WO2021195965A1 - 一种电化学装置及包括其的电子装置 - Google Patents

一种电化学装置及包括其的电子装置 Download PDF

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WO2021195965A1
WO2021195965A1 PCT/CN2020/082435 CN2020082435W WO2021195965A1 WO 2021195965 A1 WO2021195965 A1 WO 2021195965A1 CN 2020082435 W CN2020082435 W CN 2020082435W WO 2021195965 A1 WO2021195965 A1 WO 2021195965A1
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active material
negative electrode
electrochemical device
electrode active
compound
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PCT/CN2020/082435
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English (en)
French (fr)
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崔辉
郑建明
王翔
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宁德新能源科技有限公司
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Priority to PCT/CN2020/082435 priority Critical patent/WO2021195965A1/zh
Priority to US17/281,545 priority patent/US20220123365A1/en
Priority to EP20866948.1A priority patent/EP3913720A4/en
Publication of WO2021195965A1 publication Critical patent/WO2021195965A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0569—Liquid materials characterised by the solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/30—Batteries in portable systems, e.g. mobile phone, laptop
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • H01M2300/0034—Fluorinated solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H01M2300/0028—Organic electrolyte characterised by the solvent
    • H01M2300/0037—Mixture of solvents
    • H01M2300/004—Three solvents
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • This application relates to the field of energy storage technology, and in particular to an electrochemical device and an electronic device including the electrochemical device.
  • Electrochemical devices for example, lithium-ion batteries
  • higher performance requirements are put forward for lithium-ion batteries-fast charge and discharge, and excellent cycle performance.
  • this application not only considers the impedance that affects the rapid charge and discharge performance, but also considers the relationship between the solvent of the electrolyte and the film-forming additives of the electrolyte, and takes into account the negative electrode active materials and separators that affect the rapid charge and discharge performance. And other factors, optimize the relationship between the characteristics of the negative electrode active material itself and the content of the film-forming additive in the electrolyte, thereby optimizing the entire electrochemical device system.
  • This application aims to improve the fast charging performance of the electrochemical device while maintaining the cycle performance.
  • the present application provides an electrochemical device, which includes an electrolyte, a positive electrode, and a negative electrode, the negative electrode includes a negative active material layer, the negative active material layer includes a negative active material, and the electrolyte includes Fluorinated ethylene carbonate, wherein the electrochemical device satisfies the relationship:
  • R ct represents the charge transfer impedance at 50% charged state at 25 degrees Celsius
  • R cp represents the concentration polarization impedance at 50% charged state at 25 degrees Celsius
  • the mass of the fluoroethylene carbonate corresponding to 1 g of the negative electrode active material is A g
  • the specific surface area of the negative electrode active material is B m 2 /g.
  • the value of A ranges from 0.01 to 0.1, and the value of B ranges from 1.0 to 2.0.
  • R 11 is selected from hydrogen, hydroxyl, C 1-20 alkyl, C 1-20 alkoxy, C 2-20 alkenyl, C 6-30 aryl, or C 6-30 aryloxy;
  • R 12 is selected from hydrogen, C 1-20 alkyl, C 2-20 alkenyl, or C 6-30 aryl;
  • the mass of the compound of formula I corresponding to 1 g of the negative electrode active material is X g, and the value range of X is 0.035 to 0.39.
  • the compound of formula I comprises at least one of the following compounds: methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, propyl acetate Isopropyl acid, n-butyl propionate, isobutyl propionate, n-pentyl propionate, isoamyl propionate, ethyl n-butyrate, n-propyl butyrate, propyl isobutyrate, n-butyl N-pentyl acid, n-pentyl isobutyrate, n-butyl n-butyrate, isobutyl isobutyrate, or n-pentyl n-valerate.
  • the X and the porosity P of the negative active material layer satisfy the following relationship: 0.1 ⁇ X/P ⁇ 3, wherein the value of P ranges from 0.13 to 0.35.
  • the electrolyte solution further contains vinylene carbonate, wherein the mass of the vinylene carbonate corresponding to 1 g of the negative electrode active material is Cg, and the B and C satisfy the following relationship: 0.001 ⁇ C/B ⁇ 0.03.
  • the mass of the ethyl propionate corresponding to 1 g of the negative electrode active material is D g, and the C and the D satisfy the following relational formula : 1 ⁇ D/C ⁇ 240.
  • the electrolyte solution further comprises at least one of a compound of formula II or a compound of formula III:
  • R 21 and R 22 are each independently selected from an unsubstituted or fluorine-substituted C 1-5 alkyl group, and at least one of R 21 and R 22 contains fluorine;
  • R 31 and R 32 are each independently selected from unsubstituted or fluorine-substituted C 1-20 alkyl groups, and at least one of R 31 and R 32 contains fluorine, and Y is selected from -O- or
  • the mass of the compound of formula II corresponding to 1 g of the negative electrode active material is 0.015 g to 0.15 g.
  • the mass of the compound of formula III corresponding to 1 g of the negative electrode active material is 0.015 g to 0.065 g.
  • the compound of formula II comprises at least one of the following compounds: methyl difluoroacetate, ethyl difluoroacetate, propyl difluoroacetate, methyl difluoropropionate, difluoropropionic acid Ethyl, propyl difluoropropionate, methyl fluoroacetate, ethyl fluoroacetate, propyl fluoroacetate, methyl trifluoroacetate, ethyl trifluoroacetate, or propyl trifluoroacetate;
  • the compound of formula III includes at least one of the following compounds: 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, or perfluoro(2-methyl-3 -Pentanone).
  • Another aspect of the present application provides an electronic device including the electrochemical device as described above.
  • This application aims to improve the fast charging performance of the electrochemical device while maintaining the cycle performance.
  • the additional aspects and advantages of the embodiments of the present application will be partially described, shown, or explained through the implementation of the embodiments of the present application in the subsequent description.
  • Figure 1 demonstrates the R ct and R cp during the transmission of a lithium-ion battery
  • Fig. 2 shows a schematic diagram of the primary particles and the secondary particles of the negative electrode active material in an embodiment.
  • Figure 3A is the analog equivalent circuit of R ct.
  • FIG. 3B is an EIS test diagram of a lithium ion battery in an embodiment.
  • the term "about” is used to describe and illustrate small variations.
  • the term may refer to an example in which the event or situation occurs precisely and an example in which the event or situation occurs very closely.
  • the term can refer to a range of variation less than or equal to ⁇ 10% of the stated value, such as less than or equal to ⁇ 5%, less than or equal to ⁇ 4%, less than or equal to ⁇ 3%, Less than or equal to ⁇ 2%, less than or equal to ⁇ 1%, less than or equal to ⁇ 0.5%, less than or equal to ⁇ 0.1%, or less than or equal to ⁇ 0.05%.
  • a list of items connected by the term "one of” may mean any one of the listed items. 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.
  • a list of items connected by the terms “at least one of”, “at least one of” or other similar terms can mean any combination of the listed items. For example, if items A and B are listed, then the phrase “at least one of A and B" or “at least one of A or 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” or “at least one of A, B, or C” means only A; or only B; C only; A and B (exclude 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.
  • Project C can contain a single element or multiple elements.
  • the number after the capital letter “C”, such as “C 1 -C 10 ", “C 3 -C 10 “, etc., after the "C” indicates the number of carbons in a specific functional group. That is, the functional groups may include 1-10 carbon atoms and 3-10 carbon atoms, respectively.
  • C 1 -C 4 alkyl or “C 1-4 alkyl” refers to an alkyl group having 1 to 4 carbon atoms, such as CH 3 -, CH 3 CH 2 -, CH 3 CH 2 CH 2 -, (CH 3 ) 2 CH-, CH 3 CH 2 CH 2 CH 2 -, CH 3 CH 2 CH(CH 3 )- or (CH 3 ) 3 C-.
  • alkyl is expected to have 1 to 20, 1 to 18, 1 to 16, 1 to 14, 1 to 12, 1 to 10, 1 to 8, 1 to 6, 1 to 4 or 3 to 5 carbon atoms linear saturated hydrocarbon structure. "Alkyl” is also expected to have 3 to 20, 3 to 18, 3 to 16, 3 to 14, 3 to 12, 3 to 10, 3 to 8, 3 to 6, or 3 to A branched or cyclic hydrocarbon structure of 5 carbon atoms.
  • butyl means to include n-butyl, sec-butyl, isobutyl, tert-butyl And cyclobutyl;
  • propyl includes n-propyl, isopropyl and cyclopropyl.
  • 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 and so on.
  • the alkyl group may be optionally substituted.
  • alkenyl refers to a monovalent unsaturated hydrocarbon group that may 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 to 20, 2 to 18, 2 to 16, 2 to 14, 2 to 12, 2 to 10, 2 to 8. One, 2 to 6, or 2 to 4 carbon atoms and includes, for example, -C 2-4 alkenyl, -C 2-6 alkenyl, and -C 2-10 alkenyl.
  • 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.
  • aryl encompasses both monocyclic and polycyclic ring systems.
  • a polycyclic ring may have two or more rings in which two carbons are shared by two adjacent rings (the rings are "fused"), wherein at least one of the rings is aromatic, such as others
  • the ring can be a cycloalkyl, cycloalkenyl, aryl, heterocyclic, and/or heteroaryl group.
  • the aryl group can be an aryl group with 6-30 carbon atoms, an aryl group with 6-24 carbon atoms, an aryl group with 6-20 carbon atoms, an aryl group with 6-16 carbon atoms, and 6-12 carbon atoms.
  • aryl group with carbon atoms or an aryl group with 6-10 carbon atoms include, for example, phenyl, methylphenyl, propylphenyl, isopropylphenyl, benzyl and naphth-1-yl, naphth-2-yl, and the like. In addition, aryl groups may be optionally substituted.
  • aryloxy refers to the "-O-aryl” group, where aryl is as defined herein.
  • alkoxy refers to the "-O-alkyl” group, where alkyl is as defined herein.
  • halogen encompasses fluorine (F), chlorine (Cl), bromine (Br), and iodine (I), with F or Cl being preferred.
  • 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.
  • 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.
  • the electrochemical device of the present application is an electrochemical device having a positive electrode with a positive active material capable of occluding and releasing metal ions, and an electrochemical device having a negative electrode with a negative active material capable of occluding and releasing metal ions.
  • the present application provides an electrochemical device, which includes an electrolyte, a positive electrode, and a negative electrode, the negative electrode includes a negative active material layer, the negative active material layer includes a negative active material, and the electrolyte includes Fluorinated ethylene carbonate, wherein the electrochemical device satisfies the relationship:
  • R ct represents the charge transfer impedance at 50% charged state at 25 degrees Celsius
  • R cp represents the concentration polarization impedance at 50% charged state at 25 degrees Celsius
  • the mass of the fluoroethylene carbonate corresponding to 1 g of the negative electrode active material is Ag, and the specific surface area of the negative electrode active material is B m 2 /g.
  • the membrane (SEI) enters the negative electrode active material layer, and at the same time, the diffusion of lithium ions in the negative electrode active material layer is also faster, which can realize the super-high rate charging of the lithium ion battery.
  • R ct When R ct is much larger than R cp , the charge transfer of lithium ions on the surface of the negative electrode active material becomes a limiting factor. Even if R cp is already very small, although lithium ions can quickly reach the surface of the negative electrode active material, they cannot quickly complete the intercalation of the negative electrode active material, resulting in the deposition of lithium ions on the surface of the negative electrode active material layer, and lithium evolution occurs under high-rate charging. The low temperature of lithium ion batteries The performance is limited and cannot have excellent fast charging performance.
  • Figure 1 decomposes the R ct and R cp during the transmission of the lithium-ion battery.
  • the ratio of the R ct to the R cp R ct /R cp ranges from 0.7 to 1.2.
  • the value of R ct /R cp is about 0.55, about 0.6, about 0.65, about 0.7, about 0.75, about 0.8, about 0.85, about 0.9, about 0.95, about 1.0, about 1.05, about 1.1. , About 1.15, about 1.2, about 1.25, about 1.3, about 1.35, about 1.4, or about 1.45.
  • the value of R ct /R cp is about 0.54, about 0.71, about 0.92, about 1.03, about 1.15, about 1.23, about 1.37, or about 1.47.
  • the ratio A/B of the A to the B ranges from 0.005 to 0.07.
  • the value of A/B is about 0.005, about 0.006, about 0.007, about 0.008, about 0.009, about 0.01, about 0.012, about 0.014, about 0.016, about 0.018, about 0.02, about 0.022, about 0.024, about 0.026, about 0.028, about 0.03, about 0.032, about 0.034, about 0.036, about 0.038, about 0.04, about 0.042, about 0.044, about 0.046, about 0.048, about 0.05, about 0.052, about 0.054, about 0.056, About 0.058, about 0.06, about 0.062, about 0.064, about 0.066, about 0.068, about 0.07, about 0.072, about 0.074, about 0.076, about 0.078, about 0.08, about 0.082, about 0.084, about 0.086, about 0.088, about 0.09 , About 0.0
  • the value of A ranges from 0.01 to 0.1, and the value of B ranges from 1.0 to 2.0.
  • the value of A ranges from 0.02 to 0.1. In some embodiments, the value of A is about 0.01, about 0.015, about 0.02, about 0.025, about 0.03, about 0.035, about 0.04, about 0.045, about 0.05, about 0.055, about 0.06, about 0.065, about 0.07 , About 0.075, about 0.08, about 0.085, about 0.09, about 0.095, or about 0.1. In some embodiments, the value of A is about 0.01, about 0.0195, about 0.02, about 0.052, about 0.07, about 0.08, about 0.09, or about 0.1.
  • the value of B ranges from 1.1 to 1.6. In some embodiments, the value of B is about 1.0, about 1.1, about 1.2, about 1.3, about 1.4, about 1.5, about 1.6, about 1.7, about 1.8, about 1.9, or about 2.0. In some embodiments, the electrolyte contains a compound of formula I:
  • R 11 is selected from hydrogen, hydroxyl, C 1-20 alkyl, C 1-20 alkoxy, C 2-20 alkenyl, C 6-30 aryl, or C 6-30 aryloxy;
  • R 12 is selected from hydrogen, C 1-20 alkyl, C 2-20 alkenyl, or C 6-30 aryl.
  • the mass of the compound of formula I corresponding to 1 g of the negative electrode active material is X g, and the value range of X is 0.035 to 0.39.
  • R 11 is selected from: hydrogen, hydroxyl, C 1-16 alkyl, C 1-12 alkyl, C 1-10 alkyl, C 1-8 alkyl, C 1-6 alkyl or C 1-4 alkyl, C 1-16 alkoxy, C 1-12 alkoxy, C 1-10 alkoxy, C 1-8 alkoxy, C 1-6 alkoxy or C 1- 4 alkoxy, C 2-16 alkenyl group, C 2-12 alkenyl, C 2-8 alkenyl, C 2-6 alkenyl or C 2-4 alkenyl group, C 6-24 aryl Group, C 6-20 aryl group, C 6-16 aryl group, C 6-12 aryl group or C 6-10 aryl group, or C 6-24 aryloxy group, C 6-20 aryloxy group, C 6- 16 aryloxy, C 6-12 aryloxy or C 6-10 aryloxy.
  • R 11 is selected from: hydrogen, hydroxy, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, or isopentyl.
  • R 12 is selected from: hydrogen, C 1-16 alkyl, C 1-12 alkyl, C 1-10 alkyl, C 1-8 alkyl, C 1-6 alkyl, or C 1 -4 alkyl, C 2-16 alkenyl, C 2-12 alkenyl, C 2-8 alkenyl, C 2-6 alkenyl or C 2-4 alkenyl, or C 6-24 Aryl, C 6-20 aryl, C 6-16 aryl, C 6-12 aryl, or C 6-10 aryl.
  • R 12 is selected from: hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, or isopentyl.
  • the value of X ranges from 0.05 to 0.3 or 0.09 to 0.25; in some embodiments, the value of X ranges from about 0.04, about 0.045, about 0.05, about 0.055, about 0.06, about 0.065, about 0.07, about 0.075, about 0.08, about 0.085, about 0.09, about 0.095, about 0.1, about 0.12, about 0.14, about 0.16, about 0.18, about 0.2, about 0.22, about 0.24, about 0.26, about 0.28, about 0.3, About 0.32, about 0.34, about 0.36, or about 0.38. In some embodiments, the value range of X is about 0.035, about 0.093, about 0.25, about 0.32, or about 0.39.
  • the X and the A satisfy the following relationship: 0.67 ⁇ X/A ⁇ 20.
  • the X/A ratio is in the range of 0.67 to 20
  • the viscosity of the electrolyte is low, a stable SEI film is formed on the surface of the negative electrode, and it has excellent fast charging performance and good circulation.
  • the ratio X/A of the X to the A ranges from 1 to 20 or 5 to 20.
  • the value of X/A is about 0.7, about 0.8, about 0.9, about 1, about 1.5, about 2, about 2.5, about 3, about 3.5, about 4, about 4.5, about 5.
  • the value of X/A is about 0.67, about 1.79, about 4.77, about 12.82, about 16.41, or about 20.
  • the compound of formula I comprises at least one of the following compounds: methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, propyl acetate Isopropyl acid, n-butyl propionate, isobutyl propionate, n-pentyl propionate, isoamyl propionate, ethyl n-butyrate, n-propyl butyrate, propyl isobutyrate, n-butyl N-pentyl acid, n-pentyl isobutyrate, n-butyl n-butyrate, isobutyl isobutyrate, or n-pentyl n-valerate.
  • the compound of formula I is selected from at least one of ethyl acetate or ethyl propionate.
  • the X and the porosity P of the negative active material layer satisfy the following relationship: 0.1 ⁇ X/P ⁇ 3, wherein the value of P ranges from 0.13 to 0.35.
  • the ratio X/P of the X to the P ranges from 0.3 to 3; in some embodiments, the range of X/P is about 0.3, about 0.5, about 0.7, about 0.9, about 1.1, about 1.3, about 1.5, about 1.7, about 1.9, about 2.1, about 2.3, about 2.5, about 2.7, about 2.9, or about 3.0. In some embodiments, the value range of X/P is about 0.1, about 0.3, about 1.0, about 1.78, or about 3.
  • the value of P is about 0.13, about 0.15, about 0.17, about 0.19, about 0.21, about 0.23, about 0.25, about 0.27, about 0.29, about 0.31, about 0.33, or about 0.35. In some embodiments, the value of P is about 0.13, about 0.18, about 0.25, about 0.31, or about 0.35.
  • the electrolyte further includes vinylene carbonate, wherein the mass of the vinylene carbonate corresponding to 1 g of the negative electrode active material is Cg, and the B and C satisfy the following relationship: 0.001 ⁇ C/B ⁇ 0.03.
  • the ratio C/B of the C to the B ranges from 0.001 to 0.02.
  • the value of C/B is approximately 0.001, approximately 0.0015, approximately 0.002, approximately 0.0025, approximately 0.003, approximately 0.0035, approximately 0.004, approximately 0.0045, approximately 0.005, approximately 0.0055, approximately 0.006, approximately 0.0065, approximately 0.007, about 0.0075, about 0.008, about 0.0085, about 0.009, about 0.0095, about 0.01, about 0.015, about 0.02, about 0.025, or about 0.03.
  • the value of C/B is about 0.001, about 0.00125, about 0.01875, about 0.0025, or about 0.003.
  • the decomposition amount and decomposition rate of vinylene carbonate on the surface of the negative electrode active material in the electrochemical device are within a suitable range, and excessive high-impedance LiF will not be formed, which makes the electrochemical device fast charge Performance and cycle performance have been further improved.
  • the mass of the ethyl propionate corresponding to 1 g of the negative electrode active material is D g, and the C and the D satisfy the following relational formula : 1 ⁇ D/C ⁇ 240.
  • the ratio D/C of the D to the C ranges from 1 to 200, 1 to 100, 1 to 50, or 1 to 20.
  • the value of D/C is about 2, about 4, about 6, about 8, about 10, about 12, about 14, about 16, about 18, about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90, about 100, about 110, about 120, about 130, about 140, about 150, about 160, about 170, about 180, or about 190.
  • the value of D/C is about 1, about 1.5, about 2, about 2.5, about 3, about 3.5, or about 4.5. When the D/C ratio is in the above range, the fast charging performance of the electrochemical device can be further improved.
  • the electrolyte solution further comprises at least one of a compound of formula II or a compound of formula III:
  • R 21 and R 22 are each independently selected from an unsubstituted or fluorine-substituted C 1-5 alkyl group, and at least one of R 21 and R 22 contains fluorine;
  • R 31 and R 32 are each independently selected from unsubstituted or fluorine-substituted C 1-20 alkyl groups, and at least one of R 31 and R 32 contains fluorine, and Y is selected from -O- or
  • R 21 and R 22 are each independently selected from a C 1-3 alkyl group that is unsubstituted or substituted with one or more fluorines, and at least one of R 21 and R 22 contains fluorine. In some embodiments, R 21 and R 22 are each independently selected from the following groups substituted with one or more fluorine: methyl, ethyl, and propyl.
  • R 21 and R 22 are each independently selected from -CH 3 , -CH 2 F, -CHF 2 , -CF 3 , -CH 2 CH 3 , -CH 2 CH 2 F, -CH 2 CHF 2 , -CH 2 CF 3 , -CHFCH 3 , -CF 2 CH 3 , -CHFCH 2 F, or -CH 2 CH 2 CH 3 .
  • R 31 and R 32 are each independently selected from the following groups that are unsubstituted or substituted with fluorine: C 1-16 alkyl, C 1-12 alkyl, C 1-8 alkyl, C A 1-6 alkyl group or a C 1-4 alkyl group, and at least one of R 31 and R 32 contains fluorine. In some embodiments, R 31 and R 32 are each independently selected from the following groups substituted with one or more fluorine: methyl, ethyl, and propyl.
  • R 31 and R 32 are each independently selected from -CH 2 F, -CHF 2 , -CH 2 CH 2 F, -CH 2 CHF 2 , -CH 2 CF 3 , -CHFCH 3 , -CF 2 CH 3 , -CHFCH 2 F, -CF 2 CHF 2 , -CF 3 , -CF 2 CF 3 , -CF 2 CF 2 CF 3 or -CF(CF 3 ) 2 .
  • the mass of the compound of formula II corresponding to 1 g of the negative electrode active material is 0.015 g to 0.15 g.
  • the mass of the compound of formula II corresponding to 1 g of the negative electrode active material is 0.02 g to 0.1 g. In some embodiments, the mass of the compound of formula II corresponding to 1g of the negative electrode active material is about 0.015g, about 0.02g, about 0.025g, about 0.03g, about 0.035g, about 0.04g, 0.045g, about 0.05g, about 0.055g, about 0.06g, about 0.065g, about 0.07g, 0.075g, about 0.08g, about 0.085g, about 0.09g, about 0.095g, about 0.1g, about 0.11g, about 0.12g, About 0.13g, about 0.14g or about 0.15g.
  • the mass of the compound of formula II corresponding to 1 g of the negative electrode active material is about 0.015 g, about 0.037 g, about 0.076 g, about 0.098 g, about 0.13 g, or about 0.15 g.
  • the mass of the compound of formula III corresponding to 1 g of the negative electrode active material is 0.015 g to 0.065 g.
  • the mass of the compound of formula III corresponding to 1 g of the negative electrode active material is 0.02 g to 0.6 g. In some embodiments, the mass of the compound of formula II corresponding to 1g of the negative electrode active material is about 0.02g, about 0.04g, about 0.06g, about 0.08g, about 0.1g, 0.15g, about 0.2g, 0.25 g, about 0.3g, 0.35g, about 0.4g, 0.45g, about 0.5g, 0.55g, about 0.6g, or 0.65g. In some embodiments, the mass of the compound of formula III corresponding to 1 g of the negative electrode active material is about 0.015 g, about 0.022 g, about 0.0036 g, about 0.053 g, or about 0.065 g.
  • the compound of formula II comprises at least one of the following compounds: methyl difluoroacetate, ethyl difluoroacetate, propyl difluoroacetate, methyl difluoropropionate, difluoropropionic acid Ethyl ester, propyl difluoropropionate, methyl fluoroacetate, ethyl fluoroacetate, propyl fluoroacetate, methyl trifluoroacetate, ethyl trifluoroacetate, or propyl trifluoroacetate; in some embodiments, The compound of formula II includes ethyl difluoroacetate.
  • the compound of formula III comprises at least one of the following compounds: 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, or perfluoro( 2-methyl-3-pentanone). In some embodiments, the compound of formula III comprises 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether.
  • the electrolyte further includes a lithium salt and an organic solvent.
  • the lithium salt is selected from one or more of inorganic lithium salt and organic lithium salt.
  • the lithium salt contains at least one of fluorine, boron, or phosphorus.
  • the lithium salt comprises: lithium hexafluorophosphate (LiPF 6 ), lithium bistrifluoromethanesulfonimide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), bisoxalic acid Boric acid (LiBOB for short), Boric acid difluorooxalate (LiDFOB for short), lithium hexafluoroarsenate (LiAsF 6 ), lithium perchlorate (LiClO 4 ), or lithium trifluoromethanesulfonate (LiCF 3 SO 3 ) At least one of.
  • the concentration of the lithium salt is 0.5 mol/L to 1.5 mol/L. In some embodiments, the concentration of the lithium salt is 0.8 mol/L to 1.2 mol/L.
  • the organic solvent includes a carbonate solvent
  • the carbonate solvent includes a cyclic carbonate and a chain carbonate
  • the cyclic carbonate is selected from ethylene carbonate (EC) and propylene carbonate (PC) , At least one of ⁇ -butyrolactone (BL) or butylene carbonate
  • the chain carbonate is selected from dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC) ), at least one of propyl ethyl carbonate.
  • DMC dimethyl carbonate
  • DEC diethyl carbonate
  • EMC ethyl methyl carbonate
  • the amount of the cyclic carbonate is more than the chain carbonate, and the solvent system preferably does not contain the chain carbonate.
  • the electrolyte described in this application has certain characteristics: at 25°C, the electrolyte conductivity is ⁇ 7mS/cm, and at 0°C, the electrolyte conductivity is ⁇ 4mS/ cm; at 25°C, the electrolyte viscosity ⁇ 6mPa ⁇ s, at 0°C, the electrolyte viscosity ⁇ 9mPa ⁇ s; the surface tension of the electrolyte at 25°C ⁇ 40mN/m.
  • the transmission speed of lithium ions is faster, which is beneficial to realize the fast charging performance of lithium ion batteries; when the electrolyte has lower conductivity and viscosity When it is larger and the surface tension is higher, the lithium ion transmission is hindered, which is not conducive to improving the fast charge and discharge performance.
  • the negative electrode includes a current collector and a negative active material layer provided on the current collector.
  • the negative electrode active material layer includes a negative electrode active material, and the specific type of the negative electrode active material is not subject to specific restrictions, and can be selected according to requirements.
  • the negative electrode can be prepared by a preparation method known in the art.
  • the negative electrode can be obtained by mixing an active material, a conductive material, and a binder in a solvent to prepare an active material composition, and coating the active material composition on a current collector.
  • the negative electrode active material includes a material that reversibly intercalates/deintercalates lithium ions.
  • the material that reversibly intercalates/deintercalates lithium ions includes a carbon material.
  • the carbon material may be any carbon-based negative active material commonly used in lithium ion rechargeable batteries.
  • the carbon material includes, but is not limited to: crystalline carbon, amorphous carbon, or a mixture thereof.
  • the crystalline carbon may be amorphous, flake-shaped, flake-shaped, spherical or fibrous natural graphite or artificial graphite.
  • Amorphous carbon can be soft carbon, hard carbon, mesophase pitch carbide, calcined coke, and the like.
  • the negative electrode active material includes, but is not limited to: lithium metal, structured lithium metal, natural graphite, artificial graphite, mesophase carbon microspheres (abbreviated as MCMB), hard carbon, soft carbon, silicon, containing Silicon or silicon-oxygen materials, silicon-carbon composites, or any combination thereof.
  • MCMB mesophase carbon microspheres
  • the negative active material is composed of single particles and secondary particles.
  • Figure 2 shows a schematic diagram of the primary particles and secondary particles of the negative electrode active material.
  • the raw material of the negative active material includes A raw material and B raw material.
  • the single particle Dv50 of A raw material is 3 to 10 microns, and the single particle Dv50 of B raw material is 2 to 10 microns.
  • the Dv50 of the resulting secondary particles is 5 to 20 microns; wherein the addition ratio of raw material A to raw material B is 1:9 to 5:5.
  • the OI value of the negative active material (C004/C110—that is, the ratio of the peak area of the 004 peak of the negative active material to the peak area of the 110 peak) ranges from 8 to 15, which greatly reduces the lithium ion concentration.
  • the transmission distance of the negative electrode active material reduces the R cp of the lithium ion battery, increases the transmission rate of lithium ions, and improves the performance of fast charging.
  • the negative active material may further include the following orientations:
  • the distribution ratio of the layer structure in the orientation 1 is 6% to 25%
  • the distribution ratio of the layer structure in the orientation 2 is 27% to 65%
  • the distribution ratio of the layer structure in the orientation 3 is 5% to 10%.
  • the specific surface area (BET) of the negative active material is 1.0 m 2 /g to 2.0 m 2 /g.
  • the negative active material layer may include a binder, and optionally a conductive material.
  • the binder improves the bonding of the negative active material particles with each other and the bonding of the negative active material with the current collector.
  • the binder includes, but is not limited to: polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride , Polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene butadiene rubber, acrylic (ester) styrene butadiene rubber , Epoxy resin, nylon, etc.
  • conductive materials include, but are not limited to: carbon-based materials, metal-based materials, conductive polymers, or mixtures thereof.
  • the carbon-based material is selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or any combination thereof.
  • the metal-based material is selected from metal powder, metal fiber, copper, nickel, aluminum, silver.
  • the conductive polymer is a polyphenylene derivative.
  • the current collector of the negative electrode may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, foamed nickel, foamed copper, conductive metal-coated polymer substrates, and combinations thereof.
  • the current collector includes copper foil.
  • 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.
  • 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.
  • the positive electrode includes a current collector and a positive active material layer on the current collector, and the positive active material layer includes a positive active material.
  • the positive electrode active material includes at least one lithiated intercalation compound that reversibly intercalates and deintercalates lithium ions.
  • the positive active material includes a composite oxide.
  • the composite oxide contains lithium and at least one element selected from cobalt, manganese, and nickel.
  • the positive electrode active material is selected from one or more of lithium cobaltate, lithium manganate, lithium nickelate, lithium nickel cobalt manganate, or lithium nickel cobalt aluminate.
  • 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.
  • the compound used for the coating may be amorphous or crystalline.
  • the coating element contained in the coating may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or any of them. combination.
  • 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.
  • 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.
  • 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.
  • conductive materials include, but are not limited to: carbon-based materials, metal-based materials, conductive polymers, and mixtures thereof.
  • the carbon-based material is selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or any combination thereof.
  • the metal-based material is selected from metal powder, metal fiber, copper, nickel, aluminum, silver.
  • the conductive polymer is a polyphenylene derivative.
  • 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.
  • the positive electrode can be obtained by mixing an active material, a conductive material, and a binder in a solvent to prepare an active material composition, and coating the active material composition on a current collector.
  • the solvent may include N-methylpyrrolidone and the like, but is not limited thereto.
  • 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.
  • the positive electrode 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, and The obtained sheet is press-bonded to the positive electrode current collector, or these materials are dissolved or dispersed in a liquid medium to prepare a slurry, which is coated on the positive electrode current collector and dried.
  • the material in the positive active material layer includes any material known in the art.
  • 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.
  • the isolation membrane includes a polymer or an inorganic substance formed of a material that is stable to the electrolyte of the present application.
  • 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.
  • 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.
  • the substrate layer can be one layer or multiple layers. When the substrate layer is multiple layers, the polymer composition of different substrate layers can be the same or different, and the weight average molecular weight is different; when the substrate layer is multiple layers , The closed cell temperature of the polymer of different substrate layers is different.
  • At least one surface of the substrate layer is provided with a surface treatment layer
  • 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 aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, ceria, nickel oxide, zinc oxide, One or a combination of calcium oxide, zirconium oxide, 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).
  • the electrochemical device of the embodiment of the present application has improved cycle performance and high temperature stability under overdischarge conditions, and is suitable for use in various electronic 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.
  • notebook computers pen-input computers, mobile computers, e-book players, portable phones, portable fax machines, portable copiers, portable printers, 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.
  • the negative electrode active material includes first particles and second particles, wherein the first particles are secondary particles, and the secondary particles include not less than 2 primary particles.
  • the Dv50 of the primary particles in the secondary particles is 2 micrometers to 10 micrometers, and the Dv50 of the secondary particles is 5 micrometers to 20 micrometers.
  • the second particles are primary particles, and the Dv50 of the second particles is 3 ⁇ m to 10 ⁇ m.
  • the negative electrode active material with different specific surface area and porosity is obtained by controlling the graphitization temperature during preparation and the ratio of the first particles to the second particles, and the graphitization temperature ranges from 2500 to 3200 degrees Celsius. Examples of specific surface area (B) and porosity (P) are shown in the table below.
  • SBR binder styrene butadiene rubber
  • CMC thickener sodium carboxymethyl cellulose
  • the positive active material lithium cobalt oxide molecular formula is LiCoO 2
  • conductive agent acetylene black binder polyvinylidene fluoride (abbreviated as PVDF) in a weight ratio of 96:2:2 in an appropriate amount of N-methylpyrrolidone (abbreviated It is NMP)
  • NMP N-methylpyrrolidone
  • a polyethylene isolation film with a thickness of about 9 microns is selected.
  • To make a three-electrode lithium-ion battery stack the positive electrode, separator, and negative electrode in order, so that the separator is between the positive electrode and the negative electrode to isolate it; weld a thin copper wire on the side close to the negative electrode separator, and use another A small piece of isolation film covers the copper wire so that it will not contact the negative electrode; then wind the electrode assembly, place the electrode assembly in the outer packaging aluminum-plastic film, and inject the prepared electrolyte into the dried In the battery, the preparation of a three-electrode lithium ion battery is completed after vacuum packaging, standing, forming, and shaping.
  • DCR DC impedance
  • Capacity retention rate remaining discharge capacity/initial discharge capacity x 100%.
  • the DDS-307 lightning magnetic conductivity meter standard test method is used for testing.
  • the standard test method of DV2T viscometer is used for testing.
  • Examples 16 to 20 meet the requirements (1) "0.5 ⁇ R ct /R cp ⁇ 1.5 and both R ct and R cp are less than 35 milliohms", and requirements (2) "0.005 ⁇ A/B ⁇ 0.1” and requirement (3) "0.67 ⁇ X/A ⁇ 20" are further satisfied on the basis of requirement (4) "0.1 ⁇ X/P ⁇ 3, where the value of P ranges from 0.13 to 0.35”; Therefore, in the three tests of cycle, temperature rise and lithium evolution, it is comparable to the examples 9 to 13 and the example 21 that meet the requirements (1) to (3) but not meet the requirements (4). Compared with Example 16 to Example 20, significantly better technical effects have been achieved.
  • Examples 35 to 40 an appropriate amount of a compound of Formula II (such as two Ethyl fluoroacetate); In the cycle and temperature rise tests, compared with Example 10 without adding the compound of formula II, Examples 35 to 40 achieved better technical effects.
  • a compound of Formula II such as two Ethyl fluoroacetate
  • Examples 41 to 45 the electrolyte solution containing fluoroethylene carbonate (FEC) and a compound of formula I (e.g. ethyl acetate) was further added with an appropriate amount of a compound of formula III (e.g. 1,1,2,2- Tetrafluoroethyl-2,2,2-trifluoroethyl ether); In the cycle and temperature rise tests, compared with Example 10 without adding the compound of formula III, Examples 41 to 45 achieved better results Technical effect.
  • FEC fluoroethylene carbonate
  • a compound of formula I e.g. ethyl acetate
  • a compound of formula III e.g. 1,1,2,2- Tetrafluoroethyl-2,2,2-trifluoroethyl ether
  • 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, 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 “exemplary”, which are not necessarily quoting the same embodiment or example in this application.
  • the specific features, structures, materials or characteristics herein can be combined in one or more embodiments or examples in any suitable manner.

Abstract

一种电化学装置及包括其的电子装置。电化学装置包括电解液、正极及负极，负极包括负极活性材料层，负极活性材料层包括负极活性材料，电解液包括氟代碳酸乙烯酯，其中电化学装置满足下述关系式：0.5<R ct/R cp<1.5且R ct和R cp均小于35毫欧姆，及0.005≤A/B≤0.1；其中R ct表示25摄氏度时50％荷电状态下的电荷转移阻抗，R cp表示25摄氏度时50％荷电状态下的浓差极化阻抗；1g负极活性材料对应的氟代碳酸乙烯酯的质量为A g，负极活性材料的比表面积为B m 2/g。在保持电化学装置的循环性能的同时提升其快速充电性能。

Description

一种电化学装置及包括其的电子装置 技术领域
本申请涉及储能技术领域，尤其涉及一种电化学装置和包括该电化学装置的电子装置。
背景技术
电化学装置(例如，锂离子电池)具有高能量密度，长循环寿命，及无记忆效应等优点，被广泛应用于穿戴设备、智能手机、无人机，甚至电动汽车等领域。随着锂离子电池应用的拓展及信息技术的发展，对锂离子电池提出了更高的性能要求——可进行快速充放电，同时具有优异的循环性能。
现有快速充放电技术的研究往往单一改善材料(石墨或优化电解液)，关注锂离子电池单一方面的阻抗，而缺少对整个体系的深入研究，导致无法实现充电速度的大幅度提升，在追求快速充放电性能的同时不得不降低其它方面的性能，例如循环性能。
发明内容
本申请从电化学装置体系出发，不仅考虑影响快速充放电性能的阻抗，而且考虑电解液的溶剂与电解液的成膜添加剂之间的关系、兼顾影响快速充放电性能的负极活性材料及隔离膜等因素，优化负极活性材料本身特性与电解液的成膜添加剂含量的关系，从而优化整个电化学装置体系。本申请旨在保持电化学装置的循环性能的同时提升其快速充电性能。
在一些实施例中，本申请提供了一种电化学装置，其包括电解液、正极及负极，所述负极包括负极活性材料层，所述负极活性材料层包括负极活性材料，所述电解液包括氟代碳酸乙烯酯，其中所述电化学装置满足关系式：
0.5<R ct/R cp<1.5，且R ct和R cp均小于35毫欧姆，
其中R ct表示25摄氏度时50％荷电状态下的电荷转移阻抗，R cp表示25摄氏度时50％荷电状态下的浓差极化阻抗；且
0.005≤A/B≤0.1，
其中，1g所述负极活性材料对应的所述氟代碳酸乙烯酯的质量为A g，所述负极活性材料的比表面积为B m 2/g。
在一些实施例中，其中所述A的取值范围为0.01至0.1，所述B的取值范围为1.0至2.0。
在一些实施例中，其中所述电解液包含式I化合物：
Figure PCTCN2020082435-appb-000001
其中，R 11选自氢、羟基、C 1-20烷基、C 1-20烷氧基、C 2-20链烯基、C 6-30芳基、或C 6-30芳氧基；
R 12选自氢、C 1-20烷基、C 2-20链烯基、或C 6-30芳基；
其中，1g所述负极活性材料对应的所述式I化合物的质量为X g，X的取值范围为0.035至0.39。
在一些实施例中，其中所述X与所述A满足如下关系式：
0.67≤X/A≤20。
在一些实施例中，所述式I化合物包含下述化合物中的至少一种：乙酸甲酯、乙酸乙酯、乙酸丙酯、丙酸甲酯、丙酸乙酯、丙酸正丙酯、丙酸异丙酯、丙酸正丁酯、丙酸异丁酯、丙酸正戊酯、丙酸异戊酯、正丁酸乙酯、正丁酸正丙酯、异丁酸丙酯、正丁酸正戊酯、异丁酸正戊酯、正丁酸正丁酯、异丁酸异丁酯、或正戊酸正戊酯。
在一些实施例中，其中所述X与所述负极活性材料层的孔隙率P满足如下关系式：0.1≤X/P≤3，其中所述P的取值范围为0.13至0.35。
在一些实施例中，其中所述电解液还包含碳酸亚乙烯酯，其中1g所述负极活性材料对应的所述碳酸亚乙烯酯的质量为Cg，所述B和所述C满足如下关系式：0.001≤C/B≤0.03。
在一些实施例中，其中所述式I化合物包含丙酸乙酯，1g所述负极活性材料对应的所述丙酸乙酯的质量为D g，且所述C和所述D满足如下关系式：1≤D/C≤240。
在一些实施例中，其中所述电解液进一步包含式II化合物或式III化合物中的至少一者：
Figure PCTCN2020082435-appb-000002
其中，R 21及R 22各自独立选自未经取代或经氟取代的C 1-5烷基，且R 21及R 22中的至少一者含氟；
R 31及R 32各自独立选自未经取代或经氟取代的C 1-20烷基，且R 31及R 32中的至少一者含氟，Y选自-O-或
Figure PCTCN2020082435-appb-000003
在一些实施例中，其中1g所述负极活性材料对应的所述式II化合物的质量为0.015g至0.15g。
在一些实施例中，其中1g所述负极活性材料对应的所述式III化合物的质量为0.015g至0.065g。
在一些实施例中，所述式II化合物包含下述化合物中的至少一种：二氟乙酸甲酯、二氟乙酸乙酯、二氟乙酸丙酯、二氟丙酸甲酯、二氟丙酸乙酯、二氟丙酸丙酯、氟乙酸甲酯、氟乙酸乙酯、氟乙酸丙酯、三氟乙酸甲酯、三氟乙酸乙酯、或三氟乙酸丙酯；
所述式III化合物包含下述化合物中的至少一种：1,1,2,2-四氟乙基-2,2,2-三氟乙基醚、或全氟(2-甲基-3-戊酮)。
本申请的另一个方面提供了一种电子装置，所述电子装置包括如上所述的电化学装置。
本申请旨在保持电化学装置的循环性能的同时提升其快速充电性能。本申请实施例的额外层面及优点将部分地在后续说明中描述、显示、或是经由本申请实施例的实施而阐释。
附图说明
图1演示了锂离子电池传输过程中的R ct及R cp
图2给出了一个实施例中负极活性材料的一次颗粒与二次颗粒示意图。
图3A为R ct的模拟等效电路。
图3B为一个实施例中锂离子电池的EIS测试图。
具体实施方式
本申请的实施例将会被详细的描述在下文中。本申请的实施例不应该被解释为对本申请要求保护范围的限制。除非另外明确指明，本文使用的下述术语具有下文指出的含义。
如本文中所使用，术语“约”用以描述及说明小的变化。当与事件或情形结合使用时，所述术语可指代其中事件或情形精确发生的例子以及其中事件或情形极近似地发生的例子。举例来说，当结合数值使用时，术语可指代小于或等于所述数值的±10％的变化范围，例如小于或等于±5％、小于或等于±4％、小于或等于±3％、小于或等于±2％、小于或等于±1％、小于或等于±0.5％、小于或等于±0.1％、或小于或等于±0.05％。另外，有时在本文中以范围格式呈现量、比率和其它数值。应理解，此类范围格式是用于便利及简洁起见，且应灵活地理解，不仅包含明确地指定为范围限制的数值，而且包含涵盖于所述范围内的所有个别数值或子范围，如同明确地指定每一数值及子范围一般。
在具体实施方式及权利要求书中，由术语“中的一者”连接的项目的列表可意味着所列项目中的任一者。例如，如果列出项目A及B，那么短语“A及B中的一者”意味着仅A或仅B。在另一实例中，如果列出项目A、B及C，那么短语“A、B及C中的一者”意味着仅A；仅B；或仅C。项目A可包含单个元件或多个元件。项目B可包含单个元件或多个元件。项目C可包含单个元件或多个元件。
在具体实施方式及权利要求书中，由术语“中的至少一者”、“中的至少一种”或其他相似术语所连接的项目的列表可意味着所列项目的任何组合。例如，如果列出项目A及B，那么短语“A及B中的至少一者”或“A或B中的至少一者”意味着仅A；仅B；或A及B。在另一实例中，如果列出项目A、B及C，那么短语“A、B及C中的至少一者”或“A、B或C中的至少一者”意味着仅A；或仅B；仅C；A及B(排除C)；A及C(排除B)；B及C(排除A)；或A、B及C的全部。项目A可包含单个元件或多个元件。项目B可包含单个元件或多个元件。项目C可包含单个元件或多个元件。
在具体实施方式及权利要求书中，在关于碳数的表述即大写字母“C”后面的数字，例如“C 1-C 10”、“C 3-C 10”等中，在“C”之后的数字例如“1”、“3”或“10”表示具体官能团中的碳数。即，官能团分别可包括1-10个碳原子和3-10个碳原子。例如，“C 1-C 4烷基”或“C 1-4烷基”是指具有1-4个碳原子的烷基，例如CH 3-、CH 3CH 2-、CH 3CH 2CH 2-、(CH 3) 2CH-、CH 3CH 2CH 2CH 2-、 CH 3CH 2CH(CH 3)-或(CH 3) 3C-。
术语“烷基”预期是具有1至20个、1至18个、1至16个、1至14个、1至12个、1至10个、1至8个、1至6个、1至4个或3至5个碳原子的直链饱和烃结构。“烷基”还预期是具有3至20个、3至18个、3至16个、3至14个、3至12个、3至10个、3至8个、3至6个或3至5个碳原子的支链或环状烃结构。当指定具有具体碳数的烷基时，预期涵盖具有所述碳数的所有几何异构体；因此，例如，“丁基”意思是包括正丁基、仲丁基、异丁基、叔丁基和环丁基；“丙基”包括正丙基、异丙基和环丙基。烷基实例包括，但不限于甲基、乙基、正丙基、异丙基、环丙基、正丁基、异丁基、仲丁基、叔丁基、环丁基、正戊基、异戊基、新戊基、环戊基、甲基环戊基、乙基环戊基、正己基、异己基、环己基、正庚基、辛基、环丙基、环丁基、降冰片基等。另外，烷基可以是任选地被取代的。
术语“链烯基”是指可为直链或具支链且具有至少一个且通常1个、2个或3个碳碳双键的单价不饱和烃基团。除非另有定义，否则所述烯基通常含有2个到20个、2个到18个、2个到16个、2个到14个、2个到12个、2至10个、2至8个、2至6个或2至4个碳原子且包括(例如)-C 2-4烯基、-C 2-6烯基及-C 2-10烯基。代表性烯基包括(例如)乙烯基、正丙烯基、异丙烯基、正-丁-2-烯基、丁-3-烯基、正-己-3-烯基等。另外，链烯基可以是任选地被取代的。
术语“芳基”涵盖单环系统和多环系统。多环可以具有其中两个碳为两个邻接环(所述环是“稠合的”)共用的两个或更多个环，其中所述环中的至少一者是芳香族的，例如其它环可以是环烷基、环烯基、芳基、杂环和/或杂芳基。例如，芳基可为6-30个碳原子的芳基、6-24个碳原子的芳基、6-20个碳原子的芳基、6-16个碳原子的芳基、6-12个碳原子的芳基或6-10个碳原子的芳基。代表性芳基包括(例如)苯基、甲基苯基、丙基苯基、异丙基苯基、苯甲基和萘-1-基、萘-2-基等。另外，芳基可以是任选地被取代的。
术语“芳氧基”是指“-O-芳基”基团，其中芳基是如本文定义的。
术语“烷氧基”是指“-O-烷基”基团，其中烷基是如本文定义的。
当上述取代基经取代时，除另有说明的情况外，是经一个或多个卤素取代。
如本文所用，术语“卤素”涵盖氟(F)、氯(Cl)、溴(Br)及碘(I)，优选F或Cl。
电化学装置
本申请的电化学装置包括发生电化学反应的任何装置，它的具体实例包括所有种类的一次电池、二次电池、燃料电池、太阳能电池或电容器。特别地，该电化学装置是锂二次电池，包括锂金属二次电池、锂离子二次电池、锂聚合物二次电池或锂离子聚合物二次电池。在一些实施例中，本申请的电化学装置是具有能够吸留、放出金属离子的正极活性材料的正极以及具有能够吸留、放出金属离子的负极活性材料的负极的电化学装置。
在一些实施例中，本申请提供了一种电化学装置，其包括电解液、正极及负极，所述负极包括负极活性材料层，所述负极活性材料层包括负极活性材料，所述电解液包括氟代碳酸乙烯酯，其中所述电化学装置满足关系式：
0.5<R ct/R cp<1.5，且R ct和R cp均小于35毫欧姆，
其中R ct表示25摄氏度时50％荷电状态下的电荷转移阻抗，R cp表示25摄氏度时50％荷电状态下的浓差极化阻抗；且
0.005≤A/B≤0.1
其中，1g所述负极活性材料对应的所述氟代碳酸乙烯酯的质量为Ag，所述负极活性材料的比表面积为B m 2/g。
经发明人研究发现，当R ct/R cp范围在0.5<R ct/R cp<1.5，同时满足R ct及R cp均小于35毫欧姆(mΩ)时，有利于锂离子快速通过固体电解质界面膜(SEI)进入到负极活性材料层，同时锂离子在负极活性材料层中的扩散也较快，能够实现锂离子电池的超大倍率充电。
当R cp远大于R ct时，电解液在负极活性材料层中扩散的浓差极化成为锂离子电池大倍率充电的限制因素，即便R ct已经很小，由于电解液无法扩散至负极活性材料表面，锂离子电池也无法实现大倍率充电；
当R ct远大于R cp时，锂离子在负极活性材料表面的电荷转移成为限制因素。即便R cp已经很小，锂离子虽能够快速到达负极活性材料表面，但无法快速完成嵌入负极活性材料，导致锂离子在负极活性材料层表面沉积，大倍率充电下出现析锂，锂离子电池低温性能受限，无法具有优良的快充性能。
当R ct及R cp同时大于35毫欧姆时，锂离子扩散及电荷转移过程均受到限制，无法实现快充性能。
当氟代碳酸乙烯酯的质量和负极活性材料的比表面积满足上述关系时能进一步保证电解液的扩散和锂离子的传输，实现锂离子电池的快速充放电。
图1对锂离子电池传输过程中的R ct及R cp进行了分解。
在一些实施例中，所述R ct与所述R cp的比值R ct/R cp的范围为0.7至1.2。在一些实施例中，R ct/R cp的取值为约0.55、约0.6、约0.65、约0.7、约0.75、约0.8、约0.85、约0.9、约0.95、约1.0、约1.05、约1.1、约1.15、约1.2、约1.25、约1.3、约1.35、约1.4、或约1.45。在一些实施例中，R ct/R cp的取值为约0.54、约0.71、约0.92、约1.03、约1.15、约1.23、约1.37或约1.47。
在一些实施例中，所述A与所述B的比值A/B的取值范围为0.005至0.07。在一些实施例中，A/B的取值为约0.005、约0.006、约0.007、约0.008、约0.009、约0.01、约0.012、约0.014、约0.016、约0.018、约0.02、约0.022、约0.024、约0.026、约0.028、约0.03、约0.032、约0.034、约0.036、约0.038、约0.04、约0.042、约0.044、约0.046、约0.048、约0.05、约0.052、约0.054、约0.056、约0.058、约0.06、约0.062、约0.064、约0.066、约0.068、约0.07、约0.072、约0.074、约0.076、约0.078、约0.08、约0.082、约0.084、约0.086、约0.088、约0.09、约0.092、约0.094、约0.096、约0.098或约0.1。在一些实施例中，A/B的取值为约0.005、约0.0053、约0.0122、约0.04、约0.0636、约0.0889、约0.0917或约0.1。
在一些实施例中，所述A的取值范围为0.01至0.1，所述B的取值范围为1.0至2.0。
在一些实施例中，所述A的取值范围0.02至0.1。在一些实施例中，所述A的值为约0.01、约0.015、约0.02、约0.025、约0.03、约0.035、约0.04、约0.045、约0.05、约0.055、约0.06、约0.065、约0.07、约0.075、约0.08、约0.085、约0.09、约0.095或约0.1。在一些实施例中，所述A的值为约0.01、约0.0195、约0.02、约0.052、约0.07、约0.08、约0.09或约0.1。
在一些实施例中，所述B的取值范围为1.1至1.6。在一些实施例中，所述B的取值为约1.0、约1.1、约1.2、约1.3、约1.4、约1.5、约1.6、约1.7、约1.8、约1.9或约2.0。在一些实施例中，所述电解液包含式I化合物：
Figure PCTCN2020082435-appb-000004
其中，R 11选自氢、羟基、C 1-20烷基、C 1-20烷氧基、C 2-20链烯基、C 6-30芳基、或C 6-30 芳氧基；
R 12选自氢、C 1-20烷基、C 2-20链烯基、或C 6-30芳基。
经发明人研究发现，当电化学装置中进一步包含式1化合物时，能进一步改善电解液的扩散性能，进一步改善电化学装置的快速充放电性能。
其中，1g所述负极活性材料对应的所述式I化合物的质量为X g，X的取值范围为0.035至0.39。
在一些实施例中，R 11选自：氢，羟基，C 1-16烷基、C 1-12烷基、C 1-10烷基、C 1-8烷基、C 1-6烷基或C 1-4烷基，C 1-16烷氧基、C 1-12烷氧基、C 1-10烷氧基、C 1-8烷氧基、C 1-6烷氧基或C 1-4烷氧基，C 2-16链烯基、C 2-12链烯基、C 2-8链烯基、C 2-6链烯基或C 2-4链烯基，C 6-24芳基、C 6-20芳基、C 6-16芳基、C 6-12芳基或C 6-10芳基，或者C 6-24芳氧基、C 6-20芳氧基、C 6-16芳氧基、C 6-12芳氧基或C 6-10芳氧基。
在一些实施例中，R 11选自：氢，羟基，甲基、乙基、丙基、异丙基、丁基、异丁基、戊基或异戊基。
在一些实施例中，R 12选自：氢，C 1-16烷基、C 1-12烷基、C 1-10烷基、C 1-8烷基、C 1-6烷基或C 1-4烷基，C 2-16链烯基、C 2-12链烯基、C 2-8链烯基、C 2-6链烯基或C 2-4链烯基，或者C 6-24芳基、C 6-20芳基、C 6-16芳基、C 6-12芳基或C 6-10芳基。
在一些实施例中，R 12选自：氢，甲基、乙基、丙基、异丙基、丁基、异丁基、戊基或异戊基。
在一些实施例中，X的取值范围为0.05至0.3或0.09至0.25；在一些实施例中，X的取值为约0.04、约0.045、约0.05、约0.055、约0.06、约0.065、约0.07、约0.075、约0.08、约0.085、约0.09、约0.095、约0.1、约0.12、约0.14、约0.16、约0.18、约0.2、约0.22、约0.24、约0.26、约0.28、约0.3、约0.32、约0.34、约0.36、或约0.38。在一些实施例中，X的取值范围为约0.035、约0.093、约0.25、约0.32、或约0.39。
在一些实施例中，所述X与所述A满足如下关系式：0.67≤X/A≤20。当X/A比值在0.67至20的范围内时，电解液的粘度较低，在负极表面形成稳定的SEI膜，具有优异的快充性能和 良好的循环。
在一些实施例中，所述X与所述A的比值X/A的范围为1至20或5至20。在一些实施例中，所述X/A的值为约0.7、约0.8、约0.9、约1、约1.5、约2、约2.5、约3、约3.5、约4、约4.5、约5、约5.5、约6、约6.5、约7、约7.5、约8、约8.5、约9、约9.5、约10、约10.5、约11、约11.5、约12、约12.5、约13、约13.5、约14、约14.5、约15、约15.5、约16、约16.5、约17、约17.5、约18、约18.5、约19、约19.5或约20。在一些实施例中，X/A的值为约0.67、约1.79、约4.77、约12.82、约16.41或约20。
在一些实施例中，所述式I化合物包含下述化合物中的至少一种：乙酸甲酯、乙酸乙酯、乙酸丙酯、丙酸甲酯、丙酸乙酯、丙酸正丙酯、丙酸异丙酯、丙酸正丁酯、丙酸异丁酯、丙酸正戊酯、丙酸异戊酯、正丁酸乙酯、正丁酸正丙酯、异丁酸丙酯、正丁酸正戊酯、异丁酸正戊酯、正丁酸正丁酯、异丁酸异丁酯、或正戊酸正戊酯。
在一些实施例中，所述式I化合物选自乙酸乙酯或丙酸乙酯中的至少一种。
在一些实施例中，所述X与所述负极活性材料层的孔隙率P满足如下关系式：0.1≤X/P≤3，其中所述P的取值范围为0.13至0.35。
在一些实施例中，所述X与所述P的比值X/P取值范围为0.3至3；在一些实施例中，X/P的取值范围为约0.3、约0.5、约0.7、约0.9、约1.1、约1.3、约1.5、约1.7、约1.9、约2.1、约2.3、约2.5、约2.7、约2.9或约3.0。在一些实施例中，X/P的取值范围为约0.1、约0.3、约1.0、约1.78、或约3。
在一些实施例中，所述P的取值为约0.13、约0.15、约0.17、约0.19、约0.21、约0.23、约0.25、约0.27、约0.29、约0.31、约0.33或约0.35。在一些实施例中，所述P的取值为约0.13、约0.18、约0.25、约0.31或约0.35。
在一些实施例中，所述电解液还包含碳酸亚乙烯酯，其中1g所述负极活性材料对应的所述碳酸亚乙烯酯的质量为Cg，所述B和所述C满足如下关系式：0.001≤C/B≤0.03。
在一些实施例中，所述C与所述B的比值C/B的取值范围是0.001至0.02。在一些实施例中，C/B的取值是约0.001、约0.0015、约0.002、约0.0025、约0.003、约0.0035、约0.004、约0.0045、约0.005、约0.0055、约0.006、约0.0065、约0.007、约0.0075、约0.008、约0.0085、约0.009、约0.0095、约0.01、约0.015、约0.02、约0.025或约0.03。在一些实施例中，C/B的取值是约0.001、 约0.00125、约0.01875、约0.0025或约0.003。当C/B比值在上述范围时，电化学装置中碳酸亚乙烯酯在负极活性材料表面的分解量及分解速度在适宜范围内，不会形成过多高阻抗LiF，使电化学装置的快充性能和循环性能得到进一步提升。
在一些实施例中，其中所述式I化合物包含丙酸乙酯，1g所述负极活性材料对应的所述丙酸乙酯的质量为D g，且所述C和所述D满足如下关系式：1≤D/C≤240。
在一些实施例中，所述D与所述C的比值D/C的取值范围是1至200、1至100、1至50或1至20。在一些实施例中，D/C的取值是约2、约4、约6、约8、约10、约12、约14、约16、约18、约20、约30、约40、约50、约60、约70、约80、约90、约100、约110、约120、约130、约140、约150、约160、约170、约180或约190。在一些实施例中，D/C的取值是约1、约1.5、约2、约2.5、约3、约3.5或约4.5。当D/C的比值在上述范围时，能进一步改善电化学装置的快充性能。
在一些实施例中，其中所述电解液进一步包含式II化合物或式III化合物中的至少一者：
Figure PCTCN2020082435-appb-000005
其中，R 21及R 22各自独立选自未经取代或经氟取代的C 1-5烷基，且R 21及R 22中的至少一者含氟；
R 31及R 32各自独立选自未经取代或经氟取代的C 1-20烷基，且R 31及R 32中的至少一者含氟，Y选自-O-或
Figure PCTCN2020082435-appb-000006
在一些实施例中，R 21及R 22各自独立选自未经取代或经一个或多个氟取代的C 1-3烷基，且R 21及R 22中的至少一者含氟。在一些实施例中，R 21及R 22各自独立选自经一个或多个氟取代的下述基团：甲基、乙基、丙基。在一些实施例中，R 21及R 22各自独立选自-CH 3、-CH 2F、-CHF 2、-CF 3、-CH 2CH 3、-CH 2CH 2F、-CH 2CHF 2、-CH 2CF 3、-CHFCH 3、-CF 2CH 3、-CHFCH 2F、或-CH 2CH 2CH 3。
在一些实施例中，R 31及R 32各自独立选自未经取代或经氟取代的下述基团：C 1-16烷基、C 1-12烷基、C 1-8烷基、C 1-6烷基或C 1-4烷基，且R 31及R 32中的至少一者含氟。在一些实施例中， R 31及R 32各自独立选自经一个或多个氟取代的下述基团：甲基、乙基、丙基。在一些实施例中，R 31及R 32各自独立选自-CH 2F、-CHF 2、-CH 2CH 2F、-CH 2CHF 2、-CH 2CF 3、-CHFCH 3、-CF 2CH 3、-CHFCH 2F、-CF 2CHF 2、-CF 3、-CF 2CF 3、-CF 2CF 2CF 3或-CF(CF 3) 2。
在一些实施例中，1g所述负极活性材料对应的所述式II化合物的质量为0.015g至0.15g。
在一些实施例中，1g所述负极活性材料对应的所述式II化合物的质量为0.02g至0.1g。在一些实施例中，1g所述负极活性材料对应的所述式II化合物的质量为约0.015g、约0.02g、约0.025g、约0.03g、约0.035g、约0.04g、0.045g、约0.05g、约0.055g、约0.06g、约0.065g、约0.07g、0.075g、约0.08g、约0.085g、约0.09g、约0.095g、约0.1g、约0.11g、约0.12g、约0.13g、约0.14g或约0.15g。在一些实施例中，1g所述负极活性材料对应的所述式II化合物的质量为约0.015g、约0.037g、约0.076g、约0.098g、约0.13g或约0.15g。
在一些实施例中，其中1g所述负极活性材料对应的所述式III化合物的质量为0.015g至0.065g。
在一些实施例中，1g所述负极活性材料对应的所述式III化合物的质量为0.02g至0.6g。在一些实施例中，1g所述负极活性材料对应的所述式II化合物的质量为约0.02g、约0.04g、约0.06g、约0.08g、约0.1g、0.15g、约0.2g、0.25g、约0.3g、0.35g、约0.4g、0.45g、约0.5g、0.55g、约0.6g、或0.65g。在一些实施例中，1g所述负极活性材料对应的所述式III化合物的质量为约0.015g、约0.022g、约0.0036g、约0.053g或约0.065g。
在一些实施例中，所述式II化合物包含下述化合物中的至少一种：二氟乙酸甲酯、二氟乙酸乙酯、二氟乙酸丙酯、二氟丙酸甲酯、二氟丙酸乙酯、二氟丙酸丙酯、氟乙酸甲酯、氟乙酸乙酯、氟乙酸丙酯、三氟乙酸甲酯、三氟乙酸乙酯、或三氟乙酸丙酯；在一些实施例中，所述式II化合物包含二氟乙酸乙酯。
在一些实施例中，所述式III化合物包含下述化合物中的至少一种：1,1,2,2-四氟乙基-2,2,2-三氟乙基醚、或全氟(2-甲基-3-戊酮)。在一些实施例中，所述式III化合物包含1,1,2,2-四氟乙基-2,2,2-三氟乙基醚。
在一些实施例中，所述电解液进一步包括锂盐和有机溶剂。
在一些实施例中，所述锂盐选自无机锂盐和有机锂盐中的一种或多种。在一些实施例中，所述锂盐含有氟元素、硼元素或磷元素中的至少一种。在一些实施例中，所述锂盐包含：六氟 磷酸锂(LiPF 6)、双三氟甲烷磺酰亚胺锂(简写为LiTFSI)、双(氟磺酰)亚胺锂(简写为LiFSI)、双草酸硼酸(简写为LiBOB)、二氟草酸硼酸(简写为LiDFOB)、六氟砷酸锂(LiAsF 6)、高氯酸锂(LiClO 4)、或三氟甲磺酸锂(LiCF 3SO 3)中的至少一种。
在一些实施例中，所述锂盐的浓度为0.5mol/L至1.5mol/L。在一些实施例中，所述锂盐的浓度为0.8mol/L至1.2mol/L。
在一些实施例中，所述有机溶剂包含碳酸酯溶剂，碳酸酯溶剂包含环状碳酸酯及链状碳酸酯，所述环状碳酸酯选自碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、γ-丁内酯(BL)或碳酸丁烯酯中的至少一种；所述链状碳酸酯选自碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸甲乙酯(EMC)、碳酸丙乙酯中的至少一种。其中所述环状碳酸酯的量多于所述链状碳酸酯，所述的溶剂体系优选不含链状碳酸酯。
在一些实施例中，为进一步改善锂离子电池快充性能，本申请所述电解液具有一定特性：25℃时，电解液电导率≥7mS/cm，0℃时，电解液电导率≥4mS/cm；25℃时，电解液粘度≤6mPa·s，0℃时，电解液粘度≤9mPa·s；电解液25℃表面张力≤40mN/m。
当电解液具有较高的电导率、较低的粘度及较低的表面张力时，锂离子的传输速度更快，有利于实现锂离子电池的快充性能；当电解液电导率较低、粘度较大、表面张力较高时，锂离子传输受阻，不利于改善快速充放电性能。
负极
在根据本申请所述的电化学装置中，负极包括集流体和设置在集流体上的负极活性材料层。所述负极活性材料层包括负极活性材料，所述负极活性材料的具体种类均不受到具体的限制，可根据需求进行选择。
负极可以通过本领域公知的制备方法制备。例如，负极可以通过如下方法获得：在溶剂中将活性材料、导电材料和粘合剂混合，以制备活性材料组合物，并将该活性材料组合物涂覆在集流体上。
负极活性材料包括可逆地嵌入/脱嵌锂离子的材料。在一些实施例中，可逆地嵌入/脱嵌锂离子的材料包括碳材料。在一些实施例中，碳材料可以是在锂离子可充电电池中通常使用的任何基于碳的负极活性材料。在一些实施例中，碳材料包括、但不限于：结晶碳、非晶碳或它们 的混合物。结晶碳可以是无定形的、片形的、小片形的、球形的或纤维状的天然石墨或人造石墨。非晶碳可以是软碳、硬碳、中间相沥青碳化物、煅烧焦等。
在一些实施例中，负极活性材料包括、但不限于：锂金属、结构化的锂金属、天然石墨、人造石墨、中间相微碳球(简写为MCMB)、硬碳、软碳、硅、含有硅或硅氧材料、硅-碳复合物或其任意组合。
在一些实施例中，所述负极活性材料由单颗粒及二次颗粒搭配而成。图2给出了负极活性材料一次颗粒与二次颗粒示意图。
在一些实施例中，所述负极活性材料的原料包含A原料和B原料，A原料的单颗粒Dv50为3微米至10微米，B原料的单颗粒Dv50为2微米至10微米，经由造粒制成的二次颗粒的Dv50为5微米至20微米；其中原料A与原料B的添加比例为1:9至5:5。
在一些实施例中，所述负极活性材料的OI值(C004/C110—即负极活性材料004峰的峰面积与110峰的峰面积的比值)范围为8至15，这大大缩短了锂离子在负极活性材料的传输距离，降低锂离子电池的R cp，提高了锂离子的传输速率，改善快速充电的性能。
在一些实施例中，所述负极活性材料可进一步包含如下取向：
取向1的层面结构分布比例为6％至25％，取向2的层面结构分布比例为27％至65％，取向3的层面结构分布比例为5％至10％。以平行于集流体方向为平面方向，与集流体呈0度至20度倾斜角的颗粒为取向1，与集流体呈20度至70度倾斜角的颗粒为取向2，与集流体呈70度至90度倾斜角的颗粒为取向3。
在一些实施例中，所述负极活性材料的比表面积(BET)为1.0m 2/g至2.0m 2/g。
在一些实施例中，负极活性材料层可以包括粘合剂，并且可选地包括导电材料。粘合剂提高负极活性材料颗粒彼此间的结合和负极活性材料与集流体的结合。在一些实施例中，粘合剂包括但不限于：聚乙烯醇、羧甲基纤维素、羟丙基纤维素、二乙酰基纤维素、聚氯乙烯、羧化的聚氯乙烯、聚氟乙烯、含亚乙基氧的聚合物、聚乙烯吡咯烷酮、聚氨酯、聚四氟乙烯、聚偏1,1-二氟乙烯、聚乙烯、聚丙烯、丁苯橡胶、丙烯酸(酯)化的丁苯橡胶、环氧树脂、尼龙等。
在一些实施例中，导电材料包括、但不限于：基于碳的材料、基于金属的材料、导电聚合 物或它们的混合物。在一些实施例中，基于碳的材料选自天然石墨、人造石墨、碳黑、乙炔黑、科琴黑、碳纤维或其任意组合。在一些实施例中，基于金属的材料选自金属粉、金属纤维、铜、镍、铝、银。在一些实施例中，导电聚合物为聚亚苯基衍生物。
在根据本申请所述的电化学装置中，负极的集流体可以选自铜箔、镍箔、不锈钢箔、钛箔、泡沫镍、泡沫铜、覆有导电金属的聚合物基底和它们的组合。在一些实施例中，所述集流体包括铜箔。
正极
本申请的电化学装置中使用的正极的材料可以使用本领域公知的材料、构造和制造方法制备。在一些实施例中，可以采用US9812739B中记载的技术制备本申请的正极，其以全文引用的方式并入本申请中。
在一些实施例中，正极包括集流体和位于该集流体上的正极活性材料层，所述正极活性材料层包含正极活性材料。正极活性材料包括可逆地嵌入和脱嵌锂离子的至少一种锂化插层化合物。在一些实施例中，正极活性材料包括复合氧化物。在一些实施例中，该复合氧化物含有锂以及从钴、锰和镍中选择的至少一种元素。
在一些实施例中，正极活性材料选自钴酸锂、锰酸锂、镍酸锂、镍钴锰酸锂或镍钴铝酸锂中的一种或多种。
在一些实施例中，正极活性材料可以在其表面上具有涂层，或者可以与具有涂层的另一化合物混合。该涂层可以包括从涂覆元素的氧化物、涂覆元素的氢氧化物、涂覆元素的羟基氧化物、涂覆元素的碳酸氧盐和涂覆元素的羟基碳酸盐中选择的至少一种涂覆元素化合物。用于涂层的化合物可以是非晶的或结晶的。
在一些实施例中，在涂层中含有的涂覆元素可以包括Mg、Al、Co、K、Na、Ca、Si、Ti、V、Sn、Ge、Ga、B、As、Zr或它们的任意组合。可以通过任何方法来施加涂层，只要该方法不对正极活性材料的性能产生不利影响即可。例如，该方法可以包括对本领域公知的任何涂覆方法，例如喷涂、浸渍等。
正极活性材料层还包括粘合剂，并且可选地包括导电材料。粘合剂提高正极活性材料颗粒彼此间的结合，并且还提高正极活性材料与集流体的结合。
在一些实施例中，粘合剂包括，但不限于：聚乙烯醇、羟丙基纤维素、二乙酰基纤维素、聚氯乙烯、羧化的聚氯乙烯、聚氟乙烯、含亚乙基氧的聚合物、聚乙烯吡咯烷酮、聚氨酯、聚四氟乙烯、聚偏1,1-二氟乙烯、聚乙烯、聚丙烯、丁苯橡胶、丙烯酸(酯)化的丁苯橡胶、环氧树脂、尼龙等。
在一些实施例中，导电材料包括，但不限于：基于碳的材料、基于金属的材料、导电聚合物和它们的混合物。在一些实施例中，基于碳的材料选自天然石墨、人造石墨、碳黑、乙炔黑、科琴黑、碳纤维或其任意组合。在一些实施例中，基于金属的材料选自金属粉、金属纤维、铜、镍、铝、银。在一些实施例中，导电聚合物为聚亚苯基衍生物。
在一些实施例中，集流体可以是铝，但不限于此。
正极可以通过本领域公知的制备方法制备。例如，正极可以通过如下方法获得：在溶剂中将活性材料、导电材料和粘合剂混合，以制备活性材料组合物，并将该活性材料组合物涂覆在集流体上。在一些实施例中，溶剂可以包括N-甲基吡咯烷酮等，但不限于此。
在一些实施例中，正极通过在集流体上使用包括锂过渡金属系化合物粉体和粘结剂的正极活性材料层形成正极材料而制成。
在一些实施例中，正极活性材料层通常可以通过如下操作来制作：将正极材料和粘结剂(根据需要而使用的导电材料和增稠剂等)进行干式混合而制成片状，将得到的片压接于正极集流体，或者使这些材料溶解或分散于液体介质中而制成浆料状，涂布在正极集流体上并进行干燥。在一些实施例中，正极活性材料层中的材料包括任何本领域公知的材料。
隔离膜
在一些实施例中，本申请的电化学装置在正极与负极之间设有隔离膜以防止短路。本申请的电化学装置中使用的隔离膜的材料和形状没有特别限制，其可为任何现有技术中公开的技术。在一些实施例中，隔离膜包括由对本申请的电解液稳定的材料形成的聚合物或无机物等。
例如隔离膜可包括基材层和表面处理层。基材层为具有多孔结构的无纺布、膜或复合膜，基材层的材料选自聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯和聚酰亚胺中的至少一种。具体的，可选用聚丙烯多孔膜、聚乙烯多孔膜、聚丙烯无纺布、聚乙烯无纺布或聚丙烯-聚乙烯-聚丙烯多孔复合膜。基材层可以为一层或多层，当基材层为多层时，不同的基材层的聚合物的组成可 以相同，也可以不同，重均分子量不同；当基材层为多层时，不同的基材层的聚合物的闭孔温度不同。
在一些实施例中，基材层的至少一个表面上设置有表面处理层，表面处理层可以是聚合物层或无机物层，也可以是混合聚合物与无机物所形成的层。
在一些实施例中，无机物层包括无机颗粒和粘结剂，无机颗粒选自氧化铝、氧化硅、氧化镁、氧化钛、二氧化铪、氧化锡、二氧化铈、氧化镍、氧化锌、氧化钙、氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙和硫酸钡中的一种或几种的组合。粘结剂选自聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯和聚六氟丙烯中的一种或几种的组合。聚合物层中包含聚合物，聚合物的材料包括聚酰胺、聚丙烯腈、丙烯酸酯聚合物、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚偏氟乙烯或聚(偏氟乙烯-六氟丙烯)中的至少一种。
应用
本申请实施例的电化学装置具有提高循环性能及在过放电条件下的高温稳定特性，适合使用在各种电子设备中。
本申请的电化学装置的用途没有特别限定，可以用于公知的各种用途。例如笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池或锂离子电容器等。
实施例
以下，举出实施例和比较例对本申请进一步具体地进行说明，但只要不脱离其主旨，则本申请并不限定于这些实施例。
一.锂离子电池的制备
(1)负极的制备
负极活性材料包括第一颗粒及第二颗粒，其中所述第一颗粒为二次颗粒，所述二次颗粒包含不少于2个一次颗粒。所述二次颗粒中的一次颗粒的Dv50为2微米至10微米，且所述二次颗粒的Dv50为5微米至20微米。所述第二颗粒为一次颗粒，所述第二颗粒的Dv50为3微米至10微米。
通过控制制备时的石墨化温度及第一颗粒与第二颗粒配比得到不同比表面积及孔隙率的负极活性材料，石墨化温度范围为2500至3200摄氏度。示例的比表面积(B)及孔隙率(P)如下面表中所示。
将OI值(C004/C110)为8至15的负极活性材料人造石墨、粘结剂丁苯橡胶(简写为SBR)、增稠剂羧甲基纤维素钠(简写为CMC)按照重量比97.4:1.2:1.4在适量的去离子水溶剂中充分搅拌混合，使其形成均匀的负极浆料；将此浆料涂覆于负极集流体铜箔上，烘干、冷压，得到负极。
(2)正极的制备
将正极活性材料钴酸锂(分子式为LiCoO 2)、导电剂乙炔黑、粘结剂聚偏二氟乙烯(简写为PVDF)按重量比96:2:2在适量的N-甲基吡咯烷酮(简写为NMP)溶剂中充分搅拌混合，使其形成均匀的正极浆料；将此浆料涂覆于正极集流体铝箔上，烘干、冷压，得到正极。
(3)电解液的制备
电解液的制备：在含水量<10ppm的氩气气氛手套箱中，将碳酸乙烯酯(EC)、碳酸丙烯酯(PC)及碳酸二乙酯(DEC)按照3:3:4的质量比混合均匀得到非水溶剂，再将充分干燥的锂盐LiPF 6溶解于上述非水溶剂，加入特定种类和量的添加剂(添加的物质种类和量如下表中所示，电解液中各添加剂的含量是以1克负极活性材料需要该添加剂的质量(单位：克)计算。电解液中LiPF 6的浓度为约1mol/L。
(4)隔离膜的制备
选用约9微米厚的聚乙烯隔离膜。
(5)锂离子电池的制备
将正极、隔离膜、负极按顺序叠好，使隔离膜处于正极和负极之间起到隔离的作用，然后卷绕得到电极组件；将电极组件置于外包装铝塑膜中，将上述制备好的电解液注入到干燥后的电池中，经过真空封装、静置、化成、整形等工序，即完成锂离子电池的制备。
二.锂离子电池性能测试
(1)电化学阻抗谱(EIS-R ct测试)
制作三电极锂离子电池：将正极、隔离膜、负极按顺序叠好，使隔离膜处于正极和负极之间起到隔离的作用；在靠近负极隔离膜一侧焊上一条细铜丝，并用另一小片隔离膜将铜丝覆盖，使其不会与负极接触即可；然后卷绕得到电极组件，将电极组件置于外包装铝塑膜中，将上述制备好的电解液注入到干燥后的电池中，经过真空封装、静置、化成、整形等工序，即完成三电极锂离子电池的制备。
将制备好的三电极锂离子电池置于电化学工作站，按照工作电极与参比电极的顺序接好。对电化学体系施加5mV的振幅、500KHz-30mHz频率的正弦波交流信号，获得频域范围内相应电信号反馈，根据如图3A所示的模型模拟得到锂离子电池的EIS曲线(如图3B所示)。其中第一个半圆弧与X轴的右交点为电荷转移阻抗值，即实施例中的R ct，本申请所述的R ct为50％SOC(荷电状态，state of charge)状态下的值，单位为毫欧姆。
(2)直流阻抗测试(DCR-R cp测试)
以1.5C的电流将锂离子电池恒流充电至4.4V，再恒压充电至0.05C。静置30分钟；以0.1C的电流放电10秒(0.1秒取点一次，记录对应电压值U1)，以1C的电流放电360秒(0.1秒取点一次，记录对应电压值U2)。重复充放电步骤5次。“1C”是在1小时内将电池容量完全放完的电流值。
按如下公式计算得出直流阻抗(DCR)：R＝(U2-U1)/(1C-0.1C)。所得出的DCR即为本申请的浓差极化阻抗，其为50％SOC(荷电状态，state of charge)状态下的值，即实施例中的R cp，单位为毫欧姆。
(3)析锂测试
将锂离子电池在25℃下以1.5C充电至4.4V，4.4V下恒压充电至0.05C，再以1.0C恒流 放电至3.0V，循环30次，拆解观察析锂程度。未发现析锂或析锂面积<2％在此称为不析锂；析锂面积在2％至20％之间称为轻微析锂；析锂面积＞20％称为严重析锂。
(4)温升测试
在25℃温度下，将锂离子电池以0.5C的电流恒流充电至4.4V，再恒压充电至0.05C，静置60分钟；然后以0.5C的电流将锂离子电池恒流放电至3V，静置60分钟；以8C的电流将锂离子电池恒流充电至4.4V，再恒压充电至0.05C，得到8C电流充电过程中的最高温度，最高温度减去测试温度25℃，得到8C充电时的温度升高值(简称温升)，单位为摄氏度。
(5)45℃循环测试
将电池放至45℃恒温箱中，以恒定电流1.5C充电至4.4V，4.4V下恒压充电至0.05C，再以1.0C恒流放电至3.0V，此次为一个充放电循环过程，按上述方式进行800次循环充放电测试，监控容量保持率。
容量保持率＝剩余放电容量/初始放电容量x100％。
(6)电导率测试
选用DDS-307雷磁电导率仪标准测试方法进行测试。
(7)粘度测试
选用DV2T粘度计标准测试方法进行测试。
(8)表面张力测试
选用BZY202-表面张力仪标准方法。
A.按照上述方法制备实施例1至8和对比例1至3的锂离子电池，测试结果请见表1。
表1
Figure PCTCN2020082435-appb-000007
从表1可以看出，实施例1至实施例8均满足要求(1)“0.5<R ct/R cp<1.5且R ct和R cp均小于35毫欧姆”及要求(2)“0.005≤A/B≤0.1”；而对比例1至对比例3不满足上述要求(1)及要求(2)。因而，在循环、温升及析锂这三项测试中，与对比例1至对比例3相比，实施例1至实施例8明显取得了更好的技术效果；其中，实施例2至实施例5在上述三项测试中综合改善效果尤为显著。
B.按照上述方法制备实施例9至15的锂离子电池，测试结果请见表2。
表2
Figure PCTCN2020082435-appb-000008
从表2可以看出，实施例9至实施例14在含有氟代碳酸乙烯酯(FEC)的电解液中进一步加入适量的式I化合物(例如乙酸乙酯)X g，使得在满足要求(1)“0.5<R ct/R cp<1.5且R ct和R cp均小于35毫欧姆”及要求(2)“0.005≤A/B≤0.1”的同时，进一步满足要求(3)“0.67≤X/A≤20”,因而，在循环、温升及析锂这三项测试中，与满足要求(1)和要求(2)而不满足要求(3)的实施例2至实施例4及实施例15相比，实施例9至实施例14明显取得了更好的技术效果；其中，实施例10至实施例13在上述三项测试中综合改善效果尤为显著。
C.按照上述方法制备实施例16至21的锂离子电池，测试结果请见表3。
表3
Figure PCTCN2020082435-appb-000009
从表3可以看出，实施例16至实施例20在满足要求(1)“0.5<R ct/R cp<1.5且R ct和R cp均小于35毫欧姆”、要求(2)“0.005≤A/B≤0.1”、及要求(3)“0.67≤X/A≤20”的基础上进一步满足要求(4)“0.1≤X/P≤3，其中所述P的取值范围为0.13至0.35”；因而，在循环、温升及析锂这三项测试中，与满足要求(1)至要求(3)而不满足要求(4)的实施例9至实施例13及实施例21相比，实施例16至实施例20明显取得了更好的技术效果。
D.按照上述方法制备实施例22至27的锂离子电池，测试结果请见表4。
表4
Figure PCTCN2020082435-appb-000010
从表4可以看出，实施例22至实施例26是在含有氟代碳酸乙烯酯(FEC)及式I化合物(例如乙酸乙酯)的电解液中进一步加入碳酸亚乙烯酯(VC)，使得在满足要求(1)“0.5<R ct/R cp<1.5且R ct和R cp均小于35毫欧姆”、要求(2)“0.005≤A/B≤0.1”及要求(3)“0.67≤X/A≤20”的基础上的同时，进一步满足要求(5)“0.001≤C/B≤0.03”；因而，在循环、温升及析锂这三项测试中，与满足要求(1)至要求(3)而不满足要求(5)的实施例10及实施例27相比，实施例22至实施例26明显取得了更好的技术效果。
E.按照上述方法制备实施例28至34的锂离子电池，其中实施例34中乙酸乙酯与丙酸丙酯的质量比为1:1，测试结果请见表5。
表5
Figure PCTCN2020082435-appb-000011
从表5可以看出，实施例28至实施例34的电解液中除了含有氟代碳酸乙烯酯(FEC)、 乙酸乙酯、碳酸亚乙烯酯(VC)外还含有丙酸乙酯，使得在满足要求(1)“0.5<R ct/R cp<1.5且R ct和R cp均小于35毫欧姆”、要求(2)“0.005≤A/B≤0.1”、要求(3)“0.67≤X/A≤20”及要求(5)“0.001≤C/B≤0.03”的基础上，进一步满足要求(6)“1≤D/C≤240”；因而，在循环、温升及析锂这三项测试中，与满足要求(1)至要求(3)以及要求(5)而不满足要求(6)的实施例23相比，实施例28至实施例34明显取得了更好的技术效果。
F.按照上述方法制备实施例35至45的锂离子电池，测试结果请见表6。
表6
Figure PCTCN2020082435-appb-000012
注：“/”代表未加入
从表6可以看出，实施例35至实施例40中是在含有氟代碳酸乙烯酯(FEC)及式I化合物(例如乙酸乙酯)的电解液中进一步加入适量的式II化合物(例如二氟乙酸乙酯)；在循环及温升测试中，与未加入式II化合物的实施例10相比，实施例35至实施例40取得了更好的技术效果。
实施例41至实施例45中是在含有氟代碳酸乙烯酯(FEC)及式I化合物(例如乙酸乙酯)的电解液中进一步加入适量的式III化合物(例如1,1,2,2-四氟乙基-2,2,2-三氟乙基醚)；在循环及温升测试中，与未加入式III化合物的实施例10相比，实施例41至实施例45取得了更好的技术效果。
以上所述，仅是本申请的几个实施例，并非对本申请做任何形式的限制，虽然本申请以较佳实施例揭示如上，然而并非用以限制本申请，任何熟悉本专业的技术人员，在不脱离本申请技术方案的范围内，利用上述揭示的技术内容做出些许的变动或修饰均等同于等效实施案例，均属于技术方案范围内。
整个说明书中对“一些实施例”、“部分实施例”、“一个实施例”、“另一举例”、“举例”、“具体举例”或“部分举例”的引用，其所代表的意思是在本申请中的至少一个实施例或举例包含了该实施例或举例中所描述的特定特征、结构、材料或特性。因此，在整个说明书中的各处所出现的描述，例如：“在一些实施例中”、“在实施例中”、“在一个实施例中”、“在另一个举例中”，“在一个举例中”、“在特定举例中”或“举例”，其不必然是引用本申请中的相同的实施例或示例。此外，本文中的特定特征、结构、材料或特性可以以任何合适的方式在一个或多个实施例或举例中结合。
尽管已经演示和描述了说明性实施例，本领域技术人员应该理解上述实施例不能被解释为对本申请的限制，并且可以在不脱离本申请的精神、原理及范围的情况下对实施例进行改变，替代和修改。

Claims (13)

  1. 一种电化学装置，其包括电解液、正极及负极，所述负极包括负极活性材料层，所述负极活性材料层包括负极活性材料，所述电解液包括氟代碳酸乙烯酯，其中所述电化学装置满足关系式：
    0.5<R ct/R cp<1.5，且R ct和R cp均小于35毫欧姆，
    其中R ct表示25摄氏度时50％荷电状态下的电荷转移阻抗，R cp表示25摄氏度时50％荷电状态下的浓差极化阻抗；且
    0.005≤A/B≤0.1，
    其中，1g所述负极活性材料对应的所述氟代碳酸乙烯酯的质量为Ag，所述负极活性材料的比表面积为Bm 2/g。
  2. 根据权利要求1所述的电化学装置，其中所述A的取值范围为0.01至0.1，所述B的取值范围为1.0至2.0。
  3. 根据权利要求1所述的电化学装置，其中所述电解液包含式I化合物：
    Figure PCTCN2020082435-appb-100001
    其中，R 11选自氢、羟基、C 1-20烷基、C 1-20烷氧基、C 2-20链烯基、C 6-30芳基、或C 6-30芳氧基；
    R 12选自氢、C 1-20烷基、C 2-20链烯基、或C 6-30芳基；
    其中，1g所述负极活性材料对应的所述式I化合物的质量为Xg，X的取值范围为0.035至0.39。
  4. 根据权利要求3所述的电化学装置，其中所述X与所述A满足如下关系式：
    0.67≤X/A≤20。
  5. 根据权利要求3所述的电化学装置，其中所述式I化合物包含下述化合物中的至少一种：乙酸甲酯、乙酸乙酯、乙酸丙酯、丙酸甲酯、丙酸乙酯、丙酸正丙酯、丙酸异丙酯、丙酸正丁酯、丙酸异丁酯、丙酸正戊酯、丙酸异戊酯、正丁酸乙酯、正丁酸正丙酯、异丁酸丙酯、正丁酸正戊酯、异丁酸正戊酯、正丁酸正丁酯、异丁酸异丁酯、或正戊酸正戊酯。
  6. 根据权利要求3所述的电化学装置，其中所述X与所述负极活性材料层的孔隙率P满足如下关系式：0.1≤X/P≤3，其中所述P的取值范围为0.13至0.35。
  7. 根据权利要求1-3中任一项权利要求所述的电化学装置，其中所述电解液还包含碳酸亚乙烯酯，其中1g所述负极活性材料对应的所述碳酸亚乙烯酯的质量为Cg，所述B和所述C满足如下关系式：0.001≤C/B≤0.03。
  8. 根据权利要求7所述的电化学装置，其中所述式I化合物包含丙酸乙酯，1g所述负极活性材料对应的所述丙酸乙酯的质量为Dg，且所述C和所述D满足如下关系式：1≤D/C≤240。
  9. 根据权利要求1-3中任一项权利要求所述的电化学装置，其中所述电解液进一步包含式II化合物或式III化合物中的至少一者：
    Figure PCTCN2020082435-appb-100002
    其中，R 21及R 22各自独立选自未经取代或经氟取代的C 1-5烷基，且R 21及R 22中的至少一者含氟；
    R 31及R 32各自独立选自未经取代或经氟取代的C 1-20烷基，且R 31及R 32中的至少一者含氟，Y选自-O-或
    Figure PCTCN2020082435-appb-100003
  10. 根据权利要求9所述的电化学装置，其中1g所述负极活性材料对应的所述式II化合物的质量为0.015g至0.15g。
  11. 根据权利要求9所述的电化学装置，其中1g所述负极活性材料对应的所述式III化合物的质量为0.015g至0.065g。
  12. 根据权利要求9中所述的电化学装置，其中
    所述式II化合物包含下述化合物中的至少一种：二氟乙酸甲酯、二氟乙酸乙酯、二氟乙酸丙酯、二氟丙酸甲酯、二氟丙酸乙酯、二氟丙酸丙酯、氟乙酸甲酯、氟乙酸乙酯、氟乙酸丙酯、三氟乙酸甲酯、三氟乙酸乙酯、或三氟乙酸丙酯；
    所述式III化合物包含下述化合物中的至少一种：1,1,2,2-四氟乙基-2,2,2-三氟乙基醚、或全氟(2-甲基-3-戊酮)。
  13. 一种电子装置，其包括根据权利要求1-12中任一项权利要求所述的电化学装置。
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