WO2022104590A1 - 电化学装置和包含其的电子装置 - Google Patents

电化学装置和包含其的电子装置 Download PDF

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WO2022104590A1
WO2022104590A1 PCT/CN2020/129757 CN2020129757W WO2022104590A1 WO 2022104590 A1 WO2022104590 A1 WO 2022104590A1 CN 2020129757 W CN2020129757 W CN 2020129757W WO 2022104590 A1 WO2022104590 A1 WO 2022104590A1
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Prior art keywords
electrochemical device
electrolyte
propionate
layer
tab
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PCT/CN2020/129757
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English (en)
French (fr)
Inventor
刘建禹
栗文强
郑建明
徐帅
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宁德新能源科技有限公司
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Priority to PCT/CN2020/129757 priority Critical patent/WO2022104590A1/zh
Priority to CN202080020239.9A priority patent/CN113678315A/zh
Priority to JP2023530313A priority patent/JP2023550440A/ja
Priority to CN202311463358.3A priority patent/CN117374525A/zh
Priority to EP20961881.8A priority patent/EP4224587A1/en
Publication of WO2022104590A1 publication Critical patent/WO2022104590A1/zh
Priority to US18/193,995 priority patent/US20230246156A1/en

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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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • 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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • 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
    • 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
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/102—Primary casings; Jackets or wrappings characterised by their shape or physical structure
    • H01M50/105—Pouches or flexible bags
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/10—Primary casings; Jackets or wrappings
    • H01M50/172—Arrangements of electric connectors penetrating the casing
    • H01M50/174—Arrangements of electric connectors penetrating the casing adapted for the shape of the cells
    • H01M50/178—Arrangements of electric connectors penetrating the casing adapted for the shape of the cells for pouch or flexible bag cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/534—Electrode connections inside a battery casing characterised by the material of the leads or tabs
    • 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
    • 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
    • H01M2300/0048—Molten electrolytes used at high temperature
    • H01M2300/0051—Carbonates
    • 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

Definitions

  • the present application relates to the field of energy storage, and in particular, to an electrochemical device and an electronic device including the same, in particular to a lithium ion battery.
  • Electrochemical devices such as lithium-ion batteries, as the working power supply of electronic products, have the characteristics of high energy density, no memory effect, and high working voltage, and are gradually replacing traditional Ni-Cd and MH-Ni batteries.
  • people's requirements for lithium-ion batteries are constantly increasing.
  • the development of lithium-ion batteries with good cycle stability, low impedance, less self-discharge and safety is one of the main needs of the market.
  • the embodiments of the present application provide an electrochemical device in an attempt to solve at least one problem in the related art to some extent.
  • the embodiments of the present application also provide an electronic device including the electrochemical device.
  • the present application provides an electrochemical device including an electrode and an electrolyte.
  • the electrode includes a current collector, an active material layer on at least one surface of the current collector, a tab on the current collector; and a tab protection layer on the tab .
  • the tab protection layer includes a first polymer layer, and the melting point of the first polymer layer is T A °C, 110 ⁇ TA ⁇ 136.5.
  • the electrolyte includes ethylene carbonate and propylene carbonate; wherein based on the weight of the electrolyte, the sum of the weight percentages of the ethylene carbonate and the propylene carbonate is Y%, and Y is 20-80; and Y and T A satisfy: 0.147 ⁇ Y/ TA ⁇ 0.7.
  • the tab protection layer further includes a second polymer layer, the melting point of the second polymer layer is T B °C, T B ⁇ 160, and T A and T B satisfy: 0 ⁇ T B - T A ⁇ 50.
  • the first polymer layer comprises at least one of maleic anhydride graft-modified polypropylene, acidified polyolefin resin, or polyethylene.
  • the second polymer layer includes at least one of polypropylene or polypropylene modified resins.
  • the electrolyte further includes propionate, wherein the weight percentage of the propionate is 10%-60% based on the weight of the electrolyte.
  • the propionate comprises methyl propionate, ethyl propionate, propyl propionate, butyl propionate, amyl propionate, methyl fluoropropionate, ethyl fluoropropionate , at least one of propyl fluoropropionate, butyl fluoropropionate or pentyl fluoropropionate, wherein fluorine means that at least one hydrogen atom is replaced by a fluorine atom.
  • the electrolyte further includes a trimethyl acetate compound.
  • the structural formula of the trimethyl acetate compound is:
  • R is C 1 -C 10 alkyl, C 2 -C 10 alkenyl, C 1 -C 10 haloalkyl, C 2 -C 10 haloalkenyl, halogen, aryl or amide.
  • the trimethyl acetate compound includes at least one of methyl trimethyl acetate or ethyl trimethyl acetate.
  • the electrolyte further comprises at least one of a dinitrile compound or a trinitrile compound,
  • the dinitrile compound includes at least one of the following compounds:
  • the trinitrile compound includes at least one of the following compounds:
  • 1,3,5-pentanetricarbonitrile 1,2,3-propanetricarbonitrile, 1,2,6-hexanetricarbonitrile, 1,3,6-hexanetricarbonitrile, 1,2,3-tris(2- Cyanoethoxy)propane, 1,2,4-tris(2-cyanoethoxy)butane or 1,2,5-tris(cyanoethoxy)pentane.
  • the present application provides an electronic device including an electrochemical device according to an embodiment of the present application.
  • the electrochemical devices provided by the present application have improved hot box performance and high temperature storage performance.
  • FIG. 1 shows a packaging structure of a tab and a packaging bag in an embodiment of the present application.
  • FIG. 2 shows the structure of the tab protection layer in an embodiment of the present application.
  • FIG. 3 shows the structure of the tab protection layer in another embodiment of the present application.
  • FIG. 4 shows the battery structure and the position of the tab protection layer in an embodiment of the present application.
  • a list of items joined by the terms "one of,” “one of,” “one of,” or other similar terms can mean that any of the listed items one.
  • the phrase “one of A and B” means A only or B only.
  • the phrase “one of A, B, and C” means A only; B only; or C only.
  • Item A may contain a single element or multiple elements.
  • Item B may contain a single element or multiple elements.
  • Item C may contain a single element or multiple elements.
  • a list of items joined by the terms "at least one of,” “at least one of,” “at least one of,” or other similar terms may mean the listed items any combination of .
  • the phrase “at least one of A and B” means A only; B only; or A and B.
  • the phrase "at least one of A, B, and C” means A only; or B only; C only; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C.
  • Item A may contain a single element or multiple elements.
  • Item B may contain a single element or multiple elements.
  • Item C may contain a single element or multiple elements.
  • alkyl is intended to be a straight chain saturated hydrocarbon structure having 1 to 20 carbon atoms. "Alkyl” is also contemplated to be a branched or cyclic hydrocarbon structure having 3 to 20 carbon atoms.
  • the alkyl group can be an alkyl group of 1-20 carbon atoms, an alkyl group of 1-10 carbon atoms, an alkyl group of 1-5 carbon atoms, an alkyl group of 5-20 carbon atoms, an alkyl group of 5-15 carbon atoms Alkyl of carbon atoms or alkyl of 5-10 carbon atoms.
  • butyl is meant 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 et al. Additionally, alkyl groups can be optionally substituted.
  • alkenyl refers to a monovalent unsaturated hydrocarbon group that may be straight or branched and having at least one, and usually 1, 2, or 3 carbon-carbon double bonds. Unless otherwise defined, the alkenyl group typically contains 2-20 carbon atoms, such as may be alkenyl of 2-20 carbon atoms, alkenyl of 6-20 carbon atoms, alkenyl of 2-12 carbon atoms group or an alkenyl group of 2-6 carbon atoms.
  • Representative alkenyl groups include, for example, vinyl, n-propenyl, isopropenyl, n-but-2-enyl, but-3-enyl, n-hex-3-enyl, and the like. Additionally, 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 two adjacent rings (the rings are "fused"), wherein at least one of the rings is aromatic, such as other Rings can be cycloalkyl, cycloalkenyl, aryl, heterocycle and/or heteroaryl.
  • the aryl group may be a C6 - C50 aryl group, a C6 - C40 aryl group, a C6 - C30 aryl group, a C6 - C20 aryl group, or a C6 - C10 aryl group.
  • aryl groups include, for example, phenyl, methylphenyl, propylphenyl, isopropylphenyl, benzyl, and naphth-1-yl, naphth-2-yl, and the like. Additionally, aryl groups can be optionally substituted.
  • haloalkyl refers to an alkyl group in which at least one hydrogen atom is replaced by a halogen atom.
  • haloalkenyl refers to an alkenyl group in which at least one hydrogen atom is replaced by a halogen atom.
  • halogen encompasses F, Cl, Br, I.
  • substituents When the above substituents are substituted, their substituents may each be independently selected from the group consisting of halogen, alkyl, alkenyl, aryl.
  • each component is based on the weight of the electrolyte.
  • substituted or “substituted” means that it may be substituted with 1 or more (eg, 2, 3) substituents.
  • fluoro means that it may be substituted with one or more (eg, 2, 3) Fs.
  • the present application provides an electrochemical device comprising an electrode and an electrolyte:
  • the electrode includes a current collector, an active material layer on at least one surface of the current collector, a tab on the current collector; and a tab protection layer on the tab , the tab protection layer includes a first polymer layer, and the melting point of the first polymer layer is T A °C, 110 ⁇ TA ⁇ 136.5.
  • the electrolyte includes ethylene carbonate and propylene carbonate; wherein based on the weight of the electrolyte, the sum of the weight percentages of the ethylene carbonate and the propylene carbonate is Y%, and Y is 20-80; and Y and T A satisfy: 0.147 ⁇ Y/ TA ⁇ 0.7.
  • Y/ TA can improve the thermal stability of the electrochemical system of the electrochemical device, thereby improving the performance of the hot box, and at the same time, it can significantly improve the high-temperature storage performance of the lithium-ion battery.
  • TA is 110, 115, 120, 125, 130, 135, 136, 136.5, or a range of any two of these values. T A within this range can significantly improve the safety performance of electrochemical devices.
  • Y is 20, 25, 30, 35, 40, 45, 50, 55, 60, 70, 80, or a range of any two of these values.
  • the value of Y/ TA is 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.65, 0.7, or a range of any two of these values.
  • the tab protection layer further includes a second polymer layer, the melting point of the second polymer layer is T B °C, T B ⁇ 160, and T A and T B satisfy: 0 ⁇ T B - T A ⁇ 60. Within this range, the electrochemical device has better safety performance.
  • T B is a range of 138, 140, 145, 150, 155, 160, or any two of these values.
  • the value of TB - TA is 0.1, 0.5, 1, 3, 5, 10, 20, 30, 40, 50, or a range of any two of these values.
  • the first polymer layer comprises at least one of maleic anhydride graft-modified polypropylene, acidified polyolefin resin, or polyethylene.
  • the first polymer layer comprises at least one of Mitsui Chemicals QE840, QFF551, DuPont Robust 0910, DuPont Elvax, Samsung E093A, or Mitsubishi Chemical P546.
  • the second polymer layer includes at least one of polypropylene resins.
  • the second polymer layer includes at least one of Samsung CF330, TPC Corporation FS5611, or ExxonMobil 6102FL.
  • the tab protection layer is a single-layer, double-layer or triple-layer structure.
  • the tab protection layer consists of a first polymer layer. In some embodiments, the tab protection layer consists of a first polymer layer and a second polymer layer. In some embodiments, the tab protection layer consists of two first polymer layers and a second polymer layer positioned between the two first polymer layers.
  • the electrolyte further includes propionate, wherein the weight percentage of the propionate is 10%-60% based on the weight of the electrolyte. In some embodiments, the weight percent of the propionate is 10%, 20%, 30%, 40%, 50%, 60%, or a range of any two of these values, based on the weight of the electrolyte .
  • the propionate comprises methyl propionate, ethyl propionate, propyl propionate, butyl propionate, amyl propionate, methyl fluoropropionate, ethyl fluoropropionate , at least one of propyl fluoropropionate, butyl fluoropropionate or pentyl fluoropropionate, wherein fluorine means that at least one hydrogen atom is replaced by a fluorine atom.
  • the electrolyte further includes a trimethyl acetate compound.
  • the structural formula of the trimethyl acetate compound is:
  • R is C 1 -C 10 alkyl, C 2 -C 10 alkenyl, C 1 -C 10 haloalkyl, C 2 -C 10 haloalkenyl, halogen, aryl or amide.
  • R is C1 - C6 alkyl, C2 - C6 alkenyl, C1 - C6 haloalkyl, C2 - C6 haloalkenyl, halogen, aryl, or amide.
  • the trimethyl acetate compound includes at least one of methyl trimethyl acetate or ethyl trimethyl acetate.
  • the electrolyte further comprises at least one of a dinitrile compound or a trinitrile compound,
  • the dinitrile compound includes at least one of the following compounds:
  • the trinitrile compound includes at least one of the following compounds:
  • 1,3,5-pentanetricarbonitrile 1,2,3-propanetricarbonitrile, 1,2,6-hexanetricarbonitrile, 1,3,6-hexanetricarbonitrile, 1,2,3-tris(2- Cyanoethoxy)propane, 1,2,4-tris(2-cyanoethoxy)butane or 1,2,5-tris(cyanoethoxy)pentane.
  • the content of the dinitrile compound is 1%-5% based on the weight of the electrolyte. In some embodiments, the content of the dinitrile compound is 1%, 2%, 3%, 3.5%, 4.0%, 5.0%, or a range of any two of these values, based on the weight of the electrolyte.
  • the content of the trinitrile compound is 1%-5% based on the weight of the electrolyte. In some embodiments, based on the weight of the electrolyte, the content of the trinitrile compound is 1%, 2%, 3%, 3.5%, 4.0%, 5.0%, 6.0%, or any two of these values. range.
  • the electrolyte comprises a trinitrile compound and ethylene glycol bis(propionitrile) ether
  • the weight percentage of the trinitrile compound is a % based on the weight of the electrolyte
  • the content of bis(propionitrile) ether is b% and satisfies 1.0 ⁇ a+b ⁇ 6.0.
  • a+b is a range of 1.0, 2.0, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, or any two of these values.
  • 1.2 ⁇ a/b ⁇ 20 In some embodiments, 1.2 ⁇ a/b ⁇ 20. In some embodiments a/b is 2.0, 3.0, 3.3, 4.0, 5.5, 7.0, 8.5, 9.5, 12.0, 14.5, 16.5, 18.5, 20.0, or a range of any two of these values.
  • the electrolyte further comprises fluoroethylene carbonate and 1,3-propane sultone
  • the weight percentage of the fluoroethylene carbonate is c% based on the weight of the electrolyte, so The weight percentage of the 1,3-propane sultone is d%, which satisfies 6.0 ⁇ c+d ⁇ 15.0.
  • c+d is 6.0, 7.0, 8.0, 8.5, 9.0, 9.5, 10.0, 11.0, 11.5, 12.0, 13.0, 14.0, 15.0, or a range of any two of these values.
  • 1.2 ⁇ c/d ⁇ 20 In some embodiments, 1.2 ⁇ c/d ⁇ 20. In some embodiments c/d is 1.2, 2.0, 3.0, 3.3, 4.0, 5.5, 7.0, 8.5, 9.5, 12.0, 14.5, 16.5, 18.5, 20.0, or a range of any two of these values.
  • the electrolyte may further include allyl nitrile.
  • the electrochemical device includes any device that undergoes an electrochemical reaction.
  • the electrode includes a negative electrode having a negative electrode active material capable of occluding and releasing metal ions; and a positive electrode having a positive electrode active material capable of absorbing and releasing metal ions.
  • the electrochemical device further includes a separator between the positive electrode and the negative electrode.
  • the electrochemical device is a lithium secondary battery.
  • the lithium secondary battery includes, but is not limited to, a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery or a lithium ion polymer secondary battery, an all-solid-state secondary lithium battery.
  • FIG. 1 shows a packaging structure of a tab and a packaging bag in an embodiment of the present application.
  • the packaging bag 1-1 is bonded together with the metal strip 1-3 through the tab protection layer 1-2
  • the packaging bag 1-5 is bonded together with the metal strip 1-3 through the tab protection layer 1-4
  • the tab protection layers 1-2 and 1-4 are both single-layer structures, that is, composed of a first polymer layer.
  • FIG. 2 shows the structure of the tab protection layer in an embodiment of the present application.
  • the tab protection layer has a double-layer structure, wherein the tab protection layer located above the metal strip 2-3 is composed of a first polymer layer 2-1 and a second polymer layer 2-2, and is located below the metal strip 2-3
  • the tab protection layer consists of a first polymer layer 2-5 and a second polymer layer 2-4.
  • FIG. 3 shows the structure of the tab protection layer in another embodiment of the present application.
  • the tab protection layer has a three-layer structure.
  • the tab protection layer over the metal strip 3-4 consists of first polymer layers 3-1 and 3-3 and a second polymer layer 3-2 between them.
  • the tab protection layer below the metal strip 3-4 consists of first polymer layers 3-5 and 3-6 and a second polymer layer 3-6 between them.
  • the main function of the tab protection layer is to adhere to the tabs of the lithium ion battery, so that the tabs are heat-sealed with the polypropylene layer inside the packaging bag of the polymer battery.
  • the commonly used tab protection layers generally have a melting point above 140° C.
  • the present invention mainly adopts a tab protection layer with a lower melting point to achieve the purpose of dissipating heat in advance of the battery and improving the thermal safety of the battery.
  • the material, composition, and manufacturing method of the negative electrode used in the electrochemical device of the present application may include any of the techniques disclosed in the prior art.
  • the negative electrode is the negative electrode described in US Patent Application US9812739B, which is incorporated herein by reference in its entirety.
  • the negative electrode includes a current collector and a layer of negative active material on the current collector.
  • the anode active material layer includes an anode active material.
  • the negative active material includes, but is not limited to: lithium metal, structured lithium metal, natural graphite, artificial graphite, mesophase microcarbon beads (MCMB), hard carbon, soft carbon, silicon, silicon-carbon Composite, silicon-oxygen material, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO 2 , lithiated TiO 2 -Li 4 Ti 5 O 12 of spinel structure, Li-Al alloy or any of them combination.
  • MCMB mesophase microcarbon beads
  • the negative active material layer includes a binder.
  • binders include, but are not limited to: polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyfluoro Ethylene, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene Rubber, epoxy or nylon.
  • the anode active material layer includes a conductive material.
  • the conductive material includes, but is not limited to: natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, metal powder, metal fiber, copper, nickel, aluminum, silver, or polyphenylene derivative.
  • the current collector includes, but is not limited to, copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or a conductive metal clad polymer substrate.
  • the negative electrode may 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, but is not limited to: deionized water, N-methylpyrrolidone.
  • the negative electrode in the all-solid-state secondary lithium battery is a metallic lithium foil.
  • the material of the positive electrode used in the electrochemical device of the present application can be prepared using materials, configurations and manufacturing methods known in the art.
  • the positive electrodes of the present application can be prepared using the techniques described in US9812739B, which is incorporated herein by reference in its entirety.
  • the positive electrode includes a current collector and a layer of positive active material on the current collector.
  • the positive active material includes at least one lithiated intercalation compound that reversibly intercalates and deintercalates lithium ions.
  • the positive electrode active material includes a composite oxide.
  • the composite oxide contains lithium and at least one element selected from cobalt, manganese, and nickel.
  • the positive active material is selected from lithium cobalt oxide (LiCoO 2 ), lithium nickel cobalt manganese (NCM) ternary material, lithium iron phosphate (LiFePO 4 ), lithium manganate (LiMn 2 O 4 ), or their any combination of .
  • the positive active material may have a coating on its surface, or may be mixed with another compound having a coating.
  • the coating may comprise at least one selected from oxides of coating elements, hydroxides of coating elements, oxyhydroxides of coating elements, oxycarbonates of coating elements, and hydroxycarbonates of coating elements A coating element compound.
  • the compound used for the coating can be amorphous or crystalline.
  • 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 their any combination of .
  • the coating can be applied by any method as long as the method does not adversely affect the performance of the positive electrode active material.
  • the method may include any coating method known in the art, such as spraying, dipping, and the like.
  • the positive electrode active material layer also 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.
  • binders include, but are not limited to: polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-containing Oxygen polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylic (esterified) 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 powders, metal fibers, 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 on a current collector using a positive electrode active material layer including a lithium transition metal-based compound powder and a binder.
  • the positive electrode active material layer can generally be fabricated by the following operations: dry mixing the positive electrode material and the binder (conductive material and thickener, etc., as required) 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 of 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 separator 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 separator includes a polymer or inorganic or the like formed from a material that is stable to the electrolyte of the present application.
  • the release film may include a substrate layer and a surface treatment layer.
  • the base material layer is a non-woven fabric, film or composite film with a porous structure, and the material of the base material layer is selected from at least one of polyethylene, polypropylene, polyethylene terephthalate and polyimide.
  • a polypropylene porous membrane, a polyethylene porous membrane, a polypropylene non-woven fabric, a polyethylene non-woven fabric or a polypropylene-polyethylene-polypropylene porous composite membrane can be selected.
  • At least one surface of the base material layer is provided with a surface treatment layer, and the surface treatment layer may be a polymer layer or an inorganic material layer, or a layer formed by mixing a polymer and an inorganic material.
  • the inorganic layer includes inorganic particles and a binder, and the inorganic particles are selected from aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium oxide, tin oxide, ceria, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, One or a combination of yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide and barium sulfate.
  • the binder is selected from polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, One or a combination of polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene.
  • the polymer layer contains a polymer, and the material of the polymer includes polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride or poly( At least one of vinylidene fluoride-hexafluoropropylene).
  • the electrolyte used in the electrolyte of the embodiments of the present application may be an electrolyte known in the prior art, and the electrolyte includes, but is not limited to, inorganic lithium salts, such as LiClO 4 , LiAsF 6 , LiPF 6 , LiBF 4 , LiSbF 6 , LiSO 3 F , LiN ( FSO2 ) 2 , etc ; _ _ 2 ) 2 , cyclic 1,3-hexafluoropropanedisulfonimide lithium, cyclic 1,2-tetrafluoroethanedisulfonimide lithium, LiN(CF 3 SO 2 )(C 4 F 9 SO 2 ), LiC(CF 3 SO 2 ) 3 , LiPF 4 (CF 3 ) 2 , LiPF 4 (C 2 F 5 ) 2 , LiPF 4 (CF 3 SO 2 ) 2 , LiPF 4 (C 2 F 5 SO 2 ) 2 , LiBF 2 (CF 3 )
  • the said electrolyte may be used individually by 1 type, and may use 2 or more types together.
  • the electrolyte includes a combination of LiPF 6 and LiBF 4 .
  • the electrolyte includes a combination of an inorganic lithium salt such as LiPF6 or LiBF4 and a fluorine - containing organolithium salt such as LiCF3SO3 , LiN ( CF3SO2 ) 2 , LiN ( C2F5SO2 ) 2 , etc. .
  • the concentration of the electrolyte is in the range of 0.8-3 mol/L, eg, in the range of 0.8-2.5 mol/L, in the range of 0.8-2 mol/L, in the range of 1-2 mol/L, in the range of 0.5- 1.5mol/L, 0.8-1.3mol/L, 0.5-1.2mol/L, another example is 1mol/L, 1.15mol/L, 1.2mol/L, 1.5mol/L, 2mol/L or 2.5mol/L.
  • the electronic device of the present application may be any device using the electrochemical device according to the embodiments of the present application.
  • the electronic devices include, but are not limited to: notebook computers, pen input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, headsets , VCR, LCD TV, Portable Cleaner, Portable CD Player, Mini Disc, Transceiver, Electronic Notepad, Calculator, Memory Card, Portable Recorder, Radio, Backup Power, Motor, Automobile, motorcycle, Power-assisted Bicycle, Bicycle , lighting equipment, toys, game consoles, clocks, power tools, flashes, cameras, large household batteries or lithium-ion capacitors, etc.
  • lithium ion batteries The preparation of lithium ion batteries is described below by taking lithium ion batteries as an example and in conjunction with specific embodiments. Those skilled in the art will understand that the preparation methods described in this application are only examples, and any other suitable preparation methods are included in the scope of this application. within the range.
  • the positive active material lithium cobalt oxide (LiCoO 2 ), the conductive agent carbon nanotube (CNT), and the binder polyvinylidene fluoride are mixed according to the weight ratio of 95:2:3, and N-methylpyrrolidone (NMP) is added, Stir the system under the action of a vacuum mixer until the system is homogeneous to obtain a positive electrode slurry, which is uniformly coated on the positive electrode current collector aluminum foil; It was dried under vacuum for 4 hours to obtain the positive electrode.
  • NMP N-methylpyrrolidone
  • the negative electrode active material graphite, the binder styrene-butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC) are fully stirred and mixed in an appropriate amount of deionized water solvent according to the weight ratio of 95:2:3 to make it.
  • a uniform negative electrode slurry is formed; the slurry is coated on the negative electrode current collector Cu foil, dried and cold pressed to obtain a negative electrode.
  • Polyethylene (PE) diaphragm is selected as the isolation film.
  • the tab protection layer and the metal strip are compounded together by flat plate heating or high frequency heating to form a tab containing the tab protection layer, and then the tab is fixed on the positive electrode and the negative electrode by welding.
  • the positive electrode, the separator, and the negative electrode are stacked in order, so that the separator is placed between the positive electrode and the negative electrode to isolate the positive electrode and the negative electrode, and then wound, and then placed in the outer packaging foil, and the above-prepared electrolyte is injected into the In the dried battery, the preparation of the lithium ion battery is completed after vacuum packaging, standing, chemical formation, shaping and other processes.
  • the lithium-ion battery was charged at a constant current of 0.7C to 4.45V, and then charged at a constant voltage of 4.45V to a current of 0.05C.
  • the battery was placed in a high temperature box, heated to 135 °C with a temperature rise rate of 5 ⁇ 2 °C/min, maintained for 1 hour (hr), and the voltage, temperature of the battery and changes in the temperature of the hot box were recorded. Pass the test without fire or explosion. 10 batteries were tested in each group, and the number of batteries that passed the test was recorded.
  • Thickness expansion rate (%) (h1-h0)/h0 ⁇ 100%.
  • the lithium-ion battery was charged to 4.45V with a constant current of 0.7C and a constant voltage of 4.45V to a current of 0.05C. After that, the lithium-ion batteries were left for 4 hours at different temperatures (25°C, 0°C, -10°C), and then discharged to 3.0V at 0.2C. discharge capacity. Based on the discharge capacity at 25°C, the discharge capacity ratio of the lithium-ion battery at different temperatures was obtained.
  • Discharge capacity ratio (%) of lithium-ion battery at different temperatures discharge capacity at different temperatures (0°C, -10°C) / 25°C discharge capacity ⁇ 100%
  • the lithium-ion battery was allowed to stand for 30 minutes, then charged to 4.45V with a constant current rate of 0.5C, and then charged to 0.05C with a constant voltage at 4.45V, left for 5 minutes, and then stored at 85°C for 24 After a few days, measure the thickness of the battery, and calculate the expansion rate of the battery thickness by the following formula:
  • Thickness expansion ratio [(thickness after storage ⁇ thickness before storage)/thickness before storage] ⁇ 100%.
  • Table 1 shows the composition and performance test results of the lithium-ion batteries in the relevant examples.
  • the tab protection layers used in Comparative Examples D1-1 to D1-2 consist of a second polymer layer whose melting point is T B , and the second polymer layer is selected from Samsung CF330 block copolymerized polypropylene.
  • the tab protection layers of Comparative Examples D1-3 to D1-5 and Examples S1-1 to S1-7 consist of a first polymer layer with a melting point of T A , and the first polymer layer is selected from Byron 50E632 (melting point 136.5°C), 50E631 (136°C melting point), 40E529 (135°C melting point), 50E662 (130°C melting point), 4104 (125°C melting point), 4208 (110°C melting point) , Reliable 0910 (melting point 100°C).
  • Adjusting the total amount of EC+PC or adjusting the melting point of the polymer layer can obviously improve the hot box, but when the content of EC+PC is small, even adjusting the melting point will not have a good effect; when EC+PC When the content is high, adjusting the melting point of the hot box has an effect, but the electrical performance is relatively poor, so the two must be within a certain reasonable amount to have a good effect.
  • the tab protection layers in Examples S2-1 to S2-3 have a double-layer structure, including a first polymer layer and a second polymer layer.
  • the tab protection layer in Example S3-1 has a three-layer structure, that is, there is a second polymer layer between the two first polymer layers, and the melting point values TA of the first polymer layers are all 125°C.
  • the above-mentioned first polymer layer is selected from Bailong 4104 (125° C.), and the second polymer layer is selected from Samsung CF330 block copolymerized polypropylene.
  • the tab protection layer prepared by the second polymer layer in Comparative Example D1-2 was replaced by the tab protection layer of the two-layer structure and the tab protection layer of the three-layer structure.
  • the ear protection layer can also improve the hot box test performance of lithium-ion batteries. This is because whether it is a double-layer structure or a triple-layer structure, as long as it contains a low-melting-point layer, the heat can be dissipated from the battery in time at a lower temperature to avoid thermal runaway of the battery.
  • Example S4-1 and Example S4-2 are similar to the preparation of the lithium ion battery in Example S1-2, except that the composition of the electrolyte is different, as shown in Table 4 for details.
  • Table 5 shows the composition and performance test results of the lithium-ion batteries in the relevant examples.
  • the preparation process of Examples S5-1 to S5-3 is similar to that of the lithium ion battery in Example S1-2, the difference is that the composition of the electrolyte is different, as shown in Table 5 for details.
  • Table 6 shows the composition and performance test results of the lithium ion battery in the relevant examples.
  • Examples S6-1 to S6-16 are similar to the preparation process of the lithium ion battery in Example S1-2, except that the composition of the electrolyte is different, as shown in Table 6 for details.
  • Table 7 shows the composition and performance test results of the lithium ion batteries in the related examples.
  • Examples S7-1 to S7-11 are similar to the preparation process of the lithium ion battery in Example S1-2, except that the composition of the electrolyte is different, as shown in Table 7 for details.

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Abstract

本申请涉及电化学装置和包含其的电子装置。本申请提供了一种电化学装置，所述电化学装置包括：电极，所述电极包括集流体、位于所述集流体的至少一个表面上的活性材料层、位于所述集流体上的极耳以及位于所述极耳上的极耳保护层，所述极耳保护层包括第一聚合物层，所述第一聚合物层的熔点为T A℃，110≤T A≤136.5；和电解液，所述电解液包括碳酸乙烯酯和碳酸丙烯酯；其中基于所述电解液的重量，所述碳酸乙烯酯和所述碳酸丙烯酯的重量百分比之和为Y％，Y为20-80；并且Y和T A满足：0.147<Y/T A<0.7。本申请的电化学装置具有提高的热箱性能和高温存储性能。

Description

电化学装置和包含其的电子装置 技术领域
本申请涉及储能领域，具体涉及一种电化学装置和包含其的电子装置，特别是锂离子电池。
背景技术
随着智能产品的普及和应用，人们对手机、笔记本、相机等电子产品的需求逐年增加。电化学装置，如锂离子电池，作为电子产品的工作电源，具有能量密度高、无记忆效应、工作电压高等特点，正逐步取代传统的Ni-Cd、MH-Ni电池。然而随着电子产品向轻薄化和便携化的发展，人们对锂离子电池的要求不断提高，开发循环稳定性好、阻抗小、自放电少、安全的锂离子电池是市场的主要需求之一。
发明内容
本申请实施例提供了一种电化学装置，以试图在至少某种程度上解决至少一种存在于相关领域中的问题。本申请实施例还提供了包含该电化学装置的电子装置。
在一个实施例中，本申请提供了一种电化学装置，所述电化学装置包括电极和电解液。
在一个实施例中，所述电极包括集流体、位于所述集流体的至少一个表面上的活性材料层、位于所述集流体上的极耳；和位于所述极耳上的极耳保护层。所述极耳保护层包括第一聚合物层，该第一聚合物层的熔点为T A℃，110≤T A≤136.5。
在一个实施例中，所述电解液包括碳酸乙烯酯和碳酸丙烯酯；其中基于所述电解液的重量，所述碳酸乙烯酯和所述碳酸丙烯酯的重量百分比之和为Y％，Y为20-80；并且Y和T A满足：0.147<Y/T A<0.7。
在一些实施例中，所述极耳保护层进一步包括第二聚合物层，所述第二聚合物层的熔点为T B℃，T B≤160，并且T A和T B满足：0＜T B-T A≤50。
在一些实施例中，所述第一聚合物层包括马来酸酐接枝改性聚丙烯、酸化聚烯烃树 脂或聚乙烯中的至少一种。
在一些实施例中，所述第二聚合物层包括聚丙烯或聚丙烯改性树脂中的至少一种。
在一些实施例中，所述电解液进一步包括丙酸酯，其中基于所述电解液的重量，所述丙酸酯的重量百分比为10％-60％。
在一些实施例中，所述丙酸酯包括丙酸甲酯、丙酸乙酯、丙酸丙酯、丙酸丁酯、丙酸戊酯、氟代丙酸甲酯、氟代丙酸乙酯、氟代丙酸丙酯、氟代丙酸丁酯或氟代丙酸戊酯中的至少一种，其中氟代是指至少一个氢原子被氟原子取代。
在一些实施例中，所述电解液进一步包括三甲基乙酸酯化合物。
在一些实施例中，所述三甲基乙酸酯化合物的结构式为：
Figure PCTCN2020129757-appb-000001
其中，R为C 1-C 10烷基、C 2-C 10烯基、C 1-C 10卤代烷基、C 2-C 10卤代烯基、卤素、芳基或酰胺。
在一些实施例中，所述三甲基乙酸酯化合物包括三甲基乙酸甲酯或三甲基乙酸乙酯中的至少一种。
在一些实施例中，所述电解液进一步包括二腈化合物或三腈化合物中的至少一种，
其中所述二腈化合物包括如下化合物中的至少一种：
丁二腈、戊二腈、己二腈、1,5-二氰基戊烷、1,6-二氰基己烷、1,7-二氰基庚烷、1,8-二氰基辛烷、1,9-二氰基壬烷、1,10-二氰基癸烷、1,12-二氰基十二烷、四甲基丁二腈、2-甲基戊二腈、2,4-二甲基戊二腈、2,2,4,4-四甲基戊二腈或乙二醇双(丙腈)醚；
所述三腈化合物包括如下化合物中的至少一种：
1,3,5-戊三甲腈、1,2,3-丙三甲腈、1,2,6-己三甲腈、1,3,6-己三甲腈、1,2,3-三(2-氰基乙氧基)丙烷、1,2,4-三(2-氰基乙氧基)丁烷或1,2,5-三(氰基乙氧基)戊烷。
在另一个实施例中，本申请提供一种电子装置，其包括根据本申请的实施例所述的电化学装置。
本申请提供的电化学装置具有提高的热箱性能和高温存储性能。
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和显示，或是经由本申请实施例的实施而阐释。
附图说明
在下文中将简要地说明为了描述本申请实施例或现有技术所必要的附图以便于描述本申请的实施例。显而易见地，下文描述中的附图仅只是本申请中的部分实施例。对本领域技术人员而言，在不需要创造性劳动的前提下，依然可以根据这些附图中所例示的结构来获得其他实施例的附图。
图1示出了本申请一个实施例中的极耳与包装袋的封装结构。
图2示出了本申请一个实施例中的极耳保护层的结构。
图3示出了本申请另一个实施例中的极耳保护层的结构。
图4示出了本申请一个实施例中的电池结构及极耳保护层的位置。
具体实施方式
本申请的实施例将会被详细的描示在下文中。本申请的实施例不应该被解释为对本申请的限制。
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”、“中的一个”、“中的一种”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”、“中的至少一个”、“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”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”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。
如本文所用，术语“烷基”预期是具有1至20个碳原子的直链饱和烃结构。“烷基”还预期是具有3至20个碳原子的支链或环状烃结构。例如，烷基可为1-20个碳原子的烷基、1-10个碳原子的烷基、1-5个碳原子的烷基、5-20个碳原子的烷基、5-15个碳原子的烷基或5-10个碳原子的烷基。当指定具有具体碳数的烷基时，预期涵盖具有该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。
如本文所用，术语“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2-20个碳原子，例如可以为2-20个碳原子的烯基、6-20个碳原子的烯基、2-12个碳原子的烯基或2-6个碳原子的烯基。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，烯基可以是任选地被取代的。
如本文所用，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C 6-C 50芳基、C 6-C 40芳基、C 6-C 30芳基、C 6-C 20芳基或C 6-C 10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-基等等。另外，芳基可以是任选地被取代的。
如本文所用，术语“卤代烷基”指其中至少一个氢原子被卤素原子取代的烷基。术语“卤代烯基”指其中至少一个氢原子被卤素原子取代的烯基。
如本文所用，术语“卤素”涵盖F、Cl、Br、I。
当上述取代基经取代时，它们的取代基可各自独立地选自由以下组成的群组：卤素、烷 基、烯基、芳基。
如本文中所使用，各组分的含量均为基于电解液的重量得到的。
如本文所用，术语“取代”或“经取代”是指可以经1个或多个(例如2个、3个)取代基取代。例如“氟代”是指可以经1个或多个(例如2个、3个)F取代。
一、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，所述电化学装置包括电极和电解液：
在一些实施例中，所述电极包括集流体、位于所述集流体的至少一个表面上的活性材料层、位于所述集流体上的极耳；和位于所述极耳上的极耳保护层，所述极耳保护层包括第一聚合物层，所述第一聚合物层的熔点为T A℃，110≤T A≤136.5。
在一些实施例中，所述电解液包括碳酸乙烯酯和碳酸丙烯酯；其中基于所述电解液的重量，所述碳酸乙烯酯和所述碳酸丙烯酯的重量百分比之和为Y％，Y为20-80；并且Y和T A满足：0.147<Y/T A<0.7。Y/T A在此范围内使电化学装置的电化学体系热稳定性的提升，进而改善热箱性能，同时能明显提高锂离子电池的高温存储性能。
在一些实施例中，T A为110、115、120、125、130、135、136、136.5或这些数值中任意两者组成的范围。T A在此范围内能显著提升电化学装置的安全性能。
在一些实施例中，Y为20、25、30、35、40、45、50、55、60、70、80或这些数值中任意两者组成的范围。
在一些实施例中，Y/T A的值为0.1、0.2、0.3、0.4、0.5、0.6、0.65、0.7或这些数值中任意两者组成的范围。
在一些实施例中，所述极耳保护层进一步包括第二聚合物层，所述第二聚合物层的熔点为T B℃，T B≤160，并且T A和T B满足：0＜T B-T A≤60。T B-T A在此范围内，电化学装置具有更优的安全性能。
在一些实施例中，T B为138、140、145、150、155、160或这些数值中任意两者组成的范围。
在一些实施例中，T B-T A的值为0.1、0.5、1、3、5、10、20、30、40、50、或这些数值中任意两者组成的范围。
在一些实施例中，所述第一聚合物层包括马来酸酐接枝改性聚丙烯、酸化聚烯烃树 脂或聚乙烯中的至少一种。
在一些实施例中，所述第一聚合物层包括三井化学的QE840、QFF551、杜邦牢靠0910、杜邦Elvax、三星E093A、或三菱化学P546中的至少一种。
在一些实施例中，所述第二聚合物层包括聚丙烯树脂中的至少一种。
在一些实施例中，所述第二聚合物层包括三星CF330、TPC公司FS5611或埃克森美孚6102FL中的至少一种。
在一些实施例中，所述极耳保护层为单层、双层或三层结构。
在一些实施例中，所述极耳保护层由一个第一聚合物层组成。在一些实施例中，所述极耳保护层由一个第一聚合物层和一个第二聚合物层组成。在一些实施例中，所述极耳保护层由两个第一聚合物层和一个位于所述两个第一聚合物层之间的第二聚合物层组成。
在一些实施例中，所述电解液进一步包括丙酸酯，其中基于所述电解液的重量，所述丙酸酯的重量百分比为10％-60％。在一些实施例中，基于所述电解液的重量，所述丙酸酯的重量百分比为10％、20％、30％、40％、50％、60％或这些数值中任意两者组成的范围。
在一些实施例中，所述丙酸酯包括丙酸甲酯、丙酸乙酯、丙酸丙酯、丙酸丁酯、丙酸戊酯、氟代丙酸甲酯、氟代丙酸乙酯、氟代丙酸丙酯、氟代丙酸丁酯或氟代丙酸戊酯中的至少一种，其中氟代是指至少一个氢原子被氟原子取代。
在一些实施例中，所述电解液进一步包括三甲基乙酸酯化合物。
在一些实施例中，所述三甲基乙酸酯化合物的结构式为：
Figure PCTCN2020129757-appb-000002
其中，R为C 1-C 10烷基、C 2-C 10烯基、C 1-C 10卤代烷基、C 2-C 10卤代烯基、卤素、芳基或酰胺。
在一些实施例中，R为C 1-C 6烷基、C 2-C 6烯基、C 1-C 6卤代烷基、C 2-C 6卤代烯基、卤素、芳基或酰胺。
在一些实施例中，所述三甲基乙酸酯化合物包括三甲基乙酸甲酯或三甲基乙酸乙酯中的至少一种。
在一些实施例中，所述电解液进一步包括二腈化合物或三腈化合物中的至少一种，
其中所述二腈化合物包括如下化合物中的至少一种：
丁二腈、戊二腈、己二腈、1,5-二氰基戊烷、1,6-二氰基己烷、1,7-二氰基庚烷、1,8-二氰基辛烷、1,9-二氰基壬烷、1,10-二氰基癸烷、1,12-二氰基十二烷、四甲基丁二腈、2-甲基戊二腈、2,4-二甲基戊二腈、2,2,4,4-四甲基戊二腈或乙二醇双(丙腈)醚；
所述三腈化合物包括如下化合物中的至少一种：
1,3,5-戊三甲腈、1,2,3-丙三甲腈、1,2,6-己三甲腈、1,3,6-己三甲腈、1,2,3-三(2-氰基乙氧基)丙烷、1,2,4-三(2-氰基乙氧基)丁烷或1,2,5-三(氰基乙氧基)戊烷。
在一些实施例中，基于所述电解液的重量，所述二腈化合物的含量为1％-5％。在一些实施例中，基于所述电解液的重量，所述二腈化合物的含量为1％、2％、3％、3.5％、4.0％、5.0％或这些数值中任意两者组成的范围。
在一些实施例中，基于所述电解液的重量，所述三腈化合物的含量为1％-5％。在一些实施例中，基于所述电解液的重量，所述三腈化合物的含量为1％、2％、3％、3.5％、4.0％、5.0％、6.0％或这些数值中任意两者组成的范围。
在一些实施例中，所述电解液包含三腈化合物和乙二醇双(丙腈)醚，基于所述电解液的重量，所述三腈化合物的重量百分比为a％，所述乙二醇双(丙腈)醚的含量为b％，满足1.0≤a+b≤6.0。在一些实施例中，a+b为1.0、2.0、3.0、3.5、4.0、4.5、5.0、5.5、6.0或这些数值中任意两者组成的范围。
在一些实施例中，1.2≤a/b≤20。在一些实施例中a/b为2.0、3.0、3.3、4.0、5.5、7.0、8.5、9.5、12.0、14.5、16.5、18.5、20.0或这些数值中任意两者组成的范围。
在一些实施例中，所述电解液进一步包含氟代碳酸乙烯酯和1,3-丙烷磺内酯，基于所述电解液的重量，所述氟代碳酸乙烯酯的重量百分比为c％，所述1,3-丙烷磺内酯的重量百分比为d％，满足6.0≤c+d≤15.0。在一些实施例中，c+d为6.0、7.0、8.0、8.5、9.0、9.5、10.0、11.0、11.5、12.0、13.0、14.0、15.0或这些数值中任意两者组成的范围。
在一些实施例中，1.2≤c/d≤20。在一些实施例中c/d为1.2、2.0、3.0、3.3、4.0、5.5、7.0、8.5、9.5、12.0、14.5、16.5、18.5、20.0或这些数值中任意两者组成的范围。
在一些实施例中，所述电解液可进一步包括烯丙基腈。
在一些实施例中，所述电化学装置包括发生电化学反应的任何装置。
在一些实施例中，所述电极包括具有能够吸留、放出金属离子的负极活性物质的负极；和具有能够吸留、放出金属离子的正极活性物质的正极。
在一些实施例中，所述电化学装置进一步包括位于正极和负极之间的隔离膜。
在一些实施例中，所述电化学装置是锂二次电池。
在一些实施例中，锂二次电池包括，但不限于：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、全固态二次锂电池。
图1示出了本申请一个实施例中的极耳与包装袋的封装结构。包装袋1-1通过极耳保护层1-2与金属带1-3粘结在一起，且包装袋1-5通过极耳保护层1-4与金属带1-3粘结在一起，其中极耳保护层1-2和1-4均为单层结构，即由一个第一聚合物层组成。
图2示出了本申请一个实施例中的极耳保护层的结构。该极耳保护层为双层结构，其中位于金属带2-3上方的极耳保护层由第一聚合物层2-1和第二聚合物层2-2组成，位于金属带2-3下方的极耳保护层由第一聚合物层2-5和第二聚合物层2-4组成。
图3示出了本申请另一个实施例中的极耳保护层的结构。该极耳保护层为三层结构。位于金属带3-4上方的极耳保护层由第一聚合物层3-1和3-3以及位于二者之间的第二聚合物层3-2组成。位于金属带3-4下方的极耳保护层由第一聚合物层3-5和3-6以及位于二者之间的第二聚合物层3-6组成。
极耳保护层的主要作用是粘结在锂离子电池的极耳上，使得极耳与聚合物电池的包装袋内侧聚丙烯层热封在一起。目前常用的极耳保护层一般熔点均在140℃以上，本发明主要是采用熔点更低的极耳保护层以达到电池提前散热进而改善电池热安全的目的。
负极
本申请的电化学装置中使用的负极的材料、构成和其制造方法可包括任何现有技术中公开的技术。在一些实施例中，负极为美国专利申请US9812739B中记载的负极，其以全文引用的方式并入本申请中。
在一些实施例中，负极包括集流体和位于该集流体上的负极活性材料层。在一些实施例中，负极活性材料层包括负极活性材料。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(MCMB)、硬碳、软碳、硅、硅-碳复合物、硅氧材料、Li-Sn合金、Li-Sn-O合金、Sn、SnO、SnO 2、尖晶石结构的 锂化TiO 2-Li 4Ti 5O 12、Li-Al合金或其任意组合。
在一些实施例中，负极活性材料层包括粘合剂。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、环氧树脂或尼龙。
在一些实施例中，负极活性材料层包括导电材料。在一些实施例中，导电材料包括，但不限于：天然石墨、人造石墨、碳黑、乙炔黑、科琴黑、碳纤维、金属粉、金属纤维、铜、镍、铝、银或聚亚苯基衍生物。
在一些实施例中，集流体包括，但不限于：铜箔、镍箔、不锈钢箔、钛箔、泡沫镍、泡沫铜或覆有导电金属的聚合物基底。
在一些实施例中，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。
在一些实施例中，溶剂可以包括，但不限于：去离子水、N-甲基吡咯烷酮。
在一些实施例中，全固态二次锂电池中的负极为金属锂箔。
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。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(LiCoO 2)、锂镍钴锰(NCM)三元材料、磷酸亚铁锂(LiFePO 4)、锰酸锂(LiMn 2O 4)或它们的任意组合。
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、F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物质层形成正极材料而制成。
在一些实施例中，正极活性物质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，正极活性物质层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。
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。
电解质
本申请实施例的电解液使用的电解质可以为现有技术中已知的电解质，电解质包括、但不限于：无机锂盐，例如LiClO 4、LiAsF 6、LiPF 6、LiBF 4、LiSbF 6、LiSO 3F、LiN(FSO 2) 2等；含氟有机锂盐，例如LiCF 3SO 3、LiN(FSO 2)(CF 3SO 2)、LiN(CF 3SO 2) 2、LiN(C 2F 5SO 2) 2、环状1,3-六氟丙烷二磺酰亚胺锂、环状1,2-四氟乙烷二磺酰亚胺锂、LiN(CF 3SO 2)(C 4F 9SO 2)、LiC(CF 3SO 2) 3、LiPF 4(CF 3) 2、LiPF 4(C 2F 5) 2、LiPF 4(CF 3SO 2) 2、LiPF 4(C 2F 5SO 2) 2、LiBF 2(CF 3) 2、LiBF 2(C 2F 5) 2、LiBF 2(CF 3SO 2) 2、LiBF 2(C 2F 5SO 2) 2；含二羧酸配合物锂盐，例如双(草酸根合)硼酸锂、二氟草酸根合硼酸锂、三(草酸根合)磷酸锂、二氟双(草酸根合)磷酸锂、四氟(草酸根合)磷酸锂等。另外，上述电解质可以单独使用一种，也可以同时使用两种或两种以上。例如，在一些实施例中，电解质包括LiPF 6和LiBF 4的组合。在一些实施例中，电解质包括LiPF 6或LiBF 4等无机锂盐与LiCF 3SO 3、LiN(CF 3SO 2) 2、LiN(C 2F 5SO 2) 2等含氟有机锂盐的组 合。在一些实施例中，电解质的浓度在0.8-3mol/L的范围内，例如0.8-2.5mol/L的范围内、0.8-2mol/L的范围内、1-2mol/L的范围内、0.5-1.5mol/L、0.8-1.3mol/L、0.5-1.2mol/L，又例如为1mol/L、1.15mol/L、1.2mol/L、1.5mol/L、2mol/L或2.5mol/L。
二、电子装置
本申请的电子装置可为任何使用根据本申请的实施例的电化学装置的装置。
在一些实施例中，所述电子装置包括，但不限于：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。
下面以锂离子电池为例并且结合具体的实施例说明锂离子电池的制备，本领域的技术人员将理解，本申请中描述的制备方法仅是实例，其他任何合适的制备方法均在本申请的范围内。
实施例
以下说明根据本申请的锂离子电池的实施例和对比例进行性能评估。
一、锂离子电池的制备
(1)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)和其他有机溶剂按照一定的比例进行混合，其他有机溶剂选自碳酸二乙酯(DEC)、丙酸乙酯(EP)或丙酸丙酯(PP)中的至少一种，之后加入LiPF 6搅拌均匀，形成基础电解液，其中LiPF 6的浓度为1.15mol/L。在基础电解液中加入以下各表中所示的不同含量的物质得到不同实施例和对比例的电解液。本申请描述的电解液中各物质的含量均是基于电解液的重量计算得到。
在表1中EC和PC含量见表格所示，剩余有机溶剂为DEC。
(2)正极的制备
将正极活性材料钴酸锂(LiCoO 2)、导电剂碳纳米管(CNT)、粘结剂聚偏二氟乙烯按 照重量比95:2:3进行混合，加入N-甲基吡咯烷酮(NMP)，在真空搅拌机作用下搅拌至体系均匀，得到正极浆料，将正极浆料均匀涂覆于正极集流体铝箔上；在85℃下烘干后经过冷压、裁片、分切后，在85℃的真空条件下干燥4hr，得到正极。
(3)负极的制备
将负极活性物质石墨、粘结剂丁苯橡胶(SBR)、增稠剂羧甲基纤维素钠(CMC)按照重量比95:2:3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Cu箔上，烘干、冷压，得到负极。
(4)隔离膜的制备
选用聚乙烯(PE)隔膜作为隔离膜。
(5)锂离子电池的制备
采用平板加热或高频加热方式使极耳保护层和金属带复合在一起，制成含有极耳保护层的极耳，再通过焊接的方式将该极耳固定在正极和负极上。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正极和负极的作用，然后卷绕，再置于外包装箔中，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、测试方法
1、热箱测试：
在25℃下，将锂离子电池以0.7C恒流充电至4.45V，再以4.45V恒压充电至电流为0.05C。将电池放置在高温箱中，用5±2℃/min的温升速率加热到135℃，保持1小时(hr)，记录电池的电压、温度以及热箱温度的变化。不起火、不爆炸即通过测试。每组测试10只电池，记录通过测试(pass)的电池数量。
2、高温存储测试：
在25℃下，将锂离子电池静置30分钟；然后以0.5C倍率恒流充电至4.45V，再在4.45V下恒压充电至0.05C，静置5分钟，测试锂离子电池的厚度并记为h0；然后将锂离子电池放入85℃的恒温箱储存24天，测试锂离子电池的厚度并记为h1，并通过下式计算锂离子电池的厚度膨胀率：厚度膨胀率(％)＝(h1-h0)/h0×100％。
3、低温放电测试
在25℃下，将锂离子电池以0.7C恒流充电至4.45V，4.45V恒压充电至电流为0.05C。之后将锂离子电池分别在不同温度(25℃、0℃、-10℃)下静置4h后，以0.2C放电至3.0V，每次放电结束后，再静置5min，记录锂离子电池的放电容量。以25℃放电容量为基准，得到锂离子电池在不同温度下的放电容量比。
锂离子电池不同温度下的放电容量比(％)＝不同温度(0℃、-10℃)下的放电容量/25℃放电容量×100％
4、高温存储测试
在25℃下，将锂离子电池静置30分钟，然后以0.5C倍率恒流充电至4.45V，再在4.45V下恒压充电至0.05C，静置5分钟，然后在85℃下储存24天后，测量电池的厚度，通过下式计算电池厚度膨胀率：
厚度膨胀率＝[(存储后厚度-存储前厚度)/存储前厚度]×100％。
A、表1示出了相关实施例中锂离子电池的组成和性能测试结果。其中对比例D1-1到D1-2所用极耳保护层由一个第二聚合物层组成，其熔点为T B，此第二聚合物层选自三星CF330嵌段共聚聚丙烯。对比例D1-3到D1-5以及实施例S1-1到S1-7的极耳保护层由一个第一聚合物层组成，其熔点为T A，此第一聚合物层选自拜窂50E632(熔点136.5℃)、拜窂50E631(熔点136℃)、拜窂40E529(熔点135℃)、拜窂50E662(熔点130℃)、拜窂4104(熔点125℃)、拜窂4208(熔点110℃)、牢靠0910(熔点100℃)。
表1
Figure PCTCN2020129757-appb-000003
Figure PCTCN2020129757-appb-000004
其中“—”表示不具有该层物质。
由表1的测试结果可以看出，对比例D1-1和D1-2中的锂离子电池仅能通过130℃热箱测试，而132℃和135℃热箱测试通过率都很低，这是因为对比例D1-1和D1-2中极耳保护层的熔点比较高，在热箱等滥用测试时，气体无法及时冲开气袋，产生的热量在电池内部逐渐积累，非常容易导致电池起火燃烧甚至爆炸。调整EC+PC的总量或调整聚合物层的熔点对热箱都有明显的改善作用，但是当EC+PC含量较少时，即使调整熔点也起不到很好的效果；当EC+PC含量高时，调整熔点热箱有作用，但是电性能比较差，因此两者必须在一定合理用量内方能起到很好的效果。
由实施例S1-1到S1-11的测试结果可以看出，当将由第二聚合物层制备的极耳保护层替换为由第一聚合物层制备的极耳保护层时，且第一聚合物层的熔点的值T A和EC+PC的含量的值Y之间满足：0.147<Y/T A<0.7时，锂离子电池的热箱测试通过率明显提高。一方面，当在极耳保护层中引入第一聚合物层时，电池内部的气体可提前冲开气袋，便于热量及时散出，因此热箱测试有明显的改善。另一方面，由于整个电化学体系热稳定性的提升，进而改善热箱性能，同时能明显提高锂离子电池的高温存储性能。
B、表2和3示出了相关实施例中锂离子电池的组成以及性能测试结果。其中实施例S2-1至S2-3中的极耳保护层为双层结构，包含一个第一聚合物层和一个第二聚合物层。实施例S3-1中的极耳保护层为三层结构，即两个第一聚合物层中间具有一个第二聚合物层，上述第一聚合物层的熔点的值T A均为125℃。上述第一聚合物层选自拜窂4104(125℃)，第二聚合物层选自三星CF330嵌段共聚聚丙烯。
表2
Figure PCTCN2020129757-appb-000005
其中“—”表示不具有该层物质。
表3
Figure PCTCN2020129757-appb-000006
其中“—”表示不具有该层物质。
由表2和3中的测试结果可以看出，把对比例D1-2中的由第二聚合物层制备的极耳保护层替换为上述双层结构的极耳保护层和三层结构的极耳保护层，同样能够提高锂离子电池的热箱测试性能。这是由于无论是双层结构还是三层结构，只要含有低熔点层，在较低的温度均可及时将热量从电池中散出，避免电池的热失控。
C、表4示出了相关实施例中锂离子电池的组成以及性能测试结果。实施例S4-1和实施例S4-2与实施例S1-2中的锂离子电池的制备相似，不同之处在于电解液组成不同，具体见表4。
表4
Figure PCTCN2020129757-appb-000007
由表4中的测试结果可以看出，在第一聚合物层的熔点T A和EC+PC的含量Y之间满足：0.147<Y/T A<0.7的情况下，在电解液中加入一定量的丙酸丙酯或者丙酸乙酯中的至少一种，能够进一步提高锂离子电池的低温性能。
D、表5示出了相关实施例中锂离子电池的组成以及性能测试结果。实施例S5-1至S5-3的与实施例S1-2中的锂离子电池的制备过程相似，不同之处在于电解液组成不同，具体见表5。
表5
Figure PCTCN2020129757-appb-000008
由表5中的测试结果可以看出，在第一聚合物层的熔点T A和EC+PC的含量Y之间满足：0.147<Y/T A<0.7的情况下，在电解液中加入一定量的三甲基乙酸酯，能够进一步提高锂离子电池的热箱性能。
E、表6示出了相关实施例中锂离子电池的组成以及性能测试结果。实施例S6-1至S6-16与实施例S1-2中的锂离子电池的制备过程相似，不同之处电解液组成不同，具体见表6。
表6
Figure PCTCN2020129757-appb-000009
Figure PCTCN2020129757-appb-000010
由表6中的测试结果可以看出，在第一聚合物层的熔点T A和EC+PC的含量Y之间满足：0.147<Y/T A<0.7的情况下，在电解液中加入一定量的二腈化合物和三腈化合物，能够进一步提高锂离子电池的热箱性能。
F：表7示出了相关实施例中锂离子电池的组成以及性能测试结果。实施例S7-1至S7-11与实施例S1-2中的锂离子电池的制备过程相似，不同之处在于电解液的组成不同，具体见表7。
表7
Figure PCTCN2020129757-appb-000011
其中“—”表示不具有该层物质。
由表7中的测试结果可以看出，在第一聚合物层的熔点T A和EC+PC的含量Y之间满足：0.147<Y/T A<0.7的情况下，在电解液中加入一定量的氟代碳酸乙烯酯，电池的热箱性能有一定恶化，加入1,3丙烷磺内酯对热箱并无明显影响，但两者同时存在时，能够进一步提高锂离子电池的热箱性能，推测与其联合成膜有关。在两者同时存在时，同时加入二腈和三腈化合物可达到最佳的效果。
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 (11)

  1. 一种电化学装置，其包括：
    电极，所述电极包括集流体、位于所述集流体的至少一个表面上的活性材料层、位于所述集流体上的极耳；和位于所述极耳上的极耳保护层，所述极耳保护层包括第一聚合物层，所述第一聚合物层的熔点为T A℃，110≤T A≤136.5；和
    电解液，所述电解液包括碳酸乙烯酯和碳酸丙烯酯；
    其中基于所述电解液的重量，所述碳酸乙烯酯和所述碳酸丙烯酯的重量百分比之和为Y％，Y为20-80；并且
    Y和T A满足：0.147<Y/T A<0.7。
  2. 根据权利要求1所述的电化学装置，其中所述极耳保护层进一步包括第二聚合物层，所述第二聚合物层的熔点为T B℃，T B≤160，并且T A和T B满足：0＜T B-T A≤50。
  3. 根据权利要求1所述的电化学装置，其中所述第一聚合物层包括马来酸酐接枝改性聚丙烯、酸化聚烯烃树脂或聚乙烯中的至少一种。
  4. 根据权利要求2所述的电化学装置，其中所述第二聚合物层包括聚丙烯树脂。
  5. 根据权利要求1所述的电化学装置，其中所述电解液进一步包括丙酸酯，其中基于所述电解液的重量，所述丙酸酯的重量百分比为10％-60％。
  6. 根据权利要求5所述的电化学装置，其中所述丙酸酯包括丙酸甲酯、丙酸乙酯、丙酸丙酯、丙酸丁酯、丙酸戊酯、氟代丙酸甲酯、氟代丙酸乙酯、氟代丙酸丙酯、氟代丙酸丁酯或氟代丙酸戊酯中的至少一种，其中氟代是指至少一个氢原子被氟原子取代。
  7. 根据权利要求1所述的电化学装置，其中所述电解液进一步包括三甲基乙酸酯化合物。
  8. 根据权利要求7所述的电化学装置，其中所述三甲基乙酸酯化合物的结构式为
    Figure PCTCN2020129757-appb-100001
    其中，R为C 1-C 10烷基、C 2-C 10烯基、C 1-C 10卤代烷基、C 2-C 10卤代烯基、卤素、芳基或酰胺。
  9. 根据权利要求7所述的电化学装置，其中所述三甲基乙酸酯化合物包括三甲基乙酸甲酯或三甲基乙酸乙酯中的至少一种。
  10. 根据权利要求1所述的电化学装置，其中所述电解液进一步包括二腈化合物或三腈化合物中的至少一种，
    其中所述二腈化合物包括如下化合物中的至少一种：
    丁二腈、戊二腈、己二腈、1,5-二氰基戊烷、1,6-二氰基己烷、1,7-二氰基庚烷、1,8-二氰基辛烷、1,9-二氰基壬烷、1,10-二氰基癸烷、1,12-二氰基十二烷、四甲基丁二腈、2-甲基戊二腈、2,4-二甲基戊二腈、2,2,4,4-四甲基戊二腈或乙二醇双(丙腈)醚；
    所述三腈化合物包括如下化合物中的至少一种：
    1,3,5-戊三甲腈、1,2,3-丙三甲腈、1,2,6-己三甲腈、1,3,6-己三甲腈、1,2,3-三(2-氰基乙氧基)丙烷、1,2,4-三(2-氰基乙氧基)丁烷或1,2,5-三(氰基乙氧基)戊烷。
  11. 一种电子装置，其中所述电子装置包括根据权利要求1-10中的任一项所述的电化学装置。
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