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CN110336075B - Electrolyte solution, electrochemical device and electronic device comprising same - Google Patents

Electrolyte solution, electrochemical device and electronic device comprising same Download PDF

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CN110336075B
CN110336075B CN201910554050.7A CN201910554050A CN110336075B CN 110336075 B CN110336075 B CN 110336075B CN 201910554050 A CN201910554050 A CN 201910554050A CN 110336075 B CN110336075 B CN 110336075B
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CN110336075A (en
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张水蓉
徐春瑞
唐超
郑建明
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Ningde Amperex Technology Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • 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
    • 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
    • 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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Abstract

The present application relates to an electrolyte, and an electrochemical device and an electronic device including the same. The application provides an electrolyte, which includes: sulfonate quaternary ammonium salts and nitrile compounds. The electrolyte can form a stable solid electrolyte interface film on the anode and the cathode through the sulfonate quaternary ammonium salt, and can further improve the protection of the electrolyte on the anode and the cathode surfaces under the synergistic action with a nitrile compound. When the electrochemical device is stored and circulated at high temperature, the electrolyte can effectively improve the problem of high-temperature expansion of the electrochemical device, and further improve the high-temperature storage cycle performance and the high-temperature storage performance of the electrochemical device.

Description

Electrolyte solution, electrochemical device and electronic device comprising same
Technical Field
The present application relates to the field of energy storage technology, and more particularly, to an electrolyte and an electrochemical device including the same.
Background
With the popularization of consumer electronics products such as notebook computers, mobile phones, handheld game consoles, tablet computers, mobile power sources, unmanned aerial vehicles and the like, the requirements of people on electrochemical devices (for example, lithium ion batteries) therein are becoming stricter. For example, not only are electrochemical devices required to have high capacity and long operating life, but specific performance specifications such as: storing and circulating under high temperature operation. Among many electrochemical devices, lithium ion batteries have been predominant in the market due to their outstanding advantages of high energy density, high safety, low self-discharge, no memory effect, long operating life, and the like. Therefore, how to improve the cycle performance (high-temperature storage cycle performance) and the storage performance of the lithium ion battery after storage at high temperature has become one of the researches to be solved.
The cycle life of a lithium ion battery is related to the anode material, the cathode material and the electrolyte. In order to improve the cycle performance and the safety performance of the lithium ion battery, in addition to seeking for a novel anode and cathode material, the development of a novel electrolyte formula is also an important solution.
Disclosure of Invention
The present application provides an electrolyte solution in an attempt to solve at least one of the problems presented in the related art to at least some extent.
According to a first aspect of the present application, there is provided an electrolyte comprising: sulfonate quaternary ammonium salts and nitrile compounds.
In some embodiments herein, the quaternary ammonium sulfonate salt comprises at least one of the compounds represented by formula 1,
Figure BDA0002106362040000021
wherein R is11Selected from substituted or unsubstituted C1To C12Alkyl, substituted or unsubstituted C2To C12Alkenyl, substituted or unsubstituted C1To C12Alkoxy, substituted or unsubstituted C1To C12An acyloxy group; r12Selected from substituted or unsubstituted C1To C12Alkylene, substituted or unsubstituted C2To C12Alkenylene, substituted or unsubstituted C2To C12Alkynylene, substituted or unsubstituted C1To C12An alkylene acyl group; r13Selected from substituted or unsubstituted C1To C12Alkyl, substituted or unsubstituted C2To C12Alkenyl, substituted or unsubstituted C2To C12Alkynyl, substituted or unsubstituted C1To C12Alkoxy, substituted or unsubstituted C1To C12Acyloxy, substituted or unsubstituted C6To C22Aryl, substituted or unsubstituted C5To C22An aromatic hetero group; r14Selected from substituted or unsubstituted C1To C3An alkylene group; the substituent is selected from cyano, halogen; and X-represents an anionic group.
In some embodiments of the present application, the cationic group of the sulfonate quat is selected from the group consisting of
Figure BDA0002106362040000022
Figure BDA0002106362040000031
Figure BDA0002106362040000032
And combinations thereof.
In some embodiments of the present application, the anionic group of the quaternary ammonium sulfonate salt is selected from the group consisting of F-、NO3 -、PF6 -、BF4 -、AsF6 -、(FSO2)2N-、
Figure BDA0002106362040000033
Figure BDA0002106362040000034
Figure BDA0002106362040000035
And combinations thereof.
In some embodiments of the present application, the nitrile compound includes at least one of the compounds represented by formula 2, formula 3, formula 4, and formula 5,
NC-R21-CN formula 2,
Figure BDA0002106362040000036
Figure BDA0002106362040000041
Wherein R is21Selected from substituted or unsubstituted C1To C5Alkylene, substituted or unsubstituted C1To C5An alkyleneoxy group; r31And R32Each independently selected from the group consisting of a covalent bond, a substituted or unsubstituted C1To C5An alkylene group; r41、R42And R43Each independently selected from the group consisting of a covalent bond, a substituted or unsubstituted C1To C5Alkylene, substituted or unsubstituted C1To C5An alkyleneoxy group; wherein R is51Selected from substituted or unsubstituted C1To C5Alkylene, substituted or unsubstituted C2To C10Alkenylene, substituted or unsubstituted C6To C10Arylene, substituted or unsubstituted C1To C6A heterocyclic group; and wherein the substituents are selected from the group consisting of halogen, nitro, cyano, carboxy, sulfate, and combinations thereof.
In some embodiments of the present application, the nitrile compound is selected from the group consisting of
Figure BDA0002106362040000042
Figure BDA0002106362040000051
And combinations thereof.
In some embodiments of the present application, the nitrile compound is selected from the group consisting of
Figure BDA0002106362040000052
Figure BDA0002106362040000053
And combinations thereof.
In some embodiments of the present application, the electrolyte further comprises a material selected from the group consisting of
Figure BDA0002106362040000054
And combinations thereof.
In some embodiments of the present application, the electrolyte further includes a phosphazene selected from at least one of the compounds represented by formula 6,
Figure BDA0002106362040000061
wherein R is61May be selected from substituted or unsubstituted C1To C12Alkyl, substituted or unsubstituted C3To C12Cycloalkyl, substituted or unsubstituted C2To C12Alkenyl, substituted or unsubstituted C6To C22Aryl, substituted or unsubstituted C5To C22An aromatic hetero group; and the substituent is selected from cyano and halogen.
In some embodiments of the present application, the phosphazene is selected from the group consisting of
Figure BDA0002106362040000062
Figure BDA0002106362040000063
And combinations thereof.
In some embodiments of the present application, the quaternary ammonium sulfonate salt is contained in an amount of 0.1 to 10% and the nitrile compound is contained in an amount of 0.5 to 12% based on the total weight of the electrolyte.
According to a second aspect of the present application, there is provided an electrochemical device comprising: positive electrode, negative electrode, separator and electrolyte as described in the above examples.
According to a third aspect of the present application, there is provided an electronic device comprising the electrochemical device of the above embodiment.
According to one or more embodiments, the electrolyte can effectively improve the problem of high-temperature expansion of an electrochemical device during storage and circulation at high temperature, and further improve the high-temperature storage cycle performance and the high-temperature storage performance of the electrochemical device.
Additional aspects and advantages of embodiments of the present application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of embodiments of the present application.
Detailed Description
Embodiments of the present application will be described in detail below.
As used herein, the terms "substantially", "substantially" and "about" are used to describe and illustrate minor variations. When used in conjunction with an event or circumstance, the terms can refer to instances where the event or circumstance occurs precisely as well as instances where the event or circumstance occurs in close proximity. For example, when used in conjunction with numerical values, the term can refer to a range of variation that is less than or equal to ± 10% of the stated numerical value, such as less than or equal to ± 5%, less than or equal to ± 4%, less than or equal to ± 3%, less than or equal to ± 2%, less than or equal to ± 1%, less than or equal to ± 0.5%, less than or equal to ± 0.1%, or less than or equal to ± 0.05%. For example, two numerical values are considered to be "substantially" identical if the difference between the two numerical values is less than or equal to ± 10% (e.g., less than or equal to ± 5%, less than or equal to ± 4%, less than or equal to ± 3%, less than or equal to ± 2%, less than or equal to ± 1%, less than or equal to ± 0.5%, less than or equal to ± 0.1%, or less than or equal to ± 0.05%) of the mean of the values.
Additionally, amounts, ratios, and other numerical values are sometimes presented herein in a range format. It is to be understood that such range format is used for convenience and brevity, and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited.
In the detailed description and claims, a list of items connected by the terms "one of," "one of," or other similar terms may mean any one of the listed items. For example, if items a and B are listed, the phrase "one of a and B" means a alone or B alone. In another example, if items A, B and C are listed, the phrase "one of A, B and C" means only a; only B; or only C. Item a may comprise a single element or multiple elements. Item B may comprise a single element or multiple elements. Item C may comprise a single element or multiple elements.
In the detailed description and claims, a list of items linked by the term "at least one of," "at least one of," or other similar terms may mean any combination of the listed items. For example, if items a and B are listed, the phrase "at least one of a and B" means a only; only B; or A and B. In another example, if items A, B and C are listed, the phrase "at least one of A, B and C" means a only; or only B; only C; a and B (excluding C); a and C (excluding B); b and C (excluding A); or A, B and C. Item a may comprise a single element or multiple elements. Item B may comprise a single element or multiple elements. Item C may comprise a single element or multiple elements.
The following terms used herein have the meanings indicated below, unless explicitly indicated otherwise.
The term "Cx"means containing a number of x carbon atoms. E.g. C1To C10Alkyl is an alkyl group having 1 to 10 carbon atoms.
The term "hydrocarbyl" encompasses alkyl, alkenyl, alkynyl, cycloalkyl, aryl. For example, hydrocarbyl groups are contemplated as having a straight chain hydrocarbon structure of 1 to 20 carbon atoms. "hydrocarbyl" is also contemplated to be a branched or cyclic hydrocarbon structure having 3 to 20 carbon atoms. When a hydrocarbyl group having a particular carbon number is specified, all geometric isomers having that carbon number are intended to be encompassed. The hydrocarbyl group herein may also be C1To C15Hydrocarbyl radical, C1To C10Hydrocarbyl radical, C1To C5A hydrocarbon group, C5To C20Hydrocarbyl radical, C5To C15Hydrocarbyl or C5To C10A hydrocarbyl group. In addition, the hydrocarbyl group may be optionally substituted. For example, the hydrocarbyl group may be substituted with halogen, alkyl, aryl or heteroaryl groups including fluorine, chlorine, bromine and iodine.
The term "certain oxy" refers to the group L-O-, where L is alkyl, alkenyl, alkynyl, cycloalkyl, aryl, or acyl. For example, when the L group is an alkyl group, "certain oxy" may be referred to as "alkoxy"; when the L group is cycloalkyl, the "certain oxy group" may be referred to as "cycloalkoxy"; when the L group is an acyl group, the "certain oxy group" may be referred to as "acyloxy groupA base ". Alkoxy in this context may be C1To C20Alkoxy, which may also be C1To C12Alkoxy radical, C1To C10Alkoxy radical, C1To C5Alkoxy radical, C5To C20Alkoxy radical, C5To C15Alkoxy or C5To C10An alkoxy group.
The term "arylene" refers to an organic group having one hydrogen group removed from each end of the group and attached to a different bond, i.e., to an-R-group, wherein R is alkyl, alkenyl, alkynyl, cycloalkyl, aryl, alkanoyl. For example, when the R group is an alkyl group, the "arylene" may be referred to as "alkylene"; when the R group is an alkanoyl group, the "arylene group" may be referred to as "alkanoyl". The alkylene group herein may be C1To C20Alkylene, which may also be C1To C12Alkylene radical, C1To C10Alkylene radical, C1To C5Alkylene radical, C5To C20Alkylene radical, C5To C15Alkylene or C5To C10An alkylene group.
The term "alkyl" is intended to have 1 to 20 straight chain saturated hydrocarbon structures. "alkyl" is also contemplated to be a branched or cyclic hydrocarbon structure having from 3 to 20 carbon atoms. For example, the alkyl group may be C1To C20Alkyl radical, C1To C10Alkyl radical, C1To C5Alkyl radical, C5To C20Alkyl radical, C5To C15Alkyl or C5To C10An alkyl group. When an alkyl group having a particular carbon number is specified, all geometric isomers having that carbon number are intended to be encompassed; thus, for example, "butyl" is meant to include n-butyl, sec-butyl, isobutyl, tert-butyl, and cyclobutyl; "propyl" includes n-propyl, isopropyl and cyclopropyl. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclobutyl, n-pentyl, isopentyl, neopentyl, cyclopentyl, methylcyclopentyl, ethylcyclopentyl, n-hexyl, isohexyl, cyclohexyl, n-heptyl, octyl, cyclopropyl, cyclobutyl, norbornylAnd the like. In addition, the alkyl group may be optionally substituted.
The term "cycloalkyl" encompasses cyclic alkyl groups. Cycloalkyl radicals may be C3To C20Cycloalkyl radical, C6To C20Cycloalkyl radical, C3To C10Cycloalkyl radical, C3To C6A cycloalkyl group. For example, cycloalkyl groups can be cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and the like. In addition, cycloalkyl groups may be optionally substituted.
The term "alkenyl" refers to a monovalent unsaturated hydrocarbon group that can be straight or branched chain and has at least one and typically 1,2, or 3 carbon-carbon double bonds. Unless otherwise defined, the alkenyl group typically contains 2 to 20 carbon atoms and may be, for example, C2To C20Alkenyl radical, C6To C20Alkenyl radical, C2To C12Alkenyl or C2To C6An alkenyl group. Representative alkenyl groups include, by way of example, ethenyl, n-propenyl, isopropenyl, n-but-2-enyl, but-3-enyl, n-hex-3-enyl, and the like. In addition, the alkenyl group may be optionally substituted.
The term "alkynyl" refers to a monovalent unsaturated hydrocarbon group that can be straight-chain or branched and has at least one, and typically 1,2, or 3 carbon-carbon triple bonds. Unless otherwise defined, the alkynyl group typically contains 2 to 20 carbon atoms, and may be, for example, C2To C20Alkynyl, C6To C20Alkynyl, C2To C10Alkynyl or C2To C6Alkynyl. Representative alkynyl groups include, for example, ethynyl, prop-2-ynyl (n-propynyl), n-but-2-ynyl, n-hex-3-ynyl, and the like. In addition, the alkynyl group may be optionally substituted.
The term "acyl" refers to the remaining radical of an organic or inorganic oxyacid after removal of the hydroxyl group (-OH group), i.e., to the R-M (O) -group, where M is a carbon atom and R is an alkyl, alkenyl, alkynyl, cycloalkyl, aryl, or other common substituent. For example, when R is alkyl, "acyl" is "alkanoyl". Alkanoyl herein can be C1To C20An alkanoyl group which may also be C1To C12Alkanoyl radicalBase, C1To C10Alkylene radical, C1To C5Alkanoyl radical, C5To C20Alkanoyl radical, C5To C15Alkylene or C5To C10An alkanoyl group.
The term "aryl" encompasses monocyclic and polycyclic ring systems. Polycyclic rings can have two or more rings in which two carbons are common to two adjoining rings (the rings are "fused"), wherein at least one of the rings is aromatic, e.g., the other rings can be cycloalkyls, cycloalkenyls, aryls, heterocyclics, and/or heteroaryls. For example, the aryl group may be C6To C50Aryl radical, C6To C40Aryl radical, C6To C30Aryl radical, C6To C20Aryl or C6To C10And (4) an aryl group. Representative aryl groups include, for example, phenyl, methylphenyl, propylphenyl, isopropylphenyl, benzyl, and naphthalen-1-yl, naphthalen-2-yl, and the like. In addition, the aryl group may be optionally substituted.
The term "heterocyclyl" encompasses aromatic and non-aromatic cyclic groups. Heteroaromatic cyclic groups also mean aromatic hetero groups. In some embodiments, the heteroaromatic cyclic group and the heteronon-aromatic cyclic group are C including at least one heteroatom1To C50Heterocyclic group, C1To C40Heterocyclic group, C1To C30Heterocyclic group, C1To C20Heterocyclic group, C1To C10Heterocyclic group, C1To C6A heterocyclic group. Representative heterocyclyl groups include, for example, morpholinyl, piperidinyl, pyrrolidinyl, and the like, as well as cyclic ethers such as tetrahydrofuran, tetrahydropyran, and the like. In addition, the heterocyclic group may be optionally substituted.
As used herein, the term "heteroaryl" encompasses monocyclic heteroaromatic groups that may include one to three heteroatoms, such as pyrrole, furan, thiophene, imidazole, oxazole, thiazole, triazole, pyrazole, pyridine, pyrazine, pyrimidine and the like. The term heteroaryl also includes polycyclic heteroaromatic systems having two or more rings in which two atoms are common to two adjoining rings (the rings are "fused"),wherein at least one of the rings is heteroaryl and the other rings can be cycloalkyl, cycloalkenyl, aryl, heterocycle and/or heteroaryl. For example, the heteroaryl group may be C6To C50Heteroaryl group, C6To C40Heteroaryl group, C6To C30Heteroaryl group, C6To C20Heteroaryl or C6To C10A heteroaryl group. In addition, heteroaryl groups may be optionally substituted.
As used herein, the term "halogen" may be F, Cl, Br or I.
As used herein, the term "nitrile group" encompasses organic species containing an organic group-CN.
When the above substituents are substituted, the substituents may be selected from the group consisting of: halogen, alkyl, cycloalkyl, alkenyl, aryl and heteroaryl.
First, electrolyte
According to a first aspect of the present application, there is provided an electrolyte comprising a quaternary ammonium sulfonate salt and a nitrile compound. The quaternary ammonium sulfonate can form a stable Solid Electrolyte Interface (SEI) film on the surfaces of a positive electrode and a negative electrode, the SEI film can effectively reduce the incompatibility characteristic of a nitrile compound and the negative electrode, and inhibit the oxidation side reaction of an Electrolyte on the surface of the positive electrode and the reduction side reaction on the surface of the negative electrode. According to the electrolyte, the sulfonate quaternary ammonium salt and the nitrile compound are added into the electrolyte as a combination, so that the oxidation side reaction of the electrolyte on the surface of a positive electrode at high temperature can be effectively reduced, and the high-temperature storage cycle performance and the storage performance of an electrochemical device containing the electrolyte are effectively improved.
According to some embodiments of the present application, the quaternary ammonium sulfonate salt includes at least one of the compounds represented by formula 1,
Figure BDA0002106362040000111
wherein R is11Selected from substituted or unsubstituted C1To C12Alkyl, substituted or unsubstituted C2To C12Alkenyl, substituted or unsubstituted C1To C12Alkoxy, substituted or unsubstituted C1To C12One of the acyloxy groups;
R12selected from substituted or unsubstituted C1To C12Alkylene, substituted or unsubstituted C2To C12Alkenylene, substituted or unsubstituted C2To C12Alkynylene, substituted or unsubstituted C1To C12One of alkylene acyl groups;
R13selected from substituted or unsubstituted C1To C12Alkyl, substituted or unsubstituted C2To C12Alkenyl, substituted or unsubstituted C2To C12Alkynyl, substituted or unsubstituted C1To C12Alkoxy, substituted or unsubstituted C1To C12Acyloxy, substituted or unsubstituted C6To C22Aryl, substituted or unsubstituted C5To C22One of an aromatic group;
R14selected from substituted or unsubstituted C1To C3One of alkylene groups;
the substituent is selected from one of cyano and halogen; and is
X-Represents an anionic group.
In some embodiments of the present application, the cationic group of the sulfonate quat is selected from the group consisting of
Figure BDA0002106362040000121
Figure BDA0002106362040000122
And combinations thereof.
In some embodiments of the present application, the anionic group of the quaternary ammonium sulfonate salt is selected from the group consisting of F-、NO3 -、PF6 -、BF4 -、AsF6 -、(FSO2)2N-、
Figure BDA0002106362040000131
And combinations thereof.
In some embodiments herein, the quaternary ammonium sulfonate salt is selected from at least one of the compounds represented by the following structural formula:
Figure BDA0002106362040000132
Figure BDA0002106362040000141
according to some embodiments of the present application, the nitrile compound includes at least one of compounds represented by the following formula 2, formula 3, formula 4, and formula 5,
NC-R21-CN formula 2,
Figure BDA0002106362040000142
Figure BDA0002106362040000143
Wherein R is21Selected from substituted or unsubstituted C1To C5Alkylene, substituted or unsubstituted C1To C5One of alkyleneoxy groups;
R31and R32Each independently selected from the group consisting of a covalent bond, a substituted or unsubstituted C1To C5One of alkylene groups;
R41、R42and R43Each independently selected from the group consisting of a covalent bond, a substituted or unsubstituted C1To C5Alkylene, substituted or unsubstituted C1To C5One of alkyleneoxy groups;
wherein R is51Is selected from the group consisting ofSubstituted or unsubstituted C1To C5Alkylene, substituted or unsubstituted C2To C10Alkenylene, substituted or unsubstituted C6To C10Arylene, substituted or unsubstituted C1To C6One of heterocyclic groups; and is
The substituents are selected from the group consisting of halogen, nitro, cyano, carboxy, sulfate, and combinations thereof.
In some embodiments of the present application, the nitrile compound is selected from at least one of the compounds represented by the following structural formula,
Figure BDA0002106362040000144
Figure BDA0002106362040000151
it should be understood that in the above examples, the nitrile compounds of different structural formulas have different complexing and adsorbing forces, so that the nitrile compounds also have different separation effects on the electrolyte and the surface of the positive electrode. In some embodiments, as the number of "nitrile group" (-CN) groups in the nitrile compound increases, the more significant the separation effect on the electrolyte and the surface of the positive electrode can be achieved. Meanwhile, the molecular weight of the nitrile compound has a certain influence on the isolation effect, the easily-oxidizable component in the electrolyte cannot be effectively isolated from the surface of the anode due to too small molecular weight, and the easily-oxidizable component in the electrolyte can be in contact with the surface of the anode through the molecular gap of the nitrile compound due to too large molecular weight.
In some embodiments of the present application, the nitrile compound is a compound containing at least three or more nitrile groups selected from the group consisting of
Figure BDA0002106362040000161
Figure BDA0002106362040000171
Figure BDA0002106362040000172
And combinations thereof.
According to some embodiments of the present application, the quaternary ammonium sulfonate salt is contained in the electrolyte in an amount of about 0.1% to about 10% and the nitrile compound is contained in an amount of about 0.5% to about 12%, based on the total weight of the electrolyte. In some embodiments of the present application, the quaternary ammonium sulfonate salt is present in an amount of about 1% to about 6% and the nitrile compound is present in an amount of about 0.5% to about 12%, based on the total weight of the electrolyte. In some embodiments of the present disclosure, the quaternary ammonium sulfonate salt is, for example, 0.1%, 0.2%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% by weight of the electrolyte solution (based on the total weight of the electrolyte solution), and the nitrile compound is, for example, 0.5%, 0.75%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12% by weight of the electrolyte solution (based on the total weight of the electrolyte solution).
It is understood that when the quaternary ammonium sulfonate salt is more than 0.1% by total weight of the electrolyte, the quaternary ammonium sulfonate salt can form a solid electrolyte interface film on the surfaces of the positive electrode and the negative electrode, and the stability of the electrolyte at high temperature can be effectively improved. In addition, when the quaternary ammonium sulfonate salt is contained in an amount of less than 10% by weight based on the total weight of the electrolyte solution, the thickness and the resistance of the solid electrolyte interface film formed from the quaternary ammonium sulfonate salt are small, and the cycle performance of the electrochemical device is less affected.
When the content of the nitrile compound is higher than 0.5 percent based on the total weight of the electrolyte, the nitrile compound can effectively isolate transition metal dissolved from the surface of the positive electrode from easily-oxidized components in the electrolyte, and effectively reduce the oxidation side reaction of the electrolyte on the surface of the positive electrode at high temperature. In addition, when the content of the nitrile compound is less than 12% by weight based on the total weight of the electrolyte, it is possible to reduce adverse effects of the nitrile compound on the cycle performance of an electrochemical device, for example, a decrease in energy density and an increase in viscosity of the electrolyte.
In some embodiments of the present application, the quaternary ammonium sulfonate salt is present in an amount of about 0.5% to about 3% by weight, and the nitrile compound is present in an amount of about 0.5% to about 3% by weight, based on the total weight of the electrolyte.
In some embodiments of the present application, the combined total content of the quaternary ammonium sulfonate salt and the nitrile compound is about 0.6% to about 22% by weight based on the total weight of the electrolyte.
In some embodiments of the present application, the combined total content of the quaternary ammonium sulfonate salt and the nitrile compound is about 1.5% to about 14% by weight of the total electrolyte.
According to some embodiments of the present application, the electrolyte may further comprise one or more of the following compounds:
Figure BDA0002106362040000181
1, 3-dioxolane (cyclic ether 1),
Figure BDA0002106362040000182
1, 3-dioxane (cyclic ether 2),
Figure BDA0002106362040000183
1, 4-dioxane (cyclic ether 3),
Figure BDA0002106362040000184
1,3, 2-dioxazole-thiophene-2, 2-dioxide (DTD),
Figure BDA0002106362040000185
Methylene Methanedisulfonate (MMDS) and combinations thereof.
In some embodiments of the present application, at least one of 1, 3-dioxolane, 1, 3-dioxane, and 1, 4-dioxane is present in the electrolyte in an amount of about 0.01% to about 4% by weight based on the total weight of the electrolyte. In some embodiments of the present application, at least one of 1, 3-dioxolane, 1, 3-dioxane, and 1, 4-dioxane is present in the electrolyte in an amount of about 0.1% to about 3% by weight based on the total weight of the electrolyte. In some embodiments of the present application, at least one of 1, 3-dioxolane, 1, 3-dioxane, and 1, 4-dioxane is present in the electrolyte in an amount of about 0.1% to about 2% by weight based on the total weight of the electrolyte. In some embodiments of the present application, at least one of 1,3, 2-dioxazole thiophene-2, 2-dioxide and methylene methanedisulfonate is present in an amount of about 0.05% to about 4% by total weight of the electrolyte. In some embodiments of the present application, at least one of 1,3, 2-dioxazole thiophene-2, 2-dioxide and methylene methanedisulfonate is present in an amount of about 0.05% to about 3% by total weight of the electrolyte. In some embodiments of the present application, at least one of 1,3, 2-dioxazole thiophene-2, 2-dioxide and methylene methanedisulfonate is present in an amount of about 0.1% to about 2% by total weight of the electrolyte.
In some embodiments of the present application, the additive can further include a phosphazene compound including at least one of compounds represented by formula 6 below,
Figure BDA0002106362040000191
wherein R is61May be selected from substituted or unsubstituted C1To C12Alkyl, substituted or unsubstituted C3To C12Cycloalkyl, substituted or unsubstituted C2To C12Alkenyl, substituted or unsubstituted C6To C22Aryl, substituted or unsubstituted C5To C22An aromatic hetero group; and the substituents are selected from cyano, halogen.
In some embodiments herein, the phosphazene compound is selected from at least one of the compounds represented by the following structural formula:
Figure BDA0002106362040000192
in some embodiments of the present application, the phosphazene compound is present in the electrolyte in an amount of about 0.1% to about 20% by total weight of the electrolyte. In some embodiments of the present application, the phosphazene compound is present in the electrolyte in an amount of about 0.5% to about 15% by total weight of the electrolyte. In some embodiments of the present application, the phosphazene compound is present in the electrolyte in an amount of about 1% to about 13% by total weight of the electrolyte. After the phosphazene compound and the combination of the sulfonic acid ester quaternary ammonium salt and the nitrile compound are added into the electrolyte together, the high-temperature storage cycle performance can be improved, and the safety performance of an electrochemical device can be improved.
In some embodiments herein, the electrolyte further comprises an acid anhydride including, but not limited to, one or more of cyclic phosphoric acid anhydride, carboxylic acid anhydride, and carboxylic acid sulfonic anhydride. In some embodiments, the cyclic phosphoric anhydride includes, but is not limited to, one or more of trimethylphosphoric cyclic anhydride, triethylphosphoric cyclic anhydride, and tripropylphosphoric cyclic anhydride. In some embodiments, the carboxylic acid anhydride includes, but is not limited to, one or more of succinic anhydride, glutaric anhydride, and maleic anhydride. In some embodiments, the carboxylic sulfonic anhydride includes, but is not limited to, one or more of sulfobenzoic anhydride, sulfopropionic anhydride, and sulfobutyric anhydride.
In some embodiments of the present application, the acid anhydride is present in the electrolyte in an amount of about 0.1% to about 10% by weight based on the total weight of the electrolyte. In some embodiments of the present application, the acid anhydride is present in the electrolyte in an amount of about 0.5% to about 8% by total weight of the electrolyte. In some embodiments of the present application, the acid anhydride is present in the electrolyte in an amount of about 0.5% to about 7% by weight based on the total weight of the electrolyte.
In some embodiments, the electrolyte further comprises a phosphorus-containing compound including, but not limited to: one or more of trimethyl phosphate, triethyl phosphate, dimethylethyl phosphate, methyl diethyl phosphate, ethylene methyl phosphate, ethylene ethyl phosphate, triphenyl phosphate, trimethyl phosphite, triethyl phosphite, triphenyl phosphate, tris (2,2, 2-trifluoroethyl) phosphate, and tris (2,2,3,3, 3-pentafluoropropyl) phosphate.
In some embodiments of the present application, the phosphorus-containing compound is present in the electrolyte in an amount of about 0.1% to about 20% by weight based on the total weight of the electrolyte. In some embodiments of the present application, the phosphorus-containing compound is present in the electrolyte in an amount of about 0.5% to about 15% by total weight of the electrolyte. In some embodiments of the present application, the phosphorus-containing compound is present in the electrolyte in an amount of about 0.5% to about 10% by weight based on the total weight of the electrolyte.
In some embodiments, the electrolyte further comprises a lithium-containing additive including, but not limited to: lithium perchlorate (LiClO)4) Lithium hexafluoroarsenate (LiAsF)6) Lithium tetrafluoroborate (LiBF)4) Lithium tetraphenylborate (LiB (C)6H5)4) Lithium methanesulfonate (LiCH)3SO3) Lithium hexafluoroantimonate (LiSbF)6) Lithium trifluoromethanesulfonate (LiCF)3SO3) Lithium bis (trifluoromethylsulfonyl) imide (LiN (SO)2CF3)2) Tris (trifluoromethanesulfonic acid) methyllithium (LiC (SO)2CF3)3) Lithium hexafluorosilicate (LiSiF)6) Lithium difluorophosphate (LiPO)2F2) Lithium difluoro (oxalato) borate (LiODFB) and lithium bis (oxalato) borate (LiBOB).
In some embodiments of the present application, the lithium-containing additive is present in an amount of about 0.01% to about 25% by total weight of the electrolyte. In some embodiments, the lithium-containing additive is present in an amount of about 0.05% to about 22% by weight, based on the total weight of the electrolyte. In some embodiments, the lithium-containing additive is present in an amount of about 0.5%, about 1%, about 2%, about 3%, about 4%, about 5%, about 6%, about 7%, about 8%, about 9%, about 10%, or about 18% by total weight of the electrolyte.
In some embodiments, the electrolyte further comprises lithium hexafluorophosphate (LiPF)6)。
In some embodiments of the present application, the lithium hexafluorophosphate is present in an amount of about 0.5 to 2.5 mol/L. In some embodiments of the present application, the lithium hexafluorophosphate is present in an amount of about 0.8 to 2.0 mol/L. In some embodiments of the present application, the lithium hexafluorophosphate is present in an amount of about 0.8 to 1.8 mol/L. In some embodiments of the present application, the lithium hexafluorophosphate is present in an amount of about 0.5 to 1.5 mol/L.
According to some embodiments of the present application, the electrolyte may further include a non-aqueous solvent.
In some embodiments herein, the non-aqueous solvent comprises at least one of a carbonate compound, a carboxylate compound.
It is to be understood that the carbonate may be any kind of carbonate, and the carbonate compound may be a chain carbonate compound, a cyclic carbonate compound, a fluoro carbonate compound, or a combination thereof.
Examples of the chain carbonate compound are dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), Methyl Propyl Carbonate (MPC), Ethyl Propyl Carbonate (EPC), Methyl Ethyl Carbonate (MEC), and combinations thereof. Examples of the cyclic carbonate compound are Ethylene Carbonate (EC), Propylene Carbonate (PC), Butylene Carbonate (BC), Vinyl Ethylene Carbonate (VEC), and combinations thereof. Examples of the fluoro carbonate compound are 1, 2-difluoroethylene carbonate, 1, 2-trifluoroethylene carbonate, 1,2, 2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1, 2-difluoro-1-methylethylene carbonate, 1, 2-trifluoro-2-methylethylene carbonate, trifluoromethylethylene carbonate, and combinations thereof.
Examples of the carboxylate compound are methyl formate, methyl acetate, ethyl acetate, propyl propionate, n-propyl acetate, t-butyl acetate, methyl propionate, ethyl propionate, γ -Butyrolactone (BL), decalactone, valerolactone, mevalonolactone, caprolactone, and combinations thereof.
It will be understood by those skilled in the art that the electrolyte of the embodiments of the present application can be manufactured by any suitable known method according to actual manufacturing requirements without being limited thereto.
Two, electrochemical device
According to a second aspect of the present application, there is also provided an electrochemical device comprising an electrolyte according to embodiments of the present application. In some embodiments of the present application, the electrochemical device is a lithium ion battery. The lithium ion battery comprises a positive electrode, a negative electrode, an isolating membrane and the electrolyte.
Positive electrode
According to some embodiments of the present application, the positive electrode includes a positive electrode current collector and a positive electrode active material layer on a surface thereof, wherein the positive electrode active material layer includes a positive electrode active material and a conductive agent. In some embodiments, the positive current collector includes, but is not limited to, aluminum foil or nickel foil.
In some embodiments of the present application, the cathode active material is a cathode material capable of absorbing and releasing lithium (Li) (hereinafter, sometimes referred to as "a cathode material capable of absorbing/releasing lithium Li"). Examples of the positive active material may include at least one of lithium cobaltate, lithium iron phosphate, lithium manganese iron phosphate, sodium iron phosphate, lithium vanadium phosphate, sodium vanadium phosphate, lithium vanadyl phosphate, sodium vanadyl phosphate, lithium vanadate, lithium manganate, lithium nickelate, lithium nickel cobalt manganese, a lithium rich manganese-based material, lithium nickel cobalt aluminate, and lithium titanate.
In some embodiments of the present application, the positive active material includes a nickel-cobalt-manganese ternary material, examples of which may include, but are not limited to, LiNi coated with an oxide of any one or more of Al, Mg, Ti, Zr, BaCobMncO2Or Li (Li)dNieCofMng)O2Wherein a + b + c is 1, 1d +2e +3f +4g is 3, d>0. In some embodiments, the positive active material comprises LiNi1/3Co1/3Mn1/3O2、LiNi0.5Co0.2Mn0.3O2、LiNi0.4Co0.2Mn0.4O2、LiNi0.8Co0.1Mn0.1O2、LiNi0.6Co0.2Mn0.2O2At least one of (1).
In some embodiments of the present application, the positive electrode active material comprises lithium cobaltate and a nickel cobalt manganese ternary material.
In some embodiments of the present application, a mixing ratio of the lithium cobaltate and the nickel cobalt manganese ternary material in the positive electrode active material is 1: 9 to 9: 1. in other embodiments of the present application, a mixing ratio of lithium cobaltate and lithium nickel cobalt manganese oxide in the positive electrode active material is 2: 8 to 4: 6.
the positive electrode material is a combination of lithium cobaltate and a nickel-cobalt-manganese ternary material, and the safety performance of the positive electrode active material can be improved. Meanwhile, the amount of the transition metal is increased after mixing, so that the transition metal has a certain catalytic effect on film formation in the electrolyte, and the combination of the sulfonate quaternary ammonium salt and the nitrile compound can have a more effective isolation effect.
In some embodiments, the conductive agent comprises at least one of conductive carbon black, carbon fiber, acetylene black, ketjen black, graphene, carbon nanotubes. Those skilled in the art will appreciate that a wide variety of positive electrodes for use in lithium ion batteries are suitable for use in the present application and are not limited thereto.
Negative electrode
According to some embodiments of the present application, the negative electrode includes a negative electrode current collector and a negative electrode active material layer on the negative electrode current collector. In some embodiments, the negative electrode current collector includes, but is not limited to: copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymeric substrates coated with a conductive metal, and any combination thereof.
In some embodiments of the present application, the anode active material layer includes an anode active material that absorbs and releases lithium (Li) (hereinafter, sometimes referred to as "anode material capable of absorbing/releasing lithium Li"). In some embodiments, can absorb +Examples of the lithium (Li) -releasing negative electrode material may include carbon materials, metal compounds, oxides, sulfides, silicon-carbon composites, lithium nitrides such as LiN3Lithium metal, an alloy material, and a polymer material. .
In some embodiments of the present application, the negative electrode materials, compositions, and methods of making negative electrodes used in the lithium ion batteries of the present application may include any of the techniques disclosed in the prior art. The negative electrode of the embodiment of the present application may be prepared by a preparation method known in the art. In some embodiments per se, the method of preparing the negative electrode comprises the steps of: the negative active material, the conductive agent, and the binder are mixed in a solvent to prepare a negative active material composition, and the negative active material composition is coated on a negative current collector. In some embodiments, the solvent may include water, but is not limited thereto.
Isolation film
In some embodiments of the present application, the lithium ion battery of the present application is provided with a separator between the positive electrode and the negative electrode to prevent short circuits. The material and shape of the separator used in the lithium ion battery of the present application are not particularly limited, and may be any of the techniques disclosed in the prior art. In some embodiments of the present application, the separator includes a polymer or inorganic substance or the like formed of a material stable to the electrolyte of the present application.
In some embodiments of the present application, the above method for preparing a lithium ion battery comprises: the positive electrode, the separator, and the negative electrode in the above embodiments are sequentially wound or stacked, and are, for example, incorporated into an aluminum plastic film, and the electrolyte of the present application is injected, followed by vacuum packaging, standing, formation, shaping, and the like to obtain a lithium ion battery. It will be understood by those skilled in the art that the method of manufacturing the lithium ion battery may be performed by injecting the electrolyte of the present application at a suitable step during the manufacturing process of the lithium ion battery according to the manufacturing method of the final product and the required properties. In other words, the electrolyte of the present application may be injected before the lithium ion battery is assembled or at the last step during the assembly of the lithium ion battery, without being limited thereto
Those skilled in the art will appreciate that the above-described methods of making lithium ion batteries are examples only. Other methods commonly used in the art may be employed without departing from the disclosure herein. Furthermore, although illustrated above as a lithium ion battery, one skilled in the art will appreciate after reading this application that the electrolyte of the present application may be used in other suitable electrochemical devices. Such an electrochemical device includes any device in which electrochemical reactions occur, and specific examples thereof include all kinds of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors. In particular, the electrochemical device is a lithium secondary battery including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.
Electronic device
According to a third aspect of the present application, there is further provided an electronic device comprising the electrochemical device of the present application.
The electronic device of the embodiment of the present application is not particularly limited, and may be any electronic device known in the art. In some embodiments of the present application, the electronic device may include, but is not limited to, a notebook computer, a pen-input computer, a mobile computer, an electronic book player, a cellular phone, a portable facsimile machine, a portable copier, a portable printer, a headphone, a video recorder, a liquid crystal television, a portable cleaner, a portable CD player, a mini disc, a transceiver, an electronic notebook, a calculator, a memory card, a portable recorder, a radio, a backup power source, a motor, an automobile, a motorcycle, a power-assisted bicycle, a lighting fixture, a toy, a game machine, a clock, an electric power tool, a flashlight, a camera, a large household battery, a lithium ion capacitor, and the like.
Fourth, specific embodiments
Some specific examples and comparative examples are listed below and are respectively subjected to at least one of a high temperature storage cycle performance test, a high temperature storage test, a cycle performance test and a hot box test to better illustrate the beneficial effects of the technical solution of the present application.
Test method
High temperature storage cycle performance test
(1) The lithium ion battery finished product of the following example or comparative example was placed in a 45 ℃ incubator, charged to 4.4V at a constant charge rate of 0.5C and charged to 0.05C at a constant voltage of 4.4V, followed by standing for 19 hours, then discharged to 3.0V at a constant discharge rate of 0.5C, and the discharge capacity thereof was recorded as the first discharge capacity.
(2) The above-described mode (1) was repeated to perform 23 charge-discharge cycles.
(3) The lithium ion battery finished product was placed in a 45 ℃ thermostat, charged to 4.35V at a constant charge rate of 0.5C, and charged to 0.05C at a constant voltage of 4.35V, followed by standing for 19 hours, and then discharged to 3.0V at a constant discharge rate of 0.5C.
(4) The above-described mode (3) was repeated to perform the charge-discharge cycle 113 times.
(5) Then taking the discharge after charging as sequential circulation, recording the discharge capacity of each time, and calculating the battery capacity retention rate of the lithium ion battery after high-temperature storage circulation;
the battery capacity retention (%) after the nth cycle was the discharge capacity (mAh)/first discharge capacity (mAh) × 100% after the nth cycle.
High temperature storage Performance test
The finished lithium ion batteries of the following examples or comparative examples were placed in a 25 ℃ incubator, charged to 4.40V at a constant charge rate of 0.5C, then charged at constant voltage to a charge rate of 0.05C, and the thickness of the lithium ion battery was recorded as h 0; then, the lithium ion battery is placed in a thermostat at 85 ℃ for storage for 6 hours; recording the thickness of the lithium ion battery as h1, and calculating the thickness growth rate:
the thickness growth rate (%) - (h1-h0)/h0 × 100%.
Cycle performance test
The lithium ion battery finished product of the following example or comparative example was left to stand in an oven at 45 ℃ for 30 minutes, charged to 4.40V at a constant charge rate of 1.0C, then charged at a constant voltage to a charge rate of 0.05C, and then discharged to 3.0V at a constant discharge rate of 1.0C, whereby one charge-discharge cycle was taken, and the first discharge capacity was recorded. After the subsequent 300 cycles, the battery capacity retention rate was calculated.
Nail penetration test
The lithium ion battery finished product of the following example or comparative example was left to stand in an oven at 25 ℃ for 30 minutes, charged at a constant charge rate of 0.5C to 4.4V, and then charged at a constant voltage of 4.4V to a charge rate of 0.025C. And then placing the lithium ion battery in a nail penetration testing machine, and under the constant temperature environment of 25 ℃, using a steel nail with the diameter of 4mm to uniformly penetrate through the center of the lithium ion battery at the speed of 30mm/s, wherein the lithium ion battery can pass through the center without fire or explosion. And testing 20 batteries each time, and taking the number of the lithium ion batteries passing the nail penetration test as an index for evaluating the safety performance of the lithium ion batteries.
Hot box test
The lithium ion battery finished product of the following example or comparative example was placed in an oven at 25 ℃, charged to 4.25V at a constant charge rate of 0.5C, and then charged at a constant voltage at 4.25V to a charge rate of 0.05C. The lithium ion battery was then placed in a high temperature oven, warmed to 140 ℃, and held at 140 ℃ for 1 hour. And monitoring the lithium ion battery in the hot box test period, wherein the lithium ion battery passes the test as long as the lithium ion battery does not catch fire or explode in the hot box test period. And testing 10 batteries at each time, and taking the number of the lithium ion batteries passing the hot box test as an index for evaluating the performance of the hot box of the lithium ion batteries.
Preparation of (II) lithium ion battery
Preparation of the Positive electrode
Mixing lithium cobaltate (LiCoO)2) Carbon Nanotubes (CNTs) and polyvinylidene fluoride (PVDF) were mixed according to a ratio of about 96:2:2 in the solvent N-methyl pyrrolidone, and stirring uniformly to obtain the anode slurry. And (3) baking the positive current collector coated with the lithium cobaltate slurry at 120 ℃ for 1 hour by using an aluminum foil as the positive current collector, and then carrying out cold pressing, cutting into pieces and slitting to prepare the positive electrode.
Preparation of the negative electrode
Artificial graphite, sodium carboxymethylcellulose (CMC) and Styrene Butadiene Rubber (SBR) were mixed in a ratio of about 96:2:2 in deionized water, and stirring uniformly to obtain the cathode slurry. And (3) adopting copper foil as a negative current collector, baking the negative current collector coated with the negative slurry at 120 ℃ for 1 hour, and then carrying out cold pressing, cutting into pieces and slitting to prepare the negative electrode.
Preparation of the electrolyte
Ethylene Carbonate (EC), diethyl carbonate (DEC) and Propylene Carbonate (PC) were mixed in a weight ratio of 3:4:3 under an argon atmosphere, followed by addition of LiPF6Forming a base electrolyte, wherein LiPF6The concentration of (2) is 1.15 mol/L. The electrolytes of different examples and comparative examples were obtained by adding different contents of the substances shown in the following tables to the base electrolyte.
Assembly of lithium ion batteries
And (2) adopting a polyethylene film as a separation film, stacking the positive electrode, the separation film and the negative electrode in sequence to enable the separation film to be positioned between the positive electrode and the negative electrode to play a role of separation, then winding and packaging the positive electrode and the negative electrode into an aluminum-plastic film, drying the aluminum-plastic film at 80 ℃, injecting the prepared electrolyte, and carrying out the processes of vacuum packaging, standing, formation, shaping and the like to complete the preparation of the lithium ion battery.
After the lithium ion battery finished products of the above examples and comparative examples are finished, the capacity, thickness, width and length of the finished products are recorded to determine the volume energy density of the lithium ion battery. And the lithium ion batteries of examples 1 to 27 and comparative examples 1 to 3 were subjected to a high temperature storage cycle performance test and a high temperature storage test.
The electrolyte formulation ratios and compositions of examples 1 to 27 and comparative examples 1 to 3 and the test results thereof through the high temperature storage cycle performance test and the high temperature storage test are shown in table 1 below.
TABLE 1
Figure BDA0002106362040000281
Figure BDA0002106362040000291
As can be seen from the data in table 1, compared with comparative examples 1 to 3, the lithium ion battery provided by the present application can effectively improve the capacity retention rate after the high temperature storage cycle test and reduce the thickness increase rate after the high temperature storage test by adding the combination of the quaternary ammonium sulfonate and the nitrile compound into the electrolyte. Wherein, compared to comparative example 1 in which neither the quaternary ammonium sulfonate salt nor the nitrile compound is added at all, comparative examples 2 and 3 in which only one of the quaternary ammonium sulfonate salt and the nitrile compound is added have some improvement, but no significant improvement, in high-temperature storage cycle performance and high-temperature expansion of the lithium ion battery.
It can be seen from comparison of examples 7 to 13 that the problems of high-temperature storage cycle and high-temperature expansion of the lithium ion battery can be significantly improved when the battery contains 2% by weight of the nitrile compound of formula (2-2) and 1% by weight of the nitrile compound of formula (4-3) and 2% to 12% by weight of the quaternary ammonium sulfonate salt.
Further, as can be seen from comparison of examples 1 to 6, examples 2 to 3 and 5 to 6, since the nitrile compounds of the formulae (formula 4-3) and (formula 5-2) have at least three or more nitrile groups, are more effective in reducing the thickness growth rate in the high temperature storage test than the nitrile compound of the formula (formula 2-2) of examples 1 and 4, which has only two nitrile groups.
As can be seen from the above comparison, the electrochemical device of the present application effectively increases the high-temperature storage cycle efficiency thereof by adding the combination of the quaternary ammonium sulfonate salt and the nitrile compound to the electrolyte, while suppressing the thickness increase during high-temperature storage. According to the application, the sulfonate quaternary ammonium salt is added into the electrolyte to form a stable SEI film on the positive electrode and the negative electrode, and the nitrile compound is added into the electrolyte to perform a complex reaction with a transition metal on the surface of the positive electrode. According to the electrolyte, the sulfonate quaternary ammonium salt and the nitrile compound are combined, so that the incompatibility of the nitrile compound and a negative electrode can be reduced, the side reaction of the electrolyte and an anode and a negative electrode interface at a high temperature is further reduced, and the high-temperature storage cycle performance and the high-temperature thickness increase rate are improved.
In some embodiments herein, the electrolyte of the present application can further comprise other additives to further enhance the cycle performance of a lithium ion battery comprising the electrolyte. In the following examples 28 to 39, which were prepared in the same manner as in example 8 except that at least one of the compounds represented by the following structural formulae was further added in the preparation of the electrolytes of examples 28 to 39:
Figure BDA0002106362040000301
1, 3-dioxolane (cyclic ether 1),
Figure BDA0002106362040000302
1, 3-dioxane (cyclic ether 2),
Figure BDA0002106362040000303
1, 4-dioxane (cyclic ether 3),
Figure BDA0002106362040000304
1,3, 2-dioxazole-thiophene-2, 2-dioxide (DTD),
Figure BDA0002106362040000305
Methylene Methanedisulfonate (MMDS) to the electrolyte containing the combination of the quaternary ammonium sulfonate salt and the nitrile compound (example 8), and the specific components and contents of other additives are shown in table 2. And the lithium ion batteries of examples 8 and 28 to 39 were subjected to a high temperature storage cycle performance test and a cycle performance test to further illustrate the advantageous effects thereof.
The composition and content of the other additives of examples 8 and 28-39 and the results of the high temperature storage cycle performance test and the cycle performance test are shown in Table 2 below.
TABLE 2
Figure BDA0002106362040000306
Figure BDA0002106362040000311
As can be seen from the data in table 2, the high-temperature storage cycle performance and the cycle performance of the lithium ion battery can be further improved by further adding other additives to the electrolyte to which the combination of the quaternary ammonium sulfonate salt and the nitrile compound is added. As can be seen by comparing examples 8 and 28-39, the capacity retention rate of the lithium ion battery in examples 28-39 can reach 80.9% to 83.9% through the cycle performance test, and the capacity retention rate of the lithium ion battery in the high-temperature energy storage cycle performance test can reach 63.3% to 71.2%.
In other embodiments of the present application, the electrolyte further adds a phosphazene compound. In the following examples 40 to 45, the same procedure as in example 8 was conducted, except that one of the compounds represented by the following structural formulae was further added in the preparation of the electrolytes of examples 40 to 45:
Figure BDA0002106362040000312
Figure BDA0002106362040000313
the specific components and contents of the phosphazene compound added to the electrolyte containing the combination of the sulfonate quaternary ammonium salt and the nitrile compound (example 8) are shown in table 3. The lithium ion batteries of examples 8 and 40 to 45 were subjected to a high temperature storage cycle performance test and a nail penetration test to further illustrate the advantageous effects thereof.
The compositions and contents of the phosphazene compounds of examples 8 and 40 to 45 and the results of the high temperature storage cycle performance test and the nail penetration test are shown in table 3 below.
TABLE 3
Figure BDA0002106362040000321
As can be seen from the data in table 3, the further addition of the phosphazene compound to the electrolyte solution to which the combination of the quaternary ammonium sulfonate salt and the nitrile compound is added can further improve the high-temperature storage cycle performance and the nail penetration rate of the lithium ion battery. It can be seen from comparison between examples 8 and 40-45 that the number of passes of the lithium ion battery in examples 40-45 after 20 times of nail penetration tests is much higher than that of the lithium ion battery in example 8 without the phosphazene compound, which effectively improves the safety performance of the lithium ion battery. Meanwhile, the capacity retention rate of the lithium ion battery in the embodiment 40-45 added with the phosphazene compound can be slightly improved to 63.0-64.1% through a high-temperature energy storage cycle performance test.
In other embodiments of the present application, the positive electrode of the present application includes a nickel-cobalt-manganese ternary material, and due to its characteristics, a phenomenon that transition metals nickel, manganese, and cobalt are easily dissolved out occurs, and the dissolved transition metals may further catalyze a side reaction of an electrolyte, thereby bringing potential safety hazards to the lithium ion battery. This application is through in electrolyte the complex action of nitrile compound and transition metal nickel, manganese, cobalt, stable transition metal that can be better reduces it and dissolves out, simultaneously, can form SEI film at the positive pole through sulfonate quaternary ammonium salt and reduce dissolving out of transition metal, still forms stable SEI film at the negative pole simultaneously, prevents transition metal to the destruction of the SEI film on the negative pole, improves lithium ion battery's security performance. In the following examples 46 to 62 and comparative examples 4 to 6, which were prepared in the same manner as in example 1 except that the positive electrodes in examples 46 to 62 and comparative examples 4 to 6 were prepared using a nickel-cobalt-manganese ternary material (formula LiNi)0.8Co0.1Mn0.1O2) Fully stirring and mixing acetylene black serving as a conductive agent and polyvinylidene fluoride (PVDF) serving as a binder in a proper amount of N-methylpyrrolidone (NMP) solvent according to a weight ratio of 96:2:2 to form uniform positive electrode slurry; and then coating the positive electrode slurry on a positive electrode current collector and baking at 120 ℃ for 1 hour, and then performing cold pressing, slitting and slitting to prepare a positive electrode. And the lithium ion batteries of examples 46 to 62 and comparative examples 4 to 6 were subjected to a hot boxAnd testing to further illustrate the beneficial effects.
The electrolyte formulation ratios and compositions of examples 46-62 and comparative examples 4-6 and the results of the tests on the hot box test are shown in table 4 below.
TABLE 4
Figure BDA0002106362040000331
Figure BDA0002106362040000341
According to the test results in table 4, compared with comparative examples 4 to 6, examples 46 to 62 of the present application, by adding the combination of the quaternary ammonium sulfonate salt and the nitrile compound to the electrolyte, can provide a lithium ion battery that can effectively reduce the dissolution of the nickel-cobalt-manganese ternary material at high temperature, thereby increasing the passing rate of the nickel-cobalt-manganese ternary material in the hot box test and improving the safety property of the lithium ion battery.
As can be understood from the description of the above-described embodiments and comparative examples of the present application, the present application provides an electrolyte and an electrochemical device including the same, the electrolyte including the combination of the quaternary ammonium sulfonate salt and the nitrile compound, which can reduce the occurrence of side reactions of the electrolyte on a positive electrode and a negative electrode, thereby effectively improving cycle performance and high-temperature storage performance after high-temperature storage. In addition, by further including one of a cycle improving additive and a phosphazene compound in the electrolyte solution, the cycle performance of the electrochemical device at high temperatures can be further improved.
Reference throughout this specification to "some embodiments," "one embodiment," "other embodiments," "examples," "specific examples," or "partial examples" means that at least one embodiment or example in the present application includes a particular feature, structure, material, or characteristic described in the embodiment or example. Thus, throughout the specification, descriptions appear, for example: "in some embodiments," "in an embodiment," "in one embodiment," "in another example," "in one example," "in a particular example," or "by example," which do not necessarily refer to the same embodiment or example in this application. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.
Although illustrative embodiments have been illustrated and described, it will be appreciated by those skilled in the art that the above embodiments are not to be construed as limiting the application and that changes, substitutions and alterations can be made to the embodiments without departing from the spirit, principles and scope of the application.

Claims (11)

1. An electrolyte, comprising:
a sulfonate quaternary ammonium salt and a nitrile compound, wherein the nitrile compound comprises:
Figure FDF0000014762640000011
Figure FDF0000014762640000012
at least one of, and
Figure FDF0000014762640000013
Figure FDF0000014762640000014
at least one of sulfonate quaternary ammonium salts in an amount of 0.1 to 10% and nitrile compounds in an amount of 0.5 to 12%, based on the total weight of the electrolyte.
2. The electrolyte of claim 1, wherein the quaternary ammonium sulfonate salt comprises at least one of the compounds represented by formula 1,
Figure FDF0000014762640000015
wherein R is11Selected from substituted or unsubstituted C1To C12Alkyl, substituted or unsubstituted C2To C12Alkenyl, substituted or unsubstituted C1To C12Alkoxy, substituted or unsubstituted C1To C12An acyloxy group;
R12selected from substituted or unsubstituted C1To C12Alkylene, substituted or unsubstituted C2To C12Alkenylene, substituted or unsubstituted C2To C12Alkynylene, substituted or unsubstituted C1To C12An alkylene acyl group;
R13selected from substituted or unsubstituted C1To C12Alkyl, substituted or unsubstituted C2To C12Alkenyl, substituted or unsubstituted C2To C12Alkynyl, substituted or unsubstituted C1To C12Alkoxy, substituted or unsubstituted C1To C12Acyloxy, substituted or unsubstituted C6To C22Aryl, substituted or unsubstituted C5To C22An aromatic hetero group;
R14selected from substituted or unsubstituted C1To C3An alkylene group;
the substituent is selected from cyano, halogen;
X-represents an anionic group.
3. The electrolyte of claim 1, wherein the cationic group of the quaternary ammonium sulfonate salt is selected from the group consisting of
Figure FDF0000014762640000021
Figure FDF0000014762640000031
And combinations thereof.
4. The electrolyte of claim 1, wherein the anionic group of the quaternary ammonium sulfonate salt is selected from the group consisting of
F-、NO3 -、PF6 -、BF4 -、AsF6 -、(FSO2)2N-、
Figure FDF0000014762640000032
And combinations thereof.
5. The electrolyte of claim 1, wherein the nitrile compound further comprises at least one of compounds represented by formula 2, formula 3, formula 4, and formula 5
NC-R21-CN formula 2,
Figure FDF0000014762640000033
Figure FDF0000014762640000034
Wherein R is21Selected from substituted or unsubstituted C1To C5Alkylene, substituted or unsubstituted C1To C5An alkyleneoxy group;
R31and R32Each independently selected from the group consisting of a covalent bond, a substituted or unsubstituted C1To C5An alkylene group;
R41、R42and R43Each independently selected from the group consisting of a covalent bond, a substituted or unsubstituted C1To C5Alkylene, substituted or unsubstituted C1To C5An alkyleneoxy group;
wherein R is51Selected from substituted or unsubstituted C1To C5Alkylene, substituted or unsubstituted C2To C10Alkenylene, substituted or unsubstituted C6To C10Arylene, substituted or unsubstituted C1To C6A heterocyclic group;
wherein the substituents are selected from the group consisting of halogen, nitro, cyano, carboxy, sulfate, and combinations thereof.
6. The electrolyte of claim 1, wherein the nitrile compound further comprises one or more of the following compounds:
Figure FDF0000014762640000041
Figure FDF0000014762640000051
7. the electrolyte of claim 1, further comprising
Figure FDF0000014762640000052
And combinations thereof.
8. The electrolyte of claim 1, further comprising a phosphazene selected from at least one of the compounds represented by formula 6,
Figure FDF0000014762640000053
wherein R is61Selected from substituted or unsubstituted C1To C12Alkyl, substituted or unsubstituted C3To C12Cycloalkyl, substituted or unsubstituted C2To C12Alkenyl, substituted or unsubstituted C6To C22Aryl, substituted or unsubstituted C5To C22An aromatic hetero group; and
the substituent is selected from cyano and halogen.
9. The electrolyte of claim 8, wherein the phosphazene is selected from the group consisting of
Figure FDF0000014762640000054
Figure FDF0000014762640000061
And combinations thereof.
10. An electrochemical device, comprising:
a positive electrode;
a negative electrode;
an isolation film; and an electrolyte as claimed in any one of claims 1 to 9.
11. An electronic device comprising the electrochemical device of claim 10.
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