CN112956063A - Electrolyte solution, and electrochemical device and electronic device comprising same - Google Patents

Abstract

An electrolyte comprising a compound of formula I:

wherein M is₁To M₅Any one of which is M₇-an OLi group; and M₁To M₅At least one of which is M₈-a CN group; the rest is not M₇-OLi group and M₈M of the-CN group₁To M₅Each independently selected from hydrogen, substituted or unsubstituted C_1‑12Alkoxy, halogen, substituted or unsubstituted C_1‑12Alkyl, substituted or unsubstituted C_2‑12Alkenyl, substituted or unsubstituted C_2‑12Alkynyl, nitro, sulfonic acid, aldehyde, carboxyl, silicon-based or substituted or unsubstituted C_6‑12Aryl, wherein when substituted, the substituent is halogen; wherein M is₆、M₇And M₈Each independently selected from C optionally substituted with halogen_0‑5Alkylene groups. An electrochemical device and an electronic device are also provided. The electrolyte can provide good high-temperature storage performance for an electrochemical device.

Description

Electrolyte solution, and electrochemical device and electronic device comprising same

Technical Field

The present disclosure relates to the field of energy storage technologies, and particularly to an electrolyte, and an electrochemical device and an electronic device including the same.

Background

Electrochemical devices, such as lithium ion batteries, have many advantages that make them widely used in a variety of electronic devices. In the formation process of the lithium battery, a solvent or an additive in the electrolyte reacts on the surfaces of the positive electrode and the negative electrode to generate a large amount of gas, and particularly, when the battery is stored under extreme conditions, such as a fully-charged high-temperature storage process, the continuous reaction of the positive electrode and the negative electrode with the electrolyte can be caused along with the prolonging of the storage time, so that more and more gas is accumulated in the battery, and the safety of the battery is greatly reduced. Therefore, there is a need to develop a new electrolyte additive that can form a stable protective layer on the electrode surface so that the battery can effectively avoid the risk of gassing even under extreme storage conditions.

Disclosure of Invention

In order to solve the problem that a lithium ion battery in the prior art is prone to gas expansion in a high-temperature storage process, the application provides an electrolyte which can provide stable protective layers on a positive electrode and a negative electrode of an electrochemical device, so that the electrochemical device can obtain good electrochemical characteristics, such as good high-temperature storage performance.

The purpose of the application can be realized by at least the following technical scheme:

an electrolyte comprising a compound of formula I:

wherein M is₁To M₅Any one of which is M₇-an OLi group; and M₁To M₅At least one of which is M₈-a CN group; the rest is not M₇-OLi group and M₈M of the-CN group₁To M₅Each independently selected from hydrogen, substituted or unsubstituted C_1-12Alkoxy, halogen, substituted or unsubstituted C_1-12Alkyl, substituted or unsubstituted C_2-12Alkenyl, substituted or unsubstituted C_2-12Alkynyl, nitro, sulfonic acid, aldehyde, carboxyl, silicon-based or substituted or unsubstituted C_6-12Aryl, wherein when substituted, the substituent is halogen;

wherein M is₆、M₇And M₈Each independently selected from C_0-5Alkylene, halogen-substituted C_1-5Alkylene groups.

In some embodiments, the compounds of formula (I) of the present application include at least one of the compounds of formula I-1 through formula I-6:

wherein R is₁-R₁₄Each independently selected from hydrogen, halogen, substituted or unsubstituted C_1-12Alkoxy, substituted or unsubstituted C_1-12Alkyl, substituted or unsubstituted C_2-12Alkenyl, substituted or unsubstituted C_2-12Alkynyl, nitro, sulfonic acid, aldehyde, carboxyl, silicon-based or substituted or unsubstituted C_6-12Aryl, wherein when substituted,

the substituent is halogen; and n is 0 to 5.

In some embodiments, the compound of formula I comprises at least one of compound 1 to compound 16 below:

in some embodiments, the compounds of formula I described herein are present in an amount of from about 0.01% to about 10% based on the total mass of the electrolyte.

In some embodiments, the electrolyte solution of the present application further comprises at least one of an additive a, an additive B, or an additive C, wherein the additive a comprises at least one of a nitrile compound, an anhydride compound, an ether compound, a phosphate compound, a phosphite compound, or a borate compound; the additive B comprises at least one of sulfate compounds, sulfite compounds, fluoro carbonate or unsaturated carbonate; the additive C comprises at least one of a sulfonate compound, a sulfone compound or a lithium salt additive.

In some embodiments, the additive a is present in an amount of about 0.01% to about 10% based on the total mass of the electrolyte; the additive B is present in an amount of about 0.01% to about 10%; the additive C is present in an amount of about 0.01% to about 5%.

In some embodiments, the nitrile compound includes at least one of the following compounds: succinonitrile, adiponitrile, 1,3, 5-glutaronitrile, 1,3, 6-adiponitrile, 1,2, 6-adiponitrile, fumaronitrile or ethylene glycol (dipropionitrile) ether;

the acid anhydride compound comprises at least one of the following compounds: citral chaff anhydride, succinic anhydride, maleic anhydride, trifluoromethyl maleic anhydride, dimethyl maleic anhydride or propane sulfonic anhydride;

the ether compound comprises at least one of the following compounds: 1,1,2, 2-tetrafluoroethyl-2, 2,3, 3-tetrafluoropropyl ether or perfluorobutyl ether;

the phosphate ester compound comprises at least one of the following compounds: triphenyl phosphate, tris (trifluoroethyl) phosphate, or triallyl phosphate;

the phosphite ester compound comprises at least one of the following compounds: triphenyl phosphite or trimethylsilyl phosphite;

the borate ester compound comprises at least one of the following compounds: tris (hexafluoroisopropyl) borate, trimethylsilyl borate, trimethylene borate, triisopropyl borate, tributyl borate, triethyl borate, or tripropyl borate;

the sulfate ester compound comprises at least one of the following compounds: vinyl sulfate, vinyl disulfate, vinyl methylsulfate, vinyl ethylsulfate or vinyl propylsulfate;

the sulfite compound comprises at least one of the following compounds: ethylene sulfite, ethylene methyl sulfite, ethylene ethyl sulfite, ethylene propyl sulfite, or propylene sulfite;

the fluoro carbonate comprises at least one of the following compounds: fluoroethylene carbonate, methyl trifluoroethyl carbonate or trifluoromethyl ethylene carbonate;

the unsaturated carbonate includes at least one of the following compounds: ethylene carbonate or vinylene carbonate;

the sulfonate compound comprises at least one of the following compounds: 1, 3-propane sultone, 1, 4-butane sultone, 2, 4-butane sultone, propenyl-1, 3-sulfonic lactone, methylene methanedisulfonate, or a chain disulfonate;

the sulfone compound comprises at least one of the following compounds: sulfolane, cyclopentylsulfone, or 3-sulfolene;

the lithium salt additive includes at least one of the following compounds: 4, 5-dicyano-2- (trifluoromethyl) imidazolium, lithium difluorophosphate, lithium tetrafluoroborate, lithium bis fluorosulfonylimide, lithium bis trifluoromethanesulfonylimide, lithium oxalato-borate or lithium bis-fluorooxalato-borate.

The present application also provides an electrochemical device comprising a positive electrode comprising a positive active material and an electrolyte according to the present application.

In some embodiments, the positive electrode active material includes at least one element selected from Al, Zr, or Mg.

In some embodiments, the content a of Al is less than 1%, the content b of Zr is less than 1%, and the content c of Mg is less than 0.5%, based on the total mass of the cathode active material.

In some embodiments, the positive electrode material contains Al and Mg, and the content thereof satisfies the following condition: 0.005< a/c < 500.

The present application also provides an electronic device comprising an electrochemical device according to the present application.

Detailed Description

Embodiments of the present application will be described in detail below. The embodiments described herein are illustrative and are provided to provide a basic understanding of the present application. The embodiments of the present application should not be construed as limiting the present application.

As used herein, the term "about" is 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 "about" the same 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 definitions are used in this application (unless explicitly stated otherwise):

for simplicity, a "Cn-m" group refers to a group having from "n" to "m" carbon atoms, where "n" and "m" are integers. For example, "C_1-12"hydrocarbyl is a hydrocarbyl group having 1 to 12 carbon atoms," C₀"alkylene" refers to a covalent bond.

The term "hydrocarbyl" encompasses alkyl, alkenyl, alkynyl, cycloalkyl, aryl. For example, hydrocarbyl groups are contemplated as straight chain hydrocarbon structures having from 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 hydrocarbon group herein may also be a hydrocarbon group of 1 to 15 carbon atoms, a hydrocarbon group of 1 to 10 carbon atoms, a hydrocarbon group of 1 to 5 carbon atoms, a hydrocarbon group of 5 to 20 carbon atoms, a hydrocarbon group of 5 to 15 carbon atoms, or a hydrocarbon group of 5 to 10 carbon atoms. 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 "alkylene" refers to a straight or branched chain divalent hydrocarbon radical linking an aryl group in a compound of the present application to an-OLi or-CN group, wherein the hydrocarbon radical is as defined above. Exemplary hydrocarbylene groups include, but are not limited to: methylene, ethylene, propylene, n-butylene, vinylene, propenylene, n-butylene, propynylene, n-butylene, and the like. The point of attachment of the alkylene group to the aryl nucleus and to the-OLi or-CN group may be one or any two carbons in the alkylene group. Unless otherwise specified in the specification, alkylene groups are optionally substituted.

The term "alkoxy" refers to an L-O-group, wherein L is alkyl, alkenyl, alkynyl, cycloalkyl, aryl. The hydrocarbyloxy group herein may be a hydrocarbyloxy group of 1 to 20 carbon atoms, and may also be a hydrocarbyloxy group of 1 to 15 carbon atoms, a hydrocarbyloxy group of 1 to 10 carbon atoms, a hydrocarbyloxy group of 1 to 5 carbon atoms, a hydrocarbyloxy group of 5 to 20 carbon atoms, a hydrocarbyloxy group of 5 to 15 carbon atoms, or a hydrocarbyloxy group of 5 to 10 carbon atoms.

The term "alkyl" is intended to be a straight chain saturated hydrocarbon structure having from 1 to 20 carbon atoms. "alkyl" is also contemplated to be a branched or cyclic hydrocarbon structure having from 3 to 20 carbon atoms. For example, the alkyl group may be an alkyl group of 1 to 20 carbon atoms, an alkyl group of 1 to 10 carbon atoms, an alkyl group of 1 to 5 carbon atoms, an alkyl group of 5 to 20 carbon atoms, an alkyl group of 5 to 15 carbon atoms, or an alkyl group of 5 to 10 carbon atoms. When an alkyl group having a particular carbon number is specified, all geometric isomers having that carbon number are intended to be encompassed; thus, for example, "butyl" is meant to include n-butyl, sec-butyl, isobutyl, tert-butyl, and cyclobutyl; "propyl" 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, norbornyl, and the like. In addition, the alkyl group may be optionally substituted.

The term "cycloalkyl" encompasses cyclic alkyl groups. The cycloalkyl group may be a cycloalkyl group of 3 to 20 carbon atoms, a cycloalkyl group of 6 to 20 carbon atoms, a cycloalkyl group of 3 to 10 carbon atoms, a cycloalkyl group of 3 to 6 carbon atoms. 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, an alkenyl group of 2 to 20 carbon atoms, an alkenyl group of 6 to 20 carbon atoms, an alkenyl group of 2 to 10 carbon atoms, or an alkenyl group of 2 to 6 carbon atoms. 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, an alkynyl group of 2 to 20 carbon atoms, an alkynyl group of 6 to 20 carbon atoms, an alkynyl group of 2 to 10 carbon atoms, or an alkynyl group of 2 to 6 carbon atoms. 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 "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 C_6-50Aryl radical, C_6-40Aryl radical, C_6-30Aryl radical, C_6-20Aryl or C_6-10And (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 heteroaryl groups. In some embodiments, the heteroaromatic ring group and the heteronon-aromatic ring group are C including at least one heteroatom_1-50Heterocyclic group, C_1-40Heterocyclic group, C_1-30Heterocyclic group, C_1-20Heterocyclic group, C_1-10Heterocyclic group, C_1-6A heterocyclic group. Such as 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, heterocyclic, and/or heteroaryl. For example, the heteroaryl group may be C_6-50Heteroaryl group, C_6-40Heteroaryl group, C_6-30Heteroaryl group, C_6-20Heteroaryl or C_6-10A heteroaryl group. In addition, heteroaryl groups may be optionally substituted.

As used herein, the term "heteroatom" encompasses O, S, P, N, B or an isostere thereof.

As used herein, the term "halogen" may be F, Cl, Br or I.

As used herein, the term "cyano" 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

1. A compound of formula I

The present application provides an electrolyte comprising a compound of formula I:

wherein M is₁To M₅Any one of which is M₇-an OLi group; and M₁To M₅At least one of which is M₈-a CN group; the rest is not M₇-OLi group and M₈M of the-CN group₁To M₅Each independently selected from hydrogen and C_1-12Alkoxy, halogen, substituted or unsubstituted C_1-12Alkyl, substituted or unsubstituted C_2-12Alkenyl, substituted or unsubstituted C_2-12Alkynyl, nitro, sulfonic acid, aldehyde, carboxyl, silicon-based or substituted or unsubstituted C_6-12Aryl, wherein when substituted, the substituent is halogen; wherein M is₆、M₇And M₈Each independently selected from C_0-5Alkylene, halogen-substituted C_1-5Alkylene groups.

In some embodiments, M of a compound of formula I above₁To M₅Including one, two or three M₈-a CN group.

In the compounds of formula I according to the application, "C_0-5Alkylene "includes, but is not limited to: covalent bond, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, ethenyl, ethynyl, propenyl, propynyl.

In some embodiments, the compounds of formula I herein include at least one of the compounds of formula I-1 through formula I-6:

wherein R is₁To R₁₄Each independently selected from hydrogen, halogen, substituted or unsubstituted C_1-12Alkoxy, substituted or unsubstituted C_1-12Alkyl, substituted or unsubstituted C_2-12Alkenyl, substituted or unsubstituted C_2-12Alkynyl, nitro, sulfonic acid, aldehyde, carboxyl, silicon-based or substituted or unsubstituted C_6-12Aryl, wherein when substituted, the substituent is halogen; and n is 0 to 5.

In some embodiments, R in the compounds of formula I-1 through formula I-6₁To R₁₄Each independently selected from: hydrogen, substituted or unsubstituted C_1-12Alkyl, substituted or unsubstituted C_2-12Alkenyl or substituted or unsubstituted C_2-12Alkynyl.

In some embodiments, the compound of formula I comprises at least one of compound 1 to compound 16 below:

in some embodiments, the compound of formula I is present in an amount of about 0.01% to about 10% based on the total mass of the electrolyte, for example, the compound of formula I may be present in an amount of 0.01%, 0.05%, 1.0%, 2.0%, 3.0%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 8.0%, 9.0%, 10%, or a range therebetween, wherein when the amount is less than 0.01%, the concentration is too low to effectively form a film at the interface, and when the amount is more than 10%, the concentration is too low to cause severe lithium precipitation at the interface of the negative electrode, and the discharge capacity during normal temperature cycling is too low to exert the actual capacity of the battery due to consumption of a large amount of conductive lithium salt during film formation.

2. Other additives

In some embodiments, the electrolyte solution of the present application further comprises at least one of an additive a, an additive B, or an additive C, wherein the additive a comprises at least one of a nitrile compound, an anhydride compound, an ether compound, a phosphate compound, a phosphite compound, or a borate compound; the additive B comprises at least one of sulfate compounds, sulfite compounds, fluoro-carbonate or unsaturated carbonate; the additive C contains at least one of a sulfonate compound, a sulfone compound or a lithium salt additive.

In some embodiments, the electrolytes of the present application can comprise a combination of a compound of formula I as described above and any one, two, or three of the following additives: unsaturated carbonates, for example, ethylene carbonate or vinylene carbonate; sulfonate compounds, such as 1, 3-propane sultone; sulfate compounds, for example, vinyl sulfate; fluoro carbonate compounds, for example, fluoroethylene carbonate; lithium salt additives, for example, lithium difluorophosphate; nitrile compounds, such as succinonitrile and adiponitrile.

In some embodiments, the additive a and the additive B may each be present in an amount of about 0.01% to about 10% based on the total mass of the electrolyte; for example, the amounts of additive a and additive B may each be 0.01%, 0.05%, 1.0%, 2.0%, 3.0%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 8.0%, 9.0%, 10%, or a range between any two of the foregoing amounts.

In some embodiments, the additive C is present in an amount of about 0.01% to about 5% based on the total mass of the electrolyte; for example, the amount of additive C may be 0.01%, 0.05%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, or a range between any two of the foregoing amounts.

In some embodiments, the total content of additive a, additive B, and additive C described above does not exceed 20%.

(1) Additive A

In some embodiments, the nitrile compound includes at least one of the following compounds: succinonitrile, adiponitrile, 1,3, 5-pentane-trimethyl nitrile, 1,3, 6-hexane-trimethyl nitrile, 1,2, 6-hexane-trimethyl nitrile, fumaronitrile or ethylene glycol (dipropionitrile) ether.

In some embodiments, the anhydride-based compound includes at least one of the following: citral chaff anhydride, succinic anhydride, maleic anhydride, trifluoromethyl maleic anhydride, dimethyl maleic anhydride or propane sulfonic anhydride.

In some embodiments, the ether compound comprises at least one of: 1,1,2, 2-tetrafluoroethyl-2, 2,3, 3-tetrafluoropropyl ether or perfluorobutyl ether.

In some embodiments, the phosphate ester based compound comprises at least one of the following compounds: triphenyl phosphate, tris (trifluoroethyl) phosphate or triallyl phosphate.

In some embodiments, the phosphite-based compound comprises at least one of the following compounds: triphenyl phosphite or trimethylsilyl phosphite.

In some embodiments, borate ester based compounds include at least one of the following: tris (hexafluoroisopropyl) borate, trimethylsilyl borate, trimethylene borate, triisopropyl borate, tributyl borate, triethyl borate, or tripropyl borate.

The additive A can form an effective passivation layer on a cathode, the passivation layer has small influence on SEI (solid electrolyte interface) impedance, has good conductivity on ions and electrons, and has good protection effect on positive and negative interfaces when being combined with the compound shown in the formula I.

(2) Additive B

In some embodiments, the sulfate-based compound comprises at least one of the following compounds: vinyl sulfate, vinyl disulfate, vinyl methylsulfate, vinyl ethylsulfate or vinyl propylsulfate.

In some embodiments, the sulfite-based compound comprises at least one of the following compounds: vinyl sulfite, vinyl methyl sulfite, vinyl ethyl sulfite, vinyl propyl sulfite, or propylene sulfite.

In some embodiments, the fluoro-carbonate includes at least one of the following compounds: fluoroethylene carbonate, methyl trifluoroethyl carbonate or trifluoromethyl ethylene carbonate.

In some embodiments, the unsaturated carbonate includes at least one of the following compounds: ethylene carbonate or vinylene carbonate.

The additive B can form effective interface protection on a cathode interface, can ensure that the battery has a stable CEI (cathode electrolyte interface) protective layer in an initial state under the combined action of the additive B and the compound shown in the formula I, and can continuously repair the surface CEI in the long-term high-temperature storage and circulation processes, thereby effectively improving the long-term storage and circulation performance of the battery.

(3) Additive C

In some embodiments, the sulfonate compound comprises at least one of the following compounds: 1, 3-propane sultone, 1, 4-butane sultone, 2, 4-butane sultone, propenyl-1, 3-sultone, methylene methanedisulfonate, or a chain disulfonate.

In some embodiments, the sulfone compound comprises at least one of the following compounds: sulfolane, cyclopentylsulfone, or 3-sulfolene.

In some embodiments, the lithium salt-based additive includes at least one of the following compounds: 4, 5-dicyano-2- (trifluoromethyl) imidazolium, lithium difluorophosphate, lithium tetrafluoroborate, lithium bis fluorosulfonylimide, lithium bis trifluoromethanesulfonylimide, lithium oxalato-borate or lithium bis-fluorooxalato-borate.

The additive C and the compound of the formula I act together to form an effective passivation layer on positive and negative electrode interfaces, the additive has low redox activity, can continuously and slowly react on the interfaces, and can continuously repair surface CEI and SEI in long-term high-temperature storage and circulation processes, so that the long-term storage and circulation performance of the battery can be effectively improved. 3. Others

In some embodiments, the electrolyte solution of the present application further includes an organic solvent selected from at least one of cyclic carbonates, chain carbonates, carboxylates, or sulfone-based solvents.

In some embodiments, the cyclic carbonate is selected from at least one of ethylene carbonate or propylene carbonate; the chain carbonate is at least one selected from dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate and ethyl propyl carbonate; the carboxylic ester is at least one selected from ethyl acetate, ethyl propionate, propyl acetate, ethyl difluoroacetate or ethyl difluoroacetate; the sulfone solvent is at least one selected from sulfolane, n-butyl sulfone, cyclopentylsulfone, cyclohexylsulfone, 2, 4-dimethylsulfolane, 3-methyl-3-sulfolene, n-butyl sulfoxide and di-n-octylsulfone tetramethylsulfoxide.

Two, electrochemical device

The present application also provides an electrochemical device comprising an electrolyte according to the present application.

The electrochemical device of the present application 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. In some embodiments, the electrochemical device is a lithium ion battery.

Positive electrode

The electrochemical device according to the present application may further include a positive electrode including a current collector and a positive active material layer disposed on the current collector. The positive electrode active material contains at least one element selected from Al, Zr, or Mg. For example, the positive electrode active material may include Al and Zr, Al and Mg, Zr and Mg, or a combination of Al, Zr, and Mg.

In some embodiments, the content a of Al is less than 1% based on the total mass of the cathode active material, for example, the content a of Al may be less than 0.9%, less than 0.8%, less than 0.7%, less than 0.6%, less than 0.5%, or a range between any two of the above values or between any of the above values and zero.

In some embodiments, the Zr content b is less than 1% based on the total mass of the cathode active material, for example, the Zr content b may be less than 0.9%, less than 0.8%, less than 0.7%, less than 0.6%, less than 0.5%, or a range between any two of the above values or between any of the above values and zero.

In some embodiments, the content c of Mg is less than 0.5% based on the total mass of the cathode active material, for example, the content c of Mg may be less than 0.5%, less than 0.4%, less than 0.3%, less than 0.2%, less than 0.1%, or a range between any two of the above values or between any of the above values and zero.

In some embodiments, the positive electrode material contains Al and Mg, and the content thereof satisfies the following condition: 0.005< a/c < 500. For example, the ratio of a/c may be 0.004, 0.01, 0.1, 1, 10, 20, 50, 80, 100, 120, 140, 180, 200, 230, 250, 270, 300, 350, 400, 420, 450, 499, etc. The Al and Mg contents are in the range, so that the overall performance of the battery can be more effectively improved.

In some embodiments, the positive active material includes a compound that reversibly intercalates and deintercalates lithium ions. In some embodiments, the positive active material may include a composite oxide containing lithium and at least one element selected from cobalt, manganese, and nickel. In still other embodiments, the positive active material is selected from lithium cobaltate (LiCoO)₂) Lithium nickel manganese cobalt ternary material and lithium manganate (LiMn)₂O₄) Lithium nickel manganese oxide (LiNi)_0.5Mn_1.5O₄) Or lithium iron phosphate (LiFePO)₄) At least one of (1).

In some embodiments, the positive electrode active material layer may have a coating layer on the surface, or may be mixed with another compound having a coating layer.

In some embodiments, the coating may include at least one coating element compound selected from an oxide of the coating element, a hydroxide of the coating element, a oxyhydroxide of the coating element, an oxycarbonate (oxycarbonate) of the coating element, or a hydroxycarbonate (hydroxycarbonate) of the coating element.

The compounds used for the coating may be amorphous or crystalline.

In some embodiments, the coating element contained in the coating may include at least one of Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, F, or a mixture thereof.

The coating layer may be applied by any method as long as the method does not adversely affect the properties of the positive electrode active material. For example, the method may include any coating method well known to those of ordinary skill in the art, such as spraying, dipping, and the like.

In some embodiments, the positive active material layer further comprises a binder, and optionally further comprises a conductive material.

The binder may improve the binding of the positive electrode active material particles to each other, and may also improve the binding of the positive electrode active material to the current collector. In some embodiments, non-limiting examples of binders include polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene 1, 1-difluoride, polyethylene, polypropylene, styrene butadiene rubber, acrylated styrene butadiene rubber, epoxy, nylon, and the like.

The positive electrode active material layer may further include a conductive material to impart conductivity to the electrode. The conductive material may comprise any conductive material as long as it does not cause unwanted chemical changes. In some embodiments, non-limiting examples of the conductive material include carbon-based materials (e.g., natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, etc.), metal-based materials (e.g., metal powders, metal fibers, etc., including, for example, copper, nickel, aluminum, silver, etc.), conductive polymers (e.g., polyphenylene derivatives), and mixtures thereof.

In some embodiments, the current collector for the positive electrode of the secondary battery according to the present application may be aluminum (Al), but is not limited thereto.

Negative electrode

The electrochemical device according to the present application may further include a negative electrode including a current collector and a negative active material layer disposed on the current collector. The specific kind of the negative electrode active material is not particularly limited and may be selected as desired.

Specifically, in some embodiments, the negative active materialSelected from natural graphite, artificial graphite, mesophase micro carbon spheres (MCMB for short), hard carbon, soft carbon, silicon-carbon composite, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO and SnO₂Spinel-structured lithiated TiO₂-Li₄Ti₅O₁₂Or a Li-Al alloy.

In some embodiments, non-limiting examples of carbon materials include crystalline carbon, amorphous carbon, and mixtures thereof. The crystalline carbon may be natural graphite or artificial graphite in an amorphous form or in a form of a flake, a platelet, a sphere or a fiber. The amorphous carbon may be soft carbon, hard carbon, mesophase pitch carbide, calcined coke, or the like.

In some embodiments, the negative active material layer may include a binder and optionally further include a conductive material.

The binder may improve the binding of the negative active material particles to each other and the binding of the negative active material to the current collector. In some embodiments, non-limiting examples of binders include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene 1, 1-difluoride, polyethylene, polypropylene, styrene butadiene rubber, acrylated styrene butadiene rubber, epoxy, nylon, and the like.

The negative active material layer may include a conductive material, thereby imparting conductivity to the electrode. The conductive material may comprise any conductive material as long as it does not cause unwanted chemical changes. In some embodiments, non-limiting examples of the conductive material include carbon-based materials (e.g., natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, etc.), metal-based materials (e.g., metal powder, metal fiber, etc., such as copper, nickel, aluminum, silver, etc.), conductive polymers (e.g., polyphenylene derivatives), and mixtures thereof.

In some embodiments, the current collector for the negative electrode described herein may be selected from the group consisting of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymer substrates coated with a conductive metal, and combinations thereof.

Isolation film

In some embodiments, the electrochemical device of the present application is provided with a separator between the positive electrode and the negative electrode to prevent short circuit. The material and shape of the separation film used in the electrochemical device of the present application are not particularly limited. In some embodiments, the separator includes a polymer or inorganic substance or the like formed of a material stable to the electrolyte of the present application.

For example, the release film may include a substrate layer and a surface treatment layer.

In some embodiments, the substrate layer is a non-woven fabric, a film or a composite film having a porous structure, and the material of the substrate layer is selected from at least one of polyethylene, polypropylene, polyethylene terephthalate or polyimide. Specifically, in some embodiments, a polypropylene porous film, a polyethylene porous film, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite film may be used.

In some embodiments, a surface treatment layer is disposed on at least one surface of the substrate layer, and the surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by mixing a polymer and an inorganic substance.

In some embodiments, the inorganic layer comprises inorganic particles and a binder. In some embodiments, the inorganic particles are selected from at least one of alumina, silica, magnesia, titania, hafnia, tin oxide, ceria, nickel oxide, zinc oxide, calcium oxide, zirconia, yttria, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, or barium sulfate. In some embodiments, the binder is selected from at least one of polyvinylidene fluoride, copolymers of vinylidene fluoride-hexafluoropropylene, polyamides, polyacrylonitriles, polyacrylates, polyacrylic acids, polyacrylates, polyvinylpyrollidones, polyvinyl ethers, polymethyl methacrylates, polytetrafluoroethylene, or polyhexafluoropropylene.

The polymer layer comprises a polymer. In some embodiments, the polymer is selected from at least one of a polyamide, a polyacrylonitrile, an acrylate polymer, a polyacrylic acid, a polyacrylate, a polyvinylpyrrolidone, a polyvinyl ether, a polyvinylidene fluoride, or a poly (vinylidene fluoride-hexafluoropropylene).

Electronic device

The present application also provides an electronic device comprising an electrochemical device according to the present application.

The electrochemical device according to the present application is applicable to electronic apparatuses in various fields. The use of the electrochemical device of the present application is not particularly limited, and it may be used for any use known in the art. In one embodiment, the electrochemical devices of the present application can be used in, but are not limited to, the following electronic devices: notebook computers, pen-input computers, mobile computers, electronic book players, cellular phones, portable facsimile machines, portable copiers, portable printers, headphones, video recorders, liquid crystal televisions, portable cleaners, portable CD players, mini-discs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, mopeds, bicycles, lighting fixtures, toys, game machines, clocks, electric tools, flashlights, cameras, large household batteries, lithium ion capacitors, and the like.

The application achieves the following unexpected technical effects: in the formation process of the compound of the formula I, a very stable CEI and SEI protective film is easily formed on the surfaces of a positive electrode and a negative electrode. The protective film is fully fused with the matrix, and can provide a complexing point with lithium ions on the negative electrode, so that rapid ion transmission can be carried out, and simultaneously, a large amount of electrolyte deposited on the negative electrode due to irreversible reduction can be effectively inhibited. On the positive electrode, the protective film can reduce the reaction between the positive electrode and the electrolyte, and inhibit the elution of metal ions, thereby finally improving the high-temperature storage performance of the electrochemical device (for example, a lithium ion battery). In addition, the electrochemical device of the application controls the content of doping elements Al, Zr and Mg in the anode material, and adds the compound of the formula I on the basis, so that the electrolyte of the application has better film forming effect on the anode and the cathode, and the formed protective film has more excellent high-temperature stability, thereby further improving the high-temperature storage performance of the electrochemical device (such as a lithium ion battery) of the application.

Fourth, example

The present application is further illustrated below with reference to examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present application.

Examples

1. Preparation method

(1) Preparation of the electrolyte

In a drying room, uniformly mixing ethylene carbonate, propylene carbonate and diethyl carbonate according to the mass ratio of 1:1:1 to obtain the non-aqueous organic solvent. Adding 1mol/L lithium hexafluorophosphate (LiPF) to a non-aqueous organic solvent₆) And obtaining the basic electrolyte. In this base electrolyte, other additives were added according to the amounts and kinds provided in the following tables, respectively, to obtain electrolytes of respective examples and comparative examples.

(2) Preparation of positive electrode

Dissolving a positive electrode active material, a binding agent polyvinylidene fluoride (PVDF) and a conductive agent Super-P in a mass ratio of 96:2:2 into N-methylpyrrolidone (NMP) and uniformly mixing to prepare positive electrode slurry. And uniformly coating the positive electrode slurry on a positive electrode current collector aluminum foil with the thickness of 12 mu m, baking for 1h at 120 ℃ to obtain a positive electrode active material layer, and then compacting, slitting and welding tabs to obtain the positive electrode.

(3) Preparation of negative electrode

Dissolving graphite powder as a negative active material, silicon oxide powder, a sodium carboxymethylcellulose thickener (CMC) and styrene butadiene rubber as a binder in water according to a mass ratio of 81:15:2:2, fully mixing and stirring to obtain negative slurry, uniformly coating the negative slurry on a negative current collector copper foil with the thickness of 12 mu m, baking for 1h at 120 ℃, compacting to obtain a negative active material layer, and then cutting and welding tabs to obtain a negative electrode.

(4) Preparation of the Battery

A polypropylene film of 12 μm was used as a separator. The positive electrode, the isolating membrane and the negative electrode are sequentially stacked, the isolating membrane is positioned between the positive electrode and the negative electrode to play an isolating role, and then the square bare cell is wound. And (3) filling the bare cell into an aluminum foil packaging bag, baking at 80 ℃ to remove water, injecting corresponding electrolyte, and performing vacuum packaging, standing, formation, shaping and other processes to complete the preparation of the lithium ion battery.

2. Test method

The lithium ion batteries prepared in examples and comparative examples were tested for performance using the following methods.

(1) High temperature storage test

Before storage, charging to 3.65V at a constant current of 0.5C, then testing the thickness of the battery by using a thickness tester to obtain D1, continuing to charge to 4.2V at 0.5C, charging at a constant voltage until the current is 0.05C, then placing the lithium ion battery in a high-temperature box at 60 ℃ for storage for 30 days, and measuring the thickness of the battery again after the battery is cooled to obtain D2:

the battery thickness growth rate is (D2-D1) ÷ D1 × 100%

(2)45 ℃ cycle test:

the cells were placed in a 45 ℃ oven, charged to 4.2V at constant current 0.5C, charged to current 0.05C at constant voltage, discharged to 2.8V at 0.5C, cycled for 400 weeks:

the battery capacity retention rate is 400 th circle discharge capacity ÷ first circle discharge capacity × 100%

3. Test results

Examples 1 to 23 and comparative example 1

The cathode material used in examples 1 to 23 and comparative example 1 was ternary nickel cobalt manganese (LiNi)_0.8Co_0.1Mn_0.1O₂NCM811), wherein the amount of Al doped is 0.15%, the amount of Zr doped is 0.007%, and the amount of Mg doped is 0.1%. The specific test results are shown in table 1 below.

TABLE 1 test results of examples 1 to 23 and comparative example 1

Examples 1 to 23 in the table above were added with different amounts and types of compounds of formula I, and comparative example 1 was not added with a compound of formula I. As can be seen from the data in the above table, when the compound of formula I according to the present application is not added to the electrolyte, the thickness increase rate of the battery in high-temperature storage is 45%, and after the compound of formula I is added, the thickness increase of the battery is significantly improved, because the compound of formula I according to the present application can generate stable protective films on the surfaces of the positive electrode and the negative electrode during the formation process, thereby reducing the further reaction between the positive electrode and the negative electrode of the battery and the electrolyte during the high-temperature storage process, and finally achieving the purposes of reducing the storage flatulence and improving the high-temperature storage performance.

Examples 1 to 7 each added different amounts of compound 1 to the electrolyte. As can be seen from the test results of examples 1 to 7, when the compound of formula I is used in an amount ranging from 0.01 wt% to 10 wt%, complete dissolution can be ensured, thereby providing good film-forming effects and significantly improving high-temperature storage properties of electrochemical devices. When the amount of the compound of formula I is outside the range of the present application, the improvement effect is not significant. On the one hand, when the dosage of the compound shown in the formula I is too high, the compound cannot be completely dissolved and does not play a role in film formation protection; on the other hand, the excessive content of the compound in the formula I is easy to reduce or prevent other additives for improving storage in the electrolyte from reacting to form a film, so that the protection of the anode and the cathode is weakened, and the improvement of the high-temperature storage performance is not obvious.

From the test results of examples 17 to 23, it can be seen that the combined use of different compounds of formula I also improves the high-temperature storage properties of the electrochemical device.

Examples 24 to 52

Examples 24 to 52 illustrate the use of the compounds of the formula I of the present application in combination with other additives, wherein the cathode material used is ternary nickel cobalt manganese (LiNi)_0.8Co_0.1Mn_0.1O₂NCM811), wherein the amount of Al doped is 0.15%, the amount of Zr doped is 0.007%, and the amount of Mg doped is 0.1%. The specific test results are shown in table 2 below.

TABLE 2 test results for examples 24 to 52

Examples 24 to 52 show that the compounds of formula I of the present application can be used in combination with other types of additives to further improve the high temperature storage and cycling performance of electrochemical devices.

For example, as can be seen from the test results in the above table, further improvement can be achieved by the additional addition of one, two or three of the following compounds on the basis of the compound of formula I: VC (vinylene carbonate), PS (1, 3-propane sultone), DTD (vinyl sulfate), FEC (fluoroethylene carbonate), Li₂PO₂F₂(lithium difluorophosphate), ADN (adiponitrile), SN (succinonitrile), HTCN (1,3, 6-hexanetricarbonitrile), or acid anhydrides, which combinations may achieve more excellent high temperature storage and/or cycling performance.

Examples 53 to 69

The cathode material used in examples 53 to 69 was ternary nickel cobalt manganese (LiNi)_0.5Co_0.2Mn_0.3O₂NCM523), wherein the doping amounts of the respective elements are as shown in table 3 below.

TABLE 3 test results for examples 53 to 69

It can be seen from the test results of examples 53 to 69 in the above table that the battery has better high-temperature storage performance and cycle performance when the doping amount a of Al in the positive electrode material is < 1%, the doping amount b of Zr is < 1%, and the doping amount c of Mg is < 0.5%.

Reference throughout this specification to "some embodiments," "one embodiment," "another example," "an example," "a specific example," or "some examples" means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. 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 compound of formula I:

wherein M is₁To M₅Any one of which is M₇-an OLi group; and M₁To M₅At least one of which is M₈-a CN group; the rest is not M₇-OLi group and M₈M of the-CN group₁To M₅Each independently selected from hydrogen, substituted or unsubstituted C_1-12Alkoxy, halogen, substituted or unsubstituted C_1-12Alkyl, substituted or unsubstituted C_2-12Alkenyl radicalSubstituted or unsubstituted C_2-12Alkynyl, nitro, sulfonic acid, aldehyde, carboxyl, silicon-based or substituted or unsubstituted C_6-12Aryl, wherein when substituted, the substituent is halogen;

wherein M is₆、M₇And M₈Each independently selected from C_0-5Alkylene, halogen-substituted C_1-5Alkylene groups.

2. The electrolyte of claim 1, wherein the compound of formula (I) comprises at least one of compounds of formula I-1 to formula I-6:

wherein R is₁To R₁₄Each independently selected from hydrogen, halogen, substituted or unsubstituted C_1-12Alkoxy, substituted or unsubstituted C_1--12Alkyl, substituted or unsubstituted C_2-12Alkenyl, substituted or unsubstituted C_2-12Alkynyl, nitro, sulfonic acid, aldehyde, carboxyl, silicon-based or substituted or unsubstituted C_6-12Aryl, wherein when substituted, the substituent is halogen; and n is an integer of 0 to 5.

3. The electrolyte of claim 1, wherein the compound of formula I comprises at least one of the following compounds:

4. the electrolyte of claim 1, wherein the compound of formula I is present in an amount of 0.01% to 10% based on the total mass of the electrolyte.

5. The electrolyte of any one of claims 1-4, further comprising at least one of an additive A, an additive B, or an additive C, wherein the additive A comprises at least one of a nitrile compound, an anhydride compound, an ether compound, a phosphate compound, a phosphite compound, or a borate compound; the additive B comprises at least one of sulfate compounds, sulfite compounds, fluoro carbonate or unsaturated carbonate; the additive C comprises at least one of a sulfonate compound, a sulfone compound or a lithium salt additive; and is

The content of the additive A is 0.01-10% based on the total mass of the electrolyte; the content of the additive B is 0.01-10%; the content of the additive C is 0.01-5%.

6. The electrolyte of claim 5, wherein:

the nitrile compound includes at least one of the following compounds: succinonitrile, adiponitrile, 1,3, 5-pentane-trimethyl nitrile, 1,3, 6-hexane-trimethyl nitrile, 1,2, 6-hexane-trimethyl nitrile, fumaronitrile or ethylene glycol (dipropionitrile) ether;

the anhydride compound comprises at least one of the following compounds: citral chaff anhydride, succinic anhydride, maleic anhydride, trifluoromethyl maleic anhydride, dimethyl maleic anhydride or propane sulfonic anhydride;

the ether compound comprises at least one of the following compounds: 1,1,2, 2-tetrafluoroethyl-2, 2,3, 3-tetrafluoropropyl ether or perfluorobutyl ether;

the phosphate ester compound comprises at least one of the following compounds: triphenyl phosphate, tris (trifluoroethyl) phosphate, or triallyl phosphate;

the phosphite ester compound comprises at least one of the following compounds: triphenyl phosphite or trimethylsilyl phosphite;

the borate ester compound comprises at least one of the following compounds: tris (hexafluoroisopropyl) borate, trimethylsilyl borate, trimethylene borate, triisopropyl borate, tributyl borate, triethyl borate, or tripropyl borate;

the sulfate ester compound comprises at least one of the following compounds: vinyl sulfate, vinyl disulfate, vinyl methylsulfate, vinyl ethylsulfate or vinyl propylsulfate;

the sulfite compound comprises at least one of the following compounds: ethylene sulfite, ethylene methyl sulfite, ethylene ethyl sulfite, ethylene propyl sulfite, or propylene sulfite;

the fluoro carbonate includes at least one of the following compounds: fluoroethylene carbonate, methyl trifluoroethyl carbonate or trifluoromethyl ethylene carbonate;

the unsaturated carbonate includes at least one of the following compounds: ethylene carbonate or vinylene carbonate;

the sulfonate compound comprises at least one of the following compounds: 1, 3-propane sultone, 1, 4-butane sultone, 2, 4-butane sultone, propenyl-1, 3-sulfonic lactone, methylene methanedisulfonate, or a chain disulfonate;

the sulfone compound comprises at least one of the following compounds: sulfolane, cyclopentylsulfone, or 3-sulfolene;

the lithium salt additive includes at least one of the following compounds: 4, 5-dicyano-2- (trifluoromethyl) imidazolium, lithium difluorophosphate, lithium tetrafluoroborate, lithium bis fluorosulfonylimide, lithium bis trifluoromethanesulfonylimide, lithium oxalato-borate or lithium bis-fluorooxalato-borate.

7. An electrochemical device comprising a positive electrode and the electrolyte of any one of claims 1-6, the positive electrode comprising a positive electrode active material.

8. The electrochemical device according to claim 7, wherein the positive electrode active material contains at least one element selected from Al, Zr, or Mg.

9. The electrochemical device according to claim 8, wherein the Al content a is less than 1%, the Zr content b is less than 1%, and the Mg content c is less than 0.5%, based on the total mass of the cathode active material.

10. The electrochemical device according to claim 9, wherein the positive electrode material contains Al and Mg, and a content thereof satisfies the following condition: 0.005< a/c < 500.

11. An electronic device comprising the electrochemical device of any one of claims 7-10.