WO2021237846A1

WO2021237846A1 - Electrolyte solution and electrochemical device using electrolyte solution

Info

Publication number: WO2021237846A1
Application number: PCT/CN2020/097759
Authority: WO
Inventors: 文倩; 唐超; 刘俊飞; 郑建明
Original assignee: 宁德新能源科技有限公司
Priority date: 2020-05-27
Filing date: 2020-06-23
Publication date: 2021-12-02
Also published as: CN111600065A; CN111600065B

Abstract

Disclosed are an electrolyte solution and an electrochemical device using the electrolyte solution. The electrolyte solution contains a fluorosiloxane compound and a trinitrile compound, wherein the fluorosiloxane compound includes a compound of formula I, and the trinitrile compound includes at least one of a compound of formula II or a compound of formula III, with a, b, c, d, e, f, g, h and i being integers of 0-5. A lithium ion battery prepared from the electrolyte solution has improved room-temperature and high-temperature cycle performances.

Description

Electrolyte and electrochemical device using it

Technical field

This application relates to the technical field of electrochemical devices, and more specifically to an electrolyte and an electrochemical device using the electrolyte.

Background technique

With the rapid development of information technology and the proliferation of various mobile devices, the development of lithium-ion batteries has received extensive attention. Compared with other secondary batteries, lithium-ion batteries have higher working voltage, greater energy density, faster charging speed and longer working life. In order to meet people's requirements for light and small equipment, high-energy density secondary batteries have become an inevitable trend in the development of lithium-ion batteries.

Silicon has a reversible capacity of up to 4200mAh/g, making it the most promising negative electrode material for improving the energy density of lithium-ion batteries. However, the use of silicon-containing anodes also faces many challenges. For example, the large volume expansion of silicon during the charge and discharge process destroys the solid electrolyte interface (SEI) film on the silicon surface, and the side reactions between the silicon anode material and the electrolyte intensify, resulting in battery production. Gas and capacity decay rapidly, and increase the cycle expansion rate.

Summary of the invention

The embodiments of the present application provide an electrolyte and an electrochemical device using the electrolyte, in an attempt to solve at least one problem existing in the related field at least to some extent. The embodiments of the present application also provide electrochemical devices and electronic devices using the electrolyte.

In one embodiment, the present application provides an electrolyte solution comprising a fluorosiloxane compound and a trinitrile compound, wherein the fluorosiloxane compound includes a compound of formula I:

Wherein R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ are each independently selected from hydrogen, fluorine atoms, alkyl groups of 1-12 carbon atoms, fluoroalkyl groups of 1-12 carbon atoms, Cycloalkyl with 3-12 carbon atoms, fluorocycloalkyl with 3-12 carbon atoms, alkenyl with 2-12 carbon atoms, fluoroalkenyl with 2-12 carbon atoms, 3-12 A heterocyclic group of carbon atoms or a fluorinated heterocyclic group of 3-12 carbon atoms, and wherein _{at least one of R 1} , R ₂ , R ₃ , R ₄ , R ₅ , and R ₆ is a fluorine atom, Fluorinated alkyl groups with 1-12 carbon atoms, fluorinated cycloalkyl groups with 3-12 carbon atoms, fluoroalkenyl groups with 2-12 carbon atoms, or fluorinated heterocyclic groups with 3-12 carbon atoms ；

And wherein the trinitrile compound includes at least one of a compound of formula II or a compound of formula III:

Wherein, a, b, c, d, e, f, g, h and i are integers of 0-5.

In some embodiments, the fluorosiloxane compound includes at least one of the following compounds:

In some embodiments, the trinitrile compound includes at least one of the following compounds:

In some embodiments, based on the total weight of the electrolyte, the weight percentage of the fluorosiloxane compound is 0.01 wt% to 6 wt%, and the weight percentage of the trinitrile compound is 0.01 wt% to 8 wt%.

In some embodiments, the electrolyte further includes an additive, and the additive includes at least one of the following compounds: vinylene carbonate, 1,3-propane sultone, vinyl sulfate, succinonitrile, hexamethylene The dinitrile or fluoroethylene carbonate, wherein based on the total weight of the electrolyte, the weight percentage of the additive is 0.01 wt% to 20 wt%.

In another embodiment, the present application provides an electrochemical device, which includes a positive electrode, a negative electrode, and the electrolyte according to the embodiment of the present application.

In some embodiments, the anode includes a silicon-based anode active material, the silicon-based anode active material includes a silicon-containing matrix, and the silicon-containing matrix includes _{at least one of Si, silicon oxide SiO x,} or Si-M alloy. Species, wherein 0.6≤x≤2, and M is selected from at least one of Al, Ti, Fe, or Ni.

In some embodiments, the silicon-based negative electrode active material further includes an oxide Me _a O _b layer, the oxide Me _a O _b layer is located on at least a part of the surface of the silicon-containing matrix, wherein Me includes Al, Si At least one of Ti, Mn, V, Cr, Co or Zr, a is 1-3, b is 1-4, and wherein the _{thickness of the oxide Me a} O _b layer is 1 nm-500 nm.

In some embodiments, the negative electrode further includes a conductive agent, the conductive agent includes at least one of carbon nanotubes, graphene, or carbon black, wherein the carbon nanotubes have a diameter of 1-100 nm and a length of 1-50μm.

In some embodiments, the silicon-based negative active material further includes a carbon layer located on at least a part of the surface of the silicon-containing substrate, and the thickness of the carbon layer is 1-500 nm.

In another embodiment, the application provides an electronic device, which includes the electrochemical device according to the embodiment of the application.

The electrolyte provided by the application can form a stable solid electrolyte interface (SEI) protective layer on the surface of the positive and negative electrodes, and can significantly improve the normal temperature and high temperature cycle performance of the lithium ion secondary battery. Especially when applied to a battery with a silicon-based active material in the negative electrode, it can ensure the good stability of the negative electrode SEI protective layer after the battery is cycled, thereby improving the cycle performance of the battery.

The additional aspects and advantages of the embodiments of the present application will be partially described and shown in the subsequent description, or explained through the implementation of the embodiments of the present application.

Detailed ways

The embodiments of this application will be described in detail below. The embodiments of this application should not be construed as limitations on this application.

In the detailed description and claims, a list of items connected by the terms "one of", "one of", "one of" or other similar terms can mean any of the listed items. One. For example, if items A and B are listed, then the phrase "one of A and B" means only A or only B. In another example, if items A, B, and C are listed, then the phrase "one of A, B, and C" means only A; only B; or only C. Project A can contain a single element or multiple elements. Project B can contain a single element or multiple elements. Project C can contain a single element or multiple elements.

In the detailed description and claims, a list of items connected by the terms "at least one of", "at least one of", "at least one of" or other similar terms may mean the listed items Any combination of. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (exclude B); B and C (exclude A); or all of A, B, and C. Project A can contain a single element or multiple elements. Project B can contain a single element or multiple elements. Item C can contain a single element or multiple elements.

As used herein, the term "alkyl" is expected to be a linear saturated hydrocarbon structure having 1 to 20 carbon atoms. "Alkyl" is also expected to be a branched or cyclic hydrocarbon structure having 3 to 20 carbon atoms. For example, the alkyl group may be an alkyl group of 1-20 carbon atoms, an alkyl group of 1-10 carbon atoms, an alkyl group of 1-5 carbon atoms, an alkyl group of 5-20 carbon atoms, and an alkyl group of 5-15 carbon atoms. Carbon atom alkyl group or 5-10 carbon atom alkyl group. When an alkyl group having a specific carbon number is specified, it is expected to encompass all geometric isomers having that carbon number; therefore, for example, "butyl" means to include n-butyl, sec-butyl, isobutyl, and 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 Base etc. In addition, the alkyl group may be optionally substituted.

As used herein, the term "cycloalkyl" encompasses cyclic alkyl groups. The cycloalkyl group may be a cycloalkyl group of 3-20 carbon atoms, a cycloalkyl group of 6-20 carbon atoms, a cycloalkyl group of 3-12 carbon atoms, or a cycloalkyl group of 3-6 carbon atoms. For example, the cycloalkyl group may be cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and the like. In addition, cycloalkyl groups may be optionally substituted.

As used herein, the term "alkenyl" refers to a monovalent unsaturated hydrocarbon group that can be straight or branched and has at least one and usually 1, 2, or 3 carbon-carbon double bonds. Unless otherwise defined, the alkenyl group usually contains 2-20 carbon atoms, for example, it can be an alkenyl group with 2-20 carbon atoms, an alkenyl group with 6-20 carbon atoms, or an alkenyl group with 2-12 carbon atoms. Group or alkenyl of 2-6 carbon atoms. Representative alkenyl groups include, for example, vinyl, n-propenyl, isopropenyl, n-but-2-enyl, but-3-enyl, n-hex-3-enyl, and the like. In addition, alkenyl groups may be optionally substituted.

As used herein, the term "heterocyclic group" encompasses aromatic and non-aromatic cyclic groups. Heteroaromatic cyclic group also means heteroaryl. In some embodiments, the heteroaromatic ring group and the heteronon-aromatic ring group are C ₃ -C ₂₀ heterocyclic groups _{including at least one heteroatom, C 3} -C ₁₅₀ heterocyclic groups, C ₃ -C ₁₀ Heterocyclic group, C ₅ -C ₂₀ heterocyclic group, C ₅ -C ₁₀ heterocyclic group, C ₃ -C ₆ heterocyclic group. For example, morpholinyl, piperidinyl, pyrrolidinyl, etc., and cyclic ethers, such as tetrahydrofuran, tetrahydropyran, and the like. In addition, the heterocyclic group may be optionally substituted.

As used herein, the term "trinitrile compound" refers to a compound containing three -CN functional groups.

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

As used herein, the term "halogen" encompasses F, Cl, Br, I.

When the above-mentioned substituents are substituted, their substituents may be independently selected from the group consisting of halogen, alkyl, alkenyl, and aryl.

As used herein, the content of each component is based on the total weight of the electrolyte.

As used herein, the term "substituted" or "substituted" means that it can be substituted with 1 or more (eg, 2, 3) substituents. For example, "fluoro" means that it can be substituted with one or more (for example, two, three) F.

1. Electrolyte

In some embodiments, the present application provides an electrolyte solution comprising a fluorosiloxane compound and a trinitrile compound, wherein the fluorosiloxane compound includes a compound of formula I:

And wherein the trinitrile compound includes or is selected from at least one compound of formula II or formula III:

Wherein, a, b, c, d, e, f, g, h and i are integers of 0-5.

In some embodiments, the fluorosiloxane compound includes or is selected from at least one of the following compounds:

In some embodiments, the trinitrile compound includes or is selected from at least one of the following compounds:

In some embodiments, based on the total weight of the electrolyte, the weight percentage of the fluorosiloxane compound is 0.01 wt% to 6 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the fluorosiloxane compound is 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 6wt%, or a range composed of any two of these values.

In some embodiments, based on the total weight of the electrolyte, the weight percentage of the trinitrile compound is 0.01 wt% to 8 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the trinitrile compound is 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.5 wt%, 1 wt%, 1.5 wt% , 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 8wt%, or any two of these values.

In some embodiments, the electrolyte further includes an additive, and the additive includes at least one of the following compounds: vinylene carbonate, 1,3-propane sultone, vinyl sulfate, succinonitrile, and adiponitrile. Nitrile or fluoroethylene carbonate.

In some embodiments, based on the total weight of the electrolyte, the weight percentage of the additive is 0.01 wt% to 20 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the additive is 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.5 wt%, 1 wt%, 5 wt%, 6 wt%, 6.5 wt% , 7wt%, 10wt%, 11wt%, 15wt%, 18wt%, 20wt% or any two of these values.

In some embodiments, the electrolyte further includes a cyclic ether. The cyclic ether can form a film on the anode and the cathode at the same time to reduce the reaction between the electrolyte and the active material.

In some embodiments, the cyclic ether includes, but is not limited to: tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 2-methyl 1,3-dioxolane, 4-methyl Base 1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, dimethoxypropane.

In some embodiments, based on the total weight of the electrolyte, the weight percentage of the cyclic ether is 0.1 wt% to 10 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the cyclic ether is not less than 0.1 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the cyclic ether is not less than 0.5 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the cyclic ether is not more than 2 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the cyclic ether is not more than 5 wt%.

In some embodiments, the electrolyte further includes chain ether. In some embodiments, chain ethers include, but are not limited to: dimethoxymethane, 1,1-dimethoxyethane, 1,2-dimethoxyethane, diethoxymethane, 1 ,1-diethoxyethane, 1,2-diethoxyethane, ethoxymethoxymethane, 1,1-ethoxymethoxyethane, 1,2-ethoxymethyl Oxyethane.

In some embodiments, based on the total weight of the electrolyte, the weight percentage of the chain ether is 0.1 wt% to 10 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the chain ether is not less than 0.5 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the chain ether is not less than 2 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the chain ether is not less than 3 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the chain ether is not more than 10 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the chain ether is not more than 5 wt%.

In some embodiments, the electrolyte further includes a phosphorus-containing organic solvent. Phosphorus-containing organic solvents can enhance the safety performance of the electrolyte. In some embodiments, the phosphorus-containing organic solvent includes, but is not limited to: trimethyl phosphate, triethyl phosphate, dimethyl ethyl phosphate, methyl diethyl phosphate, ethylene methyl phosphate, phosphoric acid Ethylene ethyl, triphenyl phosphate, trimethyl phosphite, triethyl phosphite, triphenyl phosphite, tris(2,2,2-trifluoroethyl) phosphate, tris(2, 2,3,3,3-pentafluoropropyl) ester.

In some embodiments, based on the total weight of the electrolyte, the weight percentage of the phosphorus-containing organic solvent is 0.1 wt% to 10 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the phosphorus-containing organic solvent is not less than 0.1 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the phosphorus-containing organic solvent is not less than 0.5 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the phosphorus-containing organic solvent is not more than 2 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the phosphorus-containing organic solvent is not more than 3 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the phosphorus-containing organic solvent is not more than 5 wt%.

In some embodiments, the electrolyte further includes an aromatic fluorine-containing solvent. The aromatic fluorine-containing solvent can quickly form a film to protect the active material, and the fluorine-containing substance can improve the infiltration performance of the electrolyte to the active material. In some embodiments, the aromatic fluorine-containing solvent includes, but is not limited to: fluorobenzene, difluorobenzene, trifluorobenzene, tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene, and trifluoromethylbenzene.

In some embodiments, based on the total weight of the electrolyte, the weight percentage of the aromatic fluorine-containing solvent is about 0.1 wt% to 10 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the aromatic fluorine-containing solvent is not less than 0.5 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the aromatic fluorine-containing solvent is not less than 2 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the aromatic fluorine-containing solvent is not more than 4 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the aromatic fluorine-containing solvent is not more than 8 wt%.

In some embodiments, the electrolyte further includes a lithium salt additive. In some embodiments, the lithium salt additives include, but are not limited to, lithium trifluoromethanesulfonimide LiN(CF ₃ SO ₂ ) ₂ (LiTFSI for short), lithium bis(fluorosulfonyl)imide Li(N (SO ₂ F) ₂ ) (LiFSI for short), Lithium bisoxalate borate LiB (C ₂ O ₄ ) ₂ (LiBOB for short), lithium tetrafluorophosphate oxalate (LiPF4C2O2), lithium difluorooxalate borate LiBF ₂ (C ₂ O ₄ ) (abbreviated as LiDFOB), lithium hexafluorocesium oxide (LiCsF ₆ ).

In some embodiments, based on the total weight of the electrolyte, the weight percentage of the lithium salt additive is 0.01 wt% to 10 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the lithium salt additive is 0.1 wt% to 5 wt%. In some embodiments, based on the total weight of the electrolyte, the weight percentage of the lithium salt additive is 0.1wt%, 1wt%, 3wt%, 5wt%, 7wt%, 9wt%, 10wt% or any of these values. The range of the two.

This application provides an electrolyte containing a fluorosiloxane compound and a trinitrile compound. The electrolyte can form a stable SEI protective layer on the surface of the positive and negative electrodes, and can significantly improve the normal temperature and high temperature cycle performance of the secondary battery. Especially when applied to a battery with a silicon-based active material in the negative electrode, it can ensure the good stability of the negative electrode SEI protective layer after the battery is cycled, thereby improving the cycle performance of the battery.

2. Electrolyte

The electrolyte used in the electrolyte of the embodiment of the present application may be an electrolyte known in the prior art. The electrolyte includes, but is not limited to: inorganic lithium salts, such as LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiSO ₃ F, LiN(FSO ₂ ) ₂ etc.; fluorine-containing organic lithium salts, such as LiCF ₃ SO ₃ , LiN(FSO ₂ )(CF ₃ SO ₂ ), LiN(CF ₃ SO ₂ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) _2. Cyclic 1,3-hexafluoropropane disulfonimide lithium, cyclic 1,2-tetrafluoroethane disulfonimide lithium, LiN(CF ₃ SO ₂ )(C ₄ F ₉ SO ₂ ), LiC (CF ₃ SO ₂ ) ₃ , LiPF ₄ (CF ₃ ) ₂ , LiPF ₄ (C ₂ F ₅ ) ₂ , LiPF ₄ (CF ₃ SO ₂ ) ₂ , LiPF ₄ (C ₂ F ₅ SO ₂ ) _2. LiBF ₂ (CF ₃ ) ₂ , LiBF ₂ (C ₂ F ₅ ) ₂ , LiBF ₂ (CF ₃ SO ₂ ) ₂ , LiBF ₂ (C ₂ F ₅ SO ₂ ) ₂ ; lithium salt containing dicarboxylic acid complex For example, lithium bis(oxalato)borate, lithium difluorooxalatoborate, lithium tris(oxalato)phosphate, lithium difluorobis(oxalato)phosphate, lithium tetrafluoro(oxalato)phosphate, and the like. In addition, the above-mentioned electrolytes may be used singly, or two or more of them may be used at the same time. For example, in some embodiments, the electrolyte includes a combination of _{LiPF 6} and LiBF _4. In some embodiments, the electrolyte includes a combination of an inorganic lithium salt such as _{LiPF 6} or LiBF ₄ and a fluorine-containing organic lithium salt such as _{LiCF 3} SO ₃ , LiN(CF ₃ SO ₂ ) ₂ , and LiN(C ₂ F ₅ SO ₂ ) ₂ . In some embodiments, the concentration of the electrolyte is in the range of 0.8-3 mol/L, for example, in the range of 0.8-2.5 mol/L, in the range of 0.8-2 mol/L, in the range of 1-2 mol/L, 0.5- 1.5mol/L, 0.8-1.3mol/L, 0.5-1.2mol/L, for example, 1mol/L, 1.15mol/L, 1.2mol/L, 1.5mol/L, 2mol/L or 2.5mol/L.

Third, the negative electrode

In some embodiments, the present application provides a negative electrode including a current collector and a coating layer on the current collector, and the coating layer includes a silicon-based negative electrode active material.

In some embodiments, the silicon-based negative active material include silicon-containing body, said body comprising a silicon-containing Si, silicon oxide SiO _x, Si-M alloy is at least one, wherein, 0.6≤x≤2, M is selected from at least one of Al, Ti, Fe, or Ni.

In some embodiments, the silicon-containing matrix includes _{at least one of Si, SiO 2} , SiO, or SiC.

In some embodiments, the silicon-based negative electrode active material further includes an oxide Me _a O _b layer, the oxide Me _a O _b layer is located on at least a part of the surface of the silicon-containing matrix, wherein Me includes Al, Si At least one of, Ti, Mn, V, Cr, Co, or Zr, and a is 1-3, and b is 1-4.

In some embodiments, the _{thickness of the oxide Me a} O _b layer is 1 nm-500 nm. In some embodiments, the _{thickness of the oxide Me a} O _b layer is 1 nm, 5 nm, 10 nm, 20 nm, 30 nm, 50 nm, 80 nm, 120 nm, 150 nm, 200 nm, 300 nm, 400 nm, 450 nm, 500 nm, or any of these values. The range of the two.

In some embodiments, the oxide Me _a O _b includes at least one of _{Al 2} O ₃ , TiO ₂ , CoO, and ZrO _2.

In some embodiments, the negative electrode further includes a conductive agent, and the conductive agent includes at least one of carbon nanotubes, graphene, or carbon black.

In some embodiments, the diameter of the carbon nanotubes is 1-100 nm. In some embodiments, the diameter of the carbon nanotube is 1nm, 5nm, 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 70nm, 80nm, 90nm, 100nm or these values The range of any two of them.

In some embodiments, the length of the carbon nanotubes is 1-50 μm. In some embodiments, the length of the carbon nanotubes is 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 45 μm, 50 μm, or a range composed of any two of these values.

In some embodiments, the aspect ratio of the carbon nanotubes is 0.1-5000. In some embodiments, the aspect ratio of the carbon nanotubes is 0.1, 7, 10, 50, 100, 200, 500, 1000, 2000, 2500, 2800, 3000, 3500, 4000, 4500, 5000 or these values The range of any two of them.

In some embodiments, the silicon-based negative electrode active material further includes a carbon layer located on at least a part of the surface of the silicon-containing substrate. In some embodiments, the thickness of the carbon layer is 1-500 nm. In some embodiments, the thickness of the carbon layer is 1nm, 5nm, 10nm, 30nm, 40nm, 50nm, 80nm, 100nm, 150nm, 200nm, 250nm, 300nm, 400nm, 500nm or any two of these values. Scope.

In some embodiments, the carbon layer includes at least one of amorphous carbon, graphite, hard carbon, soft carbon, carbon black, acetylene black, or carbon nanotubes.

In some embodiments, the coating further includes graphite particles. In some embodiments, the weight ratio of the silicon-based negative active material to the graphite particles is 1:30-1:10. In some embodiments, the weight ratio of the silicon-based negative electrode active material to the graphite particles is 1:30, 1:25, 1:20, 1:15, 1:10 or any two of these values. Scope.

In some embodiments, the coating further includes a thickener. In some embodiments, the thickener includes at least one of sodium carboxymethyl cellulose (CMC-Na), lithium carboxymethyl cellulose (CMC-Li), and cellulose.

In some embodiments, the coating further includes a binder, the binder including polyacrylate, polyimide, polyamide, polyamideimide, polyvinylidene fluoride, styrene butadiene rubber, seaweed Sodium, polyvinyl alcohol, polytetrafluoroethylene, polyacrylonitrile or any combination thereof.

In some embodiments, the current collector includes copper, aluminum, nickel, copper alloy, aluminum alloy, nickel alloy, or a combination thereof.

In some embodiments, the preparation method of the silicon-based negative electrode active material (which includes a silicon-containing substrate and an oxide Me _a O _{b layer on at least a part of the surface of the silicon-containing substrate) includes:}

(1) The silicon-containing matrix and the oxide precursor MeT _n are formed into a mixed solution in the presence of an organic solvent and deionized water;

(2) Drying the mixed solution to obtain powder; and

(3) Sintering the powder at 200-1000° C. for 0.5-25 h to obtain the silicon-based negative electrode active material;

Where a is 1-3, b is 1-4,

Wherein Me includes at least one of Al, Si, Ti, Mn, Cr, V, Co or Zr,

Where T includes at least one of methoxy, ethoxy, isopropoxy or halogen, and

Where n is 1, 2, 3, or 4.

In some embodiments, the oxide precursor MeT _n includes isopropyl titanate, aluminum isopropoxide, or a combination thereof.

In some embodiments, the silicon-containing matrix is as defined above.

In some embodiments, the sintering temperature is 250-900°C. In some embodiments, the sintering temperature is 300-850°C. In some embodiments, the sintering temperature is 350-650°C. In some embodiments, the sintering temperature is 400°C, 500°C, 600°C, or 700°C.

In some embodiments, the sintering time is 1-25h. In some embodiments, the sintering time is 1-119h. In some embodiments, the sintering time is 1-14h. In some embodiments, the sintering time is 1.5-5h. In some embodiments, the sintering time is 2h, 3h, 4h, 5h, 6h, 8h, or 10h.

In some embodiments, the organic solvent includes at least one of the following solvents: ethanol, methanol, n-hexane, N,N-dimethylformamide, pyrrolidone, acetone, toluene, isopropanol, or n-propanol. In some embodiments, the organic solvent is ethanol.

In some embodiments, the halogen includes F, Cl, Br, or a combination thereof.

In some embodiments, sintering is performed under the protection of inert gas. In some embodiments, the inert gas includes nitrogen, argon, or a combination thereof.

In some embodiments, the drying is spray drying, and the drying temperature is 100-300°C.

In some embodiments, the negative electrode can be obtained by mixing the negative electrode active material, conductive agent, thickener, and binder in a solvent to prepare an active material composition slurry, and coating the slurry on On the current collector.

In some embodiments, _{the thickness of the oxide Me a} O _b layer is controlled by controlling the weight of the oxide precursor.

In some embodiments, the solvent may include, but is not limited to: N-methylpyrrolidone, deionized water.

The electrolyte according to the present application can generate a stable SEI protective layer on the surface of the silicon-based negative electrode active material. Compared with the traditional SEI layer formed by fluoroethylene carbonate (FEC) or ethylene carbonate (VC), the SEI protective layer is circulating During the process, it is not easy to peel off from the silicon-based negative electrode active material, which can effectively improve the cycle capacity retention rate of lithium-ion batteries (silicon negative electrode lithium-ion batteries) using silicon-based negative electrode active materials, and alleviate battery swelling during cycling , And can improve the high temperature resistance of the battery after cycling, and avoid thermal runaway of the silicon anode lithium ion battery.

On the other hand, although the electrolyte of the present application can effectively improve the stability of the SEI protective layer, due to the huge volume expansion of the silicon-based negative electrode active material particles, the SEI protective layer needs to continuously consume additives for repair, which accelerates the consumption of additives rate. _{In view of this, the present application provides an oxide Me a} O _b layer and/or a carbon layer on the surface of the silicon-containing substrate of a part of the silicon-based negative electrode active material _{. The oxide Me a} O _b layer or the carbon layer has a certain mechanical strength. It can effectively suppress the volume expansion of the silicon-based negative electrode active material, and can also inhibit the etching of the surface of the silicon-based negative electrode active material by HF in the electrolyte. The combined use of the electrolyte containing the SEI film-forming additive of fluorosiloxane and trinitrile compound and _{the silicon-based negative electrode active material with oxide Me a} O _b layer or carbon layer on the surface can effectively improve the performance of lithium ion batteries. Cycle stability and cycle capacity retention rate, and reduce the cycle thickness expansion rate of lithium ion batteries.

In addition, the conductivity of the silicon-based negative electrode active material is usually not very ideal, and it not only cannot support the high-rate charging performance during the full battery cycle, but also has a certain impact on the cycle performance. Carbon materials have good electrical conductivity, mechanical strength and ductility. Therefore, in order to improve the conductivity of the negative electrode containing silicon-based negative electrode active material, this application provides a carbon layer on the surface of the silicon-containing substrate of part of the silicon-based negative electrode active material. And the carbon nanotube conductive agent is doped into the negative electrode active material to effectively improve the cycle performance of the battery.

Four, electrochemical device

The electrochemical device of the present application includes any device that undergoes an electrochemical reaction, 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 of the present application is an electrochemical device having a positive electrode having a positive electrode active material capable of occluding and releasing metal ions, and a negative electrode having a negative electrode active material capable of occluding and releasing metal ions. Its characteristics are It includes the electrolyte in any of the above-mentioned embodiments of the present application.

1. Electrolyte

The electrolyte used in the electrochemical device of the present application is the electrolyte of any of the above-mentioned embodiments in the present application. In addition, the electrolytic solution used in the electrochemical device of the present application may also include other electrolytic solutions within the scope not departing from the gist of the present application.

2. Negative electrode

The negative electrode used in the electrochemical device of the present application is a conventional negative electrode in the prior art, or the negative electrode of any of the above-mentioned embodiments in this application. In addition, the negative electrode used in the electrochemical device of the present application may also include other negative electrodes within the scope not departing from the gist of the present application.

3. Positive electrode

The material of the positive electrode used in the electrochemical device of the present application can be prepared using materials, structures, and manufacturing methods known in the art. In some embodiments, the technology described in US9812739B can be used to prepare the positive electrode of the present application, which is incorporated into the present application by reference in its entirety.

In some embodiments, the positive electrode includes a current collector and a positive electrode active material layer on the current collector. The positive electrode active material includes at least one lithiated intercalation compound that reversibly intercalates and deintercalates lithium ions. In some embodiments, the positive active material includes a composite oxide. In some embodiments, the composite oxide contains lithium and at least one element selected from cobalt, manganese, and nickel.

In some embodiments, the positive electrode active material is selected from lithium cobalt oxide (LiCoO ₂ ), lithium nickel cobalt manganese (NCM) ternary material, lithium iron phosphate (LiFePO ₄ ), lithium manganese oxide (LiMn ₂ O ₄ ), or their Any combination of.

In some embodiments, the positive active material may have a coating on its surface, or may be mixed with another compound having a coating. The coating may include at least one selected from the oxide of the coating element, the hydroxide of the coating element, the oxyhydroxide of the coating element, the oxycarbonate of the coating element, and the hydroxycarbonate of the coating element. Kind of coating element compound. The compound used for the coating may be amorphous or crystalline.

In some embodiments, the coating element contained in the coating may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, F, or these Any combination of. The coating can be applied by any method as long as the method does not adversely affect the performance of the positive electrode active material. For example, the method may include any coating method known in the art, such as spraying, dipping, and the like.

The positive active material layer further includes a binder, and optionally a conductive material. The binder improves the bonding of the positive electrode active material particles to each other, and also improves the bonding of the positive electrode active material to the current collector.

In some embodiments, the binder includes, but is not limited to: polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-containing Oxygen polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene butadiene rubber, acrylic (ester) styrene butadiene rubber, epoxy resin, Nylon etc.

In some embodiments, conductive materials include, but are not limited to: carbon-based materials, metal-based materials, conductive polymers, and mixtures thereof. In some embodiments, the carbon-based material is selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or any combination thereof. In some embodiments, the metal-based material is selected from metal powder, metal fiber, copper, nickel, aluminum, silver. In some embodiments, the conductive polymer is a polyphenylene derivative.

In some embodiments, the current collector may be aluminum, but is not limited thereto.

The positive electrode can be prepared by a preparation method known in the art. For example, the positive electrode can be obtained by mixing the active material, the conductive material, and the binder in a solvent to prepare an active material composition, and coating the active material composition on a current collector. In some embodiments, the solvent may include N-methylpyrrolidone and the like, but is not limited thereto.

In some embodiments, the positive electrode is made by forming a positive electrode material using a positive electrode active material layer including lithium transition metal-based compound powder and a binder on a current collector.

In some embodiments, the positive active material layer can generally be made by the following operations: dry mixing the positive electrode material and the binder (conducting material and thickener used as needed) to form a sheet, The obtained sheet is press-bonded to the positive electrode current collector, or these materials are dissolved or dispersed in a liquid medium to form a slurry, which is coated on the positive electrode current collector and dried. In some embodiments, the material of the positive active material layer includes any material known in the art.

4. 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 circuits. The material and shape of the isolation membrane used in the electrochemical device of the present application are not particularly limited, and it may be any technology disclosed in the prior art. In some embodiments, the isolation membrane includes a polymer or an inorganic substance formed of a material that is stable to the electrolyte of the present application.

For example, the isolation film may include a substrate layer and a surface treatment layer. The substrate layer is a non-woven fabric, film or composite film with a porous structure, and the material of the substrate layer is selected from at least one of polyethylene, polypropylene, polyethylene terephthalate and polyimide. Specifically, a polypropylene porous film, a polyethylene porous film, a polypropylene non-woven fabric, a polyethylene non-woven fabric, or a polypropylene-polyethylene-polypropylene porous composite film can be selected.

A surface treatment layer is provided on at least one surface of the substrate layer, and the surface treatment layer may be a polymer layer or an inorganic substance layer, or a layer formed by a mixed polymer and an inorganic substance.

The inorganic layer includes inorganic particles and a binder. The inorganic particles are selected from alumina, silica, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, ceria, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, One or a combination of yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, and barium sulfate. The binder is selected from polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, One or a combination of polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene. The polymer layer contains a polymer, and the material of the polymer includes polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride or poly( At least one of vinylidene fluoride-hexafluoropropylene).

Five, application

The electrolyte according to the embodiments of the present application can be used to improve the rate performance, storage capacity retention rate at room temperature, and cycle and high temperature storage performance of the battery, and is suitable for use in electronic equipment including electrochemical devices.

The use of the electrochemical device of the present application is not particularly limited, and it can be used for various well-known uses. For example, notebook computers, pen-input computers, mobile computers, e-book players, portable phones, portable fax machines, portable copiers, portable printers, stereo headsets, video recorders, LCD TVs, portable cleaners, portable CD players, Mini discs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, cars, motorcycles, assisted bicycles, bicycles, lighting equipment, toys, game consoles, clocks, power tools, flashlights , Cameras, large household storage batteries or lithium-ion capacitors, etc.

In the following, a lithium ion battery is taken as an example and combined with specific examples of preparing the electrolyte of the present application and the measurement method of the electrochemical device to illustrate the preparation and performance of the lithium ion battery of the present application. Those skilled in the art will understand that, The preparation methods described in this application are only examples, and any other suitable preparation methods are within the scope of this application.

Although a lithium ion battery is used as an example, after reading this application, those skilled in the art can think that the cathode material of this application can be used in other suitable electrochemical devices. Such an electrochemical device includes any device that undergoes an electrochemical reaction, 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.

Example

Hereinafter, examples and comparative examples are given to further specifically describe the present application, but as long as the gist is not deviated, the present application is not limited to these examples.

1. Lithium-ion battery preparation

(1) Preparation of electrolyte:

In the drying room, ethylene carbonate (EC), propylene carbonate (PC) and diethyl carbonate (DEC) are mixed uniformly in a weight ratio of 20:10:70, and then fully dried lithium salt LiPF _{6 is} dissolved in The mixed solvents above obtain a basic electrolyte, wherein _{the concentration of LiPF 6} in the basic electrolyte is 1 mol/L. The different contents of fluorosiloxane, trinitrile compound and fluoroethylene carbonate (FEC) shown in Table 1 were added to the basic electrolyte to obtain electrolytes of different examples and comparative examples. The content of each substance in the electrolyte described below is calculated based on the total weight of the electrolyte.

(2) Preparation of positive electrode:

Weigh 1.42kg of solvent N-methyl-2-pyrrolidone (NMP), 1.2kg of 10% binder polyvinylidene fluoride (PVDF), 0.16kg of conductive agent conductive graphite, and 7.2kg of positive electrode active material LiCoO ₂ Fully mix and stir to obtain the positive electrode slurry. The positive electrode slurry is evenly coated on the positive electrode current collector aluminum foil with a thickness of 10 μm, and the positive electrode film is obtained by baking at 120° C. for 1 h. The positive electrode is obtained by compaction and slitting.

(3) Isolation membrane: Polyethylene (PE) porous polymer film is used as the isolation membrane.

(4) Preparation of lithium-ion battery: stack the positive electrode, separator, and negative electrode in order, so that the separator is placed between the positive electrode and the negative electrode for isolation, and then wind to obtain a bare cell; place the bare cell in an outer package In the foil, the above-prepared electrolyte is injected into the dried battery, and the preparation of the lithium-ion battery is completed through the steps of vacuum packaging, standing, forming, and shaping.

(5) Preparation of negative electrode:

1) Disperse 100g of silicon oxide (SiO, Dv50 of 7μm) powder in 300ml of organic solvent ethanol, and stir for 0.5-1h until a uniform suspension is formed;

2) Add 0.5-10g of the oxide precursor aluminum isopropoxide to the above suspension, stir for 0.5-1h until a uniform mixed solution is formed, drop deionized water into the mixed solution, the weight of the deionized water is about the precursor 3 times the weight, after the dropwise addition is complete, continue to stir for 4 hours to obtain a mixed solution;

3) Spray drying (the inlet temperature is 220°C, the outlet temperature is about 110°C) the mixed solution to obtain powder;

4) Sintering the powder at 600° C. for 2 hours to obtain _{silicon-based particles with an oxide Me a} O _b (here, Al ₂ O ₃ ) layer on the surface as a silicon-based negative electrode active material;

5) Weigh 1.2 kg of a thickener carboxymethyl cellulose sodium (CMC-Na) solution with a mass fraction of 1.5%, 0.07 kg of a binder styrene butadiene rubber emulsion with a mass fraction of 50%, and 2.0 kg of graphite powder for negative electrode activity Materials, 0.01kg of conductive carbon nanotubes, 0.4kg of silicon-based negative electrode active material (commercially purchased, Dv50 of 7μm) coated with a hard carbon layer on the surface of a silicon-containing matrix (SiO); thoroughly mix and stir the above materials to obtain a negative electrode slurry; as well as

6) The negative electrode slurry is evenly coated on the copper foil of the negative electrode current collector with a thickness of 8 μm, and the negative electrode film is obtained by baking at 120° C. for 1 hour, and the negative electrode is obtained by compaction and slitting.

Table 1 shows the types and contents of related substances in the electrolyte in Examples 1-65 and Comparative Examples 1-4 and the substances used in steps 1)-5) in Examples 1-65 and Comparative Examples 1-4 The type and dosage and related parameters. The order of the types and contents of additives in Table 1 is the same. For example, the types and contents of additives in Example 22 are FEC: 5 wt% + PS: 0.5 wt% + SN: 1.5 wt%. The thickness of the oxide Me _a O _b layer is controlled by controlling the weight of the oxide precursor.

Table 1

The "—" means that the substance does not exist.

The full names of the English abbreviations in Table 1 are as follows:

FEC: Fluorinated Ethylene Carbonate

PS: 1,3-propane sultone

SN: Succinonitrile

The following performance tests were performed on the lithium ion secondary batteries in Examples 1-65 and Comparative Examples 1-4:

(1) Normal temperature cycle performance test:

At 25℃, let the lithium ion secondary battery stand for 30 minutes, charge at a constant current of 0.5C to a voltage of 4.45V, charge at a constant voltage of 4.45V to a current of 0.05C, and stand for 5 minutes at a constant current of 0.5C Discharge to a voltage of 3.0V as a charge-discharge cycle process. The discharge capacity this time is the first discharge capacity of the lithium-ion secondary battery. The lithium-ion secondary battery is subjected to a cyclic charge and discharge test in the above manner until the capacity retention rate is less than 80%, and the test is stopped, and the number of cycles of different groups is recorded.

The capacity retention rate (%) of the lithium ion secondary battery after N cycles=discharge capacity at the Nth cycle/first discharge capacity×100%.

(2) High temperature cycle performance test:

At 45℃, let the lithium ion secondary battery stand for 30 minutes, charge at a constant current of 0.5C to a voltage of 4.45V, charge at a constant voltage of 4.45V to a current of 0.05C, and stand for 5 minutes at a constant current of 0.5C Discharge to a voltage of 3.0V as a charge-discharge cycle process. The discharge capacity this time is the first discharge capacity of the lithium-ion secondary battery. The lithium-ion secondary battery is subjected to a cyclic charge and discharge test in the above manner until the capacity retention rate is less than 80%, and the test is stopped, and the number of cycles of different groups is recorded.

Table 2 shows the performance test results of the lithium ion secondary batteries of Examples 1-65 and Comparative Examples 1-4.

Table 2

序号Serial number	25℃循环圈数Number of cycles at 25°C	45℃循环圈数45°C cycle number
实施例1Example 1	655655	353353
实施例2Example 2	668668	362362
实施例3Example 3	670670	369369
实施例4Example 4	674674	375375
实施例5Example 5	675675	379379
实施例6Example 6	674674	377377
实施例7Example 7	674674	376376
实施例8Example 8	671671	372372
实施例9Example 9	673673	374374
实施例10Example 10	673673	375375
实施例11Example 11	658658	355355
实施例12Example 12	665665	367367
实施例13Example 13	674674	374374
实施例14Example 14	673673	372372
实施例15Example 15	670670	371371
实施例16Example 16	668668	368368
实施例17Example 17	664664	352352
实施例18Example 18	673673	374374
实施例19Example 19	675675	376376
实施例20Example 20	674674	376376
实施例21Example 21	680680	381381
实施例22Example 22	678678	392392
实施例23Example 23	677677	392392
实施例24Example 24	681681	390390
实施例25Example 25	670670	374374

实施例26Example 26	677677	376376
实施例27Example 27	679679	380380
实施例28Example 28	681681	386386
实施例29Example 29	680680	397397
实施例30Example 30	678678	398398
实施例31Example 31	669669	400400
实施例32Example 32	653653	350350
实施例33Example 33	675675	388388
实施例34Example 34	672672	380380
实施例35Example 35	675675	380380
实施例36Example 36	678678	381381
实施例37Example 37	681681	381381
实施例38Example 38	685685	380380
实施例39Example 39	688688	379379
实施例40Example 40	688688	378378
实施例41Example 41	685685	375375
实施例42Example 42	662662	380380
实施例43Example 43	677677	392392
实施例44Example 44	649649	348348
实施例45Example 45	662662	376376
实施例46Example 46	663663	376376
实施例47Example 47	663663	376376
实施例48Example 48	664664	378378
实施例49Example 49	664664	378378
实施例50Example 50	670670	380380
实施例51Example 51	675675	381381
实施例52Example 52	681681	382382
实施例53Example 53	682682	382382
实施例54Example 54	682682	382382
实施例55Example 55	683683	382382
实施例56Example 56	660660	381381
实施例57Example 57	659659	373373
实施例58Example 58	630630	371371
实施例59Example 59	657657	345345
实施例60Example 60	628628	341341
实施例61Example 61	681681	380380
实施例62Example 62	680680	381381
实施例63Example 63	675675	390390
实施例64Example 64	674674	390390
实施例65Example 65	674674	389389
对比例1Comparative example 1	642642	339339
对比例2Comparative example 2	670670	327327
对比例3Comparative example 3	589589	356356
对比例4Comparative example 4	595595	357357

It can be seen from the test results of Examples 1-65 and Comparative Examples 1-4 that when the fluorosiloxane compound and the trinitrile compound are added to the electrolyte at the same time, the normal temperature and high temperature cycle performance of the lithium ion secondary battery are both Obviously improved. And when the _{thickness of the oxide Me a} O _b layer, the thickness of the carbon layer and the aspect ratio of the carbon nanotubes are within a certain range, the normal temperature and high temperature cycle performance of the lithium ion secondary battery is further improved.

References to "some embodiments", "partial embodiments", "one embodiment", "another example", "examples", "specific examples" or "partial examples" throughout the specification mean At least one embodiment or example in this application includes the specific feature, structure, material, or characteristic described in the embodiment or example. Therefore, the descriptions appearing in various places throughout the specification, such as: "in some embodiments", "in embodiments", "in one embodiment", "in another example", "in an example "In", "in a specific example" or "exemplified", which are not necessarily quoting the same embodiment or example in this application. In addition, the specific features, structures, materials, or characteristics herein can be combined in one or more embodiments or examples in any suitable manner.

Although illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above-mentioned embodiments should not be construed as limiting the present application, and the embodiments can be changed without departing from the spirit, principle, and scope of the present application , Substitution and modification.

Claims

An electrolyte solution comprising a fluorinated siloxane compound and a trinitrile compound, wherein the fluorinated siloxane compound includes a compound of formula I:

Wherein R 1 , R 2 , R 3 , R 4 , R 5 or R 6 are each independently selected from hydrogen, fluorine atoms, alkyl groups of 1-12 carbon atoms, fluoroalkyl groups of 1-12 carbon atoms, Cycloalkyl with 3-12 carbon atoms, fluorocycloalkyl with 3-12 carbon atoms, alkenyl with 2-12 carbon atoms, fluoroalkenyl with 2-12 carbon atoms, 3-12 A heterocyclic group of carbon atoms or a fluorinated heterocyclic group of 3-12 carbon atoms, and wherein at least one of R 1 , R 2 , R 3 , R 4 , R 5 or R 6 is a fluorine atom, Fluorinated alkyl groups with 1-12 carbon atoms, fluorinated cycloalkyl groups with 3-12 carbon atoms, fluoroalkenyl groups with 2-12 carbon atoms, or fluorinated heterocyclic groups with 3-12 carbon atoms ；

And wherein the trinitrile compound includes at least one of a compound of formula II or a compound of formula III:

Wherein, a, b, c, d, e, f, g, h and i are integers of 0-5.
The electrolyte according to claim 1, wherein the fluorosiloxane compound includes at least one of the following compounds:
The electrolyte according to claim 1, wherein the trinitrile compound includes at least one of the following compounds:
The electrolyte according to claim 1, wherein based on the total weight of the electrolyte, the weight percentage of the fluorosiloxane compound is 0.01 wt% to 6 wt%, and the weight percentage of the trinitrile compound is 0.01 wt% %-8wt%.
The electrolyte according to claim 1, further comprising an additive, the additive comprising at least one of the following compounds: vinylene carbonate, 1,3-propane sultone, vinyl sulfate, succinonitrile, hexamethylene Dinitrile or fluoroethylene carbonate, wherein based on the total weight of the electrolyte, the weight percentage of the additive is 0.01 wt% to 20 wt%.
An electrochemical device, wherein the electrochemical device comprises a positive electrode, a negative electrode, and the electrolyte according to any one of claims 1-5.
The electrochemical device according to claim 6, wherein the negative electrode comprises a silicon-based negative active material, the silicon-based negative active material comprises a silicon-containing matrix, and the silicon-containing matrix comprises Si, silicon oxide SiO x or Si- At least one of M alloys, wherein 0.6≤x≤2, and M is selected from at least one of Al, Ti, Fe, or Ni.
8. The electrochemical device according to claim 7, wherein the silicon-based negative electrode active material further comprises an oxide Me a O b layer, the oxide Me a O b layer is located on at least a part of the surface of the silicon-containing substrate, Wherein Me includes at least one of Al, Si, Ti, Mn, V, Cr, Co or Zr, a is 1-3, b is 1-4, and wherein the thickness of the oxide Me a O b layer is 1nm-500nm.
The electrochemical device according to claim 6, wherein the negative electrode further comprises a conductive agent, the conductive agent comprising at least one of carbon nanotubes, graphene, or carbon black, wherein the aspect ratio of the carbon nanotubes Is 0.1-50000.
8. The electrochemical device according to claim 7, wherein the silicon-based anode active material further comprises a carbon layer on at least a part of the surface of the silicon-containing substrate, and the thickness of the carbon layer It is 1-500nm.
An electronic device, wherein the electronic device comprises the electrochemical device according to any one of claims 6-10.