阅读说明：本技术 电解液和使用其的电化学装置 (Electrolyte solution and electrochemical device using the same ) 是由 文倩 唐超 刘俊飞 郑建明 于 2020-05-27 设计创作，主要内容包括：本申请涉及电解液和使用其的电化学装置。本申请的电解液包含氟代硅氧烷化合物和三腈化合物,其中所述氟代硅氧烷化合物包括式I化合物：<Image he="319" wi="700" file="DDA0002511302490000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>并且其中所述三腈化合物包括式II化合物或式III化合物中的至少一种：<Image he="202" wi="700" file="DDA0002511302490000012.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>其中,a、b、c、d、e、f、g、h和i是0-5的整数。由本申请电解液制备的锂离子电池具有改善的常温和高温循环性能。(The present application relates to an electrolyte and an electrochemical device using the same. The electrolyte of the present application comprises a fluorosilicone compound and a trinitrile compound, wherein the fluorosilicone compound comprises a compound of formula I: and wherein the trinitrile compound comprises 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 from 0 to 5. The lithium ion battery prepared by the electrolyte has improved normal-temperature and high-temperature cycle performance.)

1. An electrolyte comprising a fluorosilicone compound and a trinitrile compound, wherein the fluorosilicone compound comprises a compound of formula I:

wherein R is₁、R₂、R₃、R₄、R₅Or R₆Each independently selected from hydrogen, fluorine atom, alkyl group of 1 to 12 carbon atoms, fluoroalkyl group of 1 to 12 carbon atoms, cycloalkyl group of 3 to 12 carbon atoms, fluorocycloalkyl group of 3 to 12 carbon atoms, alkenyl group of 2 to 12 carbon atoms, fluoroalkenyl group of 2 to 12 carbon atoms, heterocyclic group of 3 to 12 carbon atoms or fluorinated heterocyclic group of 3 to 12 carbon atoms, and wherein R is₁、R₂、R₃、R₄、R₅Or R₆At least one of which is a fluorine atom, a fluoroalkyl group of 1 to 12 carbon atoms, a fluorocycloalkyl group of 3 to 12 carbon atoms, a fluoroalkenyl group of 2 to 12 carbon atoms or a fluoroheterocyclic group of 3 to 12 carbon atoms;

and wherein the trinitrile compound comprises 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 from 0 to 5.

2. The electrolyte of claim 1, wherein the fluorosilicone compound comprises at least one of:

3. the electrolyte of claim 1, wherein the trinitrile compound comprises at least one of:

4. the electrolyte of claim 1, wherein the fluorosilicone compound is present in an amount of 0.01 wt% to 6 wt% and the nitrile compound is present in an amount of 0.01 wt% to 8 wt%, based on the total weight of the electrolyte.

5. The electrolyte of claim 1, further comprising an additive comprising at least one of the following compounds: vinylene carbonate, 1, 3-propane sultone, vinyl sulfate, succinonitrile, adiponitrile or fluoroethylene carbonate, wherein the weight percentage of the additive is 0.01-20 wt% based on the total weight of the electrolyte.

6. An electrochemical device, wherein the electrochemical device comprises a positive electrode, a negative electrode, and the electrolyte of any one of claims 1-5.

7. The electrochemical device of claim 6, wherein the negative electrode comprises a silicon-based negative active material comprising a silicon-containing matrix comprising Si, silicon oxide SiO_xOr Si-M alloy, wherein x is more than or equal to 0.6 and less than or equal to 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 anode active material further comprises an oxide Me_aO_bLayer of said oxide Me_aO_bA layer is located on at least a portion of the surface of the silicon-containing substrate, wherein Me comprises at least one of Al, Si, Ti, Mn, V, Cr, Co, or Zr, a is 1-3, b is 1-4, and wherein the oxide Me is_aO_bThe thickness of the layer is 1nm-500 nm.

9. The electrochemical device of claim 6, wherein the negative electrode further comprises a conductive agent comprising at least one of carbon nanotubes, graphene, or carbon black, wherein the aspect ratio of the carbon nanotubes is between 0.1 and 50000.

10. The electrochemical device according to claim 7, wherein the silicon-based negative active material further comprises a carbon layer on at least a portion of a surface of the silicon-containing substrate, and the carbon layer has a thickness of 1-500 nm.

11. An electronic device, wherein the electronic device comprises the electrochemical device according to any one of claims 6-10.

Technical Field

The present application relates to the technical field of electrochemical devices, and more particularly, to an electrolyte and an electrochemical device using the same.

Background

With the rapid development of information technology and the proliferation of various mobile devices, the development of lithium ion batteries has received much attention. Lithium ion batteries have higher operating voltages, greater energy densities, faster charge speeds and longer operating lifetimes than other secondary batteries. In order to meet the requirements of people on light weight and small volume of equipment, a high-energy density secondary battery becomes a necessary trend for the development of lithium ion batteries.

Silicon has a reversible capacity of up to 4200mAh/g, and is the most promising negative electrode material for increasing the energy density of lithium ion batteries. However, the use of silicon-containing negative electrodes also faces many challenges, for example, the large volume expansion of silicon during charging and discharging causes the Solid Electrolyte Interface (SEI) film on the silicon surface to be damaged, the side reaction of the silicon negative electrode material and the electrolyte is aggravated, the gas generation and capacity of the battery are rapidly attenuated, and the cyclic expansion rate is increased.

Disclosure of Invention

Embodiments of the present application provide an electrolyte and an electrochemical device using the same, in an attempt to solve at least one of the problems occurring in the related art to at least some extent. The embodiment of the application also provides an electrochemical device and an electronic device using the electrolyte.

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

wherein R is₁、R₂、R₃、R₄、R₅、R₆Each independently selected from hydrogen, fluorine atoms, alkyl groups of 1 to 12 carbon atoms, fluoroalkyl groups of 3 to 12 carbon atomsA cycloalkyl group, a fluorocycloalkyl group of 3 to 12 carbon atoms, an alkenyl group of 2 to 12 carbon atoms, a fluoroalkenyl group of 2 to 12 carbon atoms, a heterocyclic group of 3 to 12 carbon atoms or a fluorinated heterocyclic group of 3 to 12 carbon atoms, and wherein R is₁、R₂、R₃、R₄、R₅、R₆At least one of which is a fluorine atom, a fluoroalkyl group of 1 to 12 carbon atoms, a fluorocycloalkyl group of 3 to 12 carbon atoms, a fluoroalkenyl group of 2 to 12 carbon atoms or a fluoroheterocyclic group of 3 to 12 carbon atoms;

and wherein the trinitrile compound comprises 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 from 0 to 5.

In some embodiments, the fluorosilicone compound includes at least one of:

in some embodiments, the trinitrile compound comprises at least one of:

in some embodiments, the fluorosilicone compound is present in an amount of 0.01 wt% to 6 wt% and the nitrile compound is present in an amount of 0.01 wt% to 8 wt%, based on the total weight of the electrolyte.

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

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

In some embodiments, the anode comprises a silicon-based anode active material comprising a silicon-containing matrix comprising Si, silicon oxide SiO_xOr Si-M alloy, wherein x is more than or equal to 0.6 and less than or equal to 2, and M is selected from at least one of Al, Ti, Fe or Ni.

In some embodiments, the silicon-based anode active material further includes an oxide Me_aO_bLayer of said oxide Me_aO_bA layer is located on at least a portion of the surface of the silicon-containing substrate, wherein Me comprises at least one of Al, Si, Ti, Mn, V, Cr, Co, or Zr, a is 1-3, b is 1-4, and wherein the oxide Me is_aO_bThe thickness of the layer is 1nm-500 nm.

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

In some embodiments, the silicon-based negative active material further comprises a carbon layer on at least a portion of the surface of the silicon-containing matrix, and the carbon layer has a thickness of 1-500 nm.

In another embodiment, the present application provides an electronic device comprising an electrochemical device according to an embodiment of the present application.

The electrolyte provided by the application can form a stable Solid Electrolyte Interface (SEI) protective layer on the surfaces of the positive electrode and the negative electrode, and can obviously improve the normal-temperature and high-temperature cycle performance of the lithium ion secondary battery. Particularly when the silicon-based active material is applied to a battery with a negative electrode containing a silicon-based active material, the good stability of an SEI (solid electrolyte interphase) protective layer of the negative electrode after the battery is cycled can be ensured, so that the cycle performance of the battery is improved.

Additional aspects and advantages of embodiments of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of embodiments of the present application.

Detailed Description

Embodiments of the present application will be described in detail below. The embodiments of the present application should not be construed as limiting the present application.

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.

As used herein, 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 can 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.

As used herein, 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 12 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" as used herein 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 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 12 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.

As used herein, the term "heterocyclic group" 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 heteroatom₃-C₂₀Heterocyclic group, C₃-C₁₅₀Heterocyclic group, C₃-C₁₀Heterocyclic group, C₅-C₂₀Heterocyclic group, C₅-C₁₀Heterocyclic group, C₃-C₆A 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 "trinitrile compound" refers to a compound containing three-CN functional groups.

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

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

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

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

As used herein, the term "substituted" or "substituted" means that it may be substituted with 1 or more (e.g., 2, 3) substituents. For example, "fluoro" means that it may be substituted with 1 or more (e.g., 2, 3) F.

First, electrolyte

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

wherein R is₁、R₂、R₃、R₄、R₅、R₆Each independently selected from hydrogen, fluorine atom, alkyl group of 1 to 12 carbon atoms, fluoroalkyl group of 1 to 12 carbon atoms, cycloalkyl group of 3 to 12 carbon atoms, fluorocycloalkyl group of 3 to 12 carbon atoms, alkenyl group of 2 to 12 carbon atoms, fluoroalkenyl group of 2 to 12 carbon atoms, heterocyclic group of 3 to 12 carbon atoms or fluorinated heterocyclic group of 3 to 12 carbon atoms, and wherein R is₁、R₂、R₃、R₄、R₅、R₆At least one of which is a fluorine atom, a fluoroalkyl group of 1 to 12 carbon atoms, a fluorocycloalkyl group of 3 to 12 carbon atoms, a fluoroalkenyl group of 2 to 12 carbon atoms or a fluoroheterocyclic group of 3 to 12 carbon atoms;

and wherein the trinitrile compound comprises or is selected from 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 from 0 to 5.

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

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

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

In some embodiments, the weight percentage of the trinitrile compound is 0.01 wt% to 8 wt% based on the total weight of the electrolyte. In some embodiments, 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%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6 wt%, 8 wt%, or a range consisting of any two of these values, based on the total weight of the electrolyte.

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

In some embodiments, the weight percentage of the additive is 0.01 wt% to 20 wt% based on the total weight of the electrolyte. In some embodiments, the weight percent 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%, 7 wt%, 10 wt%, 11 wt%, 15 wt%, 18 wt%, 20 wt%, or a range consisting of any two of these values, based on the total weight of the electrolyte.

In some embodiments, the electrolyte further comprises a cyclic ether. The cyclic ether can form a film on the cathode and the anode simultaneously, and the reaction of the electrolyte and the active material is reduced.

In some embodiments, the cyclic ethers include, but are not limited to: tetrahydrofuran, 2-methyltetrahydrofuran, 1, 3-dioxolane, 2-methyl-1, 3-dioxolane, 4-methyl-1, 3-dioxolane, 1, 3-dioxane, 1, 4-dioxane, dimethoxypropane.

In some embodiments, the weight percentage of the cyclic ether is 0.1 wt% to 10 wt% based on the total weight of the electrolyte. In some embodiments, the weight percentage of the cyclic ether is not less than 0.1 wt% based on the total weight of the electrolyte. In some embodiments, the weight percentage of the cyclic ether is not less than 0.5 wt% based on the total weight of the electrolyte. In some embodiments, the weight percentage of the cyclic ether is no greater than 2 wt% based on the total weight of the electrolyte. In some embodiments, the weight percentage of the cyclic ether is no greater than 5 wt% based on the total weight of the electrolyte.

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

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

In some embodiments, the electrolyte further comprises a phosphorus-containing organic solvent. The phosphorus-containing organic solvent 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, ethylene ethyl phosphate, triphenyl phosphate, trimethyl phosphite, triethyl phosphite, triphenyl phosphate, tris (2,2, 2-trifluoroethyl) phosphate, tris (2,2,3,3, 3-pentafluoropropyl) phosphate.

In some embodiments, the weight percentage of the phosphorus-containing organic solvent is 0.1 wt% to 10 wt% based on the total weight of the electrolyte. In some embodiments, the weight percentage of the phosphorus-containing organic solvent is not less than 0.1 wt% based on the total weight of the electrolyte. In some embodiments, the weight percentage of the phosphorus-containing organic solvent is not less than 0.5 wt% based on the total weight of the electrolyte. In some embodiments, the weight percentage of the phosphorus-containing organic solvent is no greater than 2 wt%, based on the total weight of the electrolyte. In some embodiments, the weight percentage of the phosphorus-containing organic solvent is no greater than 3 wt%, based on the total weight of the electrolyte. In some embodiments, the weight percentage of the phosphorus-containing organic solvent is no greater than 5 wt%, based on the total weight of the electrolyte.

In some embodiments, the electrolyte further comprises 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 wetting performance of the electrolyte on 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, the weight percent of the aromatic fluorine-containing solvent is about 0.1 wt% to 10 wt% based on the total weight of the electrolyte. In some embodiments, the weight percent of the aromatic fluorine-containing solvent is not less than 0.5 wt% based on the total weight of the electrolyte. In some embodiments, the weight percent of the aromatic fluorine-containing solvent is not less than 2 wt% based on the total weight of the electrolyte. In some embodiments, the weight percent of the aromatic fluorine-containing solvent is not greater than 4 wt% based on the total weight of the electrolyte. In some embodiments, the weight percent of the aromatic fluorine-containing solvent is not greater than 8 wt% based on the total weight of the electrolyte.

In some embodiments, the electrolyte further comprises a lithium salt additive. In some embodiments, the lithium salt additive includes, but is not limited to, lithium trifluoromethanesulfonylimide LiN (CF)₃SO₂)₂(abbreviated as LiTFSI), lithium bis (fluorosulfonyl) imide Li (N (SO)₂F)₂) (abbreviated as LiFSI) and lithium LiB (C) bis (oxalato-borate₂O₄)₂(abbreviated as LiBOB), lithium oxalate tetrafluorophosphate (LiPF4C2O2), lithium difluoroborate LiBF₂(C₂O₄) (abbreviated as LiDFOB) and lithium hexafluorocaesium acid (LiCSF)₆)。

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

The application provides an electrolyte containing a fluorosilicone compound and a trinitrile compound, which can form a stable SEI (solid electrolyte interphase) protective layer on the surfaces of a positive electrode and a negative electrode and can obviously improve the normal-temperature and high-temperature cycle performance of a secondary battery. Particularly when the silicon-based active material is applied to a battery with a negative electrode containing a silicon-based active material, the good stability of an SEI (solid electrolyte interphase) protective layer of the negative electrode after the battery is cycled can be ensured, so that the cycle performance of the battery is improved.

II, electrolyte

The electrolyte used in the electrolyte of the embodiment of the present application may be an electrolyte known in the art, and the electrolyte includes, but is not limited to: inorganic lithium salts, e.g. LiClO₄、LiAsF₆、LiPF₆、LiBF₄、LiSbF₆、LiSO₃F、LiN(FSO₂)₂Etc.; organic lithium salts containing fluorine, e.g. LiCF₃SO₃、LiN(FSO₂)(CF₃SO₂)、LiN(CF₃SO₂)₂、LiN(C₂F₅SO₂)₂Cyclic 1, 3-hexafluoropropane disulfonimide lithium, cyclic 1, 2-tetrafluoroethane disulfonimide lithium, LiN (CF)₃SO₂)(C₄F₉SO₂)、LiC(CF₃SO₂)₃、LiPF₄(CF₃)₂、LiPF₄(C₂F₅)₂、LiPF₄(CF₃SO₂)₂、LiPF₄(C₂F₅SO₂)₂、LiBF₂(CF₃)₂、LiBF₂(C₂F₅)₂、LiBF₂(CF₃SO₂)₂、LiBF₂(C₂F₅SO₂)₂(ii) a The dicarboxylic acid complex-containing lithium salt may, for example, be lithium bis (oxalato) borate, lithium difluorooxalato borate, lithium tris (oxalato) phosphate, lithium difluorobis (oxalato) phosphate, lithium tetrafluoro (oxalato) phosphate, or the like. The electrolyte may be used alone or in combination of two or more. For example, in some embodiments, the electrolyte comprises LiPF₆And LiBF₄Combinations of (a) and (b). In some embodiments, the electrolyte comprises LiPF₆Or LiBF₄An inorganic lithium salt and LiCF₃SO₃、LiN(CF₃SO₂)₂、LiN(C₂F₅SO₂)₂And the like, a combination of fluorine-containing organic lithium salts. In some embodiments, the concentration of the electrolyte is in the range of 0.8 to 3mol/L, such as in the range of 0.8 to 2.5mol/L, in the range of 0.8 to 2mol/L, in the range of 1 to 2mol/L, 0.5 to 1.5mol/L, 0.8 to 1.3mol/L, 0.5 to 1.2mol/L, and again, such as 1mol/L, 1.15mol/L, 1.2mol/L, 1.5mol/L, 2mol/L, or 2.5 mol/L.

Third, negative pole

In some embodiments, the present application provides an anode comprising a current collector and a coating on the current collector, the coating comprising a silicon-based anode active material.

In some embodiments, the silicon-based negative active material comprises a silicon-containing matrix comprising Si, silicon oxide SiO_xAnd at least one of Si-M alloy, wherein x is more than or equal to 0.6 and less than or equal to 2, and M is selected from at least one of Al, Ti, Fe or Ni.

In some embodiments, the silicon-containing matrix comprises Si, SiO₂At least one of SiO or SiC.

In some embodiments, the silicon-based anode active material further includes an oxide Me_aO_bLayer of said oxide Me_aO_bA layer is on at least a portion of a surface of the silicon-containing substrate, wherein Me comprises at least one of Al, Si, Ti, Mn, V, Cr, Co, or Zr, anda is 1-3, b is 1-4.

In some embodiments, the oxide Me_aO_bThe thickness of the layer is 1nm-500 nm. In some embodiments, the oxide Me_aO_bThe thickness of the layer is 1nm, 5nm, 10nm, 20nm, 30nm, 50nm, 80nm, 120nm, 150nm, 200nm, 300nm, 400nm, 450nm, 500nm, or a range consisting of any two of these values.

In some embodiments, the oxide Me_aO_bIncluding Al₂O₃、TiO₂CoO and ZrO₂At least one of (1).

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

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

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

In some embodiments, the carbon nanotubes have an aspect ratio of 0.1 to 5000. In some embodiments, the carbon nanotubes have an aspect ratio of 0.1, 7, 10, 50, 100, 200, 500, 1000, 2000, 2500, 2800, 3000, 3500, 4000, 4500, 5000, or a range consisting of any two of these values.

In some embodiments, the silicon-based negative active material further comprises a carbon layer on at least a portion of a surface of the silicon-containing matrix. In some embodiments, the carbon layer has a thickness of 1-500 nm. In some embodiments, the carbon layer has a thickness of 1nm, 5nm, 10nm, 30nm, 40nm, 50nm, 80nm, 100nm, 150nm, 200nm, 250nm, 300nm, 400nm, 500nm, or a range consisting of any two of these values.

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

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

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

In some embodiments, the coating further comprises a binder comprising polyacrylate, polyimide, polyamide, polyamideimide, polyvinylidene fluoride, styrene butadiene rubber, sodium alginate, polyvinyl alcohol, polytetrafluoroethylene, polyacrylonitrile, or any combination thereof.

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

In some embodiments, a silicon-based negative active material (which includes a silicon-containing matrix and an oxide Me on at least a portion of a surface of the silicon-containing matrix_aO_bLayer) comprising:

(1) mixing silicon-containing matrix and oxide precursor MeT_nForming 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 the temperature of 200-1000 ℃ for 0.5-25h to obtain the silicon-based negative active material;

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

wherein Me comprises at least one of Al, Si, Ti, Mn, Cr, V, Co or Zr,

wherein T comprises at least one of methoxy, ethoxy, isopropoxy, or halogen, and

wherein n is 1,2, 3 or 4.

In some embodiments, the oxide precursor MeT_nIncluding isopropyl titanate, aluminum isopropoxide, or combinations thereof.

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

In some embodiments, the sintering temperature is 250-. In some embodiments, the sintering temperature is 300-. In some embodiments, the sintering temperature is 350-. In some embodiments, the sintering temperature is 400 ℃, 500 ℃, 600 ℃, or 700 ℃.

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

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

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

In some embodiments, the sintering is performed under an inert gas blanket. In some embodiments, the inert gas comprises nitrogen, argon, or a combination thereof.

In some embodiments, the drying is spray drying at a drying temperature of 100-.

In some embodiments, the negative electrode may be obtained by: the negative active material, the conductive agent, the thickener, and the binder are mixed in a solvent to prepare an active material composition slurry, and the slurry is coated on a current collector.

In some embodiments, the oxide Me_aO_bThe thickness of the layer is controlled by controlling the oxideThe weight of the precursor.

In some embodiments, the solvent may include, but is not limited to: n-methyl pyrrolidone and deionized water.

According to the electrolyte disclosed by the application, a stable SEI (solid electrolyte interphase) protective layer can be generated on the surface of the silicon-based negative electrode active material, and compared with an SEI layer formed by the traditional fluoroethylene carbonate (FEC) or ethylene carbonate (VC), the SEI protective layer is not easy to peel off from the silicon-based negative electrode active material in a circulation process, so that the circulation capacity retention rate of a lithium ion battery (silicon negative electrode lithium ion battery) using the silicon-based negative electrode active material can be effectively improved, the expansion of the battery in the circulation process is relieved, the high-temperature resistance of the battery after circulation can be improved, and the thermal runaway of the silicon negative electrode lithium ion battery is avoided.

On the other hand, although the electrolyte can effectively improve the stability of the SEI protective layer, the SEI protective layer needs to continuously consume additives for repairing due to the huge volume expansion of the silicon-based negative active material particles, and the consumption rate of the additives is increased. In view of the above, the present application provides an oxide Me on the surface of a silicon-containing substrate of a part of silicon-based anode active material_aO_bLayer and/or carbon layer, the oxide Me_aO_bThe layer or the carbon layer has certain mechanical strength, can effectively inhibit the volume expansion of the silicon-based negative active material, and can also inhibit the etching of HF in the electrolyte on the surface of the silicon-based negative active material. An electrolyte containing an SEI film-forming additive of a fluorosilicone and a trinitrile compound and an oxide Me on the surface_aO_bThe silicon-based negative active material of the layer or the carbon layer is combined for use, so that the cycle stability and the cycle capacity retention rate of the lithium ion battery can be effectively improved, and the cycle thickness expansion rate of the lithium ion battery is reduced.

In addition, the conductivity of the silicon-based negative active material is not ideal, and the silicon-based negative active material cannot support the high-rate charging performance in the full battery cycle and also has a certain influence on the cycle performance. The carbon material has good conductivity, mechanical strength and ductility, so in order to improve the conductivity of the negative electrode containing the silicon-based negative electrode active material, the carbon layer is arranged on the surface of a silicon-containing matrix of part of the silicon-based negative electrode active material, and the carbon nanotube conductive agent is doped in the negative electrode active material, so that the cycle performance of the battery is effectively improved.

Four, electrochemical device

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, an electrochemical device according to the present application is an electrochemical device including 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, and includes an electrolytic solution according to any one of the embodiments described above.

1. Electrolyte solution

The electrolyte used in the electrochemical device of the present application is the electrolyte of any of the embodiments described above in the present application. In addition, the electrolyte used in the electrochemical device of the present application may further include other electrolytes within a range 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 a negative electrode according to any of the above embodiments in the present application. The negative electrode used in the electrochemical device of the present application may further include other negative electrodes within a range 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 may be prepared using materials, configurations, and manufacturing methods well known in the art. In some embodiments, the positive electrode of the present application can be prepared using the techniques described in US9812739B, which is incorporated by reference in its entirety.

In some embodiments, the positive electrode includes a current collector and a positive 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 electrode 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 active material is selected from lithium cobaltate (LiCoO)₂) Lithium Nickel Cobalt Manganese (NCM) ternary material, lithium iron phosphate (LiFePO)₄) Lithium manganate (LiMn)₂O₄) Or any combination thereof.

In some embodiments, the positive electrode active material may have a coating layer on a surface thereof, or may be mixed with another compound having a coating layer. The coating may comprise at least one coating element compound selected from the group consisting of an oxide of the coating element, a hydroxide of the coating element, an oxyhydroxide of the coating element, an oxycarbonate of the coating element and an oxycarbonate of the coating element. The compounds used for the coating may be amorphous or crystalline.

In some embodiments, the coating elements contained in the coating may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, F, or any combination 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 known to 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 binding of the positive electrode active material particles to each other, and also improves the binding of the positive electrode active material to the current collector.

In some embodiments, the adhesive includes, but is not limited to: polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene 1, 1-difluoroethylene, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy, nylon, and the like.

In some embodiments, the conductive material includes, but is 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 the group consisting of 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 may be prepared by a preparation method well known in the art. For example, the positive electrode can be obtained by: the active material, the conductive material, and the binder are mixed in a solvent to prepare an active material composition, and the active material composition is coated on a current collector. In some embodiments, the solvent may include, but is not limited to, N-methylpyrrolidone, and the like.

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

In some embodiments, the positive electrode active material layer may be generally fabricated by: the positive electrode material and a binder (a conductive material, a thickener, and the like, which are used as needed) are dry-mixed to form a sheet, and the obtained sheet is pressure-bonded to a positive electrode current collector, or these materials are dissolved or dispersed in a liquid medium to form a slurry, and the slurry is applied to a positive electrode current collector and dried. In some embodiments, the material of the positive electrode 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 circuit. The material and shape of the separation film used in the electrochemical device of the present application are not particularly limited, and may be any of the techniques disclosed in the prior art. 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. The substrate layer is a non-woven fabric, a film or a composite film with a porous structure, and the material of the substrate layer is at least one selected from polyethylene, polypropylene, polyethylene terephthalate and polyimide. Specifically, a polypropylene porous film, a polyethylene porous film, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite film can be used.

At least one surface of the substrate layer is provided with a surface treatment layer, and the surface treatment layer can be a polymer layer or an inorganic layer, or a layer formed by mixing a polymer and an inorganic substance.

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

Fifth, application

The electrolyte solution provided by the embodiment of the application can be used for improving the rate performance, the normal-temperature storage capacity retention rate and the cycle and high-temperature storage performance of a battery, and is suitable for being used in electronic equipment comprising an electrochemical device.

The use of the electrochemical device of the present application is not particularly limited, and the electrochemical device can be used for various known uses. Such as a notebook computer, a pen-input computer, a mobile computer, an electronic book player, a cellular phone, a portable facsimile machine, a portable copier, a portable printer, a headphone, a video recorder, a liquid crystal television, a portable cleaner, a portable CD player, a mini disc, a transceiver, an electronic organizer, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, an automobile, a motorcycle, a power-assisted bicycle, a lighting fixture, a toy, a game machine, a clock, an electric tool, a flashlight, a camera, a large-sized battery for home use, or a lithium ion capacitor.

While the following lithium ion battery is taken as an example and the specific examples for preparing the electrolyte and the test method for electrochemical devices are combined to illustrate the preparation and performance of the lithium ion battery, those skilled in the art will understand that the preparation method described in the present application is only an example, and any other suitable preparation method is within the scope of the present application.

Although illustrated as a lithium ion battery, one skilled in the art will appreciate after reading this application that the cathode materials of the present application may be used in other suitable electrochemical devices. Such an electrochemical device includes any device in which electrochemical reactions occur, and specific examples thereof include all kinds of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors. In particular, the electrochemical device is a lithium secondary battery including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.