ion batteries, an electrolyte containing the additive composition, and applications of the electrolyte.
  • lithium-ion batteries Compared with traditional secondary batteries, lithium-ion batteries have greater energy density, higher voltage, and longer cycle life. In addition, lithium-ion batteries are environmentally friendly. Therefore, lithium-ion batteries have been widely used in many fields, such as laptops, mobile phones, digital products, and electric vehicles.
  • the electrolyte which is used to transfer lithium ions between the positive and negative electrodes of the battery.
  • the electrolyte usually includes a lithium salt electrolyte, an organic solvent and an additive composition.
  • the introduction of the additive composition can improve the rate performance and cycle life of the battery, reduce the impedance of the battery, etc.
  • vinylene carbonate and vinyl carbonate are common film-forming additive compositions.
  • Vinylene carbonate and vinyl carbonate will undergo electrochemical polymerization on the surface of the negative electrode to form a dense solid electrolyte film, which prevents the electrode material and the electrolyte from contacting each other, thereby preventing the electrolyte from further reducing and decomposing on the surface of the negative electrode, and inhibiting the side reactions between the electrolyte and the electrode material.
  • the solid electrolyte film can also prevent the solvent and lithium ions from being co-embedded into the electrode material.
  • Power batteries are the power source for tools, and they require sufficient film-forming additive compositions to ensure that the batteries have sufficient cycle stability; however, the increase in the amount of film-forming additive compositions will increase costs, and the battery impedance will also increase, and the battery's rate performance and low-temperature performance will be affected by the increase in battery impedance.
  • the amount of additive compositions such as vinylene carbonate increases, in lithium-ion batteries using lithium nickel cobalt manganese oxide as the positive electrode material, the battery will experience obvious flatulence when working at high temperatures, posing a safety hazard.
  • the present application provides an electrolyte additive composition for lithium-ion batteries and an electrolyte containing the additive composition and application of electrolyte.
  • the present application provides an electrolyte additive composition for a lithium-ion battery, which adopts the following technical solution:
  • An electrolyte additive composition for a lithium ion battery comprising an unsaturated cyclic carbonate and an unsaturated chain carbonate;
  • the unsaturated cyclic carbonate comprises at least one of the following compounds:
  • R1 is a hydrocarbon group or a fluorinated hydrocarbon group containing 1 to 6 carbon atoms
  • R2 is a hydrocarbon group or a fluorinated hydrocarbon group containing 1 to 6 carbon atoms
  • the A group is a vinylene group or an ethynylene group.
  • the unsaturated linear carbonate is at least one of the following compounds:
  • the mass ratio of the unsaturated cyclic carbonate to the unsaturated linear carbonate is (0.5-5):(0.05-10).
  • the present application provides a lithium-ion battery electrolyte, which adopts the following technical solution:
  • a lithium ion battery electrolyte comprises a lithium salt electrolyte, an organic solvent and an additive composition.
  • the mass proportion of the unsaturated cyclic carbonate in the additive composition in the electrolyte is 0.5%-5%, and the mass proportion of the unsaturated chain carbonate in the additive composition is The mass proportion in the electrolyte is 0.05%-10%.
  • the organic solvent is at least one of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethylene carbonate, ethyl methyl carbonate, methyl propyl carbonate, methyl butyl carbonate, propylene carbonate, ⁇ -butyrolactone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, difluoroethyl acetate, trifluoroethyl acetate, trifluoroethyl methyl carbonate, and bistrifluoroethyl carbonate.
  • the lithium salt electrolyte is at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium difluorophosphate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(oxalatoborate), lithium difluorooxalatoborate, lithium tetrafluorooxalatophosphate, lithium difluorobis(oxalatophosphate), and lithium fluorosulfonyl(trifluoromethylsulfonyl)imide.
  • the molar concentration of the electrolyte in the electrolyte is 0.5-2 mol/L.
  • the lithium-ion battery electrolyte provided in the present application is suitable for lithium-ion batteries using lithium iron phosphate, lithium manganese oxide, lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese iron phosphate, and lithium nickel cobalt manganese aluminum oxide as positive electrodes.
  • the lithium-ion battery electrolyte provided by the present application is suitable for lithium-ion batteries using carbon materials or silicon-based materials as negative electrodes.
  • the present application uses a mixture of unsaturated cyclic carbonate and unsaturated chain carbonate as an additive composition for lithium ion battery electrolyte.
  • the lithium ion battery can have lower impedance, excellent cycle performance, especially low-temperature cycle performance, and can inhibit the bloating caused by electrolyte decomposition, and improve the battery's high-temperature cycle and high-temperature storage performance.
  • An embodiment of the present application provides an electrolyte for a lithium-ion battery.
  • the preparation method of the electrolyte comprises the following steps:
  • Step 1 In a glove box filled with nitrogen or argon, where the water and oxygen contents in the glove box are both ⁇ 0.1 ppm, the organic solvent and the lithium salt electrolyte are evenly mixed to obtain a basic electrolyte.
  • Step 2 Still in a glove box filled with nitrogen or argon, the water and oxygen content in the glove box is ⁇ 0.1ppm, add the additive composition to the basic electrolyte, mix well, and obtain an electrolyte.
  • the additive composition in this embodiment is a mixture of unsaturated cyclic carbonate and unsaturated chain carbonate.
  • R1 is a hydrocarbon group or a fluorinated hydrocarbon group containing 1 to 6 carbon atoms
  • R2 is a hydrocarbon group or a fluorinated hydrocarbon group containing 1 to 6 carbon atoms
  • the A group is a vinylene group or an ethynylene group.
  • the unsaturated linear carbonate in this embodiment is selected from the following compounds:
  • the organic solvent is selected from at least one of dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethylene carbonate, ethyl methyl carbonate, methyl propyl carbonate, methyl butyl carbonate, propylene carbonate, ⁇ -butyrolactone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, difluoroethyl acetate, trifluoroethyl acetate, trifluoroethyl methyl carbonate, and bistrifluoroethyl carbonate.
  • the organic solvent of this embodiment is a mixture of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate; further, the volume ratio of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate is 1:1:1.
  • the lithium salt electrolyte is selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium difluorophosphate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, and lithium bis(oxalate).
  • the molar concentration of the electrolyte in the electrolyte is 0.5-2 mol/L.
  • the lithium salt electrolyte in this embodiment is lithium hexafluorophosphate, and the molar concentration of lithium hexafluorophosphate is 1 mol/L.
  • This embodiment also provides a method for manufacturing a lithium-ion battery, comprising the following steps:
  • the electrolyte prepared in each embodiment and comparative example is injected into a lithium ion battery cell with LiFePO 4 or LiNi 0.5 Co 0.2 Mn 0.3 O 2 as the positive electrode material and artificial graphite as the negative electrode. After the injection, the cell is sealed and allowed to stand, formed, aged, sealed again, and capacity divided to obtain a lithium ion battery.
  • This embodiment also provides a method for detecting the performance of a lithium-ion battery, including the following detection method:
  • DCIR (V 1 - V 2 )/(5 ⁇ Qt).
  • DCIR (V 3 - V 4 )/(5 ⁇ Qt).
  • Discharge capacity retention rate at 25°C (%) discharge capacity after 500th cycle/discharge capacity after first cycle ⁇ 100%
  • Discharge capacity retention rate at 0° C. (%) discharge capacity after the 80th cycle/discharge capacity after the first cycle ⁇ 100%.
  • Discharge capacity retention rate at 25°C (%) discharge capacity after 800th cycle/discharge capacity after first cycle ⁇ 100%
  • Discharge capacity retention rate at 45° C. (%) discharge capacity after 400th cycle/discharge capacity after first cycle ⁇ 100%.
  • Battery capacity retention rate (%) retention capacity/initial capacity ⁇ 100%
  • Battery capacity recovery rate (%) recovery capacity/initial capacity ⁇ 100%.
  • Battery capacity retention rate (%) retention capacity/initial capacity ⁇ 100%
  • Battery capacity recovery rate (%) recovery capacity/initial capacity ⁇ 100%
  • Thickness expansion ratio (%) (thickness after storage - initial thickness) / initial thickness ⁇ 100%.
  • the preparation method of the electrolyte comprises the following steps:
  • Step 1 In a glove box filled with nitrogen or argon, where the water and oxygen contents in the glove box are both ⁇ 0.1ppm, ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate are mixed evenly to obtain an organic solvent mixture; the volume ratio of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate is 1:1:1. Lithium hexafluorophosphate is added to the organic solvent mixture, and the mixture is mixed evenly to obtain a basic electrolyte, in which the concentration of lithium hexafluorophosphate is 1 mol/L.
  • Step 2 Still in a glove box filled with nitrogen or argon, where the water and oxygen contents in the glove box are both ⁇ 0.1ppm, add the unsaturated cyclic carbonate in the additive composition and the unsaturated chain carbonate in the additive composition to the basic electrolyte, mix well, and obtain an electrolyte.
  • the unsaturated chain carbonate is a compound of formula (2-a), and the unsaturated cyclic carbonate is a compound of formula (1-a).
  • the mass percentage of the unsaturated chain carbonate is 1%, and the mass percentage of the unsaturated cyclic carbonate is 1%.
  • Embodiment 1 also provides a method for manufacturing a lithium ion battery, comprising the following steps:
  • the prepared electrolyte is injected into a lithium-ion battery cell with LiFePO 4 as the positive electrode material and artificial graphite as the negative electrode. After the injection, the battery is sealed and left to stand, formed, aged, resealed, and divided to obtain a lithium-ion battery.
  • Embodiment 1 also provides a method for testing the direct current impedance (DCIR) of a lithium-ion battery at room temperature, including The following steps are included:
  • DCIR (V 1 - V 2 )/(5 ⁇ Qt).
  • Example 2-6 and Comparative Examples 1-4 Compared with Example 1, the difference between Examples 2-6 and Comparative Examples 1-4 is that the additive composition formula in the battery electrolyte is different.
  • the lithium ion batteries of Examples 2-6 and Comparative Examples 1-4 all use LiFePO 4 as the positive electrode material, and the lithium ion battery performance test methods of Examples 2-6 and Comparative Examples 1-4 are the same as those of Example 1.
  • the preparation method of the electrolyte comprises the following steps:
  • Step 1 In a glove box filled with nitrogen or argon, where the water and oxygen contents in the glove box are both ⁇ 0.1ppm, ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate are mixed evenly to obtain an organic solvent mixture; the volume ratio of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate is 1:1:1. Lithium hexafluorophosphate is added to the organic solvent mixture, and the mixture is mixed evenly to obtain a basic electrolyte, in which the concentration of lithium hexafluorophosphate is 1 mol/L.
  • Step 2 Still in a glove box filled with nitrogen or argon, where the water and oxygen contents in the glove box are both ⁇ 0.1ppm, add the unsaturated cyclic carbonate in the additive composition and the unsaturated chain carbonate in the additive composition to the basic electrolyte, mix well, and obtain an electrolyte.
  • the unsaturated chain carbonate is a compound of formula (2-b), and the unsaturated cyclic carbonate is a compound of formula (1-a).
  • the mass percentage of the unsaturated chain carbonate is 1%, and the mass percentage of the unsaturated cyclic carbonate is 1%.
  • Embodiment 7 also provides a method for manufacturing a lithium ion battery, comprising the following steps:
  • the prepared electrolyte is injected into a lithium-ion battery cell with LiNi 0.5 Co 0.2 Mn 0.3 O 2 as the positive electrode material and artificial graphite as the negative electrode. After the injection, the cell is sealed and left to stand, formed, aged, sealed again, and divided to obtain a lithium-ion battery.
  • Embodiment 7 also provides a method for testing the direct current impedance (DCIR) of a lithium-ion battery at room temperature, comprising the following steps:
  • DCIR (V 3 - V 4 )/(5 ⁇ Qt).
  • Examples 8-12 and Comparative Examples 5-8 Compared with Example 7, the difference between Examples 8-12 and Comparative Examples 5-8 is that the additive composition formula in the battery electrolyte is different.
  • the lithium ion batteries of Examples 8-12 and Comparative Examples 5-8 all use LiNi 0.5 Co 0.2 Mn 0.3 O 2 as the positive electrode material, and the lithium ion battery performance test methods of Examples 8-12 and Comparative Examples 5-8 are the same as those of Example 7.
  • the preparation method of the electrolyte comprises the following steps:
  • Step 1 In a glove box filled with nitrogen or argon, where the water and oxygen contents in the glove box are both ⁇ 0.1ppm, ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate are mixed evenly to obtain an organic solvent mixture; the volume ratio of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate is 1:1:1. Lithium hexafluorophosphate is added to the organic solvent mixture, and the mixture is mixed evenly to obtain a basic electrolyte, in which the concentration of lithium hexafluorophosphate is 1 mol/L.
  • Step 2 Still in a glove box filled with nitrogen or argon, where the water and oxygen contents in the glove box are both ⁇ 0.1ppm, add the unsaturated cyclic carbonate in the additive composition and the unsaturated chain carbonate in the additive composition to the basic electrolyte, mix well, and obtain an electrolyte.
  • the unsaturated linear carbonate in Example 13 is a compound of formula (2-b), and the unsaturated cyclic
  • the carbonate is a compound of formula (1-a).
  • the mass percentage of the unsaturated chain carbonate is 2%, and the mass percentage of the unsaturated cyclic carbonate is 1%.
  • Embodiment 13 also provides a method for manufacturing a lithium ion battery, comprising the following steps:
  • the prepared electrolyte is injected into a lithium-ion battery cell with LiFePO 4 as the positive electrode material and artificial graphite as the negative electrode. After the injection, the battery is sealed and left to stand, formed, aged, resealed, and divided to obtain a lithium-ion battery.
  • Embodiment 13 also provides a method for testing the cycle performance of a lithium-ion battery, comprising the following steps:
  • the formed battery was charged to 3.65 V at 1 C constant current and constant voltage, with a cut-off current of 0.05 C, and then discharged to 2 V at 1 C constant current. After 500 cycles of charge and discharge, the discharge capacity retention rate after the 500th cycle was calculated.
  • Discharge capacity retention rate at 25°C (%) discharge capacity after 500th cycle/discharge capacity after first cycle ⁇ 100%
  • the formed battery was charged to 3.65 V at 1 C constant current and constant voltage, with a cut-off current of 0.05 C, and then discharged to 2 V at 1 C constant current. After 80 cycles of charge and discharge, the discharge capacity retention rate after the 80th cycle was calculated.
  • Discharge capacity retention rate at 0° C. (%) discharge capacity after the 80th cycle/discharge capacity after the first cycle ⁇ 100%.
  • Examples 14-18 and Comparative Examples 9-12 Compared with Example 13, the difference between Examples 14-18 and Comparative Examples 9-12 is that the additive composition formula in the battery electrolyte is different.
  • the lithium ion batteries of Examples 14-18 and Comparative Examples 9-12 all use LiFePO 4 as the positive electrode material, and the lithium ion battery performance test methods of Examples 14-18 and Comparative Examples 9-12 are the same as that of Example 13.
  • the preparation method of the electrolyte comprises the following steps:
  • Step 1 In a glove box filled with nitrogen or argon, where the water and oxygen contents in the glove box are both ⁇ 0.1ppm, ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate are mixed evenly to obtain an organic solvent mixture; the volume ratio of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate is 1:1:1. Lithium hexafluorophosphate is added to the organic solvent mixture, and the mixture is mixed evenly to obtain a basic electrolyte, in which the concentration of lithium hexafluorophosphate is 1 mol/L.
  • Step 2 Still in a glove box filled with nitrogen or argon, where the water and oxygen contents in the glove box are both ⁇ 0.1ppm, add the unsaturated cyclic carbonate in the additive composition and the unsaturated chain carbonate in the additive composition to the basic electrolyte, mix well, and obtain an electrolyte.
  • the unsaturated chain carbonate is a compound of formula (2-a), and the unsaturated cyclic carbonate is a compound of formula (1-a).
  • the mass percentage of the unsaturated chain carbonate is 0.5%, and the mass percentage of the unsaturated cyclic carbonate is 1%.
  • Embodiment 19 also provides a method for manufacturing a lithium ion battery, comprising the following steps:
  • the prepared electrolyte is injected into a lithium-ion battery cell with LiNi 0.5 Co 0.2 Mn 0.3 O 2 as the positive electrode material and artificial graphite as the negative electrode. After the injection, the cell is sealed and left to stand, formed, aged, sealed again, and divided to obtain a lithium-ion battery.
  • Embodiment 19 also provides a method for testing the cycle performance of a lithium-ion battery, comprising the following steps:
  • Discharge capacity retention rate at 25°C (%) discharge capacity after 800th cycle/discharge capacity after first cycle ⁇ 100%
  • the formed battery was charged to 4.35 V at 1 C constant current and constant voltage, with a cut-off current of 0.05 C, and then discharged to 3 V at 1 C constant current. After 400 cycles of charge and discharge, the discharge capacity retention rate after the 400th cycle was calculated.
  • Discharge capacity retention rate at 45° C. (%) discharge capacity after 400th cycle/discharge capacity after first cycle ⁇ 100%.
  • Examples 20-24 and Comparative Examples 13-16 Compared with Example 19, the difference between Examples 20-24 and Comparative Examples 13-16 is that the additive composition formula in the battery electrolyte is different.
  • the lithium ion batteries of Examples 20-24 and Comparative Examples 13-16 all use LiNi 0.5 Co 0.2 Mn 0.3 O 2 as the positive electrode material, and the lithium ion battery performance test methods of Examples 20-24 and Comparative Examples 13-16 are the same as those of Example 19.
  • the battery containing the electrolyte of the additive composition provided by the present application has a higher capacity retention rate at room temperature than the comparative example, whether it is a battery of the lithium iron phosphate system or a battery of the nickel-cobalt-manganese ternary system.
  • the capacity retention rate at low temperature is significantly improved compared with the comparative example.
  • the high temperature capacity retention rate is also well improved.
  • the preparation method of the electrolyte comprises the following steps:
  • Step 1 In a glove box filled with nitrogen or argon, where the water and oxygen contents in the glove box are both ⁇ 0.1ppm, ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate are mixed evenly to obtain an organic solvent mixture; the volume ratio of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate is 1:1:1. Lithium hexafluorophosphate is added to the organic solvent mixture, and the mixture is mixed evenly to obtain a basic electrolyte, in which the concentration of lithium hexafluorophosphate is 1 mol/L.
  • Step 2 Still in a glove box filled with nitrogen or argon, where the water and oxygen contents in the glove box are both ⁇ 0.1ppm, add the unsaturated cyclic carbonate in the additive composition and the unsaturated chain carbonate in the additive composition to the basic electrolyte, mix well, and obtain an electrolyte.
  • the unsaturated chain carbonate is a compound of formula (2-a), and the unsaturated cyclic carbonate is a compound of formula (1-a).
  • the mass percentage of the unsaturated chain carbonate is 1%, and the mass percentage of the unsaturated cyclic carbonate is 1%.
  • Embodiment 25 also provides a method for manufacturing a lithium ion battery, comprising the following steps:
  • the prepared electrolyte is injected into a lithium-ion battery cell with LiFePO 4 as the positive electrode material and artificial graphite as the negative electrode. After the injection, the battery is sealed and left to stand, formed, aged, resealed, and divided to obtain a lithium-ion battery.
  • Embodiment 25 also provides a method for testing the high temperature storage performance of a lithium ion battery, comprising the following steps:
  • Battery capacity retention rate (%) retention capacity/initial capacity ⁇ 100%
  • Battery capacity recovery rate (%) recovery capacity/initial capacity ⁇ 100%.
  • Examples 26-30 and Comparative Examples 17-20 Compared with Example 25, the difference between Examples 26-30 and Comparative Examples 17-20 is that the additive composition formula in the battery electrolyte is different.
  • the lithium ion batteries of Examples 26-30 and Comparative Examples 17-20 all use LiFePO 4 as the positive electrode material, and the lithium ion battery performance test methods of Examples 26-30 and Comparative Examples 17-20 are the same as that of Example 26.
  • the preparation method of the electrolyte comprises the following steps:
  • Step 1 In a glove box filled with nitrogen or argon, where the water and oxygen contents in the glove box are both ⁇ 0.1ppm, ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate are mixed evenly to obtain an organic solvent mixture; the volume ratio of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate is 1:1:1. Lithium hexafluorophosphate is added to the organic solvent mixture, and the mixture is mixed evenly to obtain a basic electrolyte, in which the concentration of lithium hexafluorophosphate is 1 mol/L.
  • Step 2 Still in a glove box filled with nitrogen or argon, where the water and oxygen contents in the glove box are both ⁇ 0.1ppm, add the unsaturated cyclic carbonate in the additive composition and the unsaturated chain carbonate in the additive composition to the basic electrolyte, mix well, and obtain an electrolyte.
  • the unsaturated chain carbonate is a compound of formula (2-b), and the unsaturated cyclic carbonate is a compound of formula (1-a).
  • the mass percentage of the unsaturated chain carbonate is 1%, and the mass percentage of the unsaturated cyclic carbonate is 1%.
  • Embodiment 31 also provides a method for manufacturing a lithium ion battery, comprising the following steps:
  • the prepared electrolyte is injected into a lithium-ion battery cell with LiNi 0.5 Co 0.2 Mn 0.3 O 2 as the positive electrode material and artificial graphite as the negative electrode. After the injection, the cell is sealed and left to stand, formed, aged, sealed again, and divided to obtain a lithium-ion battery.
  • Embodiment 31 also provides a method for testing the high temperature storage performance of a lithium ion battery, comprising the following steps:
  • Battery capacity retention rate (%) retention capacity/initial capacity ⁇ 100%
  • Battery capacity recovery rate (%) recovery capacity/initial capacity ⁇ 100%
  • Thickness expansion ratio (%) (thickness after storage - initial thickness) / initial thickness ⁇ 100%.
  • Examples 32-36 and Comparative Examples 21-24 Compared with Example 31, the difference between Examples 32-36 and Comparative Examples 21-24 is that the additive composition formula in the battery electrolyte is different.
  • the lithium ion batteries of Examples 32-36 and Comparative Examples 21-24 all use LiNi 0.5 Co 0.2 Mn 0.3 O 2 as the positive electrode material, and the lithium ion battery performance test methods of Examples 32-36 and Comparative Examples 21-24 are the same as that of Example 31.
  • the present application uses unsaturated cyclic carbonate and unsaturated chain carbonate as additive compositions, and uses the additive compositions in lithium-ion battery electrolytes.
  • the lithium-ion battery can have lower impedance, excellent cycle performance, especially low-temperature cycle performance, and can inhibit bloating caused by electrolyte decomposition, thereby improving the battery's high-temperature cycle and high-temperature storage performance.

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Abstract

一种锂离子电池的电解液添加剂组合物及含该添加剂组合物的电解液及电解液的应用。添加剂组合物包括不饱和环状碳酸酯和不饱和链状碳酸酯。不饱和环状碳酸酯包括以下化合物中的至少一种：式（1-a），式（1-b）,式（1-c）;不饱和链状碳酸酯的结构通式(2),其中，R 1为含有1-6个碳原子的烃基或氟代烃基，R 2为含有1-6个碳原子的烃基或氟代烃基；A基团是亚乙烯基或亚乙炔基。采用所述电解液的锂离子电池，具有阻抗低、循环性能优良等优点，而且电池的高温循环及高温储存性能均十分优异。

Description

一种锂离子电池的电解液添加剂组合物及含该添加剂组合物的电解液及电解液的应用 技术领域
本申请涉及锂离子电池领域，更具体地说，它涉及一种锂离子电池的电解液添加剂组合物及含该添加剂组合物的电解液及电解液的应用。
背景技术
锂离子电池相较于传统的二次电池，其具有更大的能量密度、更高的电压、更长的循环寿命，而且锂离子电池还具有环境友好的有点，因此锂离子电池得到多个领域得到了广泛应用，如笔记本电脑、手机、数码产品和电动汽车等领域。
锂离子的一个重要组成部分就是电解液，电解液的作用是在电池正负极之间传到锂离子。电解液通常包括锂盐电解质、有机溶剂和添加剂组合物。其中添加剂组合物的引入可以改善电池的倍率性能和循环寿命，降低电池的阻抗等。其中碳酸亚乙烯酯、乙烯基碳酸乙烯酯是常见的成膜添加剂组合物。碳酸亚乙烯酯、乙烯基碳酸乙烯酯会在负极表面发生电化学聚合，形成一层致密的固体电解质膜，阻止电极材料和电解液接触，从而阻止电解液在负极表面发生进一步的还原分解，抑制电解液和电极材料之间的副反应。同时固体电解质膜还可以防止溶剂和锂离子共嵌入电极材料。
动力电池是为工具提供动力来源的电源，需要足够的成膜添加剂组合物才可以保证电池具有足够的循环稳定性；但是，成膜添加剂组合物添加量的增加将带来成本的增大，而且电池阻抗也会随之增大，进而电池的倍率性能和低温性能等都会由于电池阻抗的增大而受影响。并且，当碳酸亚乙烯酯等添加剂组合物用量增大时，在镍钴锰酸锂等作为正极材料的锂离子电池中，电池在高温下工作会出现明显的胀气，存在安全隐患。
因此，如何研究一种添加剂组合物，使得锂离子电池具有低阻抗、高循环寿命以及优异的高低温性能，是锂离子电池领域中的重要课题。
发明内容
为了使得锂离子电池具有低阻抗、高循环寿命以及优异的高低温性能，本申请提供一种锂离子电池的电解液添加剂组合物及含该添加剂组合物的电解液 及电解液的应用。
第一方面，本申请提供一种锂离子电池的电解液添加剂组合物，采用如下的技术方案：
一种锂离子电池的电解液添加剂组合物，包括不饱和环状碳酸酯和不饱和链状碳酸酯；
所述不饱和环状碳酸酯包括以下化合物中的至少一种：
所述不饱和链状碳酸酯的结构通式如下：
其中，R1为含有1-6个碳原子的烃基或氟代烃基，R2为含有1-6个碳原子的烃基或氟代烃基；A基团是亚乙烯基或亚乙炔基。
在一个具体实施方式中，所述不饱和链状碳酸酯为以下化合物中的至少一种：

在一个具体实施方式中，所述不饱和环状碳酸酯和所述不饱和链状碳酸酯的质量比为(0.5-5)：(0.05-10)。
第二方面，本申请提供一种锂离子电池电解液，采用如下的技术方案：
一种锂离子电池电解液，包括锂盐电解质、有机溶剂和添加剂组合物。
在一个具体实施方式中，所述添加剂组合物中的不饱和环状碳酸酯在所述电解液中的质量占比为0.5％-5％，所述添加剂组合物中的不饱和链状碳酸酯在 所述电解液中的质量占比为0.05％-10％。
在一个具体实施方式中，所述有机溶剂为碳酸二甲酯、碳酸二乙酯、碳酸二丙酯、碳酸乙烯酯、碳酸甲乙酯、碳酸甲丙酯、碳酸甲丁酯、碳酸丙烯酯、γ-丁内酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、乙酸丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丁酸甲酯、丁酸乙酯、乙酸二氟乙酯、乙酸三氟乙酯、三氟乙基甲基碳酸酯、双三氟乙基碳酸酯中的至少一种。
在一个具体实施方式中，所述锂盐电解质为六氟磷酸锂、四氟硼酸锂、二氟磷酸锂、高氯酸锂、六氟砷酸锂、双氟磺酰亚胺锂、双(三氟甲基磺酰)亚胺锂、双草酸硼酸锂、二氟草酸硼酸锂、四氟草酸磷酸锂、二氟双草酸磷酸锂、氟磺酰(三氟甲基磺酰)亚胺锂中的至少一种。其中，电解液中电解质的摩尔浓度为0.5-2mol/L。
本申请提供的锂离子电池电解液，适用于以磷酸铁锂、锰酸锂、钴酸锂、镍钴锰酸锂、镍钴铝酸锂、磷酸锰铁锂、镍钴锰铝酸锂作为正极的锂离子电池中。
在一个具体实施方式中，本申请提供的锂离子电池电解液，适用于以碳材料或硅基材料为负极的锂离子电池中。
综上所述，本申请具有以下有益效果：
本申请将不饱和环状碳酸酯和不饱和链状碳酸酯的混合物，作为添加剂组合物用于锂离子电池电解液。在合适的配比下，可使锂离子电池具有较低的阻抗，优良的循环性能，尤其是低温循环性能，并且可抑制电解液分解造成的气胀，提高电池高温循环以及高温储存性能。
具体实施方式
以下结合实施例对本申请作进一步详细说明。
实施例
本申请的实施例提供了一种锂离子电池的电解液。
电解液的制备方法包括以下步骤：
步骤1：在充满氮气或氩气的手套箱中，手套箱中的水和氧含量都≤0.1ppm，将有机溶剂和锂盐电解质混合均匀得到基础电解液。
步骤2：依然在充满氮气或氩气的手套箱中，手套箱中的水和氧含量都 ≤0.1ppm，向基础电解液中加入添加剂组合物，混合均匀，得到电解液。
本实施例中的添加剂组合物是不饱和环状碳酸酯和不饱和链状碳酸酯的混合物。
本实施例中的不饱和环状碳酸酯选自以下化合物：
本实施例中，不饱和链状碳酸酯的结构通式为：
其中，R1为含有1-6个碳原子的烃基或氟代烃基，R2为含有1-6个碳原子的烃基或氟代烃基；A基团是亚乙烯基或亚乙炔基。
具体地，本实施例中的不饱和链状碳酸酯选自以下化合物：

本实施例中，有机溶剂选自碳酸二甲酯、碳酸二乙酯、碳酸二丙酯、碳酸乙烯酯、碳酸甲乙酯、碳酸甲丙酯、碳酸甲丁酯、碳酸丙烯酯、γ-丁内酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、乙酸丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丁酸甲酯、丁酸乙酯、乙酸二氟乙酯、乙酸三氟乙酯、三氟乙基甲基碳酸酯、双三氟乙基碳酸酯中的至少一种。
优选地，本实施例的有机溶剂为碳酸乙烯酯、碳酸甲乙酯和碳酸二甲酯的混合物；进一步地，碳酸乙烯酯、碳酸甲乙酯和碳酸二甲酯的体积比为1：1：1。
本实施例中，锂盐电解质选自六氟磷酸锂、四氟硼酸锂、二氟磷酸锂、高氯酸锂、六氟砷酸锂、双氟磺酰亚胺锂、双(三氟甲基磺酰)亚胺锂、双草酸 硼酸锂、二氟草酸硼酸锂、四氟草酸磷酸锂、二氟双草酸磷酸锂、氟磺酰(三氟甲基磺酰)亚胺锂中的至少一种。其中，电解液中电解质的摩尔浓度为0.5-2mol/L。
优选地，本实施例中的锂盐电解质为六氟磷酸锂，六氟磷酸锂的摩尔浓度为1mol/L。
本实施例还提供了一种锂离子电池的制作方法，包括以下步骤：
在水和氧含量都≤0.1ppm的充满氮气或氩气的手套箱中，将各实施例和对比例制备好的电解液注入由LiFePO4或LiNi0.5Co0.2Mn0.3O2作为正极材料，人造石墨作为负极的锂离子电池电芯内。注液完成后封口静置、化成、老化、二次封口、分容，得到锂离子电池。
本实施例还提供了锂离子电池性能的检测方法，包括以下检测方法：
(1)锂离子电池常温直流阻抗(DCIR)的测试方法。
以LiFePO4作为正极材料的锂离子电池中，具体步骤如下：
在25℃下，将化成后的电池按1C恒流恒压充电至3.65V，截止电流0.05C，再按1C恒流放电至2V，记录放电容量Qt。再按1C恒流恒压充电至3.65V，截止电流0.05C充满电，然后，按照1C恒流放出50％Qt的电量。静置1h，记录静置后的电压V1，再按5Qt的电流恒流放电10s，记录放电后的电压V2。
放电直流阻抗(DCIR)＝(V1-V2)/(5×Qt)。
以LiNi0.5Co0.2Mn0.3O2作为正极材料的锂离子电池中，具体步骤如下：
在25℃下，将化成后的电池按1C恒流恒压充电至4.35V，截止电流0.05C，再按1C恒流放电至3V，记录放电容量Qt。再按1C恒流恒压充电至4.35V，截止电流0.05C充满电，然后，按照1C恒流放出50％Qt的电量。静置1h，记录静置后的电压V3，再按5Qt的电流恒流放电10s，记录放电后的电压V4。
放电直流阻抗(DCIR)＝(V3-V4)/(5×Qt)。
(2)锂离子电池循环性能的测试方法。
以LiFePO4作为正极材料的锂离子电池中，具体步骤如下：
a.在25℃下，将化成后的电池按照1C恒流恒压充电至3.65V，截止电流0.05C,然后1C恒流放电至2V。充放电500个循环后，计算第500次循环后的放电容量保持率。
25℃下放电容量保持率(％)＝第500次循环后的放电容量/首次循环后的放电容量×100％
b.在0℃下，将化成后的电池按照1C恒流恒压充电至3.65V，截止电流0.05C,然后1C恒流放电至2V。充放电80个循环后，计算第80次循环后的放电容量保持率。
0℃下放电容量保持率(％)＝第80次循环后的放电容量/首次循环后的放电容量×100％。
以LiNi0.5Co0.2Mn0.3O2作为正极材料的锂离子电池中，具体步骤如下：
a.在25℃下，将化成后的电池按照1C恒流恒压充电至4.35V，截止电流0.05C,然后1C恒流放电至3V。充放电800个循环后，计算第800次循环后的放电容量保持率。
25℃下放电容量保持率(％)＝第800次循环后的放电容量/首次循环后的放电容量×100％
b.在45℃下，将化成后的电池按照1C恒流恒压充电至4.35V，截止电流0.05C,然后1C恒流放电至3V。充放电400个循环后，计算第400次循环后的放电容量保持率。
45℃下放电容量保持率(％)＝第400次循环后的放电容量/首次循环后的放电容量×100％。
(3)锂离子电池高温储存性能的测试方法。
以LiFePO4作为正极材料的锂离子电池中，具体步骤如下：
在25℃下，将电池按0.5C恒流恒压充电至3.65V，截止电流0.05C，再0.5C恒流放电至2V，记录放电容量，即为初始放电容量。然后再0.5C恒流恒压充至3.65V。将充满电的电池放置在60℃恒温环境中，存储7天。7天后取出，在25℃下静置4h，等电池冷却至室温后，按0.5C恒流放电至2V，记录放电容量，即为保持容量。按0.5C恒流恒压充电至3.65V，截止电流0.05C，再0.5C恒流放电至2V，记录放电容量，即为恢复容量。
电池容量保持率(％)＝保持容量/初始容量×100％
电池容量恢复率(％)＝恢复容量/初始容量×100％。
以LiNi0.5Co0.2Mn0.3O2作为正极材料的锂离子电池中，具体步骤如下：
在25℃下，将电池按0.5C恒流恒压充电至4.35V，截止电流0.05C，再0.5C恒流放电至3V，记录放电容量，即为初始放电容量。然后再0.5C恒流恒压充至4.35V，测量电池初始厚度。将充满电的电池放置在60℃恒温环境中，存储7天。7天后取出，在25℃下静置4h，等电池冷却至室温后，测量储存后的电池厚度。按0.5C恒流放电至3V，记录放电容量，即为保持容量。按0.5C恒流恒压充电至4.35V，截止电流0.05C，再0.5C恒流放电至3V，记录放电容量，即为恢复容量。
电池容量保持率(％)＝保持容量/初始容量×100％
电池容量恢复率(％)＝恢复容量/初始容量×100％
厚度膨胀率(％)＝(储存后厚度-初始厚度)/初始厚度×100％。
以下用具体的实施例做解释说明。
实施例1
电解液的制备方法包括以下步骤：
步骤1：在充满氮气或氩气的手套箱中，手套箱中的水和氧含量都≤0.1ppm，将碳酸乙烯酯、碳酸甲乙酯和碳酸二甲酯混合均匀，得到有机溶剂混合液；碳酸乙烯酯、碳酸甲乙酯和碳酸二甲酯的体积比为1：1：1。向有机溶剂混合液中加入六氟磷酸锂，混合均匀得到基础电解液，基础电解液中，六氟磷酸锂的浓度为1mol/L。
步骤2：依然在充满氮气或氩气的手套箱中，手套箱中的水和氧含量都≤0.1ppm，向基础电解液中加入添加剂组合物中的不饱和环状碳酸酯和添加剂组合物中的不饱和链状碳酸酯，混合均匀，得到电解液。
其中，实施例1中不饱和链状碳酸酯是式(2-a)的化合物，不饱和环状碳酸酯是式(1-a)的化合物。且最终电解液中，不饱和链状碳酸酯的质量百分含量为1％，不饱和环状碳酸酯的质量百分含量为1％。
实施例1还提供了一种锂离子电池的制作方法，包括以下步骤：
在水和氧含量都≤0.1ppm的充满氮气或氩气的手套箱中，将制备好的电解液注入由LiFePO4作为正极材料，人造石墨作为负极的锂离子电池电芯内。注液完成后封口静置、化成、老化、二次封口、分容，得到锂离子电池。
实施例1还提供了一种锂离子电池常温直流阻抗(DCIR)的测试方法，包 括以下步骤：
在25℃下，将化成后的电池按1C恒流恒压充电至3.65V，截止电流0.05C，再按1C恒流放电至2V，记录放电容量Qt。再按1C恒流恒压充电至3.65V，截止电流0.05C充满电，然后，按照1C恒流放出50％Qt的电量。静置1h，记录静置后的电压V1，再按5Qt的电流恒流放电10s，记录放电后的电压V2。
放电直流阻抗(DCIR)＝(V1-V2)/(5×Qt)。
实施例2-6及对比例1-4
相比于实施例1，实施例2-6及对比例1-4的不同之处在于，电池电解液中的添加剂组合物配方不同。实施例2-6及对比例1-4的锂离子电池均使用LiFePO4为正极材料，实施例2-6及对比例1-4的锂离子电池性能测试方法均与实施例1相同。
实施例1-6及对比例1-4的添加剂组合物配方和电池性能检测结果见表1。
表1实施例1-6及对比例1-4的添加剂组合物配方和电池性能检测结果表
实施例7
电解液的制备方法包括以下步骤：
步骤1：在充满氮气或氩气的手套箱中，手套箱中的水和氧含量都≤0.1ppm，将碳酸乙烯酯、碳酸甲乙酯和碳酸二甲酯混合均匀，得到有机溶剂混合液；碳酸乙烯酯、碳酸甲乙酯和碳酸二甲酯的体积比为1：1：1。向有机溶剂混合液中加入六氟磷酸锂，混合均匀得到基础电解液，基础电解液中，六氟磷酸锂的浓度为1mol/L。
步骤2：依然在充满氮气或氩气的手套箱中，手套箱中的水和氧含量都≤0.1ppm，向基础电解液中加入添加剂组合物中的不饱和环状碳酸酯和添加剂组合物中的不饱和链状碳酸酯，混合均匀，得到电解液。
其中，实施例7中不饱和链状碳酸酯是式(2-b)的化合物，不饱和环状碳酸酯是式(1-a)的化合物。且最终电解液中，不饱和链状碳酸酯的质量百分含量为1％，不饱和环状碳酸酯的质量百分含量为1％。
实施例7还提供了一种锂离子电池的制作方法，包括以下步骤：
在水和氧含量都≤0.1ppm的充满氮气或氩气的手套箱中，将制备好的电解液注入由LiNi0.5Co0.2Mn0.3O2作为正极材料，人造石墨作为负极的锂离子电池电芯内。注液完成后封口静置、化成、老化、二次封口、分容，得到锂离子电池。
实施例7还提供了一种锂离子电池常温直流阻抗(DCIR)的测试方法，包括以下步骤：
在25℃下，将化成后的电池按1C恒流恒压充电至4.35V，截止电流0.05C，再按1C恒流放电至3V，记录放电容量Qt。再按1C恒流恒压充电至4.35V，截止电流0.05C充满电，然后，按照1C恒流放出50％Qt的电量。静置1h，记录静置后的电压V3，再按5Qt的电流恒流放电10s，记录放电后的电压V4。
放电直流阻抗(DCIR)＝(V3-V4)/(5×Qt)。
实施例8-12及对比例5-8
相比于实施例7，实施例8-12及对比例5-8的不同之处在于，电池电解液中的添加剂组合物配方不同。实施例8-12及对比例5-8的锂离子电池均使用LiNi0.5Co0.2Mn0.3O2为正极材料，实施例8-12及对比例5-8的锂离子电池性能测试方法均与实施例7相同。
实施例7-12及对比例5-8的添加剂组合物配方和电池性能检测结果见表2。
表2实施例7-12及对比例5-8的添加剂组合物配方和电池性能检测结果表
由表1和表2中，实施例1-12和对比例1-8的测试结果可以看出，采用本申请的添加剂组合物的电解液，无论是对于磷酸铁锂体系的电池还是镍钴锰三元体系的电池，相较于只使用第一组份添加剂的对比例，放电直流阻抗都有明显的降低。
实施例13
电解液的制备方法包括以下步骤：
步骤1：在充满氮气或氩气的手套箱中，手套箱中的水和氧含量都≤0.1ppm，将碳酸乙烯酯、碳酸甲乙酯和碳酸二甲酯混合均匀，得到有机溶剂混合液；碳酸乙烯酯、碳酸甲乙酯和碳酸二甲酯的体积比为1：1：1。向有机溶剂混合液中加入六氟磷酸锂，混合均匀得到基础电解液，基础电解液中，六氟磷酸锂的浓度为1mol/L。
步骤2：依然在充满氮气或氩气的手套箱中，手套箱中的水和氧含量都≤0.1ppm，向基础电解液中加入添加剂组合物中的不饱和环状碳酸酯和添加剂组合物中的不饱和链状碳酸酯，混合均匀，得到电解液。
其中，实施例13中不饱和链状碳酸酯是式(2-b)的化合物，不饱和环状 碳酸酯是式(1-a)的化合物。且最终电解液中，不饱和链状碳酸酯的质量百分含量为2％，不饱和环状碳酸酯的质量百分含量为1％。
实施例13还提供了一种锂离子电池的制作方法，包括以下步骤：
在水和氧含量都≤0.1ppm的充满氮气或氩气的手套箱中，将制备好的电解液注入由LiFePO4作为正极材料，人造石墨作为负极的锂离子电池电芯内。注液完成后封口静置、化成、老化、二次封口、分容，得到锂离子电池。
实施例13还提供了一种锂离子电池循环性能的测试方法，包括以下步骤：
(1)在25℃下，将化成后的电池按照1C恒流恒压充电至3.65V，截止电流0.05C,然后1C恒流放电至2V。充放电500个循环后，计算第500次循环后的放电容量保持率。
25℃下放电容量保持率(％)＝第500次循环后的放电容量/首次循环后的放电容量×100％
(2)在0℃下，将化成后的电池按照1C恒流恒压充电至3.65V，截止电流0.05C,然后1C恒流放电至2V。充放电80个循环后，计算第80次循环后的放电容量保持率。
0℃下放电容量保持率(％)＝第80次循环后的放电容量/首次循环后的放电容量×100％。
实施例14-18及对比例9-12
相比于实施例13，实施例14-18及对比例9-12的不同之处在于，电池电解液中的添加剂组合物配方不同。实施例14-18及对比例9-12的锂离子电池均使用LiFePO4为正极材料，实施例14-18及对比例9-12的锂离子电池性能测试方法均与实施例13相同。
实施例13-18及对比例9-12的添加剂组合物配方和电池性能检测结果见表3。
表3实施例13-18及对比例9-12的添加剂组合物配方和电池性能检测结果表

实施例19
电解液的制备方法包括以下步骤：
步骤1：在充满氮气或氩气的手套箱中，手套箱中的水和氧含量都≤0.1ppm，将碳酸乙烯酯、碳酸甲乙酯和碳酸二甲酯混合均匀，得到有机溶剂混合液；碳酸乙烯酯、碳酸甲乙酯和碳酸二甲酯的体积比为1：1：1。向有机溶剂混合液中加入六氟磷酸锂，混合均匀得到基础电解液，基础电解液中，六氟磷酸锂的浓度为1mol/L。
步骤2：依然在充满氮气或氩气的手套箱中，手套箱中的水和氧含量都≤0.1ppm，向基础电解液中加入添加剂组合物中的不饱和环状碳酸酯和添加剂组合物中的不饱和链状碳酸酯，混合均匀，得到电解液。
其中，实施例19中不饱和链状碳酸酯是式(2-a)的化合物，不饱和环状碳酸酯是式(1-a)的化合物。且最终电解液中，不饱和链状碳酸酯的质量百分含量为0.5％，不饱和环状碳酸酯的质量百分含量为1％。
实施例19还提供了一种锂离子电池的制作方法，包括以下步骤：
在水和氧含量都≤0.1ppm的充满氮气或氩气的手套箱中，将制备好的电解液注入由LiNi0.5Co0.2Mn0.3O2作为正极材料，人造石墨作为负极的锂离子电池电芯内。注液完成后封口静置、化成、老化、二次封口、分容，得到锂离子电池。
实施例19还提供了一种锂离子电池循环性能的测试方法，包括以下步骤：
(1)在25℃下，将化成后的电池按照1C恒流恒压充电至4.35V，截止电 流0.05C,然后1C恒流放电至3V。充放电800个循环后，计算第800次循环后的放电容量保持率。
25℃下放电容量保持率(％)＝第800次循环后的放电容量/首次循环后的放电容量×100％
(2)在45℃下，将化成后的电池按照1C恒流恒压充电至4.35V，截止电流0.05C,然后1C恒流放电至3V。充放电400个循环后，计算第400次循环后的放电容量保持率。
45℃下放电容量保持率(％)＝第400次循环后的放电容量/首次循环后的放电容量×100％。
实施例20-24及对比例13-16
相比于实施例19，实施例20-24及对比例13-16的不同之处在于，电池电解液中的添加剂组合物配方不同。实施例20-24及对比例13-16的锂离子电池均使用LiNi0.5Co0.2Mn0.3O2为正极材料，实施例20-24及对比例13-16的锂离子电池性能测试方法均与实施例19相同。
实施例19-24及对比例13-16的添加剂组合物配方和电池性能检测结果见表4。
表4实施例19-24及对比例13-16的添加剂组合物配方和电池性能检测结果表

从表3和表4中实施例13-24和对比例9-16的测试结果可以看出，含有本申请提供的添加剂组合物的电解液的电池，无论是对磷酸铁锂体系的电池，还是镍钴锰三元体系的电池，常温容量保持率都较对比例高。在以磷酸铁锂体系的电池中，低温下的容量保持率，相较于对比例，有非常显著的提升。在镍钴锰三元体系的电池中，高温容量保持率也有较好的改善效果。
实施例25
电解液的制备方法包括以下步骤：
步骤1：在充满氮气或氩气的手套箱中，手套箱中的水和氧含量都≤0.1ppm，将碳酸乙烯酯、碳酸甲乙酯和碳酸二甲酯混合均匀，得到有机溶剂混合液；碳酸乙烯酯、碳酸甲乙酯和碳酸二甲酯的体积比为1：1：1。向有机溶剂混合液中加入六氟磷酸锂，混合均匀得到基础电解液，基础电解液中，六氟磷酸锂的浓度为1mol/L。
步骤2：依然在充满氮气或氩气的手套箱中，手套箱中的水和氧含量都≤0.1ppm，向基础电解液中加入添加剂组合物中的不饱和环状碳酸酯和添加剂组合物中的不饱和链状碳酸酯，混合均匀，得到电解液。
其中，实施例25中不饱和链状碳酸酯是式(2-a)的化合物，不饱和环状碳酸酯是式(1-a)的化合物。且最终电解液中，不饱和链状碳酸酯的质量百分含量为1％，不饱和环状碳酸酯的质量百分含量为1％。
实施例25还提供了一种锂离子电池的制作方法，包括以下步骤：
在水和氧含量都≤0.1ppm的充满氮气或氩气的手套箱中，将制备好的电解液注入由LiFePO4作为正极材料，人造石墨作为负极的锂离子电池电芯内。注液完成后封口静置、化成、老化、二次封口、分容，得到锂离子电池。
实施例25还提供了一种锂离子电池高温储存性能的测试方法，包括以下步骤：
在25℃下，将电池按0.5C恒流恒压充电至3.65V，截止电流0.05C，再0.5C 恒流放电至2V，记录放电容量，即为初始放电容量。然后再0.5C恒流恒压充至3.65V。将充满电的电池放置在60℃恒温环境中，存储7天。7天后取出，在25℃下静置4h，等电池冷却至室温后，按0.5C恒流放电至2V，记录放电容量，即为保持容量。按0.5C恒流恒压充电至3.65V，截止电流0.05C，再0.5C恒流放电至2V，记录放电容量，即为恢复容量。
电池容量保持率(％)＝保持容量/初始容量×100％
电池容量恢复率(％)＝恢复容量/初始容量×100％。
实施例26-30及对比例17-20
相比于实施例25，实施例26-30及对比例17-20的不同之处在于，电池电解液中的添加剂组合物配方不同。实施例26-30及对比例17-20的锂离子电池均使用LiFePO4为正极材料，实施例26-30及对比例17-20的锂离子电池性能测试方法均与实施例26相同。
实施例25-30及对比例17-20的添加剂组合物配方和电池性能检测结果见表5。
表5实施例25-30及对比例17-20的添加剂组合物配方和电池性能检测结果表

实施例31
电解液的制备方法包括以下步骤：
步骤1：在充满氮气或氩气的手套箱中，手套箱中的水和氧含量都≤0.1ppm，将碳酸乙烯酯、碳酸甲乙酯和碳酸二甲酯混合均匀，得到有机溶剂混合液；碳酸乙烯酯、碳酸甲乙酯和碳酸二甲酯的体积比为1：1：1。向有机溶剂混合液中加入六氟磷酸锂，混合均匀得到基础电解液，基础电解液中，六氟磷酸锂的浓度为1mol/L。
步骤2：依然在充满氮气或氩气的手套箱中，手套箱中的水和氧含量都≤0.1ppm，向基础电解液中加入添加剂组合物中的不饱和环状碳酸酯和添加剂组合物中的不饱和链状碳酸酯，混合均匀，得到电解液。
其中，实施例31中不饱和链状碳酸酯是式(2-b)的化合物，不饱和环状碳酸酯是式(1-a)的化合物。且最终电解液中，不饱和链状碳酸酯的质量百分含量为1％，不饱和环状碳酸酯的质量百分含量为1％。
实施例31还提供了一种锂离子电池的制作方法，包括以下步骤：
在水和氧含量都≤0.1ppm的充满氮气或氩气的手套箱中，将制备好的电解液注入由LiNi0.5Co0.2Mn0.3O2作为正极材料，人造石墨作为负极的锂离子电池电芯内。注液完成后封口静置、化成、老化、二次封口、分容，得到锂离子电池。
实施例31还提供了一种锂离子电池高温储存性能的测试方法，包括以下步骤：
在25℃下，将电池按0.5C恒流恒压充电至4.35V，截止电流0.05C，再0.5C恒流放电至3V，记录放电容量，即为初始放电容量。然后再0.5C恒流恒压充至4.35V，测量电池初始厚度。将充满电的电池放置在60℃恒温环境中，存储7天。7天后取出，在25℃下静置4h，等电池冷却至室温后，测量储存后的电池厚度。按0.5C恒流放电至3V，记录放电容量，即为保持容量。按0.5C恒流恒压充电至4.35V，截止电流0.05C，再0.5C恒流放电至3V，记录放电容量，即为恢复容量。
电池容量保持率(％)＝保持容量/初始容量×100％
电池容量恢复率(％)＝恢复容量/初始容量×100％
厚度膨胀率(％)＝(储存后厚度-初始厚度)/初始厚度×100％。
实施例32-36及对比例21-24
相比于实施例31，实施例32-36及对比例21-24的不同之处在于，电池电解液中的添加剂组合物配方不同。实施例32-36及对比例21-24的锂离子电池均使用LiNi0.5Co0.2Mn0.3O2为正极材料，实施例32-36及对比例21-24的锂离子电池性能测试方法均与实施例31相同。
实施例31-36及对比例21-24的添加剂组合物配方和电池性能检测结果见表6。
表6实施例31-36及对比例21-24的添加剂组合物配方和电池性能检测结果表
从表5和表6中实施例25-36和对比例17-24的测试结果可以看出，对比例高温储存后的容量保持率和容量恢复率表现得一般，而含有本申请提供添加剂组合物的电解液的电池，正极材料无论是磷酸铁锂还是镍钴锰三元体系，高 温储存性能都能得到改善，并且高温储存后的胀气也得到抑制。
综上，本申请将不饱和环状碳酸酯和不饱和链状碳酸酯作为添加剂组合物，并将添加剂组合物用于锂离子电池电解液。在合适的配比下，可使锂离子电池具有较低的阻抗，优良的循环性能，尤其是低温循环性能，并且可抑制电解液分解造成的气胀，提高电池高温循环以及高温储存性能。
本具体实施例仅仅是对本申请的解释，其并不是对本申请的限制，本领域技术人员在阅读完本说明书后可以根据需要对本实施例做出没有创造性贡献的修改，但只要在本申请的权利要求范围内都受到专利法的保护。

Claims (9)

  1. 一种锂离子电池的电解液添加剂组合物，其特征在于：包括不饱和环状碳酸酯和不饱和链状碳酸酯；
    所述不饱和环状碳酸酯包括以下化合物中的至少一种：
    所述不饱和链状碳酸酯的结构通式如下：
    其中，R1为含有1-6个碳原子的烃基或氟代烃基，R2为含有1-6个碳原子的烃基或氟代烃基；A基团是亚乙烯基或亚乙炔基。
  2. 根据权利要求1所述的一种锂离子电池的电解液添加剂组合物，其特征在于：所述不饱和链状碳酸酯为以下化合物中的至少一种：

  3. 根据权利要求1所述的一种锂离子电池的电解液添加剂组合物，其特征在于：所述不饱和环状碳酸酯和所述不饱和链状碳酸酯的质量比为(0.5-5)：(0.05-10)。
  4. 一种锂离子电池电解液，其特征在于：包括锂盐电解质、有机溶剂和如权利要求1-3任意一项所述的添加剂组合物。
  5. 根据权利要求4所述的一种锂离子电池电解液，其特征在于：所述添加剂组合物中的不饱和环状碳酸酯在所述电解液中的质量占比为0.5％-5％，所述添加剂组合物中的不饱和链状碳酸酯在所述电解液中的质量占比为0.05％-10％。
  6. 根据权利要求4所述的一种锂离子电池电解液，其特征在于：所述有机溶剂为碳酸二甲酯、碳酸二乙酯、碳酸二丙酯、碳酸乙烯酯、碳酸甲乙酯、碳酸 甲丙酯、碳酸甲丁酯、碳酸丙烯酯、γ-丁内酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、乙酸丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丁酸甲酯、丁酸乙酯、乙酸二氟乙酯、乙酸三氟乙酯、三氟乙基甲基碳酸酯、双三氟乙基碳酸酯中的至少一种。
  7. 根据权利要求4所述的一种锂离子电池电解液，其特征在于：所述锂盐电解质为六氟磷酸锂、四氟硼酸锂、二氟磷酸锂、高氯酸锂、六氟砷酸锂、双氟磺酰亚胺锂、双(三氟甲基磺酰)亚胺锂、双草酸硼酸锂、二氟草酸硼酸锂、四氟草酸磷酸锂、二氟双草酸磷酸锂、氟磺酰(三氟甲基磺酰)亚胺锂中的至少一种；其中，电解液中电解质的摩尔浓度为0.5-2mol/L。
  8. 一种如权利要求4-7任意一项所述的锂离子电池电解液的应用，其特征在于，所述锂离子电池电解液用于以磷酸铁锂、锰酸锂、钴酸锂、镍钴锰酸锂、镍钴铝酸锂、镍钴锰铝酸锂、磷酸锰铁锂作为正极的锂离子电池中。
  9. 根据权利要求8所述的应用，其特征在于，所述锂离子电池电解液用于以碳材料或硅基材料为负极的锂离子电池中。
PCT/CN2023/108148 2022-12-16 2023-07-19 一种锂离子电池的电解液添加剂组合物及含该添加剂组合物的电解液及电解液的应用 WO2024124903A1 (zh)

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