CN112310474A - Non-aqueous electrolyte of lithium ion battery and lithium ion battery containing electrolyte - Google Patents
Non-aqueous electrolyte of lithium ion battery and lithium ion battery containing electrolyte Download PDFInfo
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- CN112310474A CN112310474A CN201910698686.9A CN201910698686A CN112310474A CN 112310474 A CN112310474 A CN 112310474A CN 201910698686 A CN201910698686 A CN 201910698686A CN 112310474 A CN112310474 A CN 112310474A
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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
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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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
- H01M2300/00—Electrolytes
- H01M2300/0017—Non-aqueous electrolytes
- H01M2300/0025—Organic electrolyte
- H01M2300/0028—Organic electrolyte characterised by the solvent
- H01M2300/0037—Mixture of solvents
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- 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 application provides a lithium ion battery nonaqueous electrolyte which comprises a nonaqueous organic solvent, a lithium salt and one or more compounds selected from compounds shown in a formula 1, wherein R is1、R2、R3、R4Each independently selected from the group consisting of substituted or unsubstituted alkyl groups of 1 to 5 carbon atoms, substituted or unsubstituted ether groups of 1 to 5 carbon atoms, and substituted or unsubstituted unsaturated hydrocarbon groups of 2 to 5 carbon atoms, provided that R1、R2、R3、R4At least one of which is said substituted or unsubstituted unsaturated hydrocarbon group of 2 to 5 carbon atoms, R5Selected from substituted or unsubstituted alkylene groups of 1 to 5 carbon atoms, and substituted or unsubstituted ether groups of 1 to 5 carbon atoms. The invention also provides a lithium ion battery containing the nonaqueous electrolyte. The non-aqueous electrolyte can give consideration to both the high-temperature storage performance and the cycle performance of the battery.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to a lithium ion battery non-aqueous electrolyte and a lithium ion battery containing the same.
Background
Lithium ion batteries have been developed in the field of portable electronic products due to their high operating voltage, high safety, long life, no memory effect, and the like. With the development of new energy automobiles, the lithium ion battery has a huge application prospect in a power supply system for the new energy automobiles.
As one of the most important components of a lithium ion battery, an electrolyte plays a crucial role in improving the energy density, the cycle stability, and the like of the lithium ion battery. During the charging and discharging process of the lithium ion battery, the accompanying Li+The reversible intercalation/deintercalation reaction can lead the electrolyte and the electrode material to generate a series of reactions, and a layer of solid electrolyte interface film (SEI film) covering the surface of the electrode material is formed. As an electronic insulator and a lithium ion conductor, the stable SEI film can prevent the electrolyte from further contacting with an electrode material, and has positive effects on the electrochemical performance and safety performance of the lithium ion battery. On the contrary, the unstable SEI film causes the continuous consumption and reaction of lithium ions, and generates a series of irreversible byproducts, which cause the expansion of the battery, increase the internal resistance, even cause fire or explosion, and cause great hidden troubles to the safety of the battery. Therefore, the stability of the SEI film determines the performance of the lithium ion battery.
Many researchers improve the stability of the SEI film of the lithium ion battery and various performances of the battery by selecting different film forming additives (such as vinylene carbonate, fluoroethylene carbonate and ethylene carbonate). Compared with organic solvents and lithium salts, the additive has the advantages of small requirement amount, obvious effect and low cost. Therefore, the development of additives has become a core technology of electrolyte development. Aurbach et al studied Vinylene Carbonate (VC) as an additive by electrochemical and spectroscopic methods, and found that VC canCan improve the cycle performance of the battery, especially improve the cycle performance of the battery at high temperature and reduce the irreversible capacity. The main reason is that VC can be polymerized on the surface of graphite to generate a polyalkyl lithium carbonate film, thereby inhibiting the reduction of solvent and salt anions. LiClO at 1mol/L of G.H.Wrodnigg et al4Ethylene Sulfite (ES) or Propylene Sulfite (PS) with 5% (volume fraction) is added into Propylene Carbonate (PC), so that PC molecules can be effectively prevented from being embedded into a graphite electrode, and the low-temperature performance of the electrolyte can be improved. The reason for this may be, for example, that the reduction potential of ES is about 2V (vs. Li/Li)+) The SEI film is formed on the surface of the graphite negative electrode in preference to the solvent reduction. Although research shows that functional additives play a very important role in improving the performance of the battery, and the addition of the additives can make up for some defects of the electrolyte, research work on the aspect is not mature so far, for example, few reports on additives for increasing the working temperature range of the lithium ion battery exist, and the types of the additives particularly applied to high temperature are limited.
Disclosure of Invention
The invention aims to provide a lithium ion battery non-aqueous electrolyte which can simultaneously achieve the high-temperature storage performance and the cycle performance of the battery, and further provides a lithium ion battery containing the non-aqueous electrolyte.
In order to achieve the purpose of the invention, the invention adopts the following technical scheme:
according to a first aspect of the present invention, there is provided a nonaqueous electrolyte for a lithium ion battery, comprising a nonaqueous organic solvent and a lithium salt, wherein the nonaqueous electrolyte further comprises one or more compounds selected from the group consisting of compounds represented by formula 1,
wherein R is1、R2、R3、R4Each independently selected from substituted or unsubstituted alkyl group of 1-5 carbon atoms, substituted or unsubstituted ether group of 1-5 carbon atoms, substituted or unsubstitutedA substituted unsaturated hydrocarbon group of 2 to 5 carbon atoms, provided that R1、R2、R3、R4At least one of which is said substituted or unsubstituted unsaturated hydrocarbon group of 2 to 5 carbon atoms, R5Selected from substituted or unsubstituted alkylene groups of 1 to 5 carbon atoms, and substituted or unsubstituted ether groups of 1 to 5 carbon atoms.
As a preferred embodiment of the present invention, the alkyl group of 1 to 5 carbon atoms may be selected from, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, neopentyl.
As a preferred embodiment of the present invention, the unsaturated hydrocarbon group of 2 to 5 carbon atoms may be selected from, for example, vinyl, propenyl, allyl, butenyl, pentenyl, methylvinyl, methallyl, ethynyl, propynyl, propargyl, butynyl, pentynyl.
As a preferred embodiment of the present invention, the alkylene group having 1 to 5 carbon atoms may be selected from, for example, methylene, ethylene, n-propylene, isopropylene, n-butylene, isobutylene, sec-butylene, tert-butylene, n-pentylene, isopentylene, sec-pentylene, and neopentylene.
As a preferred embodiment of the present invention, the ether group having 1 to 5 carbon atoms may be selected from, for example, methyl ether, ethyl ether, methyl ethyl ether, propyl ether, methyl propyl ether, and ethyl propyl ether.
As a preferred embodiment of the present invention, the substitution is a substitution of one or more hydrogen elements with halogen; preferably, the halogen is fluorine, chlorine, bromine and iodine; further preferably, the halogen is fluorine.
As a particularly preferred embodiment of the present invention, the halogen-substituted alkyl group of 1 to 5 carbon atoms is a fluoroalkyl group of 1 to 5 carbon atoms in which one or more hydrogen elements in the alkyl group of 1 to 5 carbon atoms are substituted with fluorine elements.
As a particularly preferred embodiment of the present invention, the halogen-substituted unsaturated hydrocarbon group of 2 to 5 carbon atoms is a fluorinated unsaturated hydrocarbon group of 1 to 5 carbon atoms obtained by substituting one or more hydrogen elements in the unsaturated hydrocarbon group of 2 to 5 carbon atoms with fluorine element.
As a particularly preferred embodiment of the present invention, the halogen-substituted alkylene group of 1 to 5 carbon atoms is a fluoroalkylene group of 1 to 5 carbon atoms in which one or more hydrogen elements in the alkylene group of 1 to 5 carbon atoms are substituted with fluorine elements.
As a particularly preferred embodiment of the present invention, the halogen-substituted ether group of 1 to 5 carbon atoms is a fluoroether group of 1 to 5 carbon atoms obtained by substituting one or more hydrogen elements in an ether group of 1 to 5 carbon atoms with a fluorine element.
As a more specific preferred embodiment of the present invention, the fluoroether group of 1 to 5 carbon atoms may be selected from, for example, fluoromethyl ether, fluoroethyl ether, fluoromethyl ether, fluoropropyl ether, fluoromethyl propyl ether, and fluoroethyl propyl ether.
As still further preferred embodiments of the present invention, the compounds represented by formula 1 are compounds 1 to 22 listed in table 1 below.
Table 1: representative preferred compounds 1 to 22 of the compound represented by formula 1 of the present invention
In a preferred embodiment of the present invention, the content of the compound represented by formula 1 is 10ppm or more based on the total mass of the nonaqueous electrolytic solution. In a further preferred embodiment of the present invention, the content of the compound represented by formula 1 is 2% or less with respect to the total mass of the nonaqueous electrolytic solution. For example, the content of the compound represented by formula 1 is 10 ppm-2%, 20 ppm-1%, 50 ppm-0.5%, 100 ppm-0.3%, 200 ppm-0.2%, 300-1000ppm, 500-800ppm, or any value therebetween, with respect to the total mass of the nonaqueous electrolytic solution.
In a further preferred embodiment of the present invention, the lithium ion battery nonaqueous electrolyte further contains at least one of an unsaturated cyclic carbonate, a fluorinated cyclic carbonate, a cyclic sultone, and a cyclic sulfate ester as a film forming additive. The content of the unsaturated cyclic carbonate is 0.1-5%, the content of the fluorinated cyclic carbonate is 0.1-30%, the content of the cyclic sultone is 0.1-5%, and the content of the cyclic sulfate is 0.1-5% based on the total mass of the nonaqueous electrolyte.
In a further preferred embodiment of the present invention, the unsaturated cyclic carbonate is at least one selected from vinylene carbonate (CAS:872-36-6), vinylethylene carbonate (CAS:4427-96-7), and methylene vinyl carbonate (CAS:124222-05-5), the fluorocyclic carbonate is at least one selected from fluoroethylene carbonate (CAS:114435-02-8), trifluoroethylene carbonate (CAS:167951-80-6), and difluoroethylene carbonate (CAS:311810-76-1), the cyclic sultone is at least one selected from 1, 3-propane sultone (CAS:1120-71-4), 1, 4-butane sultone (CAS:1633-83-6), and propenyl-1, 3-sultone (CAS:21806-61-1), the cyclic sulfate is at least one selected from vinyl sulfate (CAS:1072-53-3) and 4-methyl vinyl sulfate (CAS: 5689-83-8).
In a further preferred embodiment of the present invention, the nonaqueous organic solvent is a mixture of a cyclic carbonate and a chain carbonate.
In a further preferred embodiment of the present invention, the cyclic carbonate is at least one selected from the group consisting of ethylene carbonate, propylene carbonate and butylene carbonate, and the chain carbonate is at least one selected from the group consisting of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate and propyl methyl carbonate; the lithium salt is selected from LiPF6、LiBF4、LiPO2F2、LiTFSI、LiBOB、LiDFOB、LiN(SO2F)2At least one of (1).
According to a second aspect of the present invention, there is provided a lithium ion battery comprising a positive electrode, a negative electrode and a separator interposed between the positive electrode and the negative electrode, and further comprising the lithium ion battery nonaqueous electrolyte according to the first aspect of the present invention.
In a further preferred embodiment of the present invention, the positive electrode includes a positive electrode active material selected from the group consisting of LiNixCoyMnzL(1-x-y-z)O2、LiCox’L(1-x’)O2、LiNix”L’y’Mn(2-x”-y’)O4、Liz’MPO4Wherein L is at least one of Al, Sr, Mg, Ti, Ca, Zr, Zn, Si or Fe, 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, z is more than or equal to 0 and less than or equal to 1, x + y + z is more than or equal to 0 and less than or equal to 1, 0<x ' is not less than 1, x is not less than 0.3 and not more than 0.6, y ' is not less than 0.01 and not more than 0.2, and L ' is at least one of Co, Al, Sr, Mg, Ti, Ca, Zr, Zn, Si and Fe; z' is more than or equal to 0.5 and less than or equal to 1, and M is at least one of Fe, Mn and Co.
Although the mechanism of action of the compound represented by formula 1 in the lithium ion battery nonaqueous electrolyte of the present invention is not completely understood, the inventors speculate that the compound represented by formula 1 is capable of undergoing a polymerization reaction on the electrode surface to form a passivation film during the first charge of the lithium ion battery due to the presence of at least one unsaturated hydrocarbon group, thereby inhibiting further decomposition of organic solvent molecules. In addition, the compound shown in the formula 1 can react with LiF, so that the content of high-impedance component LiF in the passivation film on the surface of the electrode is reduced, lithium ions can pass through the compound, and the high-temperature storage performance and the cycle performance of the lithium ion battery can be obviously improved. In addition, in the compound shown in formula 1, two phosphate groups are connected through a flexible alkylene group or an ether group, and compared with a group with higher rigidity, such as an alkynyl group, the compound is more beneficial to dispersion and reaction in an electrolyte, so that the high-temperature storage performance and the cycle performance of the lithium ion battery are further improved, and the reduction of the low-temperature performance can be inhibited to a certain extent.
When the content of the compound represented by formula 1 is 10ppm or more and less than 10ppm based on the total mass of the nonaqueous electrolyte, it may be difficult to sufficiently form a passivation film on the surfaces of the positive and negative electrodes, and it may be difficult to sufficiently improve the high-temperature storage performance of the nonaqueous electrolyte battery. When the content of the compound represented by formula 1 is too high, for example, more than 2%, an excessively thick passivation film may be formed on the surfaces of the positive and negative electrodes, increasing the internal resistance of the battery, thereby decreasing the cycle performance of the battery and increasing the cost of the electrolyte.
The lithium ion battery non-aqueous electrolyte also comprises at least one of unsaturated cyclic carbonate, fluorinated cyclic carbonate, cyclic sultone and cyclic sulfate as a film forming additive, and a more stable SEI film can be formed on the surface of a graphite negative electrode, so that the cycle performance of the lithium ion battery is remarkably improved.
The lithium ion battery non-aqueous electrolyte adopts the mixed solution of the cyclic carbonate organic solvent with high dielectric constant and the chain carbonate organic solvent with low viscosity as the solvent of the lithium ion battery electrolyte, so that the mixed solution of the organic solvent has high ionic conductivity, high dielectric constant and low viscosity.
Detailed Description
The invention provides a non-aqueous electrolyte of a lithium ion battery, which comprises a non-aqueous organic solvent and a lithium salt, wherein the non-aqueous electrolyte also comprises one or more compounds selected from the compounds shown in formula 1,
wherein R is1、R2、R3、R4Each independently selected from the group consisting of substituted or unsubstituted alkyl groups of 1 to 5 carbon atoms, substituted or unsubstituted ether groups of 1 to 5 carbon atoms, and substituted or unsubstituted unsaturated hydrocarbon groups of 2 to 5 carbon atoms, provided that R1、R2、R3、R4At least one of which is the substituted or unsubstituted unsaturated hydrocarbon group of 2 to 5 carbon atoms, R5Selected from substituted or unsubstituted alkylene groups of 1 to 5 carbon atoms, and substituted or unsubstituted ether groups of 1 to 5 carbon atoms.
The alkyl group of 1 to 5 carbon atoms may be selected from, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, neopentyl.
The unsaturated hydrocarbon group of 2 to 5 carbon atoms may be selected from, for example, vinyl, propenyl, allyl, butenyl, pentenyl, methylvinyl, methallyl, ethynyl, propynyl, propargyl, butynyl, pentynyl.
The alkylene group of 1 to 5 carbon atoms may be selected from, for example, methylene, ethylene, n-propylene, isopropylene, n-butylene, isobutylene, sec-butylene, tert-butylene, n-pentylene, isopentylene, sec-pentylene, neopentylene.
The ether group of 1 to 5 carbon atoms may be selected from, for example, methyl ether, ethyl ether, methyl ethyl ether, propyl ether, methyl propyl ether, ethyl propyl ether.
The substitution is that one or more hydrogen elements are substituted by halogen; preferably, the halogen is fluorine, chlorine, bromine and iodine; further preferably, the halogen is fluorine.
Specifically, the halogen-substituted alkyl group of 1 to 5 carbon atoms is a fluoroalkyl group of 1 to 5 carbon atoms in which one or more hydrogen elements are substituted with fluorine elements in the alkyl group of 1 to 5 carbon atoms.
Specifically, the halogen-substituted unsaturated hydrocarbon group of 2 to 5 carbon atoms is a fluorinated unsaturated hydrocarbon group of 2 to 5 carbon atoms in which one or more hydrogen elements are substituted with fluorine elements in the unsaturated hydrocarbon group of 2 to 5 carbon atoms.
Specifically, the halogen-substituted alkylene group having 1 to 5 carbon atoms is a fluorinated alkylene group having 1 to 5 carbon atoms in which one or more hydrogen elements are substituted with fluorine elements in the alkylene group having 1 to 5 carbon atoms.
Specifically, the halogen-substituted ether group having 1 to 5 carbon atoms is a fluoroether group having 1 to 5 carbon atoms obtained by substituting one or more hydrogen elements in an ether group having 1 to 5 carbon atoms with a fluorine element.
Further specifically, the fluoroether group of 1 to 5 carbon atoms may be selected from, for example, fluoromethyl ether, fluoroethyl ether, fluoromethyl ethyl ether, fluoropropyl ether, fluoromethyl propyl ether, and fluoroethyl propyl ether.
The method for preparing the compound of formula 1 can be known to those skilled in the art based on the common general knowledge in the field of chemical synthesis, knowing the structural formula of the compound. For example, the compound of formula 1 can be prepared by reacting phosphorus oxychloride with corresponding alcohol in an ether solvent at low temperature (-10 to 0 ℃) and normal pressure by using triethylamine as an acid-binding agent to generate corresponding phosphate, and then performing recrystallization or column chromatography purification. Taking compounds 1, 6 and 15 as examples, the synthetic route is illustrated below:
the invention also provides a lithium ion battery which comprises a positive electrode, a negative electrode, a diaphragm arranged between the positive electrode and the negative electrode and the non-aqueous electrolyte of the lithium ion battery.
The present invention is further illustrated by way of the following non-limiting examples and comparative examples.
I. Examples 1 to 11 and comparative examples 1 to 7
1) Preparation of the electrolyte
Ethylene Carbonate (EC), diethyl carbonate (DEC) and Ethyl Methyl Carbonate (EMC) were mixed in a mass ratio of EC: DEC: EMC ═ 1:1:1, and then lithium hexafluorophosphate (LiPF) was added6) To a molar concentration of 1mol/L, a base electrolyte was prepared. Then, as shown in Table 2, a specified amount of the compound represented by formula 1 and/or a specified amount of other compound listed in Table 1 was added or not added.
Specifically, examples 1 to 6 added 20ppm of compound 1, 50ppm of compound 2, 100ppm of compound 4, 500ppm of compound 6, 1000ppm of compound 8, 1% of compound 12, respectively, based on the total mass of the base electrolyte; examples 7-11 were charged with 500ppm of Compound 1 and 1% Vinylene Carbonate (VC), 500ppm of Compound 1 and 1% fluoroethylene carbonate (FEC), 500ppm of Compound 1 and 1% 1, 3-Propanesultone (PS), 500ppm of Compound 1 and 1% ethylene sulfate (DTD), 500ppm of Compound 1 and 1% LiN (SO)2F)2(ii) a Comparative example 1 the compound represented by formula 1 and other compounds were not added; comparative examples 2 to 7 in which the compound represented by formula 1 was not added, 1% of VC, 1% of FEC, 1% of PS, 1% of DTD, and 1% of LiN (SO) were added, respectively2F)2500ppm of 2-alkynyl-1, 4-bis (di (2-propynyl)) phosphate (ABPP).
2) Preparation of Positive plate
A positive electrode active material lithium nickel cobalt manganese oxide LiNi was mixed in a mass ratio of 93:4:30.6Co0.2Mn0.2O2Conductive carbon black Super-P, and a binder polyvinylidene fluoride (PVDF), and then the mixture was dispersed in N-methyl-2-pyrrolidone (NMP) to obtain a positive electrode slurry. And uniformly coating the slurry on two sides of the aluminum foil, drying, rolling and vacuum drying, and welding an aluminum outgoing line by using an ultrasonic welding machine to obtain the positive plate, wherein the thickness of the positive plate is 120-.
3) Preparation of negative plate
Mixing artificial graphite serving as a negative electrode active material, conductive carbon black Super-P, Styrene Butadiene Rubber (SBR) serving as a binder and carboxymethyl cellulose (CMC) according to a mass ratio of 94:1:2.5:2.5, and dispersing the mixture in deionized water to obtain negative electrode slurry. Coating the slurry on two sides of the copper foil, drying, rolling and vacuum drying, and welding a nickel outgoing line by using an ultrasonic welding machine to obtain a negative plate, wherein the thickness of the negative plate is 120-150 mu m.
4) Preparation of cell
And placing three layers of diaphragms with the thickness of 20 mu m between the positive plate and the negative plate, then winding the sandwich structure consisting of the positive plate, the negative plate and the diaphragms, flattening the wound body, then placing the flattened wound body into an aluminum foil packaging bag, and baking the flattened wound body in vacuum at 75 ℃ for 48 hours to obtain the battery cell to be injected with liquid.
5) Liquid injection and formation of battery core
And (3) in a glove box with the dew point controlled below-40 ℃, injecting the prepared electrolyte into a battery cell, carrying out vacuum packaging to prepare a lithium ion battery, and standing for 24 hours.
Then the first charge is normalized according to the following steps: charging at 0.05C for 180min, charging at 0.2C to 3.95V, vacuum sealing for the second time, further charging at 0.2C to 4.4V, standing at room temperature for 24h, and discharging at 0.2C to 3.0V.
Examples 12 to 17 and comparative examples 8 to 9
The base electrolyte was prepared by referring to the method described in "I. examples 1 to 11 and comparative examples 1 to 7" above, and then3, with or without the addition of specified amounts of the compound of formula 1 listed in table 1 and/or specified amounts of other compounds. Specifically, examples 12 to 17 were charged with 20ppm of compound 1, 50ppm of compound 2, 100ppm of compound 4, 500ppm of compound 6, 1000ppm of compound 8, 1% of compound 12, respectively, based on the total mass of the base electrolyte; comparative example 8 the compound represented by formula 1 was not added; comparative example 9 the compound represented by formula 1 was not added, but 2-alkynyl-1, 4-bis (di (2-propynyl)) phosphate (ABPP) was added in an amount of 500 ppm. In addition, LiNi was used as the positive electrode active material in each of examples 12 to 17 and comparative examples 8 to 90.8Co0.15Al0.05O2And preparing the positive plate. Negative plates, cells, and injection and formation of cells were prepared as described in "i. examples 1 to 11 and comparative examples 1 to 7" above.
Examples 18 to 23 and comparative examples 10 to 11
Base electrolytes were prepared by referring to the methods described in the above-mentioned "i. examples 1 to 11 and comparative examples 1 to 7", and then, as shown in table 4, a compound represented by formula 1 shown in table 1 in a specified amount and/or other compounds in specified amounts were added or not added. Specifically, examples 18 to 23 were charged with 0.1% of compound 1, 0.3% of compound 2, 0.5% of compound 4, 1% of compound 7, 1.5% of compound 8, 2% of compound 12, respectively, based on the total mass of the base electrolyte; comparative example 8 the compound represented by formula 1 was not added; in addition, LiCoO was used as the positive electrode active material in each of examples 18 to 23 and comparative example 82And preparing the positive plate. Negative plates, cells, and injection and formation of cells were prepared as described in "i. examples 1 to 11 and comparative examples 1 to 7" above. Performance testing of lithium ion batteries fabricated in examples and comparative examples
In order to verify the effect of the nonaqueous electrolyte solution of the lithium ion battery of the present invention on the battery performance, the following performance tests were performed on the lithium ion batteries fabricated in examples 1 to 23 and comparative examples 1 to 11. The tested performance comprises a high-temperature cycle performance test, a high-temperature storage performance test and a low-temperature performance test, and the specific test method comprises the following steps:
1. high temperature cycle performance test
The lithium ion batteries fabricated in examples 1 to 23 and comparative examples 1 to 11 were placed in an oven maintained at a constant temperature of 45 ℃ and charged to 4.4V (LiNi) at a constant current of 1C0.6Co0.2Mn0.2O2Artificial graphite Battery, LiCoO2Artificial graphite battery) or 4.2V (LiNi)0.8Co0.15Al0.05O2Artificial graphite cell), constant voltage charging until the current drops to 0.02C, then constant current discharging to 3.0V at 1C, and so on, recording the 1 st discharge capacity and the last discharge capacity.
The capacity retention for the high temperature cycle was calculated as follows:
battery capacity retention (%) — last discharge capacity/1 st discharge capacity × 100%.
2. High temperature storage Performance test
The lithium ion batteries fabricated in examples 1 to 23 and comparative examples 1 to 11 were formed and then charged to 4.4V (LiNi) at room temperature with a constant current and a constant voltage of 1C0.6Co0.2Mn0.2O2Artificial graphite Battery, LiCoO2Artificial graphite battery) or 4.2V (LiNi)0.8Co0.15Al0.05O2Artificial graphite battery), and then discharged to 3V at 1C after storage for 30 days in an environment of 60C, and the retention capacity and recovery capacity of the battery and the thickness of the battery after storage were measured. The calculation formula is as follows:
battery capacity retention (%) — retention capacity/initial capacity × 100%;
battery capacity recovery (%) — recovery capacity/initial capacity × 100%;
thickness expansion (%) (battery thickness after storage-initial battery thickness)/initial battery thickness × 100%.
3. Low temperature Performance test
The lithium ion batteries fabricated in examples 1 to 23 and comparative examples 1 to 11 were formed and then charged to 4.4V (LiNi) at 25 ℃ with a constant current and a constant voltage of 1C0.6Co0.2Mn0.2O2Artificial graphite Battery, LiCoO2Artificial graphite battery) or 4.2V (LiNi)0.8Co0.15Al0.05O2Artificial graphite cell) and then discharged to 3.0V with a 1C constant current and the discharge capacity was recorded. Then the 1C constant current and constant voltage is charged to 4.4V (LiNi)0.6Co0.2Mn0.2O2Artificial graphite battery) or 4.2V (LiNi)0.8Co0.15Al0.05O2Artificial graphite battery), and after placing in an environment at-20 ℃ for 12 hours, discharging at constant current of 0.2 ℃ to 3.0V, and recording the discharge capacity.
A low-temperature discharge efficiency value of-20 ℃ was 0.2C discharge capacity (-20 ℃) per 1C discharge capacity (25 ℃) x 100%.
Table 2: positive electrode active ingredient, electrolyte composition and battery performance of lithium ion batteries of examples 1 to 11 and comparative examples 1 to 7
As can be seen from the data in Table 2, LiNi was used0.6Co0.2Mn0.2O2In the case of examples 1 to 6, as compared with comparative example 1, the high-temperature cycle performance, high-temperature storage performance and low-temperature performance of the corresponding lithium ion battery were all significantly improved due to the addition of the representative compound represented by formula 1 in an amount of 20ppm to 1% relative to the total mass of the nonaqueous electrolyte solution of the lithium ion battery. Examples 1 to 6 were significantly improved in high-temperature cycle performance, high-temperature storage performance and low-temperature performance of the corresponding lithium ion batteries, due to the addition of the representative compound represented by formula 1 having a content of 20ppm to 1% relative to the total mass of the nonaqueous electrolyte solution of the lithium ion batteries, as compared with comparative example 7 in which 2-alkynyl-1, 4-bis (di (2-propynyl)) phosphate (ABPP) was added in an amount of 500ppm relative to the total mass of the nonaqueous electrolyte solution of the lithium ion batteries. While the use of ABPP in comparative example 7 also resulted in a certain reduction in low temperature performance. Examples 7 to 11 in comparison with comparative examples 2 to 6, in the nonaqueous electrolyte solution of lithium ion batteryThe compound 1 is 500ppm in addition to other compounds, and the high-temperature cycle performance, the high-temperature storage performance and the low-temperature performance of the corresponding lithium ion battery are also obviously improved.
Table 3: positive electrode active ingredient, electrolyte composition and cell performance of lithium ion batteries of examples 12 to 17 and comparative examples 8 to 9
As can be seen from the data in Table 3, LiNi was used0.8Co0.15Al0.05O2In the case of examples 12 to 17 as the positive electrode active ingredient, the high-temperature cycle performance, the high-temperature storage performance and the low-temperature performance of the corresponding lithium ion battery were all remarkably improved as compared with comparative example 8 due to the addition of the representative compound represented by formula 1 in an amount of 20ppm to 1% relative to the total mass of the nonaqueous electrolyte solution of the lithium ion battery. Examples 12 to 17 were significantly improved in high-temperature cycle performance, high-temperature storage performance and low-temperature performance of the corresponding lithium ion batteries, as compared with comparative example 9 in which 2-alkynyl-1, 4-bis (di (2-propynyl)) phosphate (ABPP) was added in an amount of 500ppm relative to the total mass of the nonaqueous electrolyte solution of the lithium ion battery, since the representative compound represented by formula 1 was added in an amount of 20ppm to 1% relative to the total mass of the nonaqueous electrolyte solution of the lithium ion battery. While the use of ABPP in comparative example 9 also resulted in a certain reduction in low temperature performance.
Table 4: positive electrode active ingredient, electrolyte composition and cell performance of lithium ion batteries of examples 18 to 23 and comparative example 8
As can be seen from the data in Table 4, LiCoO was used2In the case of using the positive electrode active material, examples 18 to 23 contained 20ppm to 1% of the representative formula 1 based on the total mass of the nonaqueous electrolyte solution of the lithium ion battery, as compared with comparative example 10The compound shown in the specification and the corresponding lithium ion battery have obviously improved high-temperature cycle performance, high-temperature storage performance and low-temperature performance. Examples 18 to 23 are significantly improved in high-temperature cycle performance, high-temperature storage performance and low-temperature performance of the corresponding lithium ion batteries by adding the representative compound represented by formula 1 in an amount of 20ppm to 1% based on the total mass of the nonaqueous electrolyte solution of the lithium ion batteries, as compared with comparative example 11 in which 2-alkynyl-1, 4-bis (di (2-propynyl)) phosphate (ABPP) is added in an amount of 500ppm based on the total mass of the nonaqueous electrolyte solution of the lithium ion batteries. While the use of ABPP in comparative example 11 also resulted in a certain reduction in low temperature performance.
The present invention has been described above using specific examples, which are only for the purpose of facilitating understanding of the present invention, and are not intended to limit the present invention. Numerous simple deductions, modifications or substitutions may be made by those skilled in the art in light of the teachings of the present invention. Such deductions, modifications or alternatives also fall within the scope of the claims of the present invention.
Claims (10)
1. A nonaqueous electrolyte solution for a lithium ion battery, comprising a nonaqueous organic solvent and a lithium salt, wherein the nonaqueous electrolyte solution further comprises one or more compounds selected from the group consisting of compounds represented by formula 1:
wherein R is1、R2、R3、R4Each independently selected from the group consisting of substituted or unsubstituted alkyl groups of 1 to 5 carbon atoms, substituted or unsubstituted ether groups of 1 to 5 carbon atoms, and substituted or unsubstituted unsaturated hydrocarbon groups of 2 to 5 carbon atoms, provided that R1、R2、R3、R4At least one of which is said substituted or unsubstituted unsaturated hydrocarbon group of 2 to 5 carbon atoms, R5Selected from substituted or unsubstituted alkylene groups of 1 to 5 carbon atoms, and substituted or unsubstituted ether groups of 1 to 5 carbon atoms.
2. The nonaqueous electrolytic solution of claim 1,
the alkyl group of 1 to 5 carbon atoms is selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, neopentyl;
the unsaturated alkyl group with 2-5 carbon atoms is selected from vinyl, propenyl, allyl, butenyl, pentenyl, methylvinyl, methallyl, ethynyl, propynyl, propargyl, butynyl and pentynyl;
the alkylene group of 1 to 5 carbon atoms is selected from the group consisting of methylene, ethylene, n-propylene, isopropylene, n-butylene, isobutylene, sec-butylene, tert-butylene, n-pentylene, isopentylene, sec-pentylene, neopentylene;
the ether group with 1-5 carbon atoms is selected from methyl ether, ethyl ether, methyl ethyl ether, propyl ether, methyl propyl ether and ethyl propyl ether;
the substitution is that one or more hydrogen elements are substituted by halogen; preferably, the halogen is fluorine.
3. The nonaqueous electrolytic solution of claim 2, wherein the compound represented by formula 1 is a compound 1 to 22:
4. the nonaqueous electrolytic solution of any one of claims 1 to 3, wherein the content of the compound represented by formula 1 is 10ppm or more with respect to the total mass of the nonaqueous electrolytic solution.
5. The nonaqueous electrolytic solution of claim 4, wherein a content of the compound represented by formula 1 is 2% or less with respect to a total mass of the nonaqueous electrolytic solution.
6. The nonaqueous electrolytic solution of claim 1, further comprising at least one of an unsaturated cyclic carbonate, a fluorinated cyclic carbonate, a cyclic sultone, and a cyclic sulfate;
preferably, the unsaturated cyclic carbonate is selected from at least one of vinylene carbonate (CAS:872-36-6), ethylene carbonate (CAS:4427-96-7), and methylene ethylene carbonate (CAS:124222-05-5), the fluorinated cyclic carbonate is selected from at least one of fluoroethylene carbonate (CAS:114435-02-8), trifluoromethyl ethylene carbonate (CAS:167951-80-6), and difluoroethylene carbonate (CAS:311810-76-1), and the cyclic sultone is selected from at least one of 1, 3-propane sultone (CAS:1120-71-4), 1, 4-butane sultone (CAS:1633-83-6), and propenyl-1, 3-sultone (CAS:21806-61-1), the cyclic sulfate is at least one selected from vinyl sulfate (CAS:1072-53-3) and 4-methyl vinyl sulfate (CAS: 5689-83-8).
7. The lithium ion battery according to claim 6, wherein the content of the unsaturated cyclic carbonate is 0.1 to 5%, the content of the fluorinated cyclic carbonate is 0.1 to 30%, the content of the cyclic sultone is 0.1 to 5%, and the content of the cyclic sulfate ester is 0.1 to 5% based on the total mass of the nonaqueous electrolyte.
8. The nonaqueous electrolytic solution of claim 1, wherein the nonaqueous organic solvent is a mixture of a cyclic carbonate and a chain carbonate;
preferably, the cyclic carbonate is selected from ethylene carbonate, propylene carbonateAt least one of an ester and a butenyl carbonate, wherein the chain carbonate is selected from at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate and propyl methyl carbonate; the lithium salt is selected from LiPF6、LiBF4、LiPO2F2、LiTFSI、LiBOB、LiDFOB、LiN(SO2F)2At least one of (1).
9. A lithium ion battery comprising a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, characterized in that the lithium ion battery further comprises the nonaqueous electrolytic solution according to any one of claims 1 to 8.
10. The lithium ion battery of claim 9, wherein the positive electrode comprises a positive active material selected from the group consisting of LiNixCoyMnzL(1-x-y-z)O2、LiCox’L(1-x’)O2、LiNix”L’y’Mn(2-x”-y’)O4、Liz’MPO4Wherein L is at least one of Al, Sr, Mg, Ti, Ca, Zr, Zn, Si or Fe, 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, z is more than or equal to 0 and less than or equal to 1, x + y + z is more than or equal to 0 and less than or equal to 1, 0<x ' is not less than 1, x is not less than 0.3 and not more than 0.6, y ' is not less than 0.01 and not more than 0.2, and L ' is at least one of Co, Al, Sr, Mg, Ti, Ca, Zr, Zn, Si and Fe; z' is more than or equal to 0.5 and less than or equal to 1, and M is at least one of Fe, Mn and Co.
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