CN115458810A - Electrolyte and lithium ion battery - Google Patents

Electrolyte and lithium ion battery Download PDF

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CN115458810A
CN115458810A CN202211417646.0A CN202211417646A CN115458810A CN 115458810 A CN115458810 A CN 115458810A CN 202211417646 A CN202211417646 A CN 202211417646A CN 115458810 A CN115458810 A CN 115458810A
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electrolyte
carbonate
compound
lithium ion
ion battery
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CN115458810B (en
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黄波
刘欣
杨小龙
梁大宇
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Gotion High Tech Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0088—Composites
    • H01M2300/0091—Composites in the form of mixtures
    • 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

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  • Materials Engineering (AREA)
  • Secondary Cells (AREA)

Abstract

The invention provides an electrolyte and a lithium ion battery. The electrolyte comprises an organic solvent and LiPF 6 And additives, wherein the additives comprise trifluoromethanesulfonic acid compounds and p-toluenesulfonyl compounds. The trifluoromethane sulfonic acid compound and the toluene sulfonyl compound are used together, a stable interfacial film can be formed on the surfaces of an NCM ternary positive electrode and a graphite negative electrode, and through the full synergistic effect of the trifluoromethane sulfonic acid compound and the toluene sulfonyl compound, the interfacial film is thin and compact, and the benzene ring structure of the toluene sulfonyl compound has high rigidity, so that the interfacial film is more stable, the ionic conductivity of the interfacial film is improved, the generation of harmful products such as HF (hydrogen fluoride) in electrolyte and the dissolution of cathode transition metal in the circulation process are prevented, the impedance of a lithium ion battery is reduced to a certain extent, and the impedance of the lithium ion battery is improvedThe cycling performance of the cell.

Description

Electrolyte and lithium ion battery
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to an electrolyte and a lithium ion battery.
Background
In recent years, lithium ion batteries have become a new research focus and have received much attention. The electric vehicle field focuses on hybrid vehicles and mobile device power supplies, etc., due to their high energy density, environmental friendliness, and economic friendliness. It is well known that cycle performance is one of the important indicators of batteries. As the battery continues to charge, it results in a continuous increase in internal resistance and generates a large amount of heat, often worsening the cycle life over multiple cycle charging.
Disclosure of Invention
The invention mainly aims to provide an electrolyte and a lithium ion battery, and aims to solve the problem that the lithium ion battery in the prior art is high in impedance.
In order to achieve the above object, according to one aspect of the present invention, there is provided an electrolyte including an organic solvent, liPF 6 And additives, wherein the additives comprise trifluoromethanesulfonic acid compounds and p-toluenesulfonyl compounds.
Further, the trifluoromethanesulfonic acid compound is a compound represented by structural formula I:
Figure 449322DEST_PATH_IMAGE001
structural formula I
Wherein R1 is selected from the group consisting of a silane group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted C 1 ~C 4 Linear alkyl, substituted or unsubstituted C of 3 ~C 6 Preferably, the trifluoromethanesulfonic acid compound is selected from any of the branched alkyl groups of (1)
Figure 554681DEST_PATH_IMAGE002
、
Figure 441865DEST_PATH_IMAGE003
、
Figure 265465DEST_PATH_IMAGE004
、
Figure 529087DEST_PATH_IMAGE005
、
Figure 597275DEST_PATH_IMAGE006
Any one or more of。
Further, the trifluoromethanesulfonic acid compound is selected from the group consisting of
Figure 717678DEST_PATH_IMAGE002
、
Figure 169519DEST_PATH_IMAGE003
、
Figure 95886DEST_PATH_IMAGE004
Any one or more of them.
Further, the p-toluenesulfonyl compound is a compound represented by the formula II,
Figure 51204DEST_PATH_IMAGE007
structural formula II
Wherein R2 is selected from any one of cyano, halogen and amino, preferably the p-toluenesulfonyl compound is selected from
Figure 670404DEST_PATH_IMAGE008
、
Figure 111006DEST_PATH_IMAGE009
、
Figure 982010DEST_PATH_IMAGE010
Any one or more of them.
Further, the mass of the additive is 0.1 to 5wt% of the total mass of the electrolyte, and the mass ratio of the trifluoromethanesulfonic acid compound to the p-toluenesulfonyl compound is preferably 1 to 5.
Further, the organic solvent includes one or more of cyclic carbonate, chain carbonate and carboxylic ester, preferably, the cyclic carbonate is selected from one or more of ethylene carbonate, propylene carbonate, butylene carbonate and γ -butyrolactone, preferably, the chain carbonate is selected from one or more of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate and ethyl propyl carbonate, preferably, the carboxylic ester is selected from one or more of methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate and ethyl butyrate, preferably, the organic solvent is selected from a combination of ethylene carbonate, diethyl carbonate and ethyl methyl carbonate, preferably, the mass ratio of ethylene carbonate, diethyl carbonate and ethyl carbonate is 1~2:1~2:2~5.
The electrolyte further comprises a lithium salt additive, the concentration of the lithium salt additive is preferably 0.3 to 1mol/L, and the lithium salt additive is preferably selected from lithium bis (fluorosulfonyl) imide and LiBF 4 Lithium bis (oxalato) borate, lithium difluoro (oxalato) phosphate, lithium bis (trifluoromethylsulfonyl) imide, phenylsulfone, tris (trimethylsilane) phosphite, vinyl sulfate and methylene methyldi-sulfonate, and further, the lithium salt additive is preferably lithium bis (fluorosulfonyl) imide, vinyl sulfate and methylene methyldi-sulfonate, or the lithium salt additive is preferably phenylsulfone, tris (trimethylsilane) phosphite, vinyl sulfate and methylene methyldi-sulfonate.
Further, the above LiPF 6 The concentration of (3) is 0.5 to 1.5mol/L, and the electrolyte preferably comprises: ethylene carbonate, diethyl carbonate, ethyl methyl carbonate, liPF 6 Vinyl sulfate, methylene methyldi-sulfonate, lithium bis-fluorosulfonylimide, and
Figure 916468DEST_PATH_IMAGE003
and
Figure 581936DEST_PATH_IMAGE008
wherein, in the step (A),
Figure 8369DEST_PATH_IMAGE003
is 2.5wt% of the electrolyte,
Figure 276540DEST_PATH_IMAGE008
0.5wt% of the electrolyte; or
Figure 704985DEST_PATH_IMAGE003
Is 0.5wt% of the electrolyte,
Figure 665987DEST_PATH_IMAGE008
2.5wt% of the electrolyte; or
Figure 314138DEST_PATH_IMAGE003
Is 0.8wt% of the electrolyte,
Figure 385999DEST_PATH_IMAGE008
2.2wt% of the electrolyte; or
Figure 435994DEST_PATH_IMAGE003
Is 1.2wt% of the electrolyte,
Figure 302319DEST_PATH_IMAGE008
is 1.8wt% of the electrolyte.
According to one aspect of the invention, a lithium ion battery is provided, which comprises a positive plate, a negative plate and an electrolyte, wherein the electrolyte is the electrolyte.
Further, the positive electrode sheet includes a positive electrode material, and preferably, the positive electrode material is LiNi （1-x-y） Co x Mn y Wherein x is more than or equal to 0 and less than or equal to 1,0 and less than or equal to 1.
By applying the technical scheme of the invention, the strong electron withdrawing property of trifluoromethyl in the trifluoromethanesulfonic acid compound enables methylsulfonyl directly connected with the trifluoromethanesulfonic acid compound to have stronger reaction activity, the trifluoromethanesulfonic acid compound can be used in combination with the tosyl compound to form a stable interface film on the surface of an NCM ternary positive electrode and a graphite negative electrode, and through the full synergistic action of the trifluoromethanesulfonic acid compound and the tosyl compound, the interface film is thin and compact, and the benzene ring structure of the tosyl compound has high rigidity, so that the interface film is more stable, the ionic conductivity of the interface film is improved, the generation of harmful products such as HF (hydrogen fluoride) in electrolyte and the dissolution of cathode transition metal in a circulating process are prevented, the impedance of a lithium ion battery is further reduced to a certain degree, and the comprehensive performances such as the circulating performance of the lithium ion battery are obviously improved.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail with reference to examples.
As analyzed by the background art, the lithium ion battery in the prior art has a problem of high impedance, and in order to solve the problem, the invention provides an electrolyte and a lithium ion battery.
In an exemplary embodiment of the present application, there is provided an electrolyte including an organic solvent, liPF 6 And additives, wherein the additives comprise trifluoromethanesulfonic acid compounds and p-toluenesulfonyl compounds.
The strong electron withdrawing property of trifluoromethyl in the trifluoromethanesulfonic acid compound enables methylsulfonyl directly connected with the trifluoromethanesulfonic acid compound to have stronger reaction activity, and the trifluoromethanesulfonic acid compound and the toluenesulfonyl compound are used together to form a stable interfacial film on the surfaces of an NCM ternary positive electrode and a graphite negative electrode.
In order to improve the film forming property of the trifluoromethanesulfonic acid compound, the trifluoromethanesulfonic acid compound is preferably a compound represented by structural formula I:
Figure 703345DEST_PATH_IMAGE001
structural formula I
Wherein R1 is selected from the group consisting of a silane group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted C 1 ~C 4 Linear alkyl, substituted or unsubstituted C of 3 ~C 6 Any of the branched alkyl groups of (1), preferably a trifluoromethanesulfonic acid-based compound selected from
Figure 949868DEST_PATH_IMAGE002
、
Figure 713425DEST_PATH_IMAGE003
、
Figure 626017DEST_PATH_IMAGE004
、
Figure 373394DEST_PATH_IMAGE005
、
Figure 662424DEST_PATH_IMAGE006
Any one or more of them.
In order to further improve the synergistic interaction between the trifluoromethanesulfonic acid compound and the p-toluenesulfonyl compound, the trifluoromethanesulfonic acid compound is preferably selected from the group consisting of
Figure 546066DEST_PATH_IMAGE002
、
Figure 160718DEST_PATH_IMAGE003
、
Figure 129811DEST_PATH_IMAGE004
Any one or more of them.
In one embodiment of the present application, the above-mentioned p-toluenesulfonyl compound is a compound having a structural formula II,
Figure 189909DEST_PATH_IMAGE007
structural formula II
Wherein R2 is selected from any one of cyano, halogen and amino, preferably the p-toluenesulfonyl compound is selected from
Figure 193637DEST_PATH_IMAGE008
、
Figure 448032DEST_PATH_IMAGE009
、
Figure 904421DEST_PATH_IMAGE010
Any one or more of them.
The p-toluenesulfonyl compound containing the substituent has higher oxidation-reduction property, and the p-toluenesulfonyl compound and the trifluoromethanesulfonic acid compound are coordinated to generate thinner and more compact CEI and SEI protective films on the surfaces of an NCM cathode and a graphite anode more easily under the synergistic action of the p-toluenesulfonyl compound and the trifluoromethanesulfonic acid compound, so that the cycling stability of the NCM cathode and the power of the graphite anode are greatly improved. On the other hand, the functional group of the p-toluenesulfonyl compound can inhibit LiPF 6 The hydrolysis reaction of the anode and the cathode can prevent harmful product HF from being generated and NCM cathode transition metal from being dissolved in the circulating process, and the circulating life of the NCM/graphite full cell is further obviously prolonged.
Preferably, the mass of the additive is 0.1 to 5wt% of the total mass of the electrolyte, and preferably, the mass ratio of the trifluoromethanesulfonic acid compound to the p-toluenesulfonyl compound is 1 to 5.
In one embodiment of the present application, preferably, the organic solvent includes any one or more of a cyclic carbonate, a chain carbonate and a carboxylic ester, preferably, the cyclic carbonate is selected from one or more of ethylene carbonate, propylene carbonate, butylene carbonate and γ -butyrolactone, preferably, the chain carbonate is selected from one or more of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propyl methyl carbonate and propyl ethyl carbonate, preferably, the carboxylic ester is selected from one or more of methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate and ethyl butyrate, preferably, the organic solvent is selected from a combination of ethylene carbonate, diethyl carbonate and ethyl methyl carbonate, and preferably, the volume ratio of ethylene carbonate, diethyl carbonate and ethyl methyl carbonate is 1 to 2 to 5.
The organic solvent can better prevent the electrolyte from being damaged by water, and is beneficial to promoting the components in the electrolyte to be more fully dissolved, so that the cooperativity among the components is improved, and the electrolyte with excellent electrical property is obtained.
In order to enhance the coordination among the lithium salt additive, the lithium salt and the additive and further improve the comprehensive performance of the electrolyte, the electrolyte preferably further comprises the lithium salt additive, the concentration of the lithium salt additive is preferably 0.3 to 1mol/L, and the lithium salt additive is preferably selected from lithium bis (fluorosulfonyl) imide and LiBF 4 Lithium bis (oxalato) borate, lithium difluoro (oxalato) phosphate, lithium bis (trifluoromethylsulfonyl) imide, phenylsulfone, tris (trimethylsilane) phosphite, vinyl sulfate and methylene methyldi-sulfonate, and further, the lithium salt additive is preferably lithium bis (fluorosulfonyl) imide, vinyl sulfate and methylene methyldi-sulfonate, or the lithium salt additive is preferably phenylsulfone, tris (trimethylsilane) phosphite, vinyl sulfate and methylene methyldi-sulfonate.
LiPF 6 The electrolyte used as the electrolyte can enhance the conductivity, the energy storage property and the environmental protection property of the lithium ion battery, and further exert LiPF 6 The preferred LiPF is LiPF 6 The concentration of (b) is 0.5 to 1.5mol/L, and the electrolyte preferably comprises: ethylene carbonate, diethyl carbonate, ethyl methyl carbonate, liPF 6 Vinyl sulfate, methylene methyldi-sulfonate, lithium bis-fluorosulfonylimide, and
Figure 535254DEST_PATH_IMAGE003
and
Figure 393488DEST_PATH_IMAGE008
wherein, in the step (A),
Figure 84364DEST_PATH_IMAGE003
is 2.5wt% of the electrolyte,
Figure 28049DEST_PATH_IMAGE008
is electricity0.5wt% of the hydrolysate; or
Figure 698458DEST_PATH_IMAGE003
Is 0.5wt% of the electrolyte,
Figure 411199DEST_PATH_IMAGE008
2.5wt% of the electrolyte; or
Figure 132030DEST_PATH_IMAGE003
Is 0.8wt% of the electrolyte,
Figure 703957DEST_PATH_IMAGE008
2.2wt% of the electrolyte; or
Figure 676592DEST_PATH_IMAGE003
Is 1.2wt% of the electrolyte,
Figure 243840DEST_PATH_IMAGE008
is 1.8wt% of the electrolyte. Further, the mass ratio of ethylene carbonate, diethyl carbonate and ethyl methyl carbonate is preferably 1 6 Is 0.7mol/L, and the concentrations of the vinyl sulfate, the methylene methanedisulfonate and the lithium bis-fluorosulfonylimide are each independently 0.1mol/L.
In another exemplary embodiment of the present application, a lithium ion battery is provided, which includes a positive electrode sheet, a negative electrode sheet, and an electrolyte, where the electrolyte is the foregoing electrolyte.
The lithium ion battery adopting the electrolyte has lower impedance, and can obviously improve the comprehensive properties of the lithium ion battery, such as cycle performance and the like.
In order to improve the coordination of the electrolyte and the positive plate and further enable the lithium ion battery to have the performances of cycle stability, lower internal resistance and the like, the positive plate preferably comprises a positive electrode material, and the positive electrode material is preferably LiNi （1-x-y） Co x Mn y Wherein x is more than or equal to 0 and less than or equal to 1,0 and less than or equal to 1.
The advantageous technical effects of the present application will be described below with reference to specific examples and comparative examples.
The compounds of structural formula I and structural formula II were purchased from the alatin reagent in the trade-off.
Example 1
Preparation of electrolyte (in 1L of electrolyte): ethylene Carbonate (EC), diethyl carbonate (DEC) and Ethyl Methyl Carbonate (EMC) were mixed at a mass ratio of EC: DEC: EMC =1 6 ) 0.1mol of vinyl sulfate (DTD), 0.1mol of Methylene Methanedisulfonate (MMDS) and 0.1mol of lithium bis (fluorosulfonyl) imide (LiFSI) are added to the mixture until the lithium salt is completely dissolved
Figure 135573DEST_PATH_IMAGE003
And 1 wt.%
Figure 929216DEST_PATH_IMAGE008
。
Preparing a positive plate: liNi prepared from nickel cobalt lithium manganate ternary material 0.7 Co 0.1 Mn 0.2 The conductive agent Super P, the adhesive PVDF and the Carbon Nano Tube (CNT) are uniformly mixed according to the mass ratio of 97.5 2 Drying at 85 ℃ and then carrying out cold pressing; then, the strips are divided, sliced and dried for 4 hours at the temperature of 85 ℃ in vacuum to prepare the lithium ion battery positive plate meeting the requirements.
Preparing a negative plate: preparing artificial graphite, a conductive agent Super P, a thickening agent CMC and a binding agent SBR (styrene butadiene rubber emulsion) into slurry according to the mass ratio of 95.5.
Preparing a lithium ion battery: and (3) preparing the positive plate, the negative plate and the diaphragm prepared by the process into the lithium ion battery with the thickness of 0.5mm, the width of 8mm and the length of 10 through a lamination process, wherein the capacity of the lithium ion battery is 3Ah, vacuum baking is carried out for 48 hours at the temperature of 85 ℃, and the electrolyte is injected to complete the battery preparation.
Examples 2 to 17 and comparative examples 1 to 4 were carried out while changing the ratio and kind of specific materials in the electrolyte, and a lithium ion battery was obtained by referring to the preparation method of example 1, and the electrolyte formulation was as shown in table 1 below.
TABLE 1
Figure 564597DEST_PATH_IMAGE011
Figure 360252DEST_PATH_IMAGE012
Figure 688465DEST_PATH_IMAGE013
Example 10
Example 10 differs from example 4 in that,
adding 0.83wt percent
Figure 562881DEST_PATH_IMAGE003
And 0.17wt%
Figure 142898DEST_PATH_IMAGE008
And finally obtaining the lithium ion battery.
Example 11
Example 11 differs from example 4 in that,
4.17wt% is added
Figure 684737DEST_PATH_IMAGE003
And 0.83wt%
Figure 793639DEST_PATH_IMAGE008
And finally obtaining the lithium ion battery.
Example 12
Example 12 differs from example 4 in that,
the trifluoromethanesulfonic acid compound is
Figure 420929DEST_PATH_IMAGE002
And finally obtaining the lithium ion secondary battery.
Example 13
Example 13 differs from example 4 in that,
the trifluoromethanesulfonic acid compound is
Figure 273479DEST_PATH_IMAGE004
And finally obtaining the lithium ion secondary battery.
Example 14
Example 14 differs from example 4 in that,
the p-toluenesulfonyl compound is
Figure 669825DEST_PATH_IMAGE009
And finally obtaining the lithium ion secondary battery.
Example 15
Example 15 differs from example 4 in that,
the p-toluenesulfonyl compound is
Figure 339841DEST_PATH_IMAGE010
And finally obtaining the lithium ion secondary battery.
Example 16
Example 16 differs from example 4 in that the solvent was Ethyl Propionate (EP), and a lithium ion secondary battery was finally obtained.
Example 17
Example 17 differs from example 4 in that the lithium salt additive was 0.1mol/L LiFSI, 0.1mol Phenylsulfone (PS), and 0.1mol tris (trimethylsilane) phosphite (TMSP), and finally a lithium ion secondary battery was obtained.
(1) Initial direct current internal resistance (DCR) test
After capacity grading, the test cells of examples 1 to 17 and comparative example 1~4 were charged to a state of charge of 50% SOC, and after standing for 30min, the sample voltage V0 at the start of discharge was recorded, and after discharging at a current I of 2C for 10s, the sample voltage V1 at the end of discharge was recorded, and the initial DC discharge internal impedance DCR = (V1-V0)/I of the test cell was calculated.
(2) Cycle performance detection
The experimental batteries of examples 1 to 17 and comparative example 1~4 were subjected to a charge-discharge cycle performance test at a charge-discharge rate of 1C under a test condition of 25 ℃, the charge-discharge voltage interval was set to 2.8 to 4.25v, and the test results were shown in table 1 after 800 cycles at room temperature.
It can be seen from the comparison between the above examples and comparative examples that, compared with the conventional additives, the combination of the trifluoromethanesulfonic acid compound and the p-toluenesulfonyl compound of the present invention as the additive can greatly reduce the direct current internal resistance of the lithium ion battery, and at the same time, the cycle is significantly improved.
From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects:
the strong electron withdrawing property of trifluoromethyl in the trifluoromethanesulfonic acid compound enables methylsulfonyl directly connected with the trifluoromethanesulfonic acid compound to have stronger reaction activity, and the trifluoromethanesulfonic acid compound and the toluenesulfonyl compound are used together to form a stable interfacial film on the surfaces of an NCM ternary positive electrode and a graphite negative electrode.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (12)

1. The electrolyte is characterized by comprising an organic solvent and LiPF 6 And an additive comprising a trifluoromethanesulfonic acid-based compound and a p-toluenesulfonyl-based compound.
2. The electrolyte of claim 1, wherein the trifluoromethanesulfonic acid-based compound is a compound having the formula I:
Figure 25514DEST_PATH_IMAGE001
structural formula I
Wherein R1 is selected from the group consisting of silyl, substituted or unsubstituted phenyl, substituted or unsubstituted C 1 ~C 4 Straight-chain alkyl, substituted or unsubstituted C 3 ~C 6 Any of the branched alkyl groups of (a).
3. The electrolyte of claim 2, wherein the trifluoromethanesulfonic acid-based compound is selected from the group consisting of
Figure 746345DEST_PATH_IMAGE002
、
Figure 52693DEST_PATH_IMAGE003
、
Figure 149962DEST_PATH_IMAGE004
、
Figure 858155DEST_PATH_IMAGE005
、
Figure 484308DEST_PATH_IMAGE006
Any one or more of them.
4. The electrolyte according to claim 3, wherein the trifluoromethanesulfonic acid-based compound is selected from the group consisting of
Figure 543531DEST_PATH_IMAGE002
、
Figure 178912DEST_PATH_IMAGE003
、
Figure 600666DEST_PATH_IMAGE004
Any one or more of them.
5. The electrolyte of any one of claims 1 to 4, wherein the p-toluenesulfonyl compound is a compound represented by structural formula II,
Figure 302781DEST_PATH_IMAGE007
structural formula II
Wherein R2 is selected from any one of cyano, halogen and amino.
6. The electrolyte of claim 5, wherein the p-toluenesulfonyl compound is selected from the group consisting of
Figure 442775DEST_PATH_IMAGE008
、
Figure 22792DEST_PATH_IMAGE009
、
Figure 705577DEST_PATH_IMAGE010
Any one or more of them.
7. The electrolyte according to claim 6, wherein the mass of the additive is 0.1 to 5wt% of the total mass of the electrolyte, and/or the mass ratio of the trifluoromethanesulfonic acid-based compound to the p-toluenesulfonyl-based compound is 1.
8. The electrolyte of claim 6, wherein the organic solvent comprises one or more of cyclic carbonate, chain carbonate and carboxylic ester, the cyclic carbonate is selected from one or more of ethylene carbonate, propylene carbonate, butylene carbonate and gamma-butyrolactone, the chain carbonate is selected from one or more of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propyl methyl carbonate and propyl ethyl carbonate, and the carboxylic ester is selected from one or more of methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate and ethyl butyrate.
9. The electrolyte of claim 6, further comprising a lithium salt additive, wherein the concentration of the lithium salt additive is 0.3 to 1mol/L, and the lithium salt additive is selected from lithium bis (fluorosulfonyl) imide and LiBF 4 Any one or more of lithium bis (oxalate) borate, lithium difluoro (oxalate) phosphate, lithium bis (trifluoromethyl) sulfonyl imide, phenyl sulfone, tris (trimethylsilyl) phosphite, vinyl sulfate and methylene methyl disulfonate.
10. The electrolyte of claim 9, wherein the LiPF is 6 The concentration of (b) is 0.5 to 1.5mol/L, and the electrolyte preferably comprises: ethylene carbonate, diethyl carbonate, ethyl methyl carbonate, liPF 6 Vinyl sulfate, methylene methyldi-sulfonate, lithium bis-fluorosulfonylimide, and
Figure 470271DEST_PATH_IMAGE003
and
Figure 707348DEST_PATH_IMAGE008
wherein, the
Figure 950111DEST_PATH_IMAGE003
2.5wt% of the electrolyte, the
Figure 983008DEST_PATH_IMAGE008
0.5wt% of the electrolyte;
or the said
Figure 387444DEST_PATH_IMAGE003
0.5wt% of the electrolyte, the
Figure 377397DEST_PATH_IMAGE008
2.5wt% of the electrolyte;
or the said
Figure 158271DEST_PATH_IMAGE003
0.8wt% of the electrolyte, the
Figure 550070DEST_PATH_IMAGE008
2.2wt% of the electrolyte;
or the said
Figure 125407DEST_PATH_IMAGE003
1.2wt% of the electrolyte, the
Figure 727290DEST_PATH_IMAGE008
Is 1.8wt% of the electrolyte.
11. A lithium ion battery comprising a positive electrode sheet, a negative electrode sheet, and an electrolyte, wherein the electrolyte is the electrolyte according to any one of claims 1 to 10.
12. The lithium ion battery of claim 11, wherein the positive plate comprises a positive electrode material, and the positive electrode material is LiNi （1-x-y） Co x Mn y Wherein x is more than or equal to 0 and less than or equal to 1,0 and less than or equal to 1.
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