CN112201855A - Electrolyte solution, electrochemical device, and electronic device - Google Patents

Electrolyte solution, electrochemical device, and electronic device Download PDF

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CN112201855A
CN112201855A CN202011118231.4A CN202011118231A CN112201855A CN 112201855 A CN112201855 A CN 112201855A CN 202011118231 A CN202011118231 A CN 202011118231A CN 112201855 A CN112201855 A CN 112201855A
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carbon atoms
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electrolyte
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CN112201855B (en
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刘建
熊亚丽
王翔
郑建明
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Ningde Amperex Technology 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
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0568—Liquid materials characterised by the solutes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—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
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    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract

An electrolyte, an electrochemical device, and an electronic device are provided in examples of the present application. Wherein the electrolyte comprises a compound shown in a formula 1 and a compound shown in a formula II:

Description

Electrolyte solution, electrochemical device, and electronic device
Technical Field
The present application relates to the field of electrochemical technologies, and in particular, to an electrolyte, an electrochemical device, and an electronic device.
Background
An electrochemical device, such as a lithium ion battery, is an energy storage device widely used at present, and with the development of the society, the requirement for the electrochemical device is higher and higher, and particularly, the requirement for the energy density of the electrochemical device is higher and higher, and increasing the working voltage is one of the important means for increasing the energy density of the electrochemical device.
Disclosure of Invention
In view of the above disadvantages of the prior art, the present application provides an electrolyte including both a compound represented by formula I and a compound represented by formula II, thereby greatly improving the cycle performance and high-temperature storage performance of an electrochemical device using the electrolyte at a high operating voltage.
The application provides an electrolyte, which comprises a compound shown in a formula 1 and a compound shown in a formula II:
Figure BDA0002731059930000011
wherein R is11、R12Each independently selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, a substituted alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a substituted alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, a substituted alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a substituted cycloalkyl group having 3 to 10 carbon atoms, a sulfanyl group having 1 to 10 carbon atoms, a substituted sulfanyl group having 1 to 10 carbon atoms, a carbonate group having 1 to 10 carbon atoms, a substituted carbonate group having 1 to 10 carbon atoms, a carbonyl group having 1 to 10 carbon atoms, a substituted carbonyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a substituted aryl group having 6 to 10 carbon atoms, wherein, when substituted, the substituent is selected from at least one of halogen or cyano;
R13、R15each independently selected from carbonyl, sulfone, alkylene with 1 to 10 carbon atoms or substituted alkylene with 1 to 10 carbon atoms, wherein, when substituted, the substituent is selected from at least one of halogen, nitrile or borate;
R14selected from covalent bond, oxygen atom, alkylene with 1 to 10 carbon atoms, substituted alkylene with 1 to 10 carbon atoms, alkenylene with 2 to 10 carbon atoms or substituted alkenylene with 2 to 10 carbon atoms, wherein, when substituted, the substituent is selected from halogen, nitrile group, borate group, alkenyl, alkynyl, ether group, carbonyl, aldehyde group, benzene ring or unsaturated groupAnd a bonded alkyl group;
R21、R24、R25each independently selected from a hydrogen atom, - (CH)2)a-O-(CH2)b-CN、-(CH2)c-O-(CH2)d-O-(CH2)-CN、-(CH2)e-O- (CH ═ CH) -CN, alkyl of 2 to 5 carbon atoms, alkoxy of 1 to 5 carbon atoms or carbonyl of 2 to 5 carbon atoms, wherein a, b, c, d, e are each independently selected from integers of 0 to 10;
R22、R23each independently selected from a covalent bond, an alkylene group having 1 to 5 carbon atoms, a substituted alkylene group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an alkenylene group having 2 to 5 carbon atoms, wherein, when substituted, the substituent is selected from an alkoxy group having 1 to 5 carbon atoms.
In the above electrolyte, the compound represented by formula I includes at least one of the following compounds:
Figure BDA0002731059930000021
Figure BDA0002731059930000031
in the above electrolyte, the compound represented by formula II includes at least one of the following compounds:
Figure BDA0002731059930000032
in the electrolyte, the mass percentage of the compound shown in the formula I in the total mass of the electrolyte is less than or equal to 3 percent; and/or the presence of a gas in the gas,
the mass percentage of the compound shown in the formula II in the total mass of the electrolyte is less than or equal to 4 percent.
In the above electrolyte, the electrolyte further includes:
at least one of a bicyclic carbonate compound, a borate compound, a chain fluorocarbonate compound, or lithium difluorophosphate.
In the above electrolytic solution, the electrolytic solution satisfies at least one of the following conditions (a) to (d):
(a) the weight percentage of the bicyclic carbonate compound in the total weight of the electrolyte is less than or equal to 5 percent;
(b) the mass percentage of the borate compound in the total mass of the electrolyte is less than or equal to 3 percent;
(c) the mass percentage of the chain-shaped fluoro carbonic ester compound in the total mass of the electrolyte is less than or equal to 15 percent;
(d) the mass percentage of the lithium difluorophosphate in the total mass of the electrolyte is less than or equal to 1 percent.
In the above electrolyte, the bicyclic carbonate compound includes at least one of the following compounds:
Figure BDA0002731059930000041
in the above electrolyte, the borate compound includes a compound represented by formula IV:
Figure BDA0002731059930000042
wherein R is41、R42、R43Each independently selected from a carbonyl group having 1 to 5 carbon atoms, a mercapto group having 1 to 5 carbon atoms, an alkyl group having 1 to 5 carbon atoms, a substituted alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, a substituted alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, a substituted alkynyl group having 2 to 5 carbon atoms, an ether group having 1 to 5 carbon atoms, a substituted ether group having 1 to 5 carbon atoms, an aryl group having 6 to 10 carbon atoms, a substituted aryl group having 6 to 10 carbon atoms, a cycloalkane having 6 to 10 carbon atoms, and a cycloalkane having 6 to 10 carbon atoms, wherein, when substituted, the substituent is selected from at least one of a halogen and a nitrile group.
In the above electrolyte, the borate compound includes at least one of the following compounds:
Figure BDA0002731059930000043
in the above electrolyte, the chain fluoro carbonate compound includes a compound represented by formula V:
Figure BDA0002731059930000051
wherein R is51、R52Each independently selected from an alkyl group having 1 to 5 carbon atoms, a fluoroalkyl group having 1 to 5 carbon atoms, a substituted alkyl group having 1 to 5 carbon atoms, or a substituted fluoroalkyl group having 1 to 5 carbon atoms, and R51And R52At least one of which is a fluoroalkyl group.
In the electrolyte solution, the chain-type fluoro carbonate compound includes at least one of the following compounds:
Figure BDA0002731059930000052
the present application also provides an electrochemical device comprising:
a positive electrode, a negative electrode, a separator, and any of the above electrolytes.
The present application also provides an electronic device comprising the electrochemical device described above.
In the electrolyte provided by the example of the application, the compound shown in the formula I and the compound shown in the formula II are introduced into the electrolyte, so that the cycle performance and the high-temperature storage performance of an electrochemical device adopting the electrolyte under high working voltage can be ensured, and the electrolyte provided by the application can be suitable for the electrochemical device with high working voltage and is beneficial to improving the energy density of the electrochemical device by improving the working voltage.
Detailed Description
Examples of the present application will be described in detail below. The examples of this application should not be construed as limiting the application.
Lithium ion batteries have become widely used electrochemical devices for energy storage today due to their advantages of environmental friendliness, high energy density, high operating voltage, long cycle life, and the like. With the development of the technology, people have higher and higher requirements for electrochemical devices, especially for energy density, and increasing the operating voltage of the electrochemical devices is an important means for increasing the energy density, however, the existing electrolyte has poor stability under high operating voltage and cannot meet the operating requirements under high operating voltage, and therefore, the electrolyte needs to be improved.
In some examples of the present application, an electrolyte is provided, including a compound represented by formula 1 and a compound represented by formula II:
Figure BDA0002731059930000061
wherein R is11、R12Each independently selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, a substituted alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a substituted alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, a substituted alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a substituted cycloalkyl group having 3 to 10 carbon atoms, a sulfanyl group having 1 to 10 carbon atoms, a substituted sulfanyl group having 1 to 10 carbon atoms, a carbonate group having 1 to 10 carbon atoms, a substituted carbonate group having 1 to 10 carbon atoms, a carbonyl group having 1 to 10 carbon atoms, a substituted carbonyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a substituted aryl group having 6 to 10 carbon atoms, wherein, when substituted, the substituent is selected from at least one of halogen or cyano;
R13、R15each independently selected from a carbonyl group, a sulfone group, an alkylene group having 1 to 10 carbon atoms, or a substituted alkylene group having 1 to 10 carbon atoms, wherein,when substituted, the substituent is selected from at least one of halogen, nitrile group or borate group;
R14selected from covalent bonds, oxygen atoms, alkylene groups having 1 to 10 carbon atoms, substituted alkylene groups having 1 to 10 carbon atoms, alkenylene groups having 1 to 10 carbon atoms or substituted alkenylene groups having 1 to 10 carbon atoms, wherein, when substituted, the substituent is selected from at least one of halogen, a nitrile group, a borate group, an alkenyl group, an alkynyl group, an ether group, a carbonyl group, an aldehyde group, a benzene ring or an alkyl group containing an unsaturated bond;
R21、R24、R25each independently selected from- (CH)2)a-O-(CH2)b-CN、-(CH2)c-O-(CH2)d-O-(CH2)-CN-(CH2)e-O- (CH ═ CH) -CN, alkyl of 2 to 5 carbon atoms, alkoxy of 1 to 5 carbon atoms or carbonyl of 2 to 5 carbon atoms, wherein a, b, c, d, e are each independently selected from integers of 0 to 10;
R22、R23each independently selected from a covalent bond, an alkylene group having 1 to 5 carbon atoms, a substituted alkylene group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an alkenylene group having 2 to 5 carbon atoms, wherein, when substituted, the substituent is selected from an alkoxy group having 1 to 5 carbon atoms.
The compound that includes formula I simultaneously in the electrolyte in the example of this application and the compound that formula II shows, not only form stable protection film at positive interface and negative pole interface, reduce the contact of electrolyte and active material, prevent the further redox decomposition of electrolyte, can also guarantee anodal in cycle process crystal structure's stability, can also effectively restrain HF to the corruption of active material simultaneously, guarantee electrochemical device's cyclicity performance under high operating voltage, consequently, can be applicable to high operating voltage's electrochemical device, thereby it improves energy density through improving operating voltage to be favorable to electrochemical device. In some examples of the present application, the electrochemical device of high operating voltage is an electrochemical device of which maximum operating voltage is not lower than 4.47V.
In some examples herein, the compound of formula I includes at least one of the compounds shown below:
Figure BDA0002731059930000071
in some examples of the present application, the compound of formula II comprises at least one of the following compounds:
Figure BDA0002731059930000081
in some examples of the present application, the percentage of the mass of the compound represented by formula I to the total mass of the electrolyte is less than or equal to 3%. In some examples of the present application, the percentage of the mass of the compound represented by formula II to the total mass of the electrolyte is 4% or less. When the mass content of the compound represented by formula I or the compound represented by formula II in the electrolyte is too high, the viscosity of the electrolyte increases to deteriorate the conductivity of the electrolyte, which is disadvantageous to the cycle performance of an electrochemical device using the electrolyte.
In some examples of the present application, the electrolyte further comprises: at least one of a bicyclic carbonate compound, a borate compound, a chain fluorocarbonate compound, or lithium difluorophosphate. In some examples, the bicyclic carbonate compound can preferentially form a stable protective film on the surface of a negative active material of an electrochemical device using the electrolyte, prevent the electrolyte from further contacting with the negative active material, and prevent transition metal ions dissolved in the electrolyte from damaging an SEI film, thereby facilitating improvement of cycle performance and high-temperature storage performance of the electrochemical device. In some examples, the borate ester compound is easily oxidized at the negative electrode of an electrochemical device using the electrolyte, and boron atoms therein are easily combined with oxygen radicals on the surface of the positive electrode active material to inhibit the release of the oxygen radicals at the positive electrode, thereby further stabilizing the crystal structure of the positive electrode active material during cycling. In some examples, fluorine atoms in the chain-type fluoro carbonate compound have strong electronegativity and weak polarity, so that the chain-type fluoro carbonate compound has higher dielectric constant and conductivity and better wettability compared with a non-fluoro compound, and meanwhile, the chain-type fluoro carbonate compound has lower highest occupied molecular orbitals and lowest unoccupied molecular orbitals, so that the chain-type fluoro carbonate compound can effectively improve the oxidation resistance of the electrolyte, prevent the electrolyte from being oxidized at a positive electrode interface under high operating voltage, and thus be beneficial to improving the cycle performance and high-temperature storage performance of an electrochemical device adopting the electrolyte provided in the examples of the present application under high operating voltage. In some examples of the present application, lithium difluorophosphate may form a corrosion-resistant inorganic substance on the surface of the active material, thereby protecting the protective film on the surface of the active material while inhibiting decomposition of lithium hexafluorophosphate and reducing generation of HF, and thus adding lithium difluorophosphate to the electrolyte is advantageous for improving cycle performance and high-temperature storage performance of an electrochemical device using the electrolyte in examples of the present application.
In some examples of the present application, the percentage of the mass of the bicyclic carbonate compound to the total mass of the electrolyte is 5% or less. In some examples, when the content of the biscyclocarbonate compound in the electrolyte exceeds 5% by mass, the conductivity in the electrolyte may be reduced.
In some examples of the present application, the borate compound is present in an amount of 3% by mass or less based on the total mass of the electrolyte.
In some examples of the present application, the percentage of the mass of the chain-like fluoro carbonate compound to the total mass of the electrolyte is 15% or less; in some examples, the chain-type fluoro carbonate compound has a relatively high viscosity, and when the chain-type fluoro carbonate compound is contained in the electrolyte in an amount of more than 15% by mass, the viscosity of the electrolyte is significantly increased to lower the conductivity of the electrolyte.
In some examples of the present application, the percentage of the mass of lithium difluorophosphate to the total mass of the electrolyte is 1% or less. In some examples, when the lithium difluorophosphate is contained in the electrolyte in an amount of more than 1% by mass, the acidity of the electrolyte may be excessively high, resulting in a decrease in the stability of the protective film on the surface of the active material, and thus, a decrease in the cycle performance and high-temperature storage performance of an electrochemical device using the electrolyte.
In some examples herein, bicyclic carbonate compounds include at least one of the compounds of formula III:
Figure BDA0002731059930000091
wherein A is selected from alkylene or a single bond, R1Is selected from
Figure BDA0002731059930000092
R32、R33Each independently selected from a hydrogen atom or a halogen atom.
In some examples herein, bicyclic carbonate compounds include at least one of the following:
Figure BDA0002731059930000101
in some examples herein, the borate ester compound comprises at least one compound of formula IV:
Figure BDA0002731059930000102
wherein R is41、R42、R43Each independently selected from a carbonyl group having 1 to 5 carbon atoms, a mercapto group having 1 to 5 carbon atoms, an alkyl group having 1 to 5 carbon atoms, a substituted alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, a substituted alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, a substituted alkynyl group having 2 to 5 carbon atoms, an ether group having 1 to 5 carbon atoms, a substituted ether group having 1 to 5 carbon atoms, an aryl group having 6 to 10 carbon atoms, a substituted aryl group having 6 to 10 carbon atoms, a cycloalkane having 6 to 10 carbon atoms, and a substituted cycloalkane having 6 to 10 carbon atoms, wherein, when substituted, the substituent is selected from a halogen or a nitrile group, up to a mercapto group, a cycloalkyl group having 1 to 5 carbon atoms, a cycloalkyl group having 6 to 10 carbon atoms, and a cycloalkyl group having 6 to 10 carbon atomsOne of them is less.
In some examples of the present application, the compound of formula IV comprises at least one of the following compounds:
Figure BDA0002731059930000103
Figure BDA0002731059930000111
in some examples herein, the chain fluoro carbonate compound comprises at least one compound of formula V:
Figure BDA0002731059930000112
wherein R is51、R52Each independently selected from an alkyl group having 1 to 5 carbon atoms, a fluoroalkyl group having 1 to 5 carbon atoms, a substituted alkyl group having 1 to 5 carbon atoms, or a substituted fluoroalkyl group having 1 to 5 carbon atoms, and R51And R52At least one of which is a fluoroalkyl group.
In some examples herein, the chain fluoro carbonate compound includes at least one of the following compounds:
Figure BDA0002731059930000113
in some examples of the present application, the electrolyte contains lithium hexafluorophosphate (LiPF)6)。
In some examples of the present application, the lithium hexafluorophosphate is present in an amount of 0.8mol/L to 1.8 mol/L.
In some examples of the present application, the electrolyte includes a non-aqueous organic solvent, wherein the non-aqueous organic solvent includes one or a combination of two or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, γ -butyrolactone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, or propyl butyrate in any ratio.
The present application further provides an electrochemical device comprising: a positive electrode, a negative electrode, a separator, and any of the above-described electrolytic solutions.
The positive electrode of the electrochemical device includes a positive electrode current collector and a positive electrode active material disposed on the positive electrode current collector. The specific type of the positive electrode active material is not particularly limited, and may be selected as desired.
In some examples of the present application, the positive active material includes a positive electrode material capable of absorbing and releasing lithium (Li). Examples of the positive electrode material capable of absorbing/releasing lithium (Li) may include lithium cobaltate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, lithium manganate, lithium iron manganese phosphate, lithium vanadium phosphate, lithium vanadyl phosphate, lithium iron phosphate, lithium titanate, and lithium-rich manganese-based materials.
In some examples of the present application, the positive active material includes LixMyAZB(1-y-z)O2Or LiNPO4Wherein M, A and B are at least one element selected from Ni, Co, Mn and Al, wherein M, A and B are not the same element, x ranges from 0.94 to 1.10, and y ranges from: y is more than 0 and less than or equal to 1, and the value range of z is as follows: z is more than 0 and less than or equal to 1, and the value range of y + z is that y + z is less than or equal to 1. LiNPO4Has olive structure, and N can be one element selected from Ni, Co, Fe, Mn, V, etc.
In some examples of the present application, the anode of the above electrochemical device includes an anode current collector and an anode active material layer disposed on the anode current collector. The specific kind of the negative electrode active material is not particularly limited and may be selected as required.
In some examples of the present application, the anode active material layer includes graphite, and in some examples, a ratio of a peak area of a (004) peak to a peak area of a (110) peak of the graphite ranges from 10 to 20, and in some examples, a particle size distribution of the graphite D50 ranges from 10 to 17 μm.
In some examples of the present application, a functional layer is included between the anode active material layer and the anode current collector, the functional layer includes a carbon material, and a ratio of a thickness of the anode active material layer to a thickness of the functional layer is 5: 1 to 99: 1.
in some examples of the present application, a conductive agent or a binder may be added to the positive electrode of the electrochemical device, and in some examples of the present application, the positive electrode further includes a carbon material, and the carbon material may include at least one of conductive carbon black, graphite, graphene, carbon nanotubes, carbon fibers, or carbon black. The binder may include at least one of polyvinylidene fluoride, copolymers of vinylidene fluoride-hexafluoropropylene, styrene-acrylate copolymers, styrene-butadiene copolymers, polyamides, polyacrylonitrile, polyacrylates, polyacrylic acids, polyacrylates, sodium carboxymethyl cellulose, polyvinyl acetate, polyvinylpyrrolidone, polyvinyl ethers, polymethyl methacrylate, polytetrafluoroethylene, or polyhexafluoropropylene.
In some examples, the separator includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyethylene terephthalate, polyimide, or aramid. For example, the polyethylene includes at least one selected from high density polyethylene, low density polyethylene, or ultra high molecular weight polyethylene. Particularly polyethylene and polypropylene, which have a good effect on preventing short circuits and can improve the stability of the battery through a shutdown effect. In some optional examples, an inorganic or organic coating is applied to the surface of the separator to enhance the hardness of the cell or to improve the adhesion of the separator to the positive and negative electrode interfaces.
In some examples, the surface of the separator may further include a porous layer disposed on at least one surface of the separator, the porous layer including inorganic particles selected from alumina (Al) and a binder2O3) Silicon oxide (SiO)2) Magnesium oxide (MgO), titanium oxide (TiO)2) Hafnium oxide (HfO)2) Tin oxide (SnO)2) Cerium oxide (CeO)2) Nickel oxide (NiO), zinc oxide (ZnO), calcium oxide (CaO), zirconium oxide (ZrO)2) Yttrium oxide (Y)2O3) Silicon carbide (SiC), boehmite,At least one of aluminum hydroxide, magnesium hydroxide, calcium hydroxide or barium sulfate. The binder is at least one selected from polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene or polyhexafluoropropylene.
The present application also provides an electronic device comprising the electrochemical device of any one of the above. The electronic device of the present application is not particularly limited, and may be any electronic device known in the art. In some examples, the electronic device may include, but is not limited to, a notebook computer, a pen-input computer, a mobile computer, an electronic book player, a portable phone, a portable facsimile, a portable copier, a portable printer, a headphone, a video recorder, a liquid crystal television, a handheld cleaner, a portable CD player, a mini disc, a transceiver, an electronic notebook, a calculator, a memory card, a portable recorder, a radio, a backup power source, a motor, an automobile, a motorcycle, a moped, a bicycle, a lighting fixture, a toy, a game machine, a clock, a power tool, a flashlight, a camera, a large household battery, a lithium ion capacitor, and the like. For example, the electronic device includes a mobile phone including a lithium ion battery.
In order to better illustrate the beneficial effects of the electrolytes proposed in the examples of the present application, the following examples will be described in conjunction with the following examples, wherein the lithium ion batteries prepared in the following examples are different only in the electrolytes, and performance tests are performed on the lithium ion batteries using different electrolytes in the following examples to illustrate the effect of the electrolytes on the performance of the lithium ion batteries.
The lithium ion batteries in the examples were prepared as follows:
preparing an electrolyte: at water content<In a 10ppm argon atmosphere glove box, Ethylene Carbonate (EC), Propylene Carbonate (PC), diethyl carbonate (DEC) were mixed in a mass ratio of 1: 1: 1 mixing homogeneously, adding LiPF6Dissolving and stirring uniformly to form a basic electrolyte solution in which LiPF6The concentration of (2) is 1.15 mol/L. The electrolyte solution used in each of the following examples is a base electrolyte solution, or an electrolyte solution obtained by adding at least one of a compound represented by formula I, a compound represented by formula II, a bicyclic carbonate compound represented by formula III, a borate ester compound represented by formula IV, a chain fluoro carbonate compound represented by formula V, or lithium difluorophosphate to a base electrolyte solution.
Preparing a positive electrode: the positive electrode active material lithium cobaltate (LiCoO)2) Or mixing the aluminum-doped lithium cobaltate, the conductive agent carbon (Super p) and the binder (polyvinylidene fluoride) according to the weight ratio of 95:2:3, adding N-methyl pyrrolidone (NMP), stirring the mixture under the action of a vacuum stirrer until the mixture is a uniform positive slurry, and then uniformly coating the positive slurry on an aluminum foil of a positive current collector; drying for 4h at 85 ℃ under vacuum, and then carrying out cold pressing, cutting into pieces and slitting to obtain the anode.
Preparing a negative electrode: fully stirring and mixing a negative active material graphite, a binder Styrene Butadiene Rubber (SBR) and a thickener sodium carboxymethyl cellulose (CMC) in a deionized water solvent according to a weight ratio of 95:2:3 to form uniform negative slurry; and coating the slurry on a Cu foil of a negative current collector, drying for 4 hours at 85 ℃ under a vacuum condition, and then carrying out cold pressing, sheet cutting and slitting to obtain the negative electrode.
Preparing a lithium ion battery: and sequentially stacking an anode, a barrier film (polyethylene PE) and a cathode to enable the barrier film to be positioned between the anode and the cathode to play a role of isolation, then winding, gluing the tail end of the separator, placing the separator in a punched aluminum foil bag, packaging the edge of the aluminum foil bag, then placing the aluminum foil bag in a vacuum oven for drying, injecting the prepared electrolyte into the battery after vacuum drying, and completing the preparation of the lithium ion battery through the processes of vacuum packaging, standing, formation, forming and the like.
The lithium ion batteries in the examples were each tested for performance according to the following method:
test method for thickness expansion rate at 85 ℃ storage: the lithium ion battery is stood for 30 minutes at 25 ℃, the initial thickness of the battery core at the moment is tested, then the battery core is charged to 4.47V at a constant current of 0.7C, then the battery core is charged to 0.05C at a constant voltage of 4.47V, the battery core is stood for 5 minutes, the thickness of the battery at the moment is tested and recorded as the initial thickness before storage, then the battery core is stored for 8 hours at 85 ℃, the battery is taken out after the storage is finished, the thickness of the battery is tested at 25 ℃, recorded as the thickness after storage, and the expansion rate of the storage thickness at 85 ℃ is calculated according to the following formula:
the storage thickness expansion ratio ═ [ (thickness after storage-initial thickness before storage)/initial thickness before storage ] × 100%.
Test method for the thickness expansion rate at 60 ℃ storage: the lithium ion battery is stood for 30 minutes at 25 ℃, the initial thickness of the battery core at the moment is tested, then the battery core is charged to 4.47V at a constant current of 0.7C, then the battery core is charged to 0.05C at a constant voltage of 4.47V, the battery core is stood for 5 minutes, the thickness of the battery at the moment is tested and recorded as the initial thickness before storage, then the battery core is stored for 24 days at 60 ℃, the battery core is taken out after the storage is finished, the thickness of the battery is tested at 25 ℃, recorded as the thickness after storage, and the expansion rate of the storage thickness at 60 ℃ is calculated by the following formula:
the storage thickness expansion ratio ═ [ (thickness after storage-initial thickness before storage)/initial thickness before storage ] × 100%.
Method for testing high-temperature capacity retention rate: charging the lithium ion battery to 4.2V at a constant current of 1.3C at 45 ℃, then charging to 4.47V at a constant current of 0.7C, finally charging at a constant voltage until the current is 0.05C, and then discharging to 3.0V at a constant current of 0.7C, wherein the first discharge capacity is recorded in the first cycle. The lithium ion battery is cycled for a plurality of times according to the above conditions. And (3) repeatedly carrying out charge and discharge cycles with the capacity of the first discharge as 100 percent until the discharge capacity retention rate is attenuated to 80 percent, stopping the test, and recording the number of cycles, namely the number of cycles at 45 ℃, as an index for evaluating the cycle performance of the lithium ion battery.
To illustrate the effect of the compounds of formula I and II in electrolytes, example SI-1Using a base electrolyte, in example SI-2To example SI-62At least one of the compounds shown in the formula I or the formula II is added into the electrolyte respectively, and the specific added compounds and performance test results are shown in Table 1.
TABLE 1
Figure BDA0002731059930000151
Figure BDA0002731059930000161
Figure BDA0002731059930000171
Comparative example SI-1And example S1-23To example S1-62It can be seen from the results of the performance test that S is compared with example S using the base electrolyteI-1, example S1-23To example S1-62The expansion rate of the thickness stored at 60 ℃ and the expansion rate of the thickness stored at 85 ℃ are reduced; comparative example SI-2To example SI-22And example S1-23To example S1-62Compared with the method in which the compound shown in the formula I or the compound shown in the formula II is added into the electrolyte, the method in which the compound shown in the formula I and the compound shown in the formula II are added into the electrolyte can further improve the cycle performance and the high-temperature storage performance of the lithium ion battery adopting the electrolyte under high operating voltage. Further, in example S1-23To example S1-62In the case where the mass content of the compound represented by formula II in the electrolyte is 4% or less, the performance is more excellent, and thus, it can be seen that the high-temperature storage performance at high operating voltage of a lithium ion battery using the electrolyte can be improved by adding the compound represented by formula II to the electrolyte, and the cycle performance at high operating voltage of a lithium ion battery using the electrolyte can also be improved by controlling the mass content of the compound represented by formula II.
From the above examples, it can be seen that in a lithium ion battery using a high operating voltage (4.47V), when the compound represented by formula I or the compound represented by formula II is added to the base electrolyte alone, the high temperature cycle and the high temperature storage of the lithium ion battery can be slightly improved, and when the compound represented by formula I and the compound represented by formula II are included in the electrolyte at the same time, the high temperature cycle and the high temperature storage of the lithium ion battery are both significantly improved. The method is mainly characterized in that when the compound shown in the formula I or the compound shown in the formula II is added independently, the protection of an electrode is weak, and the positive electrode and the negative electrode are difficult to be protected in a general formula. Not only the by-products of the electrolyte are reduced, but also the damage of the by-products of the electrolyte to the anode and cathode structures is reduced, thereby obviously improving the cycle performance and the high-temperature storage performance of the lithium ion battery adopting the electrolyte under high working voltage.
To illustrate the effect of the bicyclic carbonate compound of formula III in the electrolyte, example SIII-1To SIII-18The electrolyte is added with a compound shown in a formula I-1 and a compound shown in a formula II-1, and simultaneously, a bicyclic carbonate compound shown in a formula III-1 or a formula III-2 is added, the specific added compounds and performance test results are shown in a table 2, and an example S is added into the table 2I-25The results of the performance tests of (2) are illustrated by comparison.
TABLE 2
Figure BDA0002731059930000181
Comparative example SI-25Example S1II-1To example SIII-18As can be seen from the performance test results, after the bicyclic carbonate compound shown in the formula III-1 or the formula III-2 is further added into the electrolyte containing the compound shown in the formula I and the compound shown in the formula II, the cycle performance and the high-temperature storage performance of the lithium ion battery adopting the electrolyte are further improved under high operating voltage, because the bicyclic carbonate compound is preferentially reduced with the solvent of the electrolyte on the surface of the negative electrode to form a stable protective film, and the contact between the electrolyte and the negative electrode is further prevented. The stable SEI film can effectively prevent the damage of transition metal ions dissolved into the electrolyte to the SEI film, thereby further improving the cycle rateHigh temperature storage performance.
To illustrate the effect of the borate compounds of formula IV in electrolytes, example SIV-2To SIV-43The electrolyte solution in (1) is added with the compound shown in formula I-1 and the compound shown in formula II-1, and simultaneously added with the borate compound shown in formula IV, the specific added compound and the performance test result are shown in Table 3, and example S is added in Table 3I-25The results of the performance tests of (2) are illustrated by comparison.
TABLE 3
Figure BDA0002731059930000182
Figure BDA0002731059930000191
Comparative example SI-25Example SIV-1To example SIV-33As can be seen from the results of the performance tests, when the borate compound represented by the formula IV is further added to the electrolyte containing the compound represented by the formula I and the compound represented by the formula II, and the mass content of the borate compound represented by the formula IV in the electrolyte is less than or equal to 3%, the 85 ℃ storage thickness expansion rate, the 60 ℃ storage thickness expansion rate and the 45 ℃ cycle number of the lithium ion battery using the electrolyte are compared with those of the example SI-25All are improved. The borate compound shown in the formula IV is easy to oxidize at the negative electrode, boron atoms in the borate compound are easy to combine with oxygen radicals on the surface of lithium cobaltate, and the release of the oxygen radicals in the positive electrode is inhibited, so that the crystal structure of the positive electrode in the circulation process is further stabilized.
Comparative example SI-25And SⅣ-10It can be seen from the results of the performance test that when the mass content of the borate compound represented by formula iv is more than 3%, the high temperature cycle is deteriorated. This is because the protective film formed from the borate compound is not so stable, and when the amount of the borate compound represented by the formula IV is too large, the protective film is easily decomposed at high temperature to generate gas, and the battery is deformed to cause the cycle performance of the batteryAnd is worsened.
To illustrate the effect of the chain-type fluorocarbonate compound represented by formula V in the electrolyte solution, S is exemplifiedV-1To SV-20The electrolyte is added with a compound shown in a formula I-1 and a compound shown in a formula II-1, and simultaneously, a chain-shaped fluoro carbonate compound shown in a formula V is added, the specific added compound and the performance test result are shown in a table 4, and an example S is added into the table 4I-25The results of the performance tests of (2) are illustrated by comparison.
TABLE 4
Figure BDA0002731059930000201
Comparative example SI-25Example SV-2To example SV-20As can be seen from the results of the performance tests, after the chain-type fluoro carbonate compound represented by the formula V was further added to the electrolyte containing the compound represented by the formula I and the compound represented by the formula II, the lithium ion battery using the electrolyte exhibited a thickness expansion rate at 85 ℃ and a thickness expansion rate at 60 ℃ as compared with those of the example SI-25All are improved, when the mass content of the chain-shaped fluoro carbonic ester compound shown in the formula V in the electrolyte is less than or equal to 15 percent, the number of cycles at 45 ℃ of the lithium ion battery adopting the electrolyte is compared with that of the example SI-25All are improved. The reason is that the chain-type fluoro carbonate compound has a higher dielectric constant and a better conductivity, the chain-type fluoro carbonate compound shown in the formula V has a better wettability as a solvent than a non-fluoro solvent, and the chain-type fluoro carbonate compound shown in the formula V has a lower highest occupied molecular orbital and a lower lowest unoccupied molecular orbital, so that the oxidation resistance of the electrolyte can be effectively improved by using the chain-type fluoro carbonate compound shown in the formula V, and the electrolyte is prevented from being oxidized at a high-operating-voltage positive electrode interface.
Comparative example SI-25And SV-20It can be seen from the results of the performance test that when the mass content of the chain-type fluoro carbonate compound represented by the formula V is more than 15%, the cycle performance of the lithium ion battery using the electrolyte starts to decrease because of the decrease with the formula VThe addition of the chain-type fluoro carbonate compound reduces the electrochemical performance of the electrolyte, and the chain-type fluoro carbonate compound shown in formula V has a high viscosity, and the increase of the addition amount of the chain-type fluoro carbonate compound obviously increases the viscosity of the electrolyte and reduces the conductivity of the electrolyte, thereby causing the deterioration of the electrical performance.
To illustrate the role of lithium difluorophosphate in the electrolyte, example SVI-1To SVI-10The electrolyte solution in (1) was added with the compound represented by formula I-1 and the compound represented by formula II-1, and lithium difluorophosphate was added, and the specific compounds and performance test results are shown in Table 5, and example S was added in Table 5I-25The results of the performance tests of (2) are illustrated by comparison.
TABLE 5
Figure BDA0002731059930000211
Figure BDA0002731059930000221
Table 5 shows the effect of further addition of lithium difluorophosphate on the performance of lithium ion batteries in electrolytes containing compounds of formula I and II, from example S shown in Table 5VI-1To SVI-10As can be seen from the performance test results, in example SI-25The lithium difluorophosphate is further added on the basis of the used electrolyte, so that high-temperature circulation and high-temperature storage can be effectively improved, and corrosion-resistant inorganic substances can be formed on the surface of the active material by adding the lithium difluorophosphate, so that the damage of by-products to the protective film is avoided, the decomposition of the lithium hexafluorophosphate can be inhibited, and the generation of HF is reduced.
From example SⅥ-5To example SⅥ-10It can be seen from the results of the performance test that, when the content of lithium difluorophosphate in the electrolyte reaches a certain level, if the content of lithium difluorophosphate is continuously increased in the electrolyte, the cycle performance and the high-temperature storage performance of the lithium ion battery using the electrolyte are gradually deteriorated due to the high content of lithium difluorophosphateLithium phosphate causes the acidity of the electrolyte to be high, thereby causing the stability of the protective film on the surface of the active material to be lowered, and thus causing the cycle performance and high-temperature storage performance of the lithium ion battery using the electrolyte to be lowered.
To illustrate the combined effect of various compounds in the electrolyte, example SVII-2To SVII-9Wherein at least two of a bicyclic carbonate compound represented by the formula III-1, a borate compound represented by the formula IV-1, a chain fluoro carbonate compound represented by the formula V-3 or lithium difluorophosphate are added to the electrolyte while the compound represented by the formula I-1 and the compound represented by the formula II-1 are added, the specific addition compounds and the performance test results are shown in Table 6, and example S is added to the electrolyte in Table 6I-25、SⅢ-6、SⅣ-4、SⅤ-12And SⅥ-5The results of the performance tests of (2) are illustrated by comparison.
TABLE 6
Figure BDA0002731059930000222
Figure BDA0002731059930000231
Table 6 shows the effect of electrolytes containing various combinations of compounds on battery performance.
Comparative example SIII-6Example SVII-1To example SVII-3The performance test result shows that the cycle performance and the high-temperature storage performance of the lithium ion battery can be further improved by adding the borate compound shown in the formula IV, the chain fluoro carbonate compound shown in the formula V-3 or lithium difluorophosphate while adding the compound shown in the formula I-1 and the compound shown in the formula II-1 into the electrolyte.
Comparative example SIV-4Example SVII-5To example SVII-6As can be seen from the results of the performance tests, the compound represented by the formula I-1, the compound represented by the formula II-1 and the boric acid ester compound represented by the formula IV-1 were added to the electrolyte, and the chain-type fluoro carbonate represented by the formula V-3 was further addedThe compound or lithium difluorophosphate can further improve the cycle performance and the high-temperature storage performance of the lithium ion battery.
Comparative example SVII-4Example SVII-7To example SVII-8The performance test result shows that when the compound shown in the formula I-1, the compound shown in the formula II-1, the bicyclic carbonate compound shown in the formula III-1 and the borate compound shown in the formula IV-1 are added into the electrolyte, the chain-shaped fluoro carbonate compound shown in the formula V-3 or lithium difluorophosphate is further added, so that the cycle performance and the high-temperature storage performance of the lithium ion battery can be further improved.
From the above comparison results, it can be seen that the cycle performance and high-temperature storage performance of a lithium ion battery using the electrolyte can be further improved by adding at least two of the bicyclic carbonate compound represented by formula I-1, the borate compound represented by formula IV, the chain fluoro carbonate compound represented by formula V-3, or lithium difluorophosphate to the electrolyte while adding the compound represented by formula I-1 and the compound represented by formula II-1.
In conclusion, the compound shown in the formula I in the electrolyte can be oxidized on the surface of the positive electrode in preference to other organic solvents to form a stable CEI film, so that the interface of the positive electrode is effectively protected, and the electrolyte is prevented from being contacted with a positive electrode active substance to further oxidative decomposition; the organic compound is reduced at the negative electrode in preference to other organic compounds to form a stable SEI film, so that the negative electrode interface is effectively protected, and the damage of some byproducts to the negative electrode is inhibited; the compound shown in the formula II can effectively perform a complex reaction with high-valence cobalt on the surface of the anode to form a stable complex structure on the surface of the anode, so that the dissolution of cobalt in the anode material is effectively inhibited, the anode material is ensured to have a stable crystal structure in a circulating process, and the circulating performance and the high-temperature storage performance of an electrochemical device adopting the electrolyte under high working voltage are effectively improved.
The above description is only a preferred example of the present application and is intended to illustrate the principles of the technology employed. It will be appreciated by those skilled in the art that the scope of the disclosure herein is not limited to the particular combination of features described above, but also encompasses other arrangements formed by any combination of the above features or their equivalents without departing from the spirit of the disclosure. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.
Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order. Under certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are included in the above discussion, these should not be construed as limitations on the scope of the application. Certain features that are described in the context of separate examples can also be implemented in combination in a single example. Conversely, various features that are described in the context of a single example can also be implemented in multiple examples separately or in any suitable subcombination.
Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims (13)

1. An electrolyte comprising a compound of formula 1 and a compound of formula II:
Figure FDA0002731059920000011
wherein R is11、R12Each independently selected from the group consisting of an unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted alkyl group having 1 to 10 carbon atoms, an unsubstituted alkenyl group having 2 to 10 carbon atoms, a substituted alkenyl group having 2 to 10 carbon atoms, an unsubstituted alkynyl group having 2 to 10 carbon atoms, a substituted alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a substituted aryl group, a substituted heteroarylA cycloalkyl group having 3 to 10 carbon atoms, an unsubstituted sulfanyl group having 1 to 10 carbon atoms, a substituted sulfanyl group having 1 to 10 carbon atoms, a carbonate group having 1 to 10 carbon atoms, a substituted carbonate group having 1 to 10 carbon atoms, a carbonyl group having 1 to 10 carbon atoms, a substituted carbonyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a substituted aryl group having 6 to 10 carbon atoms, wherein, when substituted, the substituent is selected from at least one of a halogen group or a cyano group;
R13、R15each independently selected from carbonyl, sulfone, alkylene with 1 to 10 carbon atoms or substituted alkylene with 1 to 10 carbon atoms, wherein, when substituted, the substituent is selected from at least one of halogen, nitrile or borate;
R14selected from covalent bonds, oxygen atoms, alkylene groups having 1 to 10 carbon atoms, substituted alkylene groups having 1 to 10 carbon atoms, alkenylene groups having 2 to 10 carbon atoms or substituted alkenylene groups having 2 to 10 carbon atoms, wherein, when substituted, the substituent is selected from at least one of halogen, a nitrile group, a borate group, an alkenyl group, an alkynyl group, an ether group, a carbonyl group, an aldehyde group, a benzene ring or an alkyl group containing an unsaturated bond;
R21、R24、R25each independently selected from a hydrogen atom, - (CH)2)a-O-(CH2)b-CN、-(CH2)c-O-(CH2)d-O-(CH2)-CN、-(CH2)e-O- (CH ═ CH) -CN, alkyl of 2 to 5 carbon atoms, alkoxy of 1 to 5 carbon atoms or carbonyl of 2 to 5 carbon atoms, wherein a, b, c, d, e are each independently selected from integers of 0 to 10;
R22、R23each independently selected from a covalent bond, an alkylene group having 1 to 5 carbon atoms, a substituted alkylene group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an alkenylene group having 2 to 5 carbon atoms, wherein, when substituted, the substituent is selected from an alkoxy group having 1 to 5 carbon atoms.
2. The electrolyte of claim 1, wherein the compound of formula I comprises at least one of the following compounds:
Figure FDA0002731059920000021
3. the electrolyte of claim 1, wherein the compound of formula II comprises at least one of the following compounds:
Figure FDA0002731059920000022
Figure FDA0002731059920000031
4. the electrolyte of claim 1,
the mass percentage of the compound shown in the formula I in the total mass of the electrolyte is less than or equal to 3 percent; and/or the presence of a gas in the gas,
the mass percentage of the compound shown in the formula II in the total mass of the electrolyte is less than or equal to 4%.
5. The electrolyte of claim 1, further comprising: at least one of a bicyclic carbonate compound, a borate compound, a chain fluorocarbonate compound, or lithium difluorophosphate.
6. The electrolyte of claim 5, wherein the electrolyte satisfies at least one of the following conditions (a) to (d):
(a) the weight percentage of the bicyclic carbonate compound in the total weight of the electrolyte is less than or equal to 5 percent;
(b) the mass percentage of the borate compound in the total mass of the electrolyte is less than or equal to 3 percent;
(c) the mass percentage of the chain-shaped fluoro carbonate compound in the total mass of the electrolyte is less than or equal to 15 percent;
(d) the mass percentage of the lithium difluorophosphate in the total mass of the electrolyte is less than or equal to 1%.
7. The electrolyte of claim 5, wherein the biscyclocarbonate compound comprises at least one of the following compounds:
Figure FDA0002731059920000032
8. the electrolyte of claim 5, wherein the borate compound comprises a compound of formula IV:
Figure FDA0002731059920000033
wherein R is41、R42、R43Each independently selected from a carbonyl group having 1 to 5 carbon atoms, a mercapto group having 1 to 5 carbon atoms, an alkyl group having 1 to 5 carbon atoms, a substituted alkyl group having 1 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, a substituted alkenyl group having 2 to 5 carbon atoms, an alkynyl group having 2 to 5 carbon atoms, a substituted alkynyl group having 2 to 5 carbon atoms, an ether group having 1 to 5 carbon atoms, a substituted ether group having 1 to 5 carbon atoms, an aryl group having 6 to 10 carbon atoms, a substituted aryl group having 6 to 10 carbon atoms, a cycloalkane having 6 to 10 carbon atoms, and a cycloalkane having 6 to 10 carbon atoms, wherein, when substituted, the substituent is selected from at least one of a halogen and a nitrile group.
9. The electrolyte of claim 5, wherein the borate compound comprises at least one of the following compounds:
Figure FDA0002731059920000041
10. the electrolyte of claim 5, wherein the chain fluoro carbonate compound comprises a compound of formula V:
Figure FDA0002731059920000042
wherein R is51、R52Each independently selected from an alkyl group having 1 to 5 carbon atoms, a fluoroalkyl group having 1 to 5 carbon atoms, a substituted alkyl group having 1 to 5 carbon atoms, or a substituted fluoroalkyl group having 1 to 5 carbon atoms, and R51And R52At least one of which is a fluoroalkyl group.
11. The electrolyte solution according to claim 5, wherein the chain fluoro carbonate compound comprises at least one of the following compounds:
Figure FDA0002731059920000043
12. an electrochemical device, comprising:
a positive electrode, a negative electrode, a separator and the electrolyte according to any one of claims 1 to 11.
13. An electronic device comprising the electrochemical device according to claim 12.
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