WO2022110709A1 - 组合物、包含该组合物的电解液及锂离子电池 - Google Patents

组合物、包含该组合物的电解液及锂离子电池 Download PDF

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WO2022110709A1
WO2022110709A1 PCT/CN2021/096277 CN2021096277W WO2022110709A1 WO 2022110709 A1 WO2022110709 A1 WO 2022110709A1 CN 2021096277 W CN2021096277 W CN 2021096277W WO 2022110709 A1 WO2022110709 A1 WO 2022110709A1
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group
lithium
butyl
electrolyte
carbonate
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PCT/CN2021/096277
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English (en)
French (fr)
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曹哥尽
范伟贞
赵经纬
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广州天赐高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
    • H01M10/056—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
    • H01M10/42—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 present invention relates to the technical field of batteries, and in particular, to a composition, an electrolyte containing the composition, and a lithium ion battery.
  • the lithium-ion battery has the advantages of high energy density, high charging efficiency, long cycle life, etc., coupled with the growing market demand and policy orientation in recent years, so that the lithium-ion battery has been vigorously promoted , is widely used in power, energy storage, aerospace, digital and other fields.
  • composition an electrolyte containing the composition, and a lithium ion battery.
  • the composition can be added as an additive to the electrolyte, which can effectively improve the high temperature and low temperature performance of the battery.
  • a composition consisting of a first component and a second component, the first component includes at least one sulfur-containing compound of the structure shown in formula (I), and the second component includes at least one formula (II) the cyclic carbonate compound of the structure shown;
  • X 1 , X 2 are each independently a single bond, -(CR a R b ) n -, -O(CR a R b ) n -, -O-, -COO- or -NHCO-; and X 1 , X 2 is not a single key at the same time;
  • n 1 or 2;
  • R a , R b , R 1 , R 2 , R 3 , R 4 and R 5 are each independently selected from: hydrogen atom, C 1-8 alkyl, C 2-8 alkenyl, halogen, halogen-substituted C 1- 8 alkyl, hydroxyl, nitrile, phenyl, sulfonyl, fluorosulfonyl, sulfonic acid, or fluorosulfonic acid group;
  • R 6 is selected from: a hydrogen atom, a C 1-8 alkyl group, a halogen-substituted C 1-8 alkyl group or a phenyl group.
  • the sulfur-containing compound is selected from the sulfur-containing compounds represented by any of the formulae (I-1) to (I-9):
  • R a and R b are each independently selected from: a hydrogen atom, methyl, ethyl, propyl, fluoro, sulfonyl, fluorosulfonyl, sulfonic acid, or fluorosulfonic acid base;
  • R 1 , R 2 , R 3 and R 4 are each independently selected from: a hydrogen atom, a fluoro group, a hydroxyl group, a nitrile group, a phenyl group, a methyl group, an ethyl group, a propyl group, a vinyl group, a propenyl group, a sulfonyl group, a fluoro group sulfonyl group, sulfonic acid group, or fluorosulfonic acid group.
  • R 5 is selected from: hydrogen atom, fluoro, methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl, sec-butyl, tert-butyl , isopentyl, isohexyl, fluoromethyl, fluoroethyl, fluoropropyl, fluorobutyl, fluoropentyl, fluorohexyl, fluoroisopropyl, fluoroisobutyl, fluoro Substituted sec-butyl, fluoro-t-butyl, fluoroisoamyl or fluoroisohexyl;
  • R 6 is selected from: hydrogen atom, methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, isohexyl, fluoro Methyl, fluoroethyl, fluoropropyl, fluorobutyl, fluoropentyl, fluorohexyl, fluoroisopropyl, fluoroisobutyl, fluorosec-butyl, fluorotert-butyl , fluoroisoamyl or fluoroisohexyl.
  • At least one of R 5 and R 6 is selected from any of the following groups: H, F, -CF 3 , -CH 2 CF 3 , -CF 2 CF 3 , -CH 2 CH 2 CF 3 , -CF 2 CH 2 CF 3 , -CH 2 CF 2 CF 3 or -CF 2 CF 2 CF 3 .
  • the first component includes at least one of the following compounds:
  • the second component includes at least one of the following compounds:
  • the second component includes at least one of the following compounds:
  • An electrolyte solution comprising additives, the additives are the above-mentioned composition.
  • the above-mentioned electrolyte further includes a lithium salt and a solvent.
  • the additive in terms of mass percentage, the additive is 0.01%-30%, and the lithium salt is 5%-20%. %, the solvent is 50%-94.9%.
  • the lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis-oxalate borate, lithium difluorophosphate, lithium difluorooxalate phosphate, and lithium bisfluorosulfonimide; and /or
  • the solvent includes a cyclic solvent and/or a linear solvent; wherein, the cyclic solvent is selected from: ethylene carbonate, propylene carbonate, ⁇ -butyrolactone, phenyl acetate, 1,4-butylsulfonic acid At least one of lactone and 3,3,3-trifluoropropylene carbonate; the linear solvent is selected from dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, ethyl acetate, methyl propyl carbonate , Propionate, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 2,2-difluoroethyl acetate, 2,2-difluoroethyl acetate At least one of fluoroethyl propionate and 2,2-difluoroethyl methyl carbonate.
  • the cyclic solvent is selected from: ethylene carbonate, propylene carbonate,
  • a lithium ion battery includes a positive electrode material, a negative electrode material and the above-mentioned electrolyte.
  • the above composition can effectively improve the high temperature and low temperature cycle performance of the battery at the same time by using the sulfur-containing compound of the formula (I) and the cyclic carbonate of the structure of the formula (II). internal resistance. specifically:
  • the alkylated lithium sulfate generated by the decomposition of the sulfur-containing compound represented by formula (I) introduces S element into the SEI film, which increases the ionic conductivity and reduces the battery impedance;
  • the surface of the negative electrode can form a stable, uniform and thin SEI film, which can inhibit the decomposition of the solvent in the electrolyte, and the unsaturated bond can passivate the surface of the positive electrode, inhibit the dissolution of the metal ions of the positive electrode, and reduce the active substances in the high oxidation state.
  • the decomposition of the solvent can improve the high temperature performance of the battery, especially the high temperature cycle performance.
  • the cyclic carbonate with the structure shown in formula (II) can also form an SEI film on the surface of the negative electrode of the battery, thereby improving the low temperature performance of the battery, especially when the structure shown in formula (II) is used.
  • the compound is a fluorine-containing compound
  • the presence of this component reduces the freezing point of the electrolyte, increases the flash point, improves the oxidation stability, and enhances the compatibility between the electrolyte and the electrode.
  • the de-intercalation and de-insertion become smooth, so the battery impedance can be further reduced, so as to improve the low-temperature cycle effect of the battery.
  • the above composition can not only improve the high temperature and low temperature performance of the battery at the same time, but also can significantly reduce the internal resistance of the battery when the two interact. At the same time, the disadvantages of high temperature and low temperature performance of the battery are improved.
  • Fig. 1 is the dQ/dV curve diagram of embodiment 1, embodiment 2 and comparative example 2;
  • FIG. 2 is a graph of impedance curves of Example 1, Example 2 and Comparative Example 2.
  • FIG. 2 is a graph of impedance curves of Example 1, Example 2 and Comparative Example 2.
  • alkyl refers to a saturated hydrocarbon containing primary (normal) carbon atoms, or secondary carbon atoms, or tertiary carbon atoms, or quaternary carbon atoms, or a combination thereof. Phrases containing this term, for example, "C1-8 alkyl” refers to an alkyl group containing 1 to 8 carbon atoms.
  • Suitable examples include, but are not limited to: methyl (Me, -CH3 ), ethyl (Et, -CH2CH3), 1 -propyl (n-Pr, n - propyl, -CH2CH2CH ) 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 2 CH 3 ), 2-p
  • Halogen or halo refers to F, Cl, Br, or I.
  • Halo-substituted means that an optional number of H at any selected position on the corresponding group is substituted with a halogen, eg, fluoromethyl, including monofluoromethyl, difluoromethyl, trifluoromethyl.
  • a halogen eg, fluoromethyl, including monofluoromethyl, difluoromethyl, trifluoromethyl.
  • An embodiment of the present invention provides a composition, which is composed of a first component and a second component, the first component includes at least one sulfur-containing compound of the structure represented by formula (I), and the second component includes at least one A cyclic carbonate compound of the structure shown in formula (II);
  • X 1 , X 2 are each independently a single bond, -(CR a R b ) n -, -O(CR a R b ) n -, -O-, -COO- or -NHCO-; and X 1 , X 2 is not a single key at the same time;
  • n 1 or 2;
  • R a , R b , R 1 , R 2 , R 3 , R 4 and R 5 are each independently selected from: hydrogen atom, C 1-8 alkyl, C 2-8 alkenyl, halogen, halogen-substituted C 1- 8 alkyl, hydroxyl, nitrile, phenyl, sulfonyl, fluorosulfonyl, sulfonic acid, or fluorosulfonic acid group;
  • R 6 is selected from: a hydrogen atom, a C 1-8 alkyl group, a halogen-substituted C 1-8 alkyl group or a phenyl group.
  • sulfur-containing compound is selected from the sulfur-containing compounds represented by any of the structures of formulae (I-1) to (I-9):
  • R a and R b are each independently selected from: a hydrogen atom, a methyl group, an ethyl group, a propyl group, a fluoro group, a sulfonyl group, a fluorosulfonyl group, a sulfonic acid group, or a fluorosulfonic acid group; further Typically, at least one of R a and R b is H; further, both R a and R b are H.
  • R 1 , R 2 , R 3 and R 4 are each independently selected from: hydrogen atom, C 1-6 alkyl group, C 2-6 alkenyl group, fluorine, fluorine atom-substituted C 1-6 alkyl group, hydroxyl group , nitrile group, phenyl group, sulfonyl group, fluorosulfonyl group, sulfonic acid group, fluorosulfonic acid group;
  • R 1 , R 2 , R 3 and R 4 are each independently selected from: a hydrogen atom, a fluoro group, a hydroxyl group, a nitrile group, a phenyl group, a methyl group, an ethyl group, a propyl group, a vinyl group, a propenyl group, a sulfonic group Acyl, fluorosulfonyl, sulfonic acid, or fluorosulfonic acid group.
  • R 1 , R 2 , R 3 and R 4 are all hydrogen atoms or fluorine groups; in one embodiment, three of R 1 , R 2 , R 3 and R 4 are hydrogen atoms, and there are One is selected from any of the following groups: C 1-8 alkyl, C 2-8 alkenyl, halogen, halogen-substituted C 1-8 alkyl, hydroxyl, nitrile, phenyl, sulfonyl, fluorosulfonyl, sulfonic acid group, or fluorosulfonic acid group;
  • R 1 , R 2 and R 3 are hydrogen atoms, and R 4 is C 2-8 alkenyl; further, R 4 is vinyl.
  • the first component includes at least one of the following compounds:
  • R 5 is selected from: hydrogen atom, C 1-8 alkyl, C 2-8 alkenyl, halogen, halogen-substituted C 1-8 alkyl, hydroxyl, nitrile, phenyl, sulfonyl, fluorosulfonic Acyl group, sulfonic acid group, or fluorosulfonic acid group; furthermore, R 5 is selected from: hydrogen atom, fluoro group, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, isopropyl group, isopropyl group Butyl, sec-butyl, tert-butyl, isopentyl, isohexyl, fluoromethyl, fluoroethyl, fluoropropyl, fluorobutyl, fluoropentyl, fluorohexyl, fluoroiso propyl, fluoroisobutyl, fluorose
  • R 6 is selected from: a hydrogen atom, a C 1-6 alkyl group or a halogen-substituted C 1-6 alkyl group.
  • R 6 is selected from: hydrogen atom, methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, isohexyl , fluoromethyl, fluoroethyl, fluoropropyl, fluorobutyl, fluoropentyl, fluorohexyl, fluoroisopropyl, fluoroisobutyl, fluorosec-butyl, fluoro tert-butyl, fluoroisoamyl or fluoroisohexyl.
  • At least one of R 5 and R 6 is selected from groups containing fluorine elements; the cyclic carbonate compound composed of R 5 and R 6 containing fluorine atoms can reduce the freezing point of the electrolyte and improve the oxidative stability of the electrolyte. , and improve the wettability between the electrolyte and the electrode, which is more favorable to improve the low-temperature cycle performance of lithium-ion batteries.
  • R 5 and R 6 is selected from any of the following groups: H, F, -CF 3 , -CH 2 CF 3 , -CF 2 CF 3 , -CH 2 CH 2 CF 3 , - CF 2 CH 2 CF 3 , -CH 2 CF 2 CF 3 or -CF 2 CF 2 CF 3 .
  • cyclic carbonate compound has any of the following structures:
  • R 5 is selected from: H, C 1-4 alkyl, F, fluoro C 1-4 alkyl; further, R 5 Selected from: H, methyl, ethyl, propyl, isopropyl, F or trifluoromethyl.
  • the second component includes at least one of the following compounds:
  • the first component is I2, and the second component is II1; in one embodiment, the first component is I5, and the second component is II1; in one embodiment, the first component is is I7, and the second component is II1; in one embodiment, the first component is I9, and the second component is II1; in one embodiment, the first component is I11, and the second component is II1; In one embodiment, the first component is I2 and I5, and the second component is II1; in one embodiment, the first component is I7, and the second component is II4; in one embodiment, the first component is The component is I7 and the second component is II6.
  • the mass ratio of the above-mentioned first component and the second component is 1:(0.1-100); Further, the mass ratio of the above-mentioned first component and the second component is 1:(1-15); Further, the mass ratio of the first component and the second component is 1:(1-10); further, the mass ratio of the first component and the second component is 1:1.
  • the present invention also provides an electrolyte solution, including the above-mentioned composition, the composition is as described above and will not be repeated here.
  • the above electrolyte also includes a lithium salt and a solvent; further, in the electrolyte, in terms of mass percentage, the additive is 0.01%-30%, the lithium salt is 5%-20%, and the solvent is 50% -94.9%; further, the mass percentage of the first component is 0.01%-10%; further, the mass percentage of the first component is 0.03%-5%; further, the first component The mass percentage of the components is 1%-3%; further, the mass percentage of the second component is 0.01%-20%; further, the mass percentage of the first component is 0.1% -18%; further, the mass percentage of the first component is 1%-15%.
  • the technical personnel of the present invention found in the research that when the mass percentage of the first component is too high (over 10%), the SEI film formed will be too thick, which in turn will increase the impedance of the battery. If the content is too high, the solubility of lithium salts or additives will decrease, and if the content of each component of the composition is too low, the effect of improving the internal resistance and high and low temperature cycle performance of lithium ion batteries will be poor. Therefore, the content of each component of the additive should be controlled. Within the above range, the internal resistance and high and low temperature cycle performance of the battery can be more effectively improved to obtain better comprehensive performance.
  • the lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis-oxalate borate, lithium difluorophosphate, lithium difluorooxalate phosphate, and lithium bisfluorosulfonimide.
  • the solvent is selected from cyclic solvents and/or linear solvents; further, the cyclic solvent is selected from: ethylene carbonate, propylene carbonate, ⁇ -butyrolactone, phenyl acetate, 1,4- At least one of butyl sultone and 3,3,3-trifluoropropylene carbonate; further, the linear solvent is selected from dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl acetate ester, methyl propyl carbonate, propyl propionate, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 2,2-difluoroethyl acetate , at least one of 2,2-difluoroethyl propionate and 2,2-difluoroethyl methyl carbonate.
  • Another embodiment of the present invention also provides a lithium ion battery, including: a positive electrode material; a negative electrode material; and the above electrolyte.
  • the positive electrode material of the lithium ion battery includes Li 1+a (Nix Co y M 1-xy ) O 2 , Li(Ni p Mn q Co 2-pq )O 4 and LiM h (PO 4 ) One or more of m ; wherein 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 one or more of carbon, silicon-based negative electrode material and tin-based negative electrode material.
  • the lithium ion battery of the present invention by using the electrolyte solution containing the above-mentioned sulfur-containing compound and cyclic carbonate compound, in the joint action of the two, on the one hand, a stable SEI film is formed on the negative electrode, and on the other hand, the freezing point of the electrolyte solution is reduced, The wettability between the electrolyte and the electrode is improved, and the impedance of the battery is reduced, so that the above-mentioned lithium ion battery has good high temperature and low temperature cycle performance.
  • the additives are selected from the above-mentioned chemical formula I2 and chemical formula II1, and the additives I2 and II1 account for 0.03% and 1% of the weight of the electrolyte respectively;
  • the lithium salt is lithium hexafluorophosphate, and the lithium salt accounts for 13% of the weight of the electrolyte;
  • the solvent is A solvent obtained by mixing ethylene carbonate and dimethyl carbonate in a weight ratio of 1:2;
  • the positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1 O 2 ;
  • the negative electrode material is artificial graphite; and the diaphragm is a polyethylene film.
  • the pouch battery is assembled according to the conventional method.
  • the additives are selected from the above-mentioned chemical formula I2 and chemical formula II1, and the additives I2 and II1 account for 1% and 0.1% of the weight of the electrolyte respectively;
  • the lithium salt is lithium hexafluorophosphate, and the lithium salt accounts for 13% of the weight of the electrolyte;
  • the solvent is A solvent obtained by mixing ethylene carbonate and dimethyl carbonate in a weight ratio of 1:2;
  • the positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1 O 2 ;
  • the negative electrode material is artificial graphite; and the diaphragm is a polyethylene film.
  • the pouch battery is assembled according to the conventional method.
  • the additives are selected from the above-mentioned chemical formula I2 and chemical formula II1, and the additives I2 and II1 account for 1% and 1% of the weight of the electrolyte respectively;
  • the lithium salt is lithium hexafluorophosphate, and the lithium salt accounts for 13% of the weight of the electrolyte;
  • the solvent is A solvent obtained by mixing ethylene carbonate and dimethyl carbonate in a weight ratio of 1:2;
  • the positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1 O 2 ;
  • the negative electrode material is artificial graphite; and the diaphragm is a polyethylene film.
  • the pouch battery is assembled according to the conventional method.
  • the additives are selected from the above chemical formula I2 and chemical formula II1, the additives I2 and II1 account for 5% and 15% of the weight of the electrolyte respectively;
  • the lithium salt is lithium hexafluorophosphate, and the lithium salt accounts for 13% of the weight of the electrolyte;
  • the solvent is A solvent obtained by mixing ethylene carbonate and dimethyl carbonate in a weight ratio of 1:2;
  • the positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1 O 2 ;
  • the negative electrode material is artificial graphite;
  • the diaphragm is a polyethylene film.
  • the pouch battery is assembled according to the conventional method.
  • the additive is selected from the above-mentioned chemical formula I5 and chemical formula II1, the additives I5 and II1 respectively account for 1% and 1% of the weight of the electrolyte; the lithium salt is lithium hexafluorophosphate, and the lithium salt accounts for 13% of the weight of the electrolyte;
  • the solvent is A solvent obtained by mixing ethylene carbonate and dimethyl carbonate in a weight ratio of 1:2; the positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1 O 2 ; the negative electrode material is artificial graphite; and the diaphragm is a polyethylene film.
  • the pouch battery is assembled according to the conventional method.
  • the additives are selected from the above-mentioned chemical formula I9 and chemical formula II1, and the additives I9 and II1 account for 1% and 1% of the weight of the electrolyte respectively;
  • the lithium salt is lithium hexafluorophosphate, and the lithium salt accounts for 13% of the weight of the electrolyte;
  • the solvent is A solvent obtained by mixing ethylene carbonate and dimethyl carbonate in a weight ratio of 1:2;
  • the positive electrode material is LiNi0.8Co0.1Mn0.1O2;
  • the negative electrode material is artificial graphite;
  • the diaphragm is a polyethylene film.
  • the pouch battery is assembled according to the conventional method.
  • the additives are selected from the above-mentioned chemical formula I11 and chemical formula II1, the additives I9 and II1 respectively account for 1% and 1% of the weight of the electrolyte; the lithium salt is lithium hexafluorophosphate, and the lithium salt accounts for 13% of the weight of the electrolyte; the solvent is A solvent obtained by mixing ethylene carbonate and dimethyl carbonate in a weight ratio of 1:2; the positive electrode material is LiNi0.8Co0.1Mn0.1O2; the negative electrode material is artificial graphite; and the diaphragm is a polyethylene film.
  • the pouch battery is assembled according to the conventional method.
  • the additives are selected from the above-mentioned chemical formulas I2, I5 and chemical formula III1, and the additives I2, I5 and II1 respectively account for 1%, 1% and 1% of the weight of the electrolyte;
  • the lithium salt is lithium hexafluorophosphate, and the lithium salt accounts for the weight of the electrolyte. 13% by weight;
  • the solvent is a mixture of ethylene carbonate and dimethyl carbonate in a weight ratio of 1:2;
  • the positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1 O 2 ;
  • the negative electrode material is artificial graphite;
  • the separator is polyethylene membrane.
  • the pouch battery is assembled according to the conventional method.
  • the additives are selected from the above-mentioned chemical formula I7 and chemical formula II1, the additives I7 and II1 respectively account for 1% and 1% of the weight of the electrolyte; the lithium salt is lithium hexafluorophosphate, and the lithium salt accounts for 13% of the weight of the electrolyte; the solvent is A solvent obtained by mixing ethylene carbonate and dimethyl carbonate in a weight ratio of 1:2; the positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1 O 2 ; the negative electrode material is artificial graphite; and the diaphragm is a polyethylene film.
  • the pouch battery is assembled according to the conventional method.
  • the additive is selected from the above-mentioned chemical formula I7 and chemical formula II4, the additives I7 and II4 account for 1% and 1% of the weight of the electrolyte respectively;
  • the lithium salt is lithium hexafluorophosphate, and the lithium salt accounts for 13% of the weight of the electrolyte;
  • the solvent is A solvent obtained by mixing ethylene carbonate and dimethyl carbonate in a weight ratio of 1:2;
  • the positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1 O 2 ;
  • the negative electrode material is artificial graphite;
  • the diaphragm is a polyethylene film.
  • the pouch battery is assembled according to the conventional method.
  • the additives are selected from the above-mentioned chemical formula I7 and chemical formula II6, the additives I7 and II6 respectively account for 1% and 1% of the weight of the electrolyte; the lithium salt is lithium hexafluorophosphate, and the lithium salt accounts for 13% of the weight of the electrolyte; the solvent is A solvent obtained by mixing ethylene carbonate and dimethyl carbonate in a weight ratio of 1:2; the positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1 O 2 ; the negative electrode material is artificial graphite; and the diaphragm is a polyethylene film.
  • the pouch battery is assembled according to the conventional method.
  • the additives are selected from the above-mentioned chemical formula I7 and chemical formula II4, and the additives I7 and II4 account for 1% and 1% of the weight of the electrolyte respectively;
  • the lithium salts are lithium hexafluorophosphate and lithium bisfluorosulfonimide, lithium hexafluorophosphate and bisfluorosulfonic acid Lithium imide accounts for 12% and 1% of the weight of the electrolyte, respectively;
  • the solvent is a mixture of ethylene carbonate and dimethyl carbonate in a weight ratio of 1:2;
  • the positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1 O 2 ;
  • the negative electrode material is artificial graphite;
  • the diaphragm is polyethylene film.
  • the pouch battery is assembled according to the conventional method.
  • the additives are selected from the above-mentioned chemical formula I7 and chemical formula II4, and the additives I7 and II4 account for 1% and 1% of the weight of the electrolyte respectively;
  • the lithium salts are lithium hexafluorophosphate and lithium bisfluorosulfonimide, lithium hexafluorophosphate and bisfluorosulfonic acid Lithium imide accounts for 12% and 1% of the weight of the electrolyte, respectively;
  • the solvent is a mixture of ethylene carbonate and 2,2-difluoroethyl acetate in a weight ratio of 1:2;
  • the positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1 O 2 ;
  • the negative electrode material is artificial graphite;
  • the separator is a polyethylene film.
  • the pouch battery is assembled according to the conventional method.
  • Comparative Example 1 Compared with Example 1, the difference of Comparative Example 1 is that the electrolyte does not contain compounds of general formula I and general formula II.
  • Comparative Example 2 Compared with Example 1, the difference of Comparative Example 2 is that the additive is a vinylene carbonate (VC) additive in an amount of 1% by weight of the electrolyte.
  • VC vinylene carbonate
  • Comparative Example 3 Compared with Example 1, the difference of Comparative Example 3 is that the additive is a vinyl sulfate (DTD) additive of 1% by weight of the electrolyte.
  • DTD vinyl sulfate
  • Comparative Example 4 Compared with Example 1, the difference of Comparative Example 4 is that the additives are vinylene carbonate (VC) and vinyl sulfate (DTD) additives which account for 1% by weight of the electrolyte, respectively.
  • VC vinylene carbonate
  • DTD vinyl sulfate
  • Comparative Example 5 is different in that the additive is I2 at 1% by weight of the electrolyte.
  • Comparative Example 6 is different in that the additive is II1 at 1% by weight of the electrolyte.
  • High temperature cycle performance Place the divided lithium-ion battery in an incubator at 45°C, charge it to 4.2V with a constant current and voltage of 1C, and then discharge it to 3.0V with a constant current of 1C for 600 cycles. Determination of the capacity retention rate of lithium-ion batteries.
  • Low temperature cycle performance place the divided lithium-ion battery in a -10°C incubator, discharge it to 2.5V at a current of 0.5C, and then charge it to 4.2V at a constant current and voltage of 0.2C, and cycle After 100 weeks, the capacity retention rate of the lithium-ion battery was measured.
  • the dQ/dV curve is to differentiate the capacity and voltage of the battery during the precharging process, and the obtained graph can directly observe the reduction reaction of the lithium-ion battery electrolyte during the charging process.
  • Example 1 and Example 2 have obvious reduction peaks, indicating that the cyclic carbonate represented by Formula II can be preferentially reduced on the negative electrode surface to form an SEI film. It can be seen from FIG. 2 that, compared with Comparative Example 2, Example 1 and Example 2 have the effect of significantly reducing the battery impedance. It is illustrated that the additives in the above embodiments can form an SEI film on the negative electrode, reduce the battery impedance, and then play a role in improving the high temperature and low temperature cycle performance of the battery.

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Abstract

一种组合物、包含该组合物的电解液及锂离子电池，该组合物由第一组分和第二组分组成，第一组分包括至少一种式(I)所示结构的含硫化合物，第二组分包括至少一种式(II)所示结构的环状碳酸酯化合物；该组合物作为添加剂添加到电解液中，能够有效改善电池的高温和低温性能。

Description

组合物、包含该组合物的电解液及锂离子电池 技术领域
本发明涉及电池技术领域，特别涉及组合物、包含该组合物的电解液及锂离子电池。
背景技术
作为新型储能器件之一的锂离子电池，由于其本身具有能量密度高、充电效率高、循环寿命长等优点，加上近年来日益增长的市场需求与政策导向，使得锂离子电池得到大力推广，被广泛应用于动力、储能、航天、数码等领域。
锂离子电池的应用领域与应用环境不断扩大，人们对电池的性能的需求不断提高，如较低的电池内阻、优异的高温和低温循环寿命。一般来说，含硫类添加剂对降低电池阻抗有一定作用，进而改善电池的高温性能和低温放电性能。三井化学报道了使用环状硫酸酯化合物作为添加剂来抑制电池初始电阻，进而改善电池的输出特性。硫酸乙烯酯作为有代表性的环状的硫酸酯添加剂，对电池高温性能和低温放电性能均有一定的改善，同时具有一定的降低电池阻抗作用。由于其本身不稳定性，加上含硫类添加剂虽然对高温性能和低温放电性能有一定改善作用，但对低温循环改善效果欠佳，使得满足不了人们的新需求。
因此，兼顾继续开发一种能够改善电池高温和低温循环性能的电解液。
发明内容
基于此，有必要提供一种组合物、包含该组合物的电解液及锂离子电池，该组合物能够作为添加剂添加如电解液中，能够有效地改善电池高温和低温性能。
一种组合物，由第一组分和第二组分组成，所述第一组分包括至少一种式(I)所示结构的含硫化合物，所述第二组分包括至少一种式(II)所示结构的环状碳酸酯化合物；
Figure PCTCN2021096277-appb-000001
X 1、X 2各自独立地为单键、-(CR aR b) n-、-O(CR aR b) n-、-O-、-COO-或-NHCO-；且X 1、X 2不同时为单键；
n为1或2；
R a、R b、R 1、R 2、R 3、R 4和R 5各自独立地选自：氢原子、C 1-8烷基、C 2-8烯基、卤素、卤素取代C 1-8烷基、羟基、腈基、苯基、磺酰基、氟代磺酰基、磺酸基、或氟代磺酸基；
R 6选自：氢原子、C 1-8烷基、卤素取代C 1-8烷基或苯基。
在其中一实施例中，所述含硫化合物选自式(I-1)～(I-9)任一结构所示含硫化合物：
Figure PCTCN2021096277-appb-000002
Figure PCTCN2021096277-appb-000003
在其中一实施例中，R a和R b各自独立地选自：氢原子、甲基、乙基、丙基、氟基、磺酰基、氟代磺酰基、磺酸基、或氟代磺酸基；
R 1、R 2、R 3和R 4各自独立地选自：氢原子、氟基、羟基、腈基、苯基、甲基、乙基、丙基、乙烯基、丙烯基、磺酰基、氟代磺酰基、磺酸基、或氟代磺酸基。
在其中一实施例中，R 5选自：氢原子、氟基、甲基、乙基、丙基、丁基、戊基、己基、异丙基、异丁基、仲丁基、叔丁基、异戊基、异己基、氟代甲基、氟代乙基、氟代丙基、氟代丁基、氟代戊基、氟代己基、氟代异丙基、氟代异丁基、氟代仲丁基、氟代叔丁基、氟代异戊基或氟代异己基；
R 6选自：氢原子、甲基、乙基、丙基、丁基、戊基、己基、异丙基、异丁基、仲丁基、叔丁基、异戊基、异己基、氟代甲基、氟代乙基、氟代丙基、氟代丁基、氟代戊基、氟代己基、氟代异丙基、氟代异丁基、氟代仲丁基、氟代叔丁基、氟代异戊基或氟代异己基。
在其中一实施例中，R 5和R 6中至少有一个选自以下任一基团：H、F、-CF 3、-CH 2CF 3、-CF 2CF 3、-CH 2CH 2CF 3、-CF 2CH 2CF 3、-CH 2CF 2CF 3或-CF 2CF 2CF 3。
在其中一实施例中，所述第一组分包括至少一种以下化合物：
所述第二组分包括至少一种以下化合物：
Figure PCTCN2021096277-appb-000004
Figure PCTCN2021096277-appb-000005
所述第二组分包括至少一种以下化合物：
Figure PCTCN2021096277-appb-000006
一种电解液，包括添加剂，所述添加剂为上述组合物。
在其中一实施例中，上述电解液还包括锂盐和溶剂，在所述电解液中，以质 量百分含量计，所述添加剂为0.01％-30％，所述锂盐为5％-20％，所述溶剂为50％-94.9％。
在其中一实施例中，所述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、二氟草酸磷酸锂及双氟磺酰亚胺锂中的至少一种；和/或
所述溶剂包括环型溶剂和/或线型溶剂；其中，所述环型溶剂选自：碳酸乙烯酯、碳酸丙烯酯、γ-丁内酯、乙酸苯酯、1，4-丁基磺酸内酯及3，3，3-三氟碳酸丙烯酯中的至少一种；所述线型溶剂选自碳酸二甲酯、碳酸甲乙酯、碳酸二乙酯、乙酸乙酯、碳酸甲丙酯、丙酸丙酯、1，1，2，2-四氟乙基-2，2，3，3-四氟丙基醚、2，2-二氟乙基乙酸酯、2，2-二氟乙基丙酸酯及2，2-二氟乙基碳酸甲酯中的至少一种。
一种锂离子电池，包括正极材料、负极材料和上述电解液。
有益效果：
上述组合物通过采用式(I)所示结构的含硫化合物和式(II)所示结构的环状碳酸酯，二者相互协同作用，能够有效地同时改善电池高温和低温循环性能，降低电池内阻。具体地：
一方面，式(I)所示结构的含硫化合物分解产生的烷基化硫酸锂给SEI膜引入了S元素，增加离子电导率，降低电池阻抗；另外，由于芳香环的存在使得锂离子电池的负极表面能够形成稳定、均匀、轻薄的SEI膜，可以抑制电解液中溶剂的分解，且不饱和键可以使得正极表面钝化，抑制正极金属离子的溶出，同时降低高氧化态的活性物质对溶剂的分解作用，从而达到改善电池的高温性能效果，尤其是高温循环性能。另一方面，式(II)所示结构的环状碳酸酯作为优异的成膜添加剂，同样能在电池负极表面形成SEI膜，进而能够改善电池低温性能，特别是当式(II)所示结构化合物为含氟元素的化合物时，该组分的存在，使电解液凝固点降低、闪点提高、氧化稳定性提高以及电解液与电极之间的兼容性增强，进而在低温环境下，锂离子嵌入与脱嵌变得顺畅，因此进一步能降低电池阻抗，从而达到改善电池低温循环效果。
此外，上述组合物不仅能够达到同时改善电池高温和低温性能作用，二者相互作用，能够显著降低电池内阻，且两种组分组合在一起没有明显的负面影 响，克服了传统技术方案中无法同时改善电池高温和低温性能的弊端。
附图说明
图1为实施例1、实施例2和对比例2的dQ/dV曲线图；
图2为实施例1、实施例2和对比例2的阻抗曲线图。
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。
术语解释
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- 8烷基”是指包含1～8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)。
“烯基”是指包含具有至少一个不饱和部位，即碳-碳sp 2双键的正碳原子、仲碳原子、叔碳原子或环碳原子的烃。包含该术语的短语，例如，“C 2- 8烯基”是指包含2～8个碳原子的烯基。合适的实例包括但不限于：乙烯基(-CH＝CH 2)、丙烯基(-CH 2CH＝CH 2)、环戊烯基(-C 5H 7)和5-己烯基(-CH 2CH 2CH 2CH 2CH＝CH 2)。
卤素”或“卤基”是指F、Cl、Br或I。
“卤素取代”表述相应基团上任意选位置任选数量的H被卤素取代，例如氟代甲基，包括一氟甲基、二氟甲基、三氟甲基。
详细解释
本发明一实施方式提供了一种组合物，由第一组分和第二组分组成，第一组分包括至少一种式(I)所示结构的含硫化合物，第二组分包括至少一种式(II)所示结构的环状碳酸酯化合物；
Figure PCTCN2021096277-appb-000007
X 1、X 2各自独立地为单键、-(CR aR b) n-、-O(CR aR b) n-、-O-、-COO-或-NHCO-；且X 1、X 2不同时为单键；
n为1或2；
R a、R b、R 1、R 2、R 3、R 4和R 5各自独立地选自：氢原子、C 1-8烷基、C 2-8烯基、卤素、卤素取代C 1-8烷基、羟基、腈基、苯基、磺酰基、氟代磺酰基、磺酸基、或氟代磺酸基；
R 6选自：氢原子、C 1-8烷基、卤素取代C 1-8烷基或苯基。
进一步地，含硫化合物选自式(I-1)～(I-9)任一结构所示含硫化合物：
Figure PCTCN2021096277-appb-000008
进一步地，R a和R b各自独立地选自：氢原子、甲基、乙基、丙基、氟基、磺酰基、氟代磺酰基、磺酸基、或氟代磺酸基；更进一步地，R a和R b中至少有一个为H；更进一步地，R a和R b均为H。
进一步地，R 1、R 2、R 3和R 4各自独立地选自：氢原子、C 1-6烷基、C 2-6烯基、氟、氟原子取代C 1-6烷基、羟基、腈基、苯基、磺酰基、氟代磺酰基、磺酸基、氟代磺酸基；
进一步地，R 1、R 2、R 3和R 4各自独立地选自：氢原子、氟基、羟基、腈基、苯基、甲基、乙基、丙基、乙烯基、丙烯基、磺酰基、氟代磺酰基、磺酸基、或氟代磺酸基。
在一实施例中，R 1、R 2、R 3和R 4均为氢原子或氟基；在一实施例中，R 1、 R 2、R 3和R 4中有三个为氢原子，有一个选自以下任一基团：C 1-8烷基、C 2-8烯基、卤素、卤素取代C 1-8烷基、羟基、腈基、苯基、磺酰基、氟代磺酰基、磺酸基、或氟代磺酸基；
在一实施例中，R 1、R 2和R 3为氢原子，R 4为C 2-8烯基；更进一步地，R 4为乙烯基。
进一步地，第一组分包括至少一种以下化合物：
Figure PCTCN2021096277-appb-000009
进一步地，R 5选自：氢原子、C 1-8烷基、C 2-8烯基、卤素、卤素取代C 1-8烷基、羟基、腈基、苯基、磺酰基、氟代磺酰基、磺酸基、或氟代磺酸基；更进一步地，R 5选自：氢原子、氟基、甲基、乙基、丙基、丁基、戊基、己基、异丙基、异丁基、仲丁基、叔丁基、异戊基、异己基、氟代甲基、氟代乙基、氟代丙基、氟代丁基、氟代戊基、氟代己基、氟代异丙基、氟代异丁基、氟代仲 丁基、氟代叔丁基、氟代异戊基或氟代异己基；
进一步地，R 6选自：氢原子、C 1-6烷基或卤素取代C 1-6烷基。
进一步地，R 6选自：氢原子、甲基、乙基、丙基、丁基、戊基、己基、异丙基、异丁基、仲丁基、叔丁基、异戊基、异己基、氟代甲基、氟代乙基、氟代丙基、氟代丁基、氟代戊基、氟代己基、氟代异丙基、氟代异丁基、氟代仲丁基、氟代叔丁基、氟代异戊基或氟代异己基。
进一步地，R 5和R 6中至少有一个选自含有氟元素的基团；含有氟原子的R 5和R 6组成的环状碳酸酯化合物能降低电解液的凝固点，提高电解液氧化稳定性，以及改善电解液与电极之间的浸润性，更有利的提高锂离子电池的低温循环性能。
更进一步地，R 5和R 6中至少有一个选自以下任一基团：H、F、-CF 3、-CH 2CF 3、-CF 2CF 3、-CH 2CH 2CF 3、-CF 2CH 2CF 3、-CH 2CF 2CF 3或-CF 2CF 2CF 3。
进一步地，环状碳酸酯化合物具有以下任一结构：
Figure PCTCN2021096277-appb-000010
进一步地，上述通式(II-1)～(II-3)中，R 5选自：H、C 1-4烷基、F、氟代C 1-4烷基；更进一步地，R 5选自：H、甲基、乙基、丙基、异丙基、F或三氟甲基。
进一步地，第二组分包括至少一种以下化合物：
Figure PCTCN2021096277-appb-000011
在一实施例中，第一组分为I2，第二组分为II1；在一实施例中，第一组分为I5，第二组分为II1；在一实施例中，第一组分为I7，第二组分为II1；在一实施例中，第一组分为I9，第二组分为II1；在一实施例中，第一组分为I11，第二组分为II1；在一实施例中，第一组分为I2和I5，第二组分为II1；在一实施例中，第一组分为I7，第二组分为II4；在一实施例中，第一组分为I7，第二组分为II6。
进一步地，上述第一组分和第二组分的质量比为1:(0.1-100)；进一步地，上述第一组分和第二组分的质量比为1:(1-15)；进一步地，上述第一组分和第二组分的质量比为1:(1-10)；进一步地，上述第一组分和第二组分的质量比为1:1。
本发明还提供了一种电解液，包括上述组合物，组合物如上所述，在此不再进行赘述。
进一步地，上述电解液还包括锂盐和溶剂；更进一步地，在电解液中，以质量百分含量计，添加剂为0.01％-30％，锂盐为5％-20％，溶剂为50％-94.9％；更进一步地，第一组分的质量百分含量为0.01％-10％；更进一步地，第一组分的质量百分含量为0.03％-5％；更进一步地，第一组分的质量百分含量为1％-3％；更进一步地，第二组分的质量百分含量为0.01％-20％；更进一步地，第一组分 的质量百分含量为0.1％-18％；更进一步地，第一组分的质量百分含量为1％-15％。
本发明技术人员在研究中发现，当第一组分的质量百分含量过高(超过10％)会导致形成的SEI膜过厚，进而会增大电池的阻抗，当第二组分的含量过高则会导致锂盐或添加剂溶解度降低，而组合物的各组分含量太低则对锂离子电池的内阻与高低温循环性能的改善效果欠佳，故将添加剂的各组分含量控制在上述范围内，能够更有效地改善电池的内阻和高低温循环性能，以获得更优的综合性能。
在一实施例中，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、二氟草酸磷酸锂及双氟磺酰亚胺锂中的至少一种。
在一实施例中，溶剂选自环型溶剂和/或线型溶剂；进一步地，环型溶剂选自：碳酸乙烯酯、碳酸丙烯酯、γ-丁内酯、乙酸苯酯、1，4-丁基磺酸内酯及3，3，3-三氟碳酸丙烯酯中的至少一种；更进一步地，线型溶剂选自碳酸二甲酯、碳酸甲乙酯、碳酸二乙酯、乙酸乙酯、碳酸甲丙酯、丙酸丙酯、1，1，2，2-四氟乙基-2，2，3，3-四氟丙基醚、2，2-二氟乙基乙酸酯、2，2-二氟乙基丙酸酯及2，2-二氟乙基碳酸甲酯中的至少一种。
本发明另一实施例还提供了一种锂离子电池，包括：正极材料；负极材料；以及上述电解液。
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碳、硅基负极材料及锡基负极材料中的一种或几种。
本发明中锂离子电池，通过采用含有上述含硫化合物和环状碳酸酯化合物的电解液，在二者的共同作用，一方面在负极形成稳定的SEI膜，另一方面降低电解液的凝固点，改善电解液与电极之间的浸润性，降低了电池的阻抗，从而使上述锂离子电池具有良好的高温和低温循环性能。
下面列举具体实施例来对本发明进行说明。
实施例1
本实施例中，添加剂选自上述化学式I2和化学式II1，添加剂I2和II1分别占电解液的重量的0.03％和1％；锂盐为六氟磷酸锂，锂盐占电解液的重量的13％；溶剂为碳酸乙烯酯和碳酸二甲酯按重量比为1:2混合而成的溶剂；正极材料为LiNi 0.8Co 0.1Mn 0.1O 2；负极材料为人造石墨；隔膜为聚乙烯膜。按照常规方法组装成软包电池。
实施例2
本实施例中，添加剂选自上述化学式I2和化学式II1，添加剂I2和II1分别占电解液的重量的1％和0.1％；锂盐为六氟磷酸锂，锂盐占电解液的重量的13％；溶剂为碳酸乙烯酯和碳酸二甲酯按重量比为1:2混合而成的溶剂；正极材料为LiNi 0.8Co 0.1Mn 0.1O 2；负极材料为人造石墨；隔膜为聚乙烯膜。按照常规方法组装成软包电池。
实施例3
本实施例中，添加剂选自上述化学式I2和化学式II1，添加剂I2和II1分别占电解液的重量的1％和1％；锂盐为六氟磷酸锂，锂盐占电解液的重量的13％；溶剂为碳酸乙烯酯和碳酸二甲酯按重量比为1:2混合而成的溶剂；正极材料为LiNi 0.8Co 0.1Mn 0.1O 2；负极材料为人造石墨；隔膜为聚乙烯膜。按照常规方法组装成软包电池。
实施例4
本实施例中，添加剂选自上述化学式I2和化学式II1，添加剂I2和II1分别占电解液的重量的5％和15％；锂盐为六氟磷酸锂，锂盐占电解液的重量的13％；溶剂为碳酸乙烯酯和碳酸二甲酯按重量比为1:2混合而成的溶剂；正极材料为LiNi 0.8Co 0.1Mn 0.1O 2；负极材料为人造石墨；隔膜为聚乙烯膜。按照常规方法组装成软包电池。
实施例5
本实施例中，添加剂选自上述化学式I5和化学式II1，添加剂I5和II1分别占电解液的重量的1％和1％；锂盐为六氟磷酸锂，锂盐占电解液的重量的13％； 溶剂为碳酸乙烯酯和碳酸二甲酯按重量比为1:2混合而成的溶剂；正极材料为LiNi 0.8Co 0.1Mn 0.1O 2；负极材料为人造石墨；隔膜为聚乙烯膜。按照常规方法组装成软包电池。
实施例6
本实施例中，添加剂选自上述化学式I9和化学式II1，添加剂I9和II1分别占电解液的重量的1％和1％；锂盐为六氟磷酸锂，锂盐占电解液的重量的13％；溶剂为碳酸乙烯酯和碳酸二甲酯按重量比为1:2混合而成的溶剂；正极材料为LiNi0.8Co0.1Mn0.1O2；负极材料为人造石墨；隔膜为聚乙烯膜。按照常规方法组装成软包电池。
实施例7
本实施例中，添加剂选自上述化学式I11和化学式II1，添加剂I9和II1分别占电解液的重量的1％和1％；锂盐为六氟磷酸锂，锂盐占电解液的重量的13％；溶剂为碳酸乙烯酯和碳酸二甲酯按重量比为1:2混合而成的溶剂；正极材料为LiNi0.8Co0.1Mn0.1O2；负极材料为人造石墨；隔膜为聚乙烯膜。按照常规方法组装成软包电池。
实施例8
本实施例中，添加剂选自上述化学式I2、I5和化学式II1，添加剂I2、I5和II1分别占电解液的重量的1％、1％和1％；锂盐为六氟磷酸锂，锂盐占电解液的重量的13％；溶剂为碳酸乙烯酯和碳酸二甲酯按重量比为1:2混合而成的溶剂；正极材料为LiNi 0.8Co 0.1Mn 0.1O 2；负极材料为人造石墨；隔膜为聚乙烯膜。按照常规方法组装成软包电池。
实施例9
本实施例中，添加剂选自上述化学式I7和化学式II1，添加剂I7和II1分别占电解液的重量的1％和1％；锂盐为六氟磷酸锂，锂盐占电解液的重量的13％；溶剂为碳酸乙烯酯和碳酸二甲酯按重量比为1:2混合而成的溶剂；正极材料为LiNi 0.8Co 0.1Mn 0.1O 2；负极材料为人造石墨；隔膜为聚乙烯膜。按照常规方法组装成软包电池。
实施例10
本实施例中，添加剂选自上述化学式I7和化学式II4，添加剂I7和II4分别占电解液的重量的1％和1％；锂盐为六氟磷酸锂，锂盐占电解液的重量的13％；溶剂为碳酸乙烯酯和碳酸二甲酯按重量比为1:2混合而成的溶剂；正极材料为LiNi 0.8Co 0.1Mn 0.1O 2；负极材料为人造石墨；隔膜为聚乙烯膜。按照常规方法组装成软包电池。
实施例11
本实施例中，添加剂选自上述化学式I7和化学式II6，添加剂I7和II6分别占电解液的重量的1％和1％；锂盐为六氟磷酸锂，锂盐占电解液的重量的13％；溶剂为碳酸乙烯酯和碳酸二甲酯按重量比为1:2混合而成的溶剂；正极材料为LiNi 0.8Co 0.1Mn 0.1O 2；负极材料为人造石墨；隔膜为聚乙烯膜。按照常规方法组装成软包电池。
实施例12
本实施例中，添加剂选自上述化学式I7和化学式II4，添加剂I7和II4分别占电解液的重量的1％和1％；锂盐为六氟磷酸锂和双氟磺酰亚胺锂，六氟磷酸锂和双氟磺酰亚胺锂分别占电解液的重量的12％和1％；溶剂为碳酸乙烯酯和碳酸二甲酯按重量比为1:2混合而成的溶剂；正极材料为LiNi 0.8Co 0.1Mn 0.1O 2；负极材料为人造石墨；隔膜为聚乙烯膜。按照常规方法组装成软包电池。
实施例13
本实施例中，添加剂选自上述化学式I7和化学式II4，添加剂I7和II4分别占电解液的重量的1％和1％；锂盐为六氟磷酸锂和双氟磺酰亚胺锂，六氟磷酸锂和双氟磺酰亚胺锂分别占电解液的重量的12％和1％；溶剂为碳酸乙烯酯和2，2-二氟乙基乙酸酯按重量比为1:2混合而成的溶剂；正极材料为LiNi 0.8Co 0.1Mn 0.1O 2；负极材料为人造石墨；隔膜为聚乙烯膜。按照常规方法组装成软包电池。
对比例1
与实施例1相比，对比例1的不同之处在于，电解液中不含通式I和通式II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，添加剂为占电解液重量的1％的碳酸亚乙烯酯(VC)添加剂。
对比例3
与实施例1相比，对比例3的不同之处在于，添加剂为占电解液重量的1％的硫酸乙烯酯(DTD)添加剂。
对比例4
与实施例1相比，对比例4的不同之处在于，添加剂为分别占电解液重量的1％的碳酸亚乙烯酯(VC)和硫酸乙烯酯(DTD)添加剂。
对比例5
与实施例3相比，对比例5的不同之处在于，添加剂为占电解液重量的1％的I2。
对比例6
与实施例3相比，对比例6的不同之处在于，添加剂为占电解液重量的1％的II1。
锂离子电池高低温循环性能测试
对实施例1～实施例13、对比例1～对比例6中的锂离子电池进行高低温循环性能测试，测试方法为：
高温循环性能：将分容后的锂离子电池置于45℃的恒温箱中，以1C的电流恒流恒压充电至4.2V，然后以1C的电流恒流放电至3.0V，循环600周，测定锂离子电池的容量保持率。
低温循环性能：将分容后的锂离子电池置于-10℃的恒温箱中，以0.5C的电流恒流放电至2.5V，然后以0.2C的电流恒流恒压充电至4.2V，循环100周，测定锂离子电池的容量保持率。
dQ/dV曲线：dQ/dV曲线是将电池在预充过程的容量和电压进行微分，所得到的图形可直接观察锂离子电池电解液在充电过程中所发生的还原反应。
测试结果如表1所示：
表1
Figure PCTCN2021096277-appb-000012
由表1可知，实施例1～实施例13中的锂离子电池的高温循环性能、低温循环性能优于对比例1～对比例6。说明实施例1～实施例13中的电解液添加剂能够有效改善锂离子电池的高温循环和低温循环性能。
且由图1可知，实施例1和实施例2相对于对比例2来说，存在明显的还原峰，说明通式II所示的环状碳酸酯能在负极表面优先还原，形成SEI膜。由图2可知，实施例1和实施例2相对于对比例2来说有明显降低电池阻抗作用。说明上述实施例中的添加剂能在负极形成SEI膜，降低电池阻抗，进而起着改善电池高温和低温循环性能的作用。
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. 一种组合物，其特征在于，由第一组分和第二组分组成，所述第一组分包括至少一种式(I)所示结构的含硫化合物，所述第二组分包括至少一种式(II)所示结构的环状碳酸酯化合物；
    Figure PCTCN2021096277-appb-100001
    X 1、X 2各自独立地为：单键、-(CR aR b) n-、-O(CR aR b) n-、-O-、-COO-或-NHCO-；且X 1、X 2不同时为单键；n为1或2；
    R a、R b、R 1、R 2、R 3、R 4和R 5各自独立地选自：氢原子、C 1-8烷基、C 2-8烯基、卤素、卤素取代C 1-8烷基、羟基、腈基、苯基、磺酰基、氟代磺酰基、磺酸基、或氟代磺酸基；
    R 6选自：氢原子、C 1-8烷基、卤素取代C 1-8烷基或苯基。
  2. 根据权利要求1所述的组合物，其特征在于，所述含硫化合物选自式(I-1)～(I-9)任一结构所示含硫化合物：
    Figure PCTCN2021096277-appb-100002
    Figure PCTCN2021096277-appb-100003
  3. 根据权利要求1所述的组合物，其特征在于，R a和R b各自独立地选自：氢原子、甲基、乙基、丙基、氟基、磺酰基、氟代磺酰基、磺酸基、或氟代磺酸基；
    R 1、R 2、R 3和R 4各自独立地选自：氢原子、氟基、羟基、腈基、苯基、甲基、乙基、丙基、乙烯基、丙烯基、磺酰基、氟代磺酰基、磺酸基、或氟代磺酸基。
  4. 根据权利要求1所述的组合物，其特征在于，R 5选自：氢原子、氟基、甲基、乙基、丙基、丁基、戊基、己基、异丙基、异丁基、仲丁基、叔丁基、异戊基、异己基、氟代甲基、氟代乙基、氟代丙基、氟代丁基、氟代戊基、氟代己基、氟代异丙基、氟代异丁基、氟代仲丁基、氟代叔丁基、氟代异戊基或氟代异己基；
    R 6选自：氢原子、甲基、乙基、丙基、丁基、戊基、己基、异丙基、异丁基、仲丁基、叔丁基、异戊基、异己基、氟代甲基、氟代乙基、氟代丙基、氟代丁基、氟代戊基、氟代己基、氟代异丙基、氟代异丁基、氟代仲丁基、氟代叔丁基、氟代异戊基或氟代异己基。
  5. 根据权利要求4所述的组合物，其特征在于，R 5和R 6中至少有一个选自以下任一基团：H、F、-CF 3、-CH 2CF 3、-CF 2CF 3、-CH 2CH 2CF 3、-CF 2CH 2CF 3、-CH 2CF 2CF 3或-CF 2CF 2CF 3。
  6. 根据权利要求1-5任一项所述的组合物，其特征在于，所述第一组分包括至少一种以下化合物：
    Figure PCTCN2021096277-appb-100004
    所述第二组分包括至少一种以下化合物：
    Figure PCTCN2021096277-appb-100005
    Figure PCTCN2021096277-appb-100006
  7. 一种电解液，其特征在于，包括添加剂，所述添加剂为权利要求1-6任一项所述的组合物。
  8. 根据权利要求7所述的电解液，其特征在于，还包括锂盐和溶剂，在所述电解液中，以质量百分含量计，所述添加剂为0.01％-30％，所述锂盐为5％-20％，所述溶剂为50％-94.9％。
  9. 根据权利要求8所述的电解液，其特征在于，所述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、二氟草酸磷酸锂及双氟磺酰亚胺锂中的至少一种；和/或
    所述溶剂包括环型溶剂和/或线型溶剂；其中，所述环型溶剂选自：碳酸乙烯酯、碳酸丙烯酯、γ-丁内酯、乙酸苯酯、1，4-丁基磺酸内酯及3，3，3-三氟碳酸丙烯酯中的至少一种；所述线型溶剂选自碳酸二甲酯、碳酸甲乙酯、碳酸二乙酯、乙酸乙酯、碳酸甲丙酯、丙酸丙酯、1，1，2，2-四氟乙基-2，2，3，3-四氟丙基醚、2，2-二氟乙基乙酸酯、2，2-二氟乙基丙酸酯及2，2-二氟乙基碳酸甲酯中的至少一种。
  10. 一种锂离子电池，其特征在于，包括正极材料、负极材料和权利要求7-9任一项所述的电解液。
PCT/CN2021/096277 2020-11-30 2021-05-27 组合物、包含该组合物的电解液及锂离子电池 WO2022110709A1 (zh)

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