CN113471532A - Electrolyte, preparation method thereof and lithium ion battery - Google Patents

Electrolyte, preparation method thereof and lithium ion battery Download PDF

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CN113471532A
CN113471532A CN202010236947.8A CN202010236947A CN113471532A CN 113471532 A CN113471532 A CN 113471532A CN 202010236947 A CN202010236947 A CN 202010236947A CN 113471532 A CN113471532 A CN 113471532A
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additive
electrolyte
equal
lithium
lithium ion
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CN113471532B (en
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李伟善
关雄聪
李梦
方伟亮
廖友好
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South China Normal University
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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
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention relates to an electrolyte, a preparation method thereof and a lithium ion battery. The electrolyte comprises an organic solvent, a lithium salt and an additive, wherein the additive is at least one of a first additive and a second additive. Specifically, the first additive is at least one of the compounds shown in the formula (I), and the second additive is at least one of the compounds shown in the formula (II). The electrolyte is applied to the lithium ion battery, and the high-temperature performance and the low-temperature performance of the lithium ion battery can be effectively improved.

Description

Electrolyte, preparation method thereof and lithium ion battery
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to an electrolyte, a preparation method thereof and a lithium ion battery.
Background
The lithium ion battery has the advantages of high energy density, long cycle life, cyclic utilization and the like, so that the lithium ion battery can be widely applied to the fields of digital products, automobiles, aerospace and the like. With the increasing consumer demand, consumers have made higher demands on the performance of lithium ion batteries. For example, consumers expect that lithium ion batteries have good performance under different temperature conditions to adapt to use environments with large day-night temperature difference and large north-south temperature difference.
However, the conventional lithium ion battery has good performance only at normal temperature, or can be normally used only at a single high temperature or low temperature. When the temperature span of the use environment is large (such as-10 ℃ to 40 ℃), the traditional lithium ion battery is difficult to have good high-temperature performance and low-temperature performance.
Disclosure of Invention
Therefore, the electrolyte, the preparation method thereof and the lithium ion battery are needed to be provided, and the electrolyte applied to the lithium ion battery can improve the interface property of the electrode and the electrolyte of the lithium ion battery, so that the lithium ion battery can well give consideration to both high-temperature performance and low-temperature performance.
The specific scheme for solving the technical problems is as follows:
an object of the present invention is to provide an electrolyte including an organic solvent, a lithium salt, and an additive, the additive being at least one of a first additive and a second additive;
the first additive is at least one of compounds shown as a formula (I);
Figure BDA0002431311810000021
the second additive is at least one of compounds shown as a formula (II);
Figure BDA0002431311810000022
wherein R is1～R12Each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted C1～20Alkyl, substituted or unsubstituted C1～20Alkoxy, substituted or unsubstituted C2～20Alkenyl, getSubstituted or unsubstituted C6～26Aryl, substituted or unsubstituted C6～26An aryloxy group.
In one embodiment, R1～R12Are the same group.
In one embodiment, the additive is 0.5-3% by mass of the electrolyte.
In one embodiment, the additives are a first additive and a second additive, and the mass ratio of the first additive to the second additive is (0.25-2): 1.
In one embodiment, the organic solvent is formed by mixing a ring-shaped solvent and a linear solvent according to a mass ratio of 1 (1-3).
In one embodiment, the cyclic solvent is at least one of ethylene carbonate, propylene carbonate, gamma-butyrolactone and gamma-valerolactone;
and/or the linear solvent is at least one of dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl acetate and methyl propyl carbonate.
In one embodiment, the lithium salt is at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium dioxalate, lithium difluorooxalate, lithium trifluoromethanesulfonate, lithium perchlorate, lithium hexafluoroarsenate, and lithium bistrifluoromethylsulfonyl imide.
Another object of the present invention is to provide a method for preparing the electrolyte solution described in any of the above embodiments, wherein the method comprises the following steps:
mixing the lithium salt with the organic solvent to obtain an electrolyte preform;
and adding the additive into the electrolyte preform, and uniformly mixing.
In addition to the above objects, another object of the present invention is to provide a lithium ion battery, which includes a positive electrode plate, a negative electrode plate, and the electrolyte described in any of the above embodiments or the electrolyte obtained by the above preparation method.
In one embodiment, theThe active material of the positive pole piece is selected from: LiMn2O4、LiNixCoyM1-x-yO2、LiFe1-aMaPO4、Li2Mn1-bO4And Li1+cMn1-zMzO2Wherein M is selected from Ni, Fe, Co, Mn, Al, Cr, Mg, Zr, Mo, V, Ti, B and F, x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, x + y is more than or equal to 0 and less than or equal to 1, z is more than or equal to 0 and less than or equal to 1, a is more than or equal to 0 and less than or equal to 1, B is more than or equal to 0 and less than or equal to 1, and c is more than or equal to 0 and less than or equal to 0.2; and/or the presence of a gas in the gas,
the active substance of the negative pole piece is at least one of graphite, a silicon-carbon composite material and lithium titanate.
The additive in the electrolyte is at least one of the compound shown in the formula (I) and the compound shown in the formula (II), and when the additive is used in the lithium ion battery, the problem of diffusion inside the lithium ion battery can be effectively solved, the interface property of an electrode and the electrolyte of the lithium ion battery is improved, the interface impedance is reduced, a stable SEI film is formed on the surface of a negative electrode of the lithium ion battery, the insertion and the removal of lithium ions are smoother at low temperature, and the low-temperature performance of the lithium ion battery is improved. Meanwhile, the compound shown in the formula (I) and the compound shown in the formula (II) can be coordinated with transition metal ions to form a complex, so that the dissolution of metal ions of the positive electrode is inhibited, and the decomposition of an organic solvent at high temperature is reduced, thereby improving the high-temperature performance of the lithium ion battery.
According to the preparation method of the electrolyte, the lithium salt is mixed with the organic solvent, and then the additive is added, so that the electrolyte capable of effectively improving the high-temperature performance and the low-temperature performance of the lithium ion battery can be obtained, the operation is simple and feasible, and the preparation method is suitable for large-scale production.
The lithium ion battery comprises the positive pole piece, the negative pole piece and the electrolyte, and the additive improves the interface property of the electrode pole piece and the electrolyte, so that the lithium ion battery still has good high-temperature performance and low-temperature performance under the condition of large environmental temperature span.
Drawings
FIG. 1 is a graph showing the cycle performance of the lithium ion batteries of examples 1 to 3 and comparative example 2 of the present invention at 25 ℃.
Fig. 2 is a graph showing cycle performance at 45 ℃ of the lithium ion batteries in example 3 and comparative example 2 of the present invention.
FIG. 3 is a graph showing the cycle performance at-10 ℃ of lithium ion batteries in example 3 and comparative example 2 of the present invention.
Detailed Description
In order that the invention may be more fully understood, reference will now be made to the accompanying examples. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
An embodiment of the present invention provides an electrolyte, including an organic solvent, a lithium salt, and an additive, where the additive is at least one of a first additive and a second additive;
the first additive is at least one of compounds shown in a formula (I);
Figure BDA0002431311810000051
the second additive is at least one of compounds shown in a formula (II);
Figure BDA0002431311810000052
wherein R is1～R12Each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted C1～20Alkyl, substituted or unsubstituted C1～20Alkoxy, substituted or unsubstituted C2～20Alkenyl, substituted or unsubstituted C6～26Aryl, substituted or unsubstituted C6～26An aryloxy group.
In one specific example, R1～R12Are the same group.
Specifically, R1～R12Are all methyl.
In a specific example, the mass percentage of the additive in the electrolyte is 0.5-3%.
As a preferable scheme, the mass percent of the additive in the electrolyte is 0.8-1.5%. Specifically, the mass percentage of the additive in the electrolyte is 0.9%, 1%, 1.1%, 1.15%, 1.2%, 1.25%, 1.3%, 1.4%.
In a specific example, the additives are a first additive and a second additive, and the mass ratio of the first additive to the second additive is (0.25-2): 1. Preferably, the mass ratio of the first additive to the second additive is 0.8:1, 1:1, 1.5:1, 1.8: 1. Specifically, the mass percentage of the first additive in the electrolyte is 0.5%, and the mass percentage of the second additive in the electrolyte is 0.5%. Or the mass percentage of the first additive in the electrolyte is 0.5%, and the mass percentage of the second additive in the electrolyte is 1%. Or the mass percentage of the first additive in the electrolyte is 1%, and the mass percentage of the second additive in the electrolyte is 0.5%. Or the mass percentage of the first additive in the electrolyte is 1%, and the mass percentage of the second additive in the electrolyte is 1%.
In a specific example, the organic solvent is formed by mixing a ring-shaped solvent and a linear solvent according to a mass ratio of 1 (1-3).
Specifically, the cyclic solvent is at least one of ethylene carbonate, propylene carbonate, gamma-butyrolactone and gamma-valerolactone;
the linear solvent is at least one of dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl acetate and methyl propyl carbonate.
In a specific example, the lithium salt is at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium dioxalate, lithium difluorooxalate, lithium trifluoromethanesulfonate, lithium perchlorate, lithium hexafluoroarsenate, and lithium bistrifluoromethylsulfonyl imide.
In addition, in the composition of the electrolyte, the mass percentage of the lithium salt in the electrolyte is 15-20%.
Another embodiment of the present invention provides a method for preparing the electrolyte solution in the above embodiment, including the steps of:
mixing lithium salt with an organic solvent to obtain an electrolyte preform;
adding the additive into the electrolyte preform, and uniformly mixing.
In addition to the above embodiments, another embodiment of the present invention provides a lithium ion battery, which includes a positive electrode plate, a negative electrode plate, and the electrolyte in the above embodiments or the electrolyte obtained by the above preparation method.
It can be understood that the positive electrode sheet of the lithium ion battery in this embodiment includes a positive electrode current collector and a positive electrode membrane coated on the surface of the positive electrode current collector, and the positive electrode membrane includes a positive electrode active material (i.e., an active material of the positive electrode sheet), a conductive agent and a binder. Wherein, the active material of the positive pole piece is selected from: LiMn2O4、LiNixCoyM1-x-yO2、LiFe1-aMaPO4、Li2Mn1-bO4And Li1+cMn1-zMzO2Wherein M is selected from Ni, Fe, Co, Mn, Al, Cr, Mg, Zr, Mo, V, Ti, B and F, x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, x + y is more than or equal to 0 and less than or equal to 1, z is more than or equal to 0 and less than or equal to 1, a is more than or equal to 0 and less than or equal to 1, B is more than or equal to 0 and less than or equal to 1, and c is more than or equal to 0 and less than or equal to 0.2.
It can be understood that the negative electrode sheet of the lithium ion battery in this embodiment includes a negative electrode current collector and a negative electrode membrane coated on the surface of the negative electrode current collector, and the negative electrode membrane includes a negative electrode active material (i.e., an active material of the negative electrode sheet), a conductive agent and a binder. The active substance of the negative pole piece is at least one of graphite, a silicon-carbon composite material and lithium titanate.
It is to be understood that the conductive agent may be at least one of carbon black, conductive graphite, carbon fiber, carbon nanotube, and graphene. The binder may be at least one of polyvinylidene fluoride, polytetrafluoroethylene, styrene-butadiene rubber, polyacrylic acid, polyvinyl alcohol, and polymethyl methacrylate.
It is understood that the separator may be a polyethylene film, a polypropylene microporous film, a gel polymer electrolyte film, or the like, during the preparation of the lithium ion battery.
The additive in the electrolyte in the embodiment is at least one of the compound shown in the formula (I) and the compound shown in the formula (II), and when the additive is used in the lithium ion battery, the problem of diffusion inside the lithium ion battery can be effectively solved, the interface property of an electrode and the electrolyte of the lithium ion battery is improved, the interface impedance is reduced, a stable SEI film is formed on the surface of a negative electrode of the lithium ion battery, the insertion and removal of lithium ions are smoother at low temperature, and the low-temperature performance of the lithium ion battery is improved. Meanwhile, the compound shown in the formula (I) and the compound shown in the formula (II) can be coordinated with transition metal ions to form a complex, so that the dissolution of metal ions of the positive electrode is inhibited, and the decomposition of an organic solvent at high temperature is particularly reduced, thereby improving the high-temperature performance of the lithium ion battery.
In describing the present invention, amounts, ratios, and other numerical values are sometimes presented herein in a range format. It is to be understood that such range format is used for convenience and brevity, and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited.
In the description of the present invention, a list of items connected by the term "at least one of", or other similar terms may mean any combination of the listed items. For example, if items a and B are listed, the phrase "at least one of a and B" means a alone, or B alone, or a and B. In still other examples, if items A, B and C are listed, the phrase "at least one of A, B and C" means all of a alone, or B alone, or C alone, or a and B (excluding C), or a and C (excluding B), or B and C (excluding a), or a and B and C. While item a may comprise a single unit or multiple units. Item B may comprise a single unit or multiple units. Item C may comprise a single unit or multiple units.
In the description of the present invention, a number following an expression regarding carbon number, i.e., capital letter "C", such as "C1～20”、“C2～20In "etc., the numbers after" C "such as" 1 "," 2 "or" 20 "represent the number of carbons in the specific functional group. That is, the functional groups may include 1 to 20 carbon atoms and 2 to 20 carbon atoms, respectively. For example, "C1～4Alkyl "refers to an alkyl group having 1 to 4 carbon atoms, such as CH3-、CH3CH2-、CH3CH2CH2-、(CH3)2CH-、CH3CH2CH2CH2-、CH3CH2CH(CH3) -or (CH)3)3C-。
In the description of the present invention, "alkyl" is intended to be a straight-chain saturated hydrocarbon structure having 1 to 20 carbon atoms. "alkyl" is also contemplated to be a branched or cyclic hydrocarbon structure having from 3 to 20 carbon atoms. For example, the alkyl group may be an alkyl group of 1 to 20 carbon atoms, an alkyl group of 1 to 10 carbon atoms, an alkyl group of 1 to 5 carbon atoms, an alkyl group of 5 to 20 carbon atoms, an alkyl group of 5 to 15 carbon atoms, or an alkyl group of 5 to 10 carbon atoms. When an alkyl group having a particular carbon number is specified, all geometric isomers having that carbon number are intended to be encompassed. Thus, for example, "butyl" is meant to include n-butyl, sec-butyl, isobutyl, tert-butyl, and cyclobutyl. "propyl" is meant to include n-propyl, isopropyl and cyclopropyl. Alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclobutyl, n-pentyl, isopentyl, neopentyl, cyclopentyl, methylcyclopentyl, ethylcyclopentyl, n-hexyl, isohexyl, cyclohexyl, n-heptyl, octyl, cyclopropyl, cyclobutyl, norbornyl, and the like. In addition, the alkyl group may be optionally substituted.
In the description of the present invention, "alkylene" encompasses straight-chain and branched alkylene groups. For example, the alkylene group may be C1～50Alkylene radical, C1～40Alkylene radical, C1～30Alkylene radical, C1～20Alkylene radical, C1～10Alkylene radical, C1～6Alkylene radical, C2～6Alkylene radical, C2～5An alkylene group. In addition, the alkylene group may be optionally substituted.
In the description of the present invention, "aryl" encompasses monocyclic and polycyclic ring systems. The polycyclic ring can have two or more rings in which two carbons are common to two adjoining rings, at least one of which is aromatic, e.g., the other rings can be cycloalkyls, cycloalkenyls, aryls, heterocyclics, and/or heteroaryls. For example, the aryl group may be C6～50Aryl radical, C6～40Aryl radical, C6～30Aryl radical, C6～20Aryl or C6～26And (4) an aryl group. Representative aryl groups include phenyl, methylphenyl, propylphenyl, isopropylphenyl, benzyl, and naphthalen-1-yl, naphthalen-2-yl, and the like.
In the description of the present invention, "alkenyl" refers to a monovalent unsaturated hydrocarbon group that may be straight-chain or branched and has at least one and typically 1, 2, or 3 carbon-carbon double bonds. Unless otherwise defined, the alkenyl group generally contains 2 to 20 carbon atoms, and may be, for example, an alkenyl group of 2 to 20 carbon atoms, an alkenyl group of 6 to 20 carbon atoms, an alkenyl group of 2 to 12 carbon atoms, or an alkenyl group of 2 to 6 carbon atoms. Representative alkenyl groups include ethenyl, n-propenyl, isopropenyl, n-but-2-enyl, but-3-enyl, n-hex-3-enyl, and the like. In addition, the alkenyl group may be optionally substituted.
In the description of the present invention, the term "alkoxy" includes alkoxy having 1 to 20 carbon atoms, alkoxy having 1 to 10 carbon atoms, alkoxy having 1 to 5 carbon atoms, alkoxy having 5 to 20 carbon atoms, alkoxy having 5 to 15 carbon atoms, or alkoxy having 5 to 10 carbon atoms. In addition, alkoxy groups may be optionally substituted.
When the above substituents are substituted, their substituents may each be independently selected from the group consisting of: halogen, alkyl, alkenyl, alkynyl, aryl.
The following are specific examples.
R in the following examples and comparative examples1～R12Are all methyl.
Example 1
(1) And (4) preparing an electrolyte.
The method comprises the following steps: mixing Ethylene Carbonate (EC), methyl ethyl carbonate (EMC) and dimethyl carbonate (DMC) according to the mass ratio of EC to EMC to DMC of 3 to 5 to 2 at room temperature to obtain an organic solvent;
step two: adding lithium hexafluorophosphate into the organic solvent in the step one, controlling the mass percentage of lithium hexafluorophosphate in the electrolyte to be 15%, and uniformly stirring to obtain an electrolyte preform;
step three: and C, adding a first additive into the electrolyte preform obtained in the step two, controlling the mass percentage of the first additive in the electrolyte to be 0.5%, and uniformly stirring to obtain the electrolyte.
(2) And (5) preparing the lithium ion battery.
With LiNi0.5Co0.2Mn0.3O2The electrolyte prepared in this example was combined with a conductive agent (carbon black), a binder (polyvinylidene fluoride), and a separator (polyethylene film), and was packaged, left to stand, formed, and shaped to assemble a lithium ion battery.
Example 2
Compared with the embodiment 1, the difference of the embodiment is that the additive is the second additive, and the mass percentage of the second additive in the electrolyte is 0.5%.
Example 3
Compared with the embodiment 1, the difference of the embodiment is that the additives in the embodiment are the first additive and the second additive, the mass percentage of the first additive in the electrolyte is 0.5%, and the mass percentage of the second additive in the electrolyte is 0.5%.
Example 4
Compared with the embodiment 1, the difference of the embodiment is that the additives in the embodiment are the first additive and the second additive, the mass percentage of the first additive in the electrolyte is 0.5%, and the mass percentage of the second additive in the electrolyte is 1%.
Example 5
Compared with the embodiment 1, the difference of the embodiment is that the additives in the embodiment are the first additive and the second additive, the mass percentage of the first additive in the electrolyte is 0.5%, and the mass percentage of the second additive in the electrolyte is 2%.
Example 6
Compared with the embodiment 1, the difference of the embodiment is that the additive is the first additive, and the mass percentage of the first additive in the electrolyte is 1%.
Example 7
Compared with the embodiment 1, the difference of the embodiment is that the additives in the embodiment are the first additive and the second additive, the mass percentage of the first additive in the electrolyte is 1%, and the mass percentage of the second additive in the electrolyte is 0.5%.
Example 8
Compared with the embodiment 1, the difference of the embodiment is that the additives in the embodiment are the first additive and the second additive, the mass percentage of the first additive in the electrolyte is 1%, and the mass percentage of the second additive in the electrolyte is 1%.
Example 9
Compared with the embodiment 1, the difference of the embodiment is that the additives in the embodiment are the first additive and the second additive, the mass percentage of the first additive in the electrolyte is 1%, and the mass percentage of the second additive in the electrolyte is 2%.
Comparative example 1
In contrast to example 1, the additive of this comparative example was butyl sultone.
Comparative example 2
The comparative example is different from example 1 in that the additive in the comparative example is a first additive, and the mass percentage of the first additive in the electrolyte is 0.2%.
Comparative example 3
The comparative example is different from example 1 in that the additive in the comparative example is a second additive, and the mass percentage of the second additive in the electrolyte is 0.2%.
Comparative example 4
The comparative example is different from example 1 in that the additives in the comparative example are a first additive and a second additive, the mass percentage of the first additive in the electrolyte is 0.1%, and the mass percentage of the second additive in the electrolyte is 0.1%.
Comparative example 5
The comparative example is different from example 1 in that the additive in the comparative example is a first additive, and the mass percentage of the first additive in the electrolyte is 5.5%.
Comparative example 6
The comparative example is different from example 1 in that the additive in the comparative example is a second additive, and the mass percentage of the second additive in the electrolyte is 5.5%.
Comparative example 7
The comparative example is different from example 1 in that the additives in the comparative example are a first additive and a second additive, the mass percentage of the first additive in the electrolyte is 0.6%, and the mass percentage of the second additive in the electrolyte is 0.3%.
Comparative example 8
The comparative example is different from example 1 in that the additives in the comparative example are a first additive and a second additive, the mass percentage of the first additive in the electrolyte is 0.1%, and the mass percentage of the second additive in the electrolyte is 0.5%.
Test example 1
The lithium ion batteries prepared in examples 1 to 9 and comparative examples 1 to 8 were subjected to charge-discharge cycle performance tests at 25 ℃, 3.0V to 4.35V, and 1C rate, and the test results are shown in table 1. Wherein, the cycle performance graphs of the examples 1-3 and the comparative example 2 are shown in the attached figure 1.
Test example 2
The lithium ion batteries prepared in examples 1 to 9 and comparative examples 1 to 8 were subjected to charge-discharge cycle performance tests at 45 ℃, 3.0V to 4.35V, and 1C rate, and the test results are shown in table 1. Wherein, the cycle performance chart of the embodiment 3 and the comparative example 2 is shown in the attached figure 2.
Test example 3
The lithium ion batteries prepared in examples 1 to 9 and comparative examples 1 to 8 were subjected to charge-discharge cycle performance tests at-10 ℃, 3.0V to 4.35V, and 1C rate, and the test results are shown in table 1. Wherein, the cycle performance chart of the embodiment 3 and the comparative example 2 is shown in the attached figure 3.
Test example 4
After cycling the lithium ion batteries prepared in examples 1 to 9 and comparative examples 1 to 8 at a charge-discharge rate of 1C for 3 times, the lithium ion batteries were stored at a high temperature of 60 ℃ for 7 days in a full-charge state and then subjected to a discharge test, and the obtained discharge capacity was divided by the discharge capacity of the first cycle to obtain the capacity retention rate after high-temperature storage, wherein the test results are shown in Table 1.
Test example 5
After cycling the lithium ion batteries prepared in examples 1 to 9 and comparative examples 1 to 8 at a charge-discharge rate of 1C for 3 times, the expansion rate of the batteries was measured after storing at a high temperature of 60 ℃ for 7 days in a full-charge state, and the calculation method was as shown in formula (III), and the test results are shown in Table 1.
(T-T) percent swelling ratio0)×100/T0Formula (III)
Wherein T is the thickness of the battery after high-temperature storage, T0Is the cell thickness before high temperature storage.
TABLE 1
Figure BDA0002431311810000141
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. An electrolyte, characterized by: the lithium ion battery comprises an organic solvent, a lithium salt and an additive, wherein the additive is at least one of a first additive and a second additive;
the first additive is at least one of compounds shown as a formula (I);
Figure FDA0002431311800000011
the second additive is at least one of compounds shown as a formula (II);
Figure FDA0002431311800000012
wherein R is1～R12Each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted C1～20Alkyl, substituted or unsubstituted C1～20Alkoxy, substituted or unsubstituted C2～20Alkenyl, substituted or unsubstituted C6～26Aryl, substituted or unsubstituted C6～26An aryloxy group.
2. The electrolyte of claim 1, wherein: r1～R12Are the same group.
3. The electrolyte of claim 1, wherein: the mass percentage of the additive in the electrolyte is 0.5-3%.
4. The electrolyte of claim 1, wherein: the additive is a first additive and a second additive, and the mass ratio of the first additive to the second additive is (0.25-2): 1.
5. The electrolyte of any one of claims 1 to 4, wherein: the organic solvent is formed by mixing a ring-shaped solvent and a linear solvent according to a mass ratio of 1 (1-3).
6. The electrolyte of claim 5, wherein: the ring-shaped solvent is at least one of ethylene carbonate, propylene carbonate, gamma-butyrolactone and gamma-valerolactone;
and/or the linear solvent is at least one of dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl acetate and methyl propyl carbonate.
7. The electrolyte of any of claims 1-4 and 6, wherein: the lithium salt is at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium dioxalate borate, lithium difluorooxalate borate, lithium trifluoromethanesulfonate, lithium perchlorate, lithium hexafluoroarsenate and lithium bistrifluoromethylsulfonyl imide.
8. A method for preparing the electrolyte according to any one of claims 1 to 7, wherein: the method comprises the following steps:
mixing the lithium salt with the organic solvent to obtain an electrolyte preform;
and adding the additive into the electrolyte preform, and uniformly mixing.
9. A lithium ion battery, characterized by: the electrolyte comprises a positive pole piece, a negative pole piece and the electrolyte as claimed in any one of claims 1 to 7 or the electrolyte prepared by the preparation method as claimed in claim 8.
10. The lithium ion battery of claim 9, wherein: the active substance of the positive pole piece is selected from: LiMn2O4、LiNixCoyM1-x-yO2、LiFe1-aMaPO4、Li2Mn1-bO4And Li1+cMn1-zMzO2Wherein M is selected from Ni, Fe, Co, Mn, Al, Cr, Mg, Zr, Mo, V, Ti, B and F, x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, x + y is more than or equal to 0 and less than or equal to 1, z is more than or equal to 0 and less than or equal to 1, a is more than or equal to 0 and less than or equal to 1, B is more than or equal to 0 and less than or equal to 1, and c is more than or equal to 0 and less than or equal to 0.2; and/or the presence of a gas in the gas,
the active substance of the negative pole piece is at least one of graphite, a silicon-carbon composite material and lithium titanate.
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Publication number Priority date Publication date Assignee Title
CN1385919A (en) * 2001-05-11 2002-12-18 三星Sdi株式会社 Electrolytic solution for lithium secondary cell and lithium cell containing same
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CN109088099A (en) * 2018-06-28 2018-12-25 华南师范大学 A kind of sulphonyl class electrolysis additive for taking into account high temperature performance and the electrolyte containing the additive
WO2019050161A1 (en) * 2017-09-06 2019-03-14 삼성에스디아이 주식회사 Lithium secondary battery
KR20190080040A (en) * 2017-12-28 2019-07-08 파낙스 이텍(주) Non-Aqueous Electrolyte Solution for Secondary Battery and Secondary Battery Comprising the Same

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Publication number Priority date Publication date Assignee Title
CN1385919A (en) * 2001-05-11 2002-12-18 三星Sdi株式会社 Electrolytic solution for lithium secondary cell and lithium cell containing same
CN107293776A (en) * 2016-04-12 2017-10-24 宁德时代新能源科技股份有限公司 Electrolyte and lithium ion battery
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