CN113394461A - High-voltage additive for lithium battery electrolyte, electrolyte and lithium battery - Google Patents

High-voltage additive for lithium battery electrolyte, electrolyte and lithium battery Download PDF

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CN113394461A
CN113394461A CN202110846537.XA CN202110846537A CN113394461A CN 113394461 A CN113394461 A CN 113394461A CN 202110846537 A CN202110846537 A CN 202110846537A CN 113394461 A CN113394461 A CN 113394461A
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lithium
electrolyte
carbonate
additive
lithium battery
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CN113394461B (en
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高田慧
李立飞
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Tianmu Lake Institute of Advanced Energy Storage Technologies Co Ltd
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Tianmu Lake Institute of Advanced Energy Storage Technologies Co Ltd
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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
    • 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
    • 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
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    • Y02E60/10—Energy storage using batteries

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Abstract

The invention relates to a high-voltage additive for a lithium battery electrolyte, the electrolyte and a lithium battery. The high-voltage additive is a 2, 5-disulfonyl nitrile group thiophene compound or a 2, 5-disulfonyl cyanate group thiophene compound, and the structural formula is as follows:

Description

High-voltage additive for lithium battery electrolyte, electrolyte and lithium battery
Technical Field
The invention relates to the technical field of lithium batteries, in particular to a high-voltage additive for a lithium battery electrolyte, the electrolyte and a lithium battery.
Background
Since the commercialization in the 90 s of the 20 th century, lithium batteries have been widely used because of their advantages of high energy density, high charge and discharge efficiency, low self-discharge, long service life, and environmental friendliness. The method is applied to the fields of consumer electronics, aerospace, military, electric tools, electric automobiles and the like.
With the development of the technology, people have higher and higher requirements on the energy density of lithium ion batteries in the consumer field and the power battery field, and the improvement of the working voltage of the lithium battery becomes one of the technologies for improving the energy density of the lithium battery.
The development of high energy density lithium batteries is started from two aspects at present, namely, the development of new high gram capacity anode and cathode materials and the improvement of charge and discharge voltage of the lithium batteries. The charging and discharging voltage of the lithium battery is improved, the mass energy density and the volume energy density of the lithium battery can be improved, the cost of the lithium battery can be reduced, and the lithium battery becomes a hotspot of research of people.
However, when a high-voltage lithium battery is researched, researchers in the industry find that, with the increase of the voltage of the lithium battery, in an application scene of the high-voltage lithium battery, the traditional lithium battery electrolyte not only can generate oxidative decomposition by itself, but also can generate chemical reaction with a positive electrode material, so that the performance of the battery is deteriorated, and the service life of the battery is seriously shortened. Therefore, the technical development of the electrolyte matched with the high-voltage lithium battery becomes a key point.
Disclosure of Invention
The embodiment of the invention provides a high-voltage additive for a lithium battery electrolyte, the electrolyte and a lithium battery, wherein the additive acts on the electrolyte, so that a positive electrode transition metal can be stabilized, oxygen precipitation of a positive electrode material is inhibited, the impedance of the surface of the positive electrode material is reduced, and the performance of the positive electrode material is improved; and thiophene can be polymerized under the high voltage of the anode to form an electrolyte interface phase (CEI) film with a net structure, so that the stability is enhanced, and the anode material is protected in all directions. The cycle life and the high-temperature storage life of the lithium ion battery prepared by using the electrolyte containing the additive under the high-voltage condition are obviously prolonged.
In a first aspect, an embodiment of the present invention provides a high voltage additive for a lithium battery electrolyte, where the high voltage additive is a 2, 5-disulfonyl nitrile thiophene compound or a 2, 5-disulfonyl cyanate thiophene compound, and a structural formula of the high voltage additive is as follows:
Figure BDA0003180770060000021
wherein, R is alkyl and/or halogenated alkyl with 1-6 carbon atoms, and M is one of nitrile group or cyanate.
Preferably, the halo in the haloalkyl group is a partial or complete substitution of halo.
Preferably, the halogen specifically includes one or more of fluorine, chlorine and bromine.
In a second aspect, embodiments of the present invention provide an electrolyte, including the high voltage additive according to the first aspect.
Preferably, the electrolyte further comprises: lithium salt electrolyte, organic solvent and auxiliary additive; the addition amount of the high-voltage additive accounts for 0.1-5 wt% of the total mass of the electrolyte.
Further preferably, the lithium salt electrolyte includes: one or more of lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis-oxalate borate, lithium difluoro-bis-oxalate phosphate, lithium difluorophosphate, lithium trifluoromethylsulfonate, lithium bis (pentafluoroethylsulfonimide), lithium bis (trifluoromethylsulfonimide) and lithium bis (fluorosulfonimide);
the organic solvent includes: one or more mixtures of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propyl methyl carbonate, gamma-butyrolactone, ethyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, ethyl butyrate, tetrahydrofuran, 2-methyltetrahydrofuran, 1, 2-dimethoxyethane, and halogenated derivatives thereof;
the auxiliary additive comprises: one or more of vinylene carbonate, vinyl ethylene carbonate, vinyl acetate, vinyl sulfite, propylene sulfite, vinyl sulfate, 1, 3-propanesultone, propenyl-1, 3-propanesultone, 1, 4-butanesultone, methylene methanedisulfonate, hexamethyldisilazane, magnesium trifluoromethanesulfonate, tris (pentafluorophenyl) boron, tris (trimethylsilane) phosphate, tris (trimethylsilane) phosphite, methylnonafluoro-n-butyl ether, octafluoropentyl-tetrafluoroethyl ether, succinonitrile, adiponitrile, 1,3, 6-hexanetrinitrile, ethylene glycol bis (propionitrile) ether, sulfones and acid anhydride.
Preferably, the addition amount of the lithium salt electrolyte accounts for 0.01-20 wt% of the total mass of the electrolyte;
the adding amount of the organic solvent accounts for 70-90 wt% of the total mass of the electrolyte;
the addition amount of the auxiliary additive is 0.1-10 wt% of the total mass of the electrolyte.
In a third aspect, an embodiment of the present invention provides a lithium battery, including the electrolyte according to the second aspect.
Preferably, the positive electrode material of the lithium battery specifically includes: any one of lithium cobaltate, lithium manganate, lithium nickel manganese oxide, a lithium-rich material, a nickel cobalt manganese ternary material and a nickel cobalt aluminum ternary material.
The high-voltage additive provided by the embodiment of the invention can stabilize the transition metal of the positive electrode, inhibit the oxygen precipitation of the positive electrode material, reduce the impedance of the surface of the positive electrode material and improve the performance of the positive electrode material; and thiophene can be polymerized under the high voltage of the anode to form an electrolyte interface phase (CEI) film with a net structure, so that the stability is enhanced, and the anode material is protected in all directions. The cycle life and the high-temperature storage life of the lithium ion battery prepared by using the electrolyte containing the additive under the high-voltage condition are obviously prolonged.
Detailed Description
The high-voltage additive is a 2, 5-disulfonyl nitrile group thiophene compound or a 2, 5-disulfonyl cyanate group thiophene compound, and the structural formula is as follows:
Figure BDA0003180770060000041
wherein R is alkyl and/or halogenated alkyl with 1-6 carbon atoms, and the halogenation in the halogenated alkyl is partial substitution or total substitution of halogen. Halogen specifically includes one or more of fluorine, chlorine, bromine.
M is one of nitrile group or cyanate ester.
The high-voltage additive provided by the invention can be used in the lithium battery electrolyte, and preferably, the addition amount of the high-voltage additive accounts for 0.1-5 wt% of the total mass of the electrolyte.
The electrolyte also comprises: lithium salt electrolyte, organic solvent and auxiliary additive; wherein the lithium salt electrolyte may include: one or more of lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis-oxalate borate, lithium difluoro-bis-oxalate phosphate, lithium difluorophosphate, lithium trifluoromethylsulfonate, lithium bis (pentafluoroethylsulfonimide), lithium bis (trifluoromethylsulfonimide) and lithium bis (fluorosulfonimide); the organic solvent may include: one or more mixtures of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propyl methyl carbonate, gamma-butyrolactone, ethyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, ethyl butyrate, tetrahydrofuran, 2-methyltetrahydrofuran, 1, 2-dimethoxyethane, and halogenated derivatives thereof; the auxiliary additives may include: one or more of vinylene carbonate, vinyl ethylene carbonate, vinyl acetate, vinyl sulfite, propylene sulfite, vinyl sulfate, 1, 3-propanesultone, propenyl-1, 3-propanesultone, 1, 4-butanesultone, methylene methanedisulfonate, hexamethyldisilazane, magnesium trifluoromethanesulfonate, tris (pentafluorophenyl) boron, tris (trimethylsilane) phosphate, tris (trimethylsilane) phosphite, methylnonafluoro-n-butyl ether, octafluoropentyl-tetrafluoroethyl ether, succinonitrile, adiponitrile, 1,3, 6-hexanetrinitrile, ethylene glycol bis (propionitrile) ether, sulfones and acid anhydride.
Furthermore, the adding amount of the lithium salt electrolyte accounts for 0.01-20 wt% of the total mass of the electrolyte; the adding amount of the organic solvent accounts for 70-90 wt% of the total mass of the electrolyte; the addition amount of the auxiliary additive is 0.1-10 wt% of the total mass of the electrolyte.
The electrolyte is used in a lithium battery, and particularly, the positive electrode material is any one of lithium cobaltate, lithium manganate, lithium nickel manganese oxide, a lithium-rich material, a nickel-cobalt-manganese ternary material and a nickel-cobalt-aluminum ternary material.
According to the high-voltage additive provided by the invention, the nitrile group or the cyanate group in the additive can be combined with high-valence transition metal ions of the positive electrode material, so that the oxygen precipitation of the positive electrode material is inhibited, and the structure of the positive electrode material is stabilized; sulfonyl in the additive forms a substance which contains sulfur and is good and stable in guiding lithium ions at the positive electrode, so that the impedance of the surface of the material is reduced, and the positive electrode is protected to be stable; the thiophene group of the additive is polymerized at the positive electrode under high voltage, and is matched with the two functional groups to form a reticular, composite and stable CEI film, so that the positive electrode material is efficiently protected, and the performance of the lithium battery under the high voltage condition is improved. The cycle life and the high-temperature storage life of the lithium ion battery prepared by using the electrolyte containing the additive under the high-voltage condition are obviously prolonged.
The specific implementation of the high voltage additive provided by the invention and the characteristics of applying the high voltage additive in an electrolyte are respectively illustrated by a plurality of specific examples.
Example 1
The embodiment provides a high-voltage additive A for lithium battery electrolyte:
Figure BDA0003180770060000051
in argon atmosphere, the environmental index is H2O≤0.5ppm，O2In a glove box with the mass ratio of less than or equal to 2.0ppm, organic solvents of Ethylene Carbonate (EC), Propylene Carbonate (PC), fluoroethylene carbonate (FEC) and Ethyl Methyl Carbonate (EMC) are added according to the mass ratio of EC: PC: FEC: EMC 10: 15: 5: 70 are mixed and then a lithium salt LiPF is added6And LiDFOB, wherein LiPF6The content of (A) is 10% by mass of the solution, the content of LiDFOB is 5%, then 0.5% by mass of an auxiliary additive Vinylene Carbonate (VC) is added, and then 1% of a high-voltage additive A is added to prepare an electrolyte I.
Example 2
The embodiment provides a high-voltage additive B for lithium battery electrolyte, which comprises the following components in percentage by weight:
Figure BDA0003180770060000061
in argon atmosphere, the environmental index is H2O≤0.5ppm，O2In a glove box with the mass ratio of less than or equal to 2.0ppm, organic solvents of Ethylene Carbonate (EC), Propylene Carbonate (PC), fluoroethylene carbonate (FEC) and Ethyl Methyl Carbonate (EMC) are added according to the mass ratio of EC: PC: FEC: EMC 10: 15: 5: 70 are mixed and then a lithium salt LiPF is added6And LiDFOB, wherein LiPF6The content of (A) is 10% by mass of the solution, the content of LiDFOB is 5%, then 0.5% by mass of an auxiliary additive Vinylene Carbonate (VC) is added, and then 1% of a high-voltage additive B is added to prepare an electrolyte II.
Example 3
The embodiment provides a high-voltage additive C for lithium battery electrolyte:
Figure BDA0003180770060000062
in argon atmosphere, the environmental index is H2O≤0.5ppm，O2In a glove box with the mass ratio of less than or equal to 2.0ppm, organic solvents of Ethylene Carbonate (EC), Propylene Carbonate (PC), fluoroethylene carbonate (FEC) and Ethyl Methyl Carbonate (EMC) are added according to the mass ratio of EC: PC: FEC: EMC 10: 15: 5: 70 are mixed and then a lithium salt LiPF is added6And LiDFOB, wherein LiPF6The content of (2) is 10% by mass of the solution, the content of LiDFOB is 5%, then 0.5% by mass of an auxiliary additive Vinylene Carbonate (VC) is added, and then 1% of a high-voltage additive C is added to prepare an electrolyte III.
Example 4
The embodiment provides a high-voltage additive D for lithium battery electrolyte:
Figure BDA0003180770060000071
in argon atmosphere, the environmental index is H2O≤0.5ppm，O2In a glove box with the mass ratio of less than or equal to 2.0ppm, organic solvents of Ethylene Carbonate (EC), Propylene Carbonate (PC), fluoroethylene carbonate (FEC) and Ethyl Methyl Carbonate (EMC) are added according to the mass ratio of EC: PC: FEC: EMC 10: 15: 5: 70 are mixed and then a lithium salt LiPF is added6And LiDFOB, wherein LiPF6The content of (2) is 10% by mass of the solution, the content of LiDFOB is 5%, then 0.5% by mass of an auxiliary additive Vinylene Carbonate (VC) is added, and then 1% of a high voltage additive D is added to prepare an electrolyte IV.
Example 5
The embodiment provides a high-voltage additive E for lithium battery electrolyte:
Figure BDA0003180770060000072
in argon atmosphere, the environmental index is H2O≤0.5ppm，O2In a glove box with the mass ratio of less than or equal to 2.0ppm, organic solvents of Ethylene Carbonate (EC), Propylene Carbonate (PC), fluoroethylene carbonate (FEC) and Ethyl Methyl Carbonate (EMC) are added according to the mass ratio of EC: PC: FEC: EMC 10: 15: 5: 70 are mixed and then a lithium salt LiPF is added6And LiDFOB, wherein LiPF6The content of (a) is 10% by mass of the solution and the content of LiDFOB is 5% by mass, then 0.5% by mass of an auxiliary additive Vinylene Carbonate (VC) is added, and then 1% by mass of a high voltage additive E is added to prepare an electrolyte V.
Example 6
The embodiment provides a high-voltage additive F for lithium battery electrolyte:
Figure BDA0003180770060000081
in argon atmosphere, the environmental index is H2O≤0.5ppm，O2In a glove box with the concentration less than or equal to 2.0ppm, adding organic solvent ethylene carbonate(EC), Propylene Carbonate (PC), fluoroethylene carbonate (FEC), methylethyl carbonate (EMC) in a mass ratio EC: PC: FEC: EMC 10: 15: 5: 70 are mixed and then a lithium salt LiPF is added6And LiDFOB, wherein LiPF6The content of (2) is 10% by mass of the solution, the content of LiDFOB is 5%, then 0.5% by mass of an auxiliary additive Vinylene Carbonate (VC) is added, and then 1% of a high-voltage additive F is added to prepare an electrolyte VI.
Example 7
This example uses the same high voltage additive a as example 1:
in argon atmosphere, the environmental index is H2O≤0.5ppm，O2In a glove box with the mass ratio of less than or equal to 2.0ppm, organic solvents of Ethylene Carbonate (EC), Propylene Carbonate (PC), fluoroethylene carbonate (FEC) and Ethyl Methyl Carbonate (EMC) are added according to the mass ratio of EC: PC: FEC: EMC 10: 15: 5: 70 are mixed and then a lithium salt LiPF is added6And LiDFOB, wherein LiPF6The content of (A) is 10% by mass of the solution, the content of LiDFOB is 5%, then 0.5% by mass of an auxiliary additive Vinylene Carbonate (VC) is added, and then 2% of a high-voltage additive A is added to prepare an electrolyte VII.
Example 8
This example used the same high voltage additive D as example 4:
in argon atmosphere, the environmental index is H2O≤0.5ppm，O2In a glove box with the mass ratio of less than or equal to 2.0ppm, organic solvents of Ethylene Carbonate (EC), Propylene Carbonate (PC), fluoroethylene carbonate (FEC) and Ethyl Methyl Carbonate (EMC) are added according to the mass ratio of EC: PC: FEC: EMC 10: 15: 5: 70 are mixed and then a lithium salt LiPF is added6And LiDFOB, wherein LiPF6The content of (A) is 10% by mass of the solution, the content of LiDFOB is 5%, then 0.5% by mass of an auxiliary additive Vinylene Carbonate (VC) is added, and then 2% of a high-voltage additive D is added to prepare the electrolyte VIII.
Example 9
This example uses the high voltage additive B of example 2 and the high voltage additive D of example 4:
in argon atmosphere, the environmental index is H2O≤0.5ppm，O2In a glove box with the mass ratio of less than or equal to 2.0ppm, organic solvents of Ethylene Carbonate (EC), Propylene Carbonate (PC), fluoroethylene carbonate (FEC) and Ethyl Methyl Carbonate (EMC) are added according to the mass ratio of EC: PC: FEC: EMC 10: 15: 5: 70 are mixed and then a lithium salt LiPF is added6And LiDFOB, wherein LiPF6The content of (2) is 10% by mass of the solution and the content of LiDFOB is 5% by mass, then 0.5% by mass of an auxiliary additive Vinylene Carbonate (VC) is added, and then 0.5% by mass of a high voltage additive B and 1.5% by mass of a high voltage additive D are added to prepare an electrolyte IX.
Example 10
This example uses the high voltage additive a of example 1 and the high voltage additive D of example 4:
in argon atmosphere, the environmental index is H2O≤0.5ppm，O2In a glove box with the mass ratio of less than or equal to 2.0ppm, organic solvents of Ethylene Carbonate (EC), Propylene Carbonate (PC), fluoroethylene carbonate (FEC) and Ethyl Methyl Carbonate (EMC) are added according to the mass ratio of EC: PC: FEC: EMC 10: 15: 5: 70 are mixed and then a lithium salt LiPF is added6And LiDFOB, wherein LiPF6The content of (2) is 10% by mass of the solution and the content of LiDFOB is 5% by mass, then 0.5% by mass of an auxiliary additive Vinylene Carbonate (VC) is added, and then 1% of a high voltage additive A and 1% of a high voltage additive D are added to prepare an electrolyte X.
For comparison, the invention also provides a comparative example for subsequent test comparison.
Comparative example 1
In argon atmosphere, the environmental index is H2O≤0.5ppm，O2In a glove box with the mass ratio of less than or equal to 2.0ppm, organic solvents of Ethylene Carbonate (EC), Propylene Carbonate (PC), fluoroethylene carbonate (FEC) and Ethyl Methyl Carbonate (EMC) are added according to the mass ratio of EC: PC: FEC: EMC 10: 15: 5: 70 are mixed and then a lithium salt LiPF is added6And LiDFOB, wherein LiPF6The content of (A) is based on the quality of the solutionA comparative electrolyte solution 1 was prepared by adding Vinylene Carbonate (VC), an auxiliary additive, in an amount of 10% by mass and a content of LiDFOB of 5% by mass, to 0.5% by mass.
Comparative example 2
In argon atmosphere, the environmental index is H2O≤0.5ppm，O2In a glove box with the mass ratio of less than or equal to 2.0ppm, organic solvents of Ethylene Carbonate (EC), Propylene Carbonate (PC), fluoroethylene carbonate (FEC) and Ethyl Methyl Carbonate (EMC) are added according to the mass ratio of EC: PC: FEC: EMC 10: 15: 5: 70 are mixed and then a lithium salt LiPF is added6And LiDFOB, wherein LiPF6The content of (b) was 10% by mass and the content of LiDFOB was 5% by mass, and then Vinylene Carbonate (VC), Polystyrene (PS), Succinonitrile (SN) as auxiliary additives were added in the amounts of 0.5%, 1% and 1% by mass, respectively, to prepare comparative electrolyte 2.
The electrolyte of each of the above specific examples and comparative examples was used for lithium battery preparation and testing, and the lithium battery preparation and testing methods were as follows:
selecting lithium cobaltate suitable for high voltage as a positive electrode material, and preparing the positive electrode material LiCoO2Uniformly mixing Carbon Nanotubes (CNTs) and polyvinylidene fluoride (PVDF) according to a ratio of 98:1:1, coating the mixture on an aluminum foil current collector, drying the aluminum foil current collector by an oven, rolling the aluminum foil current collector on a roller press, and compacting the aluminum foil current collector to obtain the aluminum foil current collector with the compaction density of 4.0g/cm3And obtaining the required positive plate.
Selecting artificial graphite as a negative electrode material, and mixing the artificial graphite, carboxymethyl cellulose (CMC), a conductive agent Super P and a binder Styrene Butadiene Rubber (SBR) according to a ratio of 95: 1.2: 1.8: 2 to obtain a negative pole piece, wherein the compacted density of the pole piece is 1.5g/cm3。
The preparation method comprises the steps of selecting a Polyethylene (PE) film coated with ceramic as an isolation film (9um PE base film +3um ceramic), and manufacturing a pole piece into a small soft package battery of 2Ah by a lamination method, wherein the electrolyte in the embodiment is respectively adopted as the electrolyte. The performance of the electrolyte, namely the effect of the high-voltage additive, is measured by testing a small soft package battery. The charge-discharge voltage window under the test condition is 3.0-4.5V; the cycling test of the cell was carried out at room temperature 25 ℃ and at elevated temperature 45 ℃ respectively, and the cycling charge and discharge currents were all 0.5C. Specific results are shown in table 1 below.
Figure BDA0003180770060000111
TABLE 1
As can be seen from the data in table 1, compared with comparative electrolyte 1 and comparative electrolyte 2, the electrolyte added with the high-voltage additive of the present invention can improve the cycle life of the lithium battery at room temperature and at high temperature to a certain extent in a suitable addition range.
According to the high-voltage additive provided by the invention, the nitrile group or the cyanate group in the additive can be combined with high-valence transition metal ions of the positive electrode material, so that the oxygen precipitation of the positive electrode material is inhibited, and the structure of the positive electrode material is stabilized; sulfonyl in the additive forms a substance which contains sulfur and is good and stable in guiding lithium ions at the positive electrode, so that the impedance of the surface of the material is reduced, and the positive electrode is protected to be stable; the thiophene group of the additive is polymerized at the positive electrode under high voltage, and is matched with the two functional groups to form a reticular, composite and stable CEI film, so that the positive electrode material is efficiently protected, and the performance of the lithium battery under the high voltage condition is improved. The cycle life and the high-temperature storage life of the lithium ion battery prepared by using the electrolyte containing the additive under the high-voltage condition are obviously prolonged.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (9)

1. The high-voltage additive for the lithium battery electrolyte is characterized by being a 2, 5-disulfonyl nitrile thiophene compound or a 2, 5-disulfonyl cyanate thiophene compound, and having a structural formula as follows:
Figure FDA0003180770050000011
wherein, R is alkyl and/or halogenated alkyl with 1-6 carbon atoms, and M is one of nitrile group or cyanate.
2. The high voltage additive of claim 1 wherein the halo in the haloalkyl group is a partial or full substitution of a halogen.
3. High voltage additive according to claim 1, wherein the halogen comprises in particular one or more of fluorine, chlorine, bromine.
4. An electrolyte, characterized in that it comprises a high voltage additive according to any one of the preceding claims 1 to 3.
5. The electrolyte of claim 4, further comprising: lithium salt electrolyte, organic solvent and auxiliary additive; the addition amount of the high-voltage additive accounts for 0.1-5 wt% of the total mass of the electrolyte.
6. The electrolyte of claim 5, wherein the lithium salt electrolyte comprises: one or more of lithium perchlorate, lithium hexafluoroarsenate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis-oxalate borate, lithium difluoro-bis-oxalate phosphate, lithium difluorophosphate, lithium trifluoromethylsulfonate, lithium bis (pentafluoroethylsulfonimide), lithium bis (trifluoromethylsulfonimide) and lithium bis (fluorosulfonimide);
the organic solvent includes: one or more mixtures of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propyl methyl carbonate, gamma-butyrolactone, ethyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, ethyl butyrate, tetrahydrofuran, 2-methyltetrahydrofuran, 1, 2-dimethoxyethane, and halogenated derivatives thereof;
the auxiliary additive comprises: one or more of vinylene carbonate, vinyl ethylene carbonate, vinyl acetate, vinyl sulfite, propylene sulfite, vinyl sulfate, 1, 3-propanesultone, propenyl-1, 3-propanesultone, 1, 4-butanesultone, methylene methanedisulfonate, hexamethyldisilazane, magnesium trifluoromethanesulfonate, tris (pentafluorophenyl) boron, tris (trimethylsilane) phosphate, tris (trimethylsilane) phosphite, methylnonafluoro-n-butyl ether, octafluoropentyl-tetrafluoroethyl ether, succinonitrile, adiponitrile, 1,3, 6-hexanetrinitrile, ethylene glycol bis (propionitrile) ether, sulfones and acid anhydride.
7. The electrolyte of claim 5,
the addition amount of the lithium salt electrolyte accounts for 0.01-20 wt% of the total mass of the electrolyte;
the adding amount of the organic solvent accounts for 70-90 wt% of the total mass of the electrolyte;
the addition amount of the auxiliary additive is 0.1-10 wt% of the total mass of the electrolyte.
8. A lithium battery comprising the electrolyte of claim 4.
9. The lithium battery as claimed in claim 8, wherein the positive electrode material of the lithium battery specifically comprises: any one of lithium cobaltate, lithium manganate, lithium nickel manganese oxide, a lithium-rich material, a nickel cobalt manganese ternary material and a nickel cobalt aluminum ternary material.
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CN105742709A (en) * 2016-04-20 2016-07-06 东莞市杉杉电池材料有限公司 Electrolyte for lithium-ion battery and lithium-ion battery employing electrolyte
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