CN113991180B - Lithium ion battery electrolyte and lithium ion battery - Google Patents

Lithium ion battery electrolyte and lithium ion battery Download PDF

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CN113991180B
CN113991180B CN202111290307.6A CN202111290307A CN113991180B CN 113991180 B CN113991180 B CN 113991180B CN 202111290307 A CN202111290307 A CN 202111290307A CN 113991180 B CN113991180 B CN 113991180B
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electrolyte
carbonate
ion battery
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熊伟
孙结岩
马斌
陈杰
杨山
李载波
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Huizhou Liwinon Energy Technology Co Ltd
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/056Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564Accumulators 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
    • H01M10/0566Liquid materials
    • H01M10/0567Liquid materials characterised by the additives
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/052Li-accumulators
    • H01M10/0525Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/42Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00Electrolytes
    • H01M2300/0017Non-aqueous electrolytes
    • H01M2300/0025Organic electrolyte
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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    • Y02E60/10Energy storage using batteries

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Abstract

The invention provides a lithium ion battery electrolyte and a lithium ion battery, which comprise lithium salt, an organic solvent and an additive, wherein the additive comprises a first additive and a second additive, and the first additive is a first compound with a structural formula I and/or a second compound with a structural formula II. Compared with the prior art, the electrolyte disclosed by the invention can participate in the formation of the positive and negative passive films to improve the stability of the positive and negative electrode interface films, and can inhibit the oxidative decomposition of the electrolyte on the positive electrode, so that the stability of a system is improved, the cycle performance is further improved, and the electrolyte is more suitable for a high-voltage lithium ion battery.

Description

Lithium ion battery electrolyte and lithium ion battery
Technical Field
The invention relates to the field of lithium batteries, in particular to a lithium ion battery electrolyte and a lithium ion battery.
Background
Lithium ion batteries are widely used by people due to the characteristics of high working voltage, large specific energy, long cycle life, no memory effect and the like, and are generally applied to the field of 3C digital consumer electronics at present. With the coming of the 5G era, people also put higher demands on the service life of the lithium ion battery, and the improvement of the cycle life of the lithium ion battery is imminent. The following main aspects affect the cycle life of the battery by the electrolyte:
1. lithium ion positive electrode interface stability: along with the rising of charging voltage, anodal electric potential constantly promotes, and the stability of anodal structure worsens, promotes the oxidizing power to electrolyte simultaneously, and anodal interface side reaction aggravation worsens the circulation.
2. Lithium ion negative electrode interface stability: with the increase of the charging voltage, the dissolution of the transition metal ions at the positive terminal is intensified, and the dissolved transition metal ions pass through the diaphragm to deposit on the negative interface, so that the recombination impedance of the negative SEI film is increased, and the cycle performance is deteriorated.
In view of the above, it is necessary to provide a technical solution to the above problems.
Disclosure of Invention
The invention aims to: aiming at the defects of the prior art, the invention provides the lithium ion battery electrolyte, which not only can participate in the formation of the anode and cathode passive films to improve the stability of the anode and cathode interface films, but also can inhibit the oxidative decomposition of the electrolyte on the anode, thereby improving the stability of the system and further improving the cycle performance.
In order to achieve the purpose, the invention adopts the following technical scheme:
the lithium ion battery electrolyte comprises lithium salt, an organic solvent and an additive, wherein the additive comprises a first additive and a second additive, and the first additive is a first compound with a structural formula I and/or a second compound with a structural formula II;
Figure 1
wherein R is 1 ~R 3 Each independently selected from any one of hydrogen atom, halogen atom, nitrile group, hydroxyl group, alkoxy group, alkyl group and substitute thereof; r 4 ~R 9 Each independently selected from a halogen atom, an alkyl group of 1 to 5 carbon atoms or a substitute thereof.
Preferably, the first additive is at least one of the following structural formulas:
Figure BDA0003334475510000031
preferably, the mass of the first additive is 0.01 to 5wt% of the total mass of the electrolyte.
Preferably, the second additive is at least one of fluoroethylene carbonate (FEC), vinylene Carbonate (VC), vinyl sulfate (DTD), 1,3-Propanesultone (PS), ethylene carbonate (VEC), 1,2-difluoroethylene carbonate (DFEC), methylene Methanedisulfonate (MMDS), propylene Sultone (PST), ethylene Sulfite (ES), vinyl Ethylene Sulfite (VES), citraconic anhydride (MSDS), tris (trimethylalkane) borate (TMSB), tris (trimethylalkane) phosphate (TMSP), succinonitrile (SN), adiponitrile (ADN), ethylene glycol bis (propionitrile) ether (EGBE), hexanetrinitrile (HTCN).
Preferably, the total content of the second additive is 0.1-15 wt% of the total mass of the electrolyte.
Preferably, the organic solvent is at least one of carbonates, carboxylates and fluorinated organic solvents; the carbonate is one or more of Ethylene Carbonate (EC), propylene Carbonate (PC), diethyl carbonate (DEC), ethyl Methyl Carbonate (EMC), dimethyl carbonate (DMC) and Methyl Propyl Carbonate (MPC); the carboxylic acid esters are one or more of Ethyl Propionate (EP), propyl Propionate (PP), ethyl Acetate (EA), ethyl n-butyrate (EB), propyl Acetate (PA), gamma-butyrolactone (GBL), acetonitrile (AN) and Sulfolane (SUL); the fluorinated organic solvent is one or more of fluoroethylene carbonate, propylene carbonate, 4-trifluoromethyl ethylene carbonate, methyl trifluoroethyl carbonate, bis trifluoroethyl carbonate and ethyl difluoroacetate.
Preferably, the mass of the organic solvent is 10 to 70wt% of the total mass of the electrolyte.
Preferably, the lithium salt is lithium hexafluorophosphate (LiPF) 6 ) Lithium difluorophosphate (LiPF) 2 O 2 ) Lithium difluorobis (oxalato) phosphate (LiPF) 2 (C 2 O 4 ) 2 ) Lithium tetrafluoro oxalate phosphate (LiPF) 4 C 2 O 4 ) Lithium oxalate phosphate (LiPO) 2 C 2 O 4 ) Lithium bis (oxalato) borate (LiBOB), lithium difluoro (oxalato) borate (LiODFB), lithium tetrafluoroborate (LiBF) 4 ) Lithium bis (fluorosulfonyl) imide (LiTFSI) and lithium bis (fluorosulfonyl) imide (LiFSI).
Preferably, the mass of the lithium salt is 12 to 18wt% of the total mass of the electrolyte.
The invention also provides a lithium ion battery, which comprises a positive plate, a negative plate, a diaphragm and electrolyte, wherein the diaphragm is arranged between the positive plate and the negative plate, and the electrolyte is the lithium ion battery electrolyte.
Compared with the prior art, the invention has the beneficial effects that: the electrolyte provided by the invention contains the additive of the first compound with the structural formula I and/or the second compound with the structural formula II, so that on one hand, the boric acid functional group with the structure can participate in the formation of a passivation film on the surface of a positive electrode, the interface impedance of the positive electrode is reduced, and the oxygen decomposition of the electrolyte on the surface of the positive electrode is inhibited; on the other hand, the carbonyl/carbonate groups contained in the electrolyte can participate in the formation of the SEI film on the surface of the negative electrode, so that the ionic conductivity of the SEI film of the negative electrode can be improved, the impedance of the SEI film can be reduced, and the cycle performance can be improved. Therefore, the electrolyte can participate in the formation of the positive and negative passive films to improve the stability of the positive and negative electrode interface films and inhibit the oxidative decomposition of the electrolyte in the positive electrode, thereby improving the stability of the system and further improving the cycle performance, and is more suitable for high-voltage lithium ion batteries.
Detailed Description
The invention provides a lithium ion battery electrolyte, which comprises a lithium salt, an organic solvent and an additive, wherein the additive comprises a first additive and a second additive, and the first additive is a first compound with a structural formula I and/or a second compound with a structural formula II;
Figure 2
wherein R is 1 ~R 3 Each independently selected from any one of hydrogen atom, halogen atom, nitrile group, hydroxyl group, alkoxy group, alkyl group and substitute thereof; r 4 ~R 9 Each independently selected from a halogen atom, an alkyl group of 1 to 5 carbon atoms or a substitute thereof.
In some embodiments, for a first compound of formula I, when R is 1 ~R 3 When the nitrile group is preferred, the nitrile group can complex metal ions on the surface of the cathode, so that the high-temperature storage performance is improved; when R is 1 ~R 3 Preferably, the trifluoromethyl substituent enhances the electrochemical stability of the first compound as a whole.
In some embodiments, for the second compound of formula II, when R is 4 ~R 9 Preferably, fluorine atoms are selected, so that the SEI component of the negative electrode can be further optimized, the impedance of the battery can be further reduced, and the cycle performance can be improved.
Preferably, the first additive is at least one of the following structural formulas:
Figure BDA0003334475510000061
Figure BDA0003334475510000071
further, the mass of the first additive accounts for 0.01-0.1 wt%, 0.1-0.3 wt%, 0.3-0.5 wt%, 0.5-0.7 wt%, 0.7-1 wt%, 1-1.2 wt%, 1.2-1.5 wt%, 1.5-1.8 wt%, 1.8-2 wt%, 2-3 wt%, 3-4 wt%, 4-5 wt% of the total mass of the electrolyte. The first additive with proper content can participate in the formation of the passive films of the positive and negative electrodes, improve the stability of the interfacial film of the positive and negative electrodes, and inhibit the oxidative decomposition of the electrolyte on the positive electrode, thereby improving the stability of the system and further improving the cycle performance.
Further, the second additive is at least one of fluoroethylene carbonate (FEC), vinylene Carbonate (VC), vinyl sulfate (DTD), 1,3-Propanesultone (PS), ethylene carbonate (VEC), 1,2-difluorovinyl carbonate (DFEC), methylene Methanedisulfonate (MMDS), propylene Sultone (PST), vinyl sulfite (ES), vinyl sulfite (VES), citraconic anhydride (MSDS), tris (trimethylalkane) borate (TMSB), tris (trimethylalkane) phosphate (TMSP), succinonitrile (SN), adiponitrile (ADN), ethylene glycol bis (propionitrile) ether (EGBE), hexanetrinitrile (HTCN). The second additive is a conventional high-voltage additive, and under the combined action of the second additive and the first additive, the effect of the second additive can be exerted, the effect of the first additive can be further promoted, the stability of the positive and negative electrode interface films can be improved, and the cycle performance can be improved.
Furthermore, the total content of the second additive is 0.1-0.5 wt%, 0.5-1 wt%, 1-3 wt%, 3-5 wt%, 5-6 wt%, 6-8 wt%, 8-10 wt% and 10-15 wt% of the total mass of the electrolyte.
Further, the organic solvent is at least one of carbonates, carboxylates and fluorinated organic solvents; the carbonate is one or more of Ethylene Carbonate (EC), propylene Carbonate (PC), diethyl carbonate (DEC), ethyl Methyl Carbonate (EMC), dimethyl carbonate (DMC) and Methyl Propyl Carbonate (MPC); the carboxylic acid esters are one or more of Ethyl Propionate (EP), propyl Propionate (PP), ethyl Acetate (EA), ethyl n-butyrate (EB), propyl Acetate (PA), gamma-butyrolactone (GBL), acetonitrile (AN) and Sulfolane (SUL); the fluorinated organic solvent is one or more of fluoroethylene carbonate, propylene carbonate, 4-trifluoromethyl ethylene carbonate, methyl trifluoroethyl carbonate, bis trifluoroethyl carbonate and ethyl difluoroacetate.
Further, the mass of the organic solvent is 10-70 wt% of the total mass of the electrolyte. Specifically, when the organic solvent is a carbonate solvent, the mass of the organic solvent is 10 to 70wt% of the total mass of the electrolyte; when the organic solvent is a carboxylic ester solvent, the mass of the organic solvent is 10-60 wt% of the total mass of the electrolyte; and when the organic solvent is a fluorinated organic solvent, the mass of the organic solvent is 10-50 wt% of the total mass of the electrolyte. The content of different types of solvents is different, and the solvents can be better matched with additives and lithium salts so as to better improve the electrochemical performance of the battery.
Further, the lithium salt is lithium hexafluorophosphate (LiPF) 6 ) Lithium difluorophosphate (LiPF) 2 O 2 ) Lithium difluorobis (oxalato) phosphate (LiPF) 2 (C 2 O 4 ) 2 ) Lithium tetrafluoro oxalate phosphate (LiPF) 4 C 2 O 4 ) Lithium oxalate phosphate (LiPO) 2 C 2 O 4 ) Lithium bis (oxalato) borate (LiBOB), lithium difluoro (oxalato) borate (LiODFB), lithium tetrafluoroborate (LiBF) 4 ) Lithium bis (fluorosulfonyl) imide (LiTFSI) and lithium bis (fluorosulfonyl) imide (LiFSI). Preferably, the lithium salt comprises at least lithium hexafluorophosphate and the remaining at least one lithium salt.
Preferably, the mass of the lithium salt is 12-18 wt% of the total mass of the electrolyte; wherein the mass of the lithium hexafluorophosphate can be 12.5 to 17wt percent of the total mass of the electrolyte; the mass of the rest lithium salt is 0.1-5 wt% of the total mass of the electrolyte.
The invention also provides a lithium ion battery, which comprises a positive plate, a negative plate, a diaphragm and electrolyte, wherein the diaphragm is arranged between the positive plate and the negative plate, and the electrolyte is the lithium ion battery electrolyte. The lithium ion battery is a high-voltage lithium ion battery, the upper limit cut-off voltage is more than or equal to 4.2V, and the preferable upper limit cut-off voltage is more than or equal to 4.45V.
The positive plate comprises a positive current collector and a positive active substance layer coated on the positive current collector, wherein the positive active substance layer comprises a positive active substance, a positive conductive agent and a positive binder. The positive active material may be of a chemical formula including but not limited to Li a Ni x Co y M z O 2-b N b (wherein 0.95. Ltoreq. A. Ltoreq.1.2. X>0,y ≥ 0,z ≥ 0, and x + y + z =1,0 ≤ b ≤ 1,M is selected from one or more of Mn and Al, and N is selected from one or more of F, P, and S), and the positive electrode active material can also be selected from one or more of LiCoO 2 、LiNiO 2 、 LiVO 2 、LiCrO 2 、LiMn 2 O 4 、LiCoMnO 4 、Li 2 NiMn 3 O 8 、LiNi 0.5 Mn 1.5 O 4 、LiCoPO 4 、 LiMnPO 4 、LiFePO 4 、LiNiPO 4 、LiCoFSO 4 、CuS 2 、FeS 2 、MoS 2 、NiS、TiS 2 And the like. The positive electrode active material may also be modified, and the method of modifying the positive electrode active material should be known to those skilled in the art, for example, the positive electrode active material may be modified by coating, doping, etc., and the material used in the modification process may be one or more of Al, B, P, zr, si, ti, ge, sn, mg, ce, W, etc. The positive electrode current collector is generally a structure or a part for collecting current, and may be any material suitable for use as a positive electrode current collector of a lithium ion battery in the art, for example, the positive electrode current collector may include, but is not limited to, a metal foil, and the like, and more specifically, may include, but is not limited to, an aluminum foil, and the like.
The negative plate comprises a negative fluid and a negative active material layer coated on the negative current collector, wherein the negative active material layer comprises a negative active material, a negative conductive agent and a negative binder. The negative active material may be one or more of graphite, soft carbon, hard carbon, carbon fiber, mesocarbon microbeads, silicon-based materials, tin-based materials, lithium titanate or other metals capable of forming an alloy with lithium. Wherein, the graphite can be selected from one or more of artificial graphite, natural graphite and modified graphite; the silicon-based material can be one or more selected from simple substance silicon, silicon-oxygen compound, silicon-carbon compound and silicon alloy; the tin-based material can be one or more selected from simple substance tin, tin oxide compound and tin alloy. The negative electrode current collector is generally a structure or a part for collecting current, and the negative electrode current collector may be any material suitable for use as a negative electrode current collector of a lithium ion battery in the art, for example, the negative electrode current collector may include, but is not limited to, a metal foil, and the like, and more specifically, may include, but is not limited to, a copper foil, and the like.
And the separator may be various materials suitable for lithium ion battery separators in the art, and for example, may be one or a combination of more of polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester, natural fiber, and the like, including but not limited thereto.
In order to make the technical solutions and advantages of the present invention clearer, the present invention and its advantageous effects will be described in further detail with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.
Example 1
A lithium ion battery comprises a positive plate, a negative plate, a diaphragm and electrolyte, wherein the diaphragm and the electrolyte are arranged between the positive plate and the negative plate at intervals, lithium cobaltate is used as a positive active substance in the positive plate, graphite is used as a negative active substance in the negative plate, and the diaphragm is a polypropylene diaphragm.
Preparing an electrolyte: in an argon-filled glove box, moisture content < 10ppm, oxygen content < 1ppm, ethylene Carbonate (EC), propylene Carbonate (PC), ethyl methyl carbonate (DEC), propyl Propionate (PP) were mixed in a mass ratio of 1 6 ) To obtain a mixture of the organic solvent and the lithium salt, finally, 0.5wt% of the first compound having the structure shown in formula i and 0.5wt% of Vinylene Carbonate (VC) based on the total weight of the electrolyte are added and uniformly stirred to obtain the electrolyte of the lithium ion battery of the embodiment.
Preparing a soft package battery: stacking the prepared positive plate, the diaphragm and the negative plate in sequence, enabling the diaphragm to be positioned between the positive plate and the negative plate, and winding to obtain a bare cell; and (3) placing the bare cell into an aluminum plastic film outer package, injecting the prepared electrolyte into the dried battery, packaging, standing, forming, shaping and grading to finish the preparation of the 4.50V lithium ion battery.
Examples 2 to 22 and comparative examples 1 to 3 were prepared according to the above-described preparation method, except that the contents of each material of the electrolyte, specific materials and contents, were as follows in table 1, from example 1.
TABLE 1
Figure BDA0003334475510000101
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Figure BDA0003334475510000111
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Figure BDA0003334475510000121
Performance test
The lithium ion batteries and the electrolytes thereof obtained in examples 1 to 22 and comparative examples 1 to 3 were subjected to a relevant performance test.
1) High-temperature cycle performance test: at 45 ℃, the batteries after capacity grading are charged to 4.50V at constant current and constant voltage according to 1.5C, the current is cut off at 0.05C, then the batteries are discharged to 3.0V at constant current according to 0.5C, and the capacity retention rate in the week 300 is calculated after the batteries are charged and discharged for 300 cycles according to the cycle, wherein the calculation formula is as follows: cycle capacity retention rate (%) at 300 weeks (%) = (cycle discharge capacity at 300 weeks/first cycle discharge capacity) × 100%.
2) And (3) testing the normal-temperature cycle performance: at 25 ℃, the battery after capacity grading is charged to 4.50V at constant current and constant voltage of 1.5C, the current is cut off at 0.05C, then the battery is discharged to 3.0V at constant current of 0.5C, and the capacity retention rate in the 500 th week is calculated after the battery is charged and discharged for 300 cycles according to the cycle, wherein the calculation formula is as follows: cycle capacity retention (%) at 500 weeks (= cycle discharge capacity at 500 weeks/first cycle discharge capacity) × 100%.
The test results are shown in table 2 below.
TABLE 2
Figure BDA0003334475510000131
Figure BDA0003334475510000141
It can be seen from the test results of the above examples 1 to 22 and comparative examples 1 to 3 that the normal temperature cycle performance and the high temperature cycle performance of the lithium ion battery are improved after the electrolyte additive of the present invention is added. The additive can participate in the formation of a passive film on the surface of a positive electrode and a negative electrode and inhibit the oxidative decomposition of electrolyte, and ensures the stability of a positive electrode interface film and a negative electrode interface film, so that the normal-temperature and high-temperature cycle performance of the lithium ion battery is improved, and the additive is more suitable for the lithium ion battery with high voltage of more than 4.45V.
In addition, as can be seen from a comparison of examples 1 to 22, the improvement of the cycle performance of the lithium ion battery may be different by specifically using the first compound and the second compound having different structures. As in example 13, use is made of A 6 The additive with the structural formula brings better effect than the additive A 3 The additive of the structural formula is commonly influenced by the whole structure of the additive, and the effect difference brought by different structural formulas is caused by the interaction among a main functional group, an auxiliary functional group and a bond.
Furthermore, it can be seen from the comparison of examples 1 to 22 that different contents of the first additive also have an effect on the cycle performance of the lithium ion battery. The performance improvement is gradually enhanced along with the increase of the content, but the performance improvement is limited after a certain content is reached, the content is continuously increased, and the cycle performance is reduced. Preferably, the content of the first additive is kept between 0.5 and 1.5wt% for better improvement effect.
In conclusion, in a high-voltage system with the voltage of more than 4.45V, the lithium ion battery provided by the invention still has a better cycle performance, and the application range of the lithium ion battery is greatly widened.
Variations and modifications to the above-described embodiments may also occur to those skilled in the art, which fall within the scope of the invention as disclosed and taught herein. Therefore, the present invention is not limited to the above-mentioned embodiments, and any obvious improvement, replacement or modification made by those skilled in the art based on the present invention is within the protection scope of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims (7)

1. The lithium ion battery electrolyte is characterized by comprising a lithium salt, an organic solvent and additives, wherein the additives comprise a first additive and a second additive, and the first additive is a first compound with a structural formula I and/or a second compound with a structural formula II;
Figure QLYQS_1
formula I; />
Figure QLYQS_2
Formula II;
wherein R is 1 、R 2 Each independently selected from any one of hydrogen atom, nitrile group, alkoxy, alkyl and fluoroalkyl; r3 is any one of hydrogen atom, halogen atom, nitrile group, hydroxyl group, alkoxy group, alkyl group and fluoroalkyl group; r 4 ~R 9 Each independently selected from any one of halogen atom, alkyl with 1-5 carbon atoms and fluoroalkyl with 1-5 carbon atoms;
wherein the mass of the first additive is 0.01 to 5wt% of the total mass of the electrolyte;
wherein the total content of the second additive is 0.1 to 15wt% of the total mass of the electrolyte;
the second additive is at least one of fluoroethylene carbonate, vinylene carbonate, vinyl sulfate, 1,3-propane sultone, ethylene carbonate, 1,2-difluoro ethylene carbonate, methylene methanedisulfonate, propylene sultone, vinyl sulfite, citraconic anhydride, tri (trimethyl alkane) borate, tri (trimethyl alkane) phosphate, succinonitrile, adiponitrile, ethylene glycol bis (propionitrile) ether and hexane trinitrile.
2. The lithium ion battery electrolyte of claim 1, wherein the first additive is at least one of the following structural formulas:
Figure QLYQS_3
;/>
Figure QLYQS_4
;/>
Figure QLYQS_5
;/>
Figure QLYQS_6
3. the lithium ion battery electrolyte of claim 1, wherein the organic solvent is at least one of carbonates, carboxylates, fluorinated organic solvents; the carbonate is one or more of ethylene carbonate, propylene carbonate, diethyl carbonate, methyl ethyl carbonate, dimethyl carbonate and methyl propyl carbonate; the carboxylic ester is one or more of ethyl propionate, propyl propionate, ethyl acetate, ethyl n-butyrate and propyl acetate; the fluorinated organic solvent is one or more of fluoroethylene carbonate, propylene carbonate, 4-trifluoromethyl ethylene carbonate, methyl trifluoroethyl carbonate, bis trifluoroethyl carbonate and ethyl difluoroacetate.
4. The lithium ion battery electrolyte of claim 3, wherein the mass of the organic solvent is 10 to 70wt% of the total mass of the electrolyte.
5. The lithium-ion battery electrolyte of claim 1, wherein the lithium salt is at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium difluorobis (oxalato) phosphate, lithium tetrafluorooxalato phosphate, lithium oxalato phosphate, lithium bis (oxalato) borate, lithium difluorooxalato borate, lithium tetrafluoroborate, and lithium bis (fluorosulfonylimide).
6. The lithium ion battery electrolyte of claim 5, wherein the mass of the lithium salt is 12 to 18wt% of the total mass of the electrolyte.
7. A lithium ion battery comprising a positive plate, a negative plate, a separator and an electrolyte, wherein the separator is spaced between the positive plate and the negative plate, and the electrolyte is the lithium ion battery electrolyte of any one of claims 1~6.
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