WO2021195908A1 - 改善电池循环性能的方法和电子装置 - Google Patents

改善电池循环性能的方法和电子装置 Download PDF

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Publication number
WO2021195908A1
WO2021195908A1 PCT/CN2020/082255 CN2020082255W WO2021195908A1 WO 2021195908 A1 WO2021195908 A1 WO 2021195908A1 CN 2020082255 W CN2020082255 W CN 2020082255W WO 2021195908 A1 WO2021195908 A1 WO 2021195908A1
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Prior art keywords
battery
charging
stage
voltage
current
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PCT/CN2020/082255
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English (en)
French (fr)
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贺俊
崔辉
郑强
方占召
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宁德新能源科技有限公司
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Priority to PCT/CN2020/082255 priority Critical patent/WO2021195908A1/zh
Priority to CN202080009254.3A priority patent/CN113785428B/zh
Priority to EP20928397.7A priority patent/EP4131562A4/en
Publication of WO2021195908A1 publication Critical patent/WO2021195908A1/zh
Priority to US17/957,002 priority patent/US20230042859A1/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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/44—Methods for charging or discharging
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
    • 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
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/417—Polyolefins
    • 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
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/443—Particulate material
    • 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
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • 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
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/457—Separators, membranes or diaphragms characterised by the material having a layered structure comprising three or more layers
    • 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
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
    • H01M50/461—Separators, membranes or diaphragms characterised by their combination with electrodes with adhesive layers between electrodes and separators
    • 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
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/491—Porosity
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/007—Regulation of charging or discharging current or voltage
    • H02J7/00712—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters
    • H02J7/007182—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters in response to battery voltage
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
    • H01M2010/4271—Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing
    • 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
    • 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

  • This application relates to the field of battery technology, and in particular to a method and electronic device for improving battery cycle performance.
  • the electrolyte containing the carboxylate solvent has the characteristics of low viscosity and high kinetics, which can effectively increase the charging speed of lithium-ion batteries and effectively improve the cycle performance under low temperature conditions.
  • the carboxylic acid ester solvents are active and prone to side reactions between the positive and negative electrodes of the battery. Especially under high temperature conditions, it is easy to produce gas side reactions, which will cause the cell to expand and deform, and affect the high temperature cycle and storage performance of the battery.
  • An embodiment of the present application provides a method for improving the cycle performance of a battery, which is applied to a battery.
  • the method includes: in a first stage, charging the battery with a first stage current to a first stage voltage; In the second stage, the battery is charged to the second stage voltage with the second stage current, the second stage voltage is greater than the first stage voltage, and the second stage current is less than the first stage current;
  • the battery includes an electrolyte containing an organic solvent, the organic solvent includes a chain carboxylic acid ester compound, and the weight percentage of the chain carboxylic acid ester compound to the organic solvent is 10% to 70%.
  • the chain carboxylic acid ester compound is selected from at least one of the compounds represented by formula I:
  • R 1 is selected from hydrogen atom, halogen atom, hydroxyl group, alkyl group having 1 to 20 carbon atoms, alkoxy group having 1 to 20 carbon atoms, alkenyl group having 1 to 20 carbon atoms, carbon An aryl group having 6 to 30 atoms or an aryloxy group having 6 to 30 carbon atoms;
  • R 2 is selected from a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, and a carbon number of 1 to 20 The alkenyl group or the aryl group having 6 to 30 carbon atoms.
  • the chain carboxylic acid ester compound is selected from methyl formate, methyl acetate, ethyl formate, ethyl acetate, propyl acetate, ethyl propionate, methyl propionate, propionic acid N-propyl, isopropyl propionate, methyl propionate, n-propyl propionate, isopropyl propionate, n-butyl propionate, isobutyl propionate, n-pentyl propionate, isoamyl propionate , Ethyl n-butyrate, n-propyl n-butyrate, propyl isobutyrate, n-pentyl n-butyrate, n-pentyl isobutyrate, n-butyl n-butyrate, isobutyl isobutyrate and n-valeric acid At least one of n-acetate, ethyl formate
  • the electrolyte further includes a lithium salt selected from lithium hexafluorophosphate, lithium difluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium perchlorate, and difluorosulfonyl At least one of lithium imide, lithium bistrifluoromethanesulfonimide, lithium bisoxalate borate, and lithium difluorooxalate borate.
  • the battery further includes a positive electrode sheet, a negative electrode sheet, and a separator provided between the positive electrode sheet and the negative electrode sheet.
  • the polymer adhesive layer includes polymer particles, and the number of stacked layers of the polymer particles in the polymer adhesive layer does not exceed four.
  • the polymer particles are polyvinylidene chloride, polyvinylidene fluoride-hexafluoropropylene copolymer, styrene-butadiene copolymer, polyacrylonitrile, butadiene-acrylonitrile polymerization
  • the particle size of the polymer particles is 0.2 ⁇ m- 2 ⁇ m.
  • the coverage area ratio of the polymer adhesive layer to the porous substrate or the heat-resistant coating is 15%-85%.
  • the binding force between the separator and the positive electrode sheet or the negative electrode sheet is greater than or equal to 3 N/m.
  • the second stage adopts the first charging method or the second charging method to charge the battery to the second stage voltage;
  • the average value of the charging current of the jth charging substage is less than the charging current of the first phase, and the average value of the charging current of the j+1th charging substage is less than or equal to the jth charging current.
  • the charging current of the electronic phase is less than the charging current of the first phase.
  • the first stage adopts a third charging method to charge the battery to the first stage voltage
  • the third charging method adopts the first charging method or the second charging method
  • the number of charging sub-stages K between the two is the same; or when the third charging method adopts the second charging method In the charging mode, the number of charging sub-stages D between the two is the same.
  • the first stage voltage is equal to the charge limit voltage of the battery, and the second stage voltage is less than the oxidative decomposition voltage of the electrolyte in the battery.
  • the second stage voltage is less than or equal to the first stage voltage plus 500 millivolts.
  • the method further includes: in the third stage, performing constant voltage charging on the battery with the second stage voltage.
  • An embodiment of the present application also provides an electronic device, including a battery and a battery management module, the battery includes an electrolyte containing an organic solvent, the organic solvent includes a chain carboxylic acid ester compound, the chain carboxylic acid The weight percentage of the ester compound and the organic solvent is 10%-70%, and the battery management module is used to perform any of the methods described above.
  • the embodiment of the present application combines an electrolyte containing a high content of carboxylic acid esters and a specific charging method (increasing the charging limit voltage of the battery), which can increase the charging speed of the battery, significantly shorten the full charge time of the battery, and can also shorten The time that the positive electrode of the battery is under high voltage reduces the time for the positive electrode to react with the electrolyte under high voltage, thereby improving the cycle performance of the battery. In addition, by using a highly adhesive separator, the cycle performance of the battery can be further improved.
  • Fig. 1 is a schematic diagram of an electronic device according to an embodiment of the present application.
  • Fig. 2 is a flowchart of a method for improving battery cycle performance according to an embodiment of the present application.
  • FIG. 3 is a first specific embodiment of the method for improving the cycle performance of the battery shown in FIG. 1.
  • Fig. 4 is a schematic diagram showing changes in current and voltage with time during battery charging according to the first embodiment of the present application.
  • Fig. 5 is a schematic diagram showing changes in current and voltage with time during battery charging according to the second embodiment of the present application.
  • Fig. 6 is a schematic diagram showing the change of power and voltage with time in the first stage and the change of current and voltage with time in the second stage according to an embodiment of the present application.
  • Fig. 7 is a schematic diagram of changes in current and voltage with time during battery charging according to the third embodiment of the present application.
  • Fig. 8 is a schematic diagram showing changes in current and voltage with time during battery charging according to the fourth embodiment of the present application.
  • FIG. 9 is a second specific embodiment of the method for improving the cycle performance of the battery shown in FIG. 1.
  • Fig. 10 is a third specific embodiment of the method for improving the cycle performance of the battery shown in Fig. 1.
  • FIG. 11 is a fourth specific embodiment of the method for improving the cycle performance of the battery shown in FIG. 1.
  • FIG. 12 shows the change of the lithium potential of the battery cathode when the battery is charged by the new charging method in the conventional charging method and the method for improving the cycle performance of the battery.
  • Figure 13 is a comparison diagram of the conductivity of solvent electrolytes with different carboxylate content.
  • Figure 14 is a schematic diagram of the full battery impedance.
  • Figure 15 is a schematic diagram of the comparison of the adhesion of different isolation films.
  • FIG. 1 is a schematic diagram of an electronic device according to an embodiment of the application.
  • the electronic device 1 includes a battery 10, a control unit 11 and a battery management module 12.
  • the battery 10, the control unit 11 and the battery management module 12 may be connected via a bus or directly.
  • the battery 10 includes at least one battery cell, and the battery 10 can be repeatedly charged in a rechargeable manner.
  • the battery is a lithium ion battery.
  • the control unit 11 may control the battery management module 12 to execute the method for improving battery cycle performance.
  • the control unit 11 can be a microcontroller (Microcontroller, MCU), a processor (Processor), or an application-specific integrated circuit (ASIC), etc., and can control the battery management module 12 to execute The method for improving the cycle performance of the battery.
  • MCU microcontroller
  • processor processor
  • ASIC application-specific integrated circuit
  • FIG. 1 is only an example of the electronic device 1.
  • the electronic device 1 may also include more or fewer elements, or have different element configurations.
  • the electronic device 1 may be an electric motorcycle, an electric bicycle, an electric car, a mobile phone, a tablet computer, a digital assistant, a personal computer, or any other suitable rechargeable equipment.
  • the electronic device 1 may also include other components such as a wireless fidelity (Wireless Fidelity, WiFi) unit, a Bluetooth unit, a speaker, etc., which will not be repeated here.
  • a wireless fidelity (Wireless Fidelity, WiFi) unit Wireless Fidelity, WiFi
  • a Bluetooth unit Bluetooth unit
  • speaker etc., which will not be repeated here.
  • FIG. 2 is a flowchart of a method for improving battery cycle performance according to an embodiment of the present application.
  • the method for improving the cycle performance of a battery applied to a battery includes the following steps:
  • Step S21 In the first stage, the battery is charged to the first stage voltage with the first stage current.
  • Step S22 In the second stage, the battery is charged to the second stage voltage with the second stage current, the second stage voltage is greater than the first stage voltage, and the second stage current is smaller than the first stage voltage Current
  • the battery includes an electrolyte containing an organic solvent
  • the organic solvent includes a chain carboxylic acid ester compound
  • the weight percentage of the chain carboxylic acid ester compound to the organic solvent is 10% to 70%.
  • chain carboxylic acid ester compound is selected from at least one of the compounds represented by formula I:
  • R 1 is selected from hydrogen atom, halogen atom, hydroxyl group, alkyl group having 1 to 20 carbon atoms, alkoxy group having 1 to 20 carbon atoms, alkenyl group having 1 to 20 carbon atoms, carbon An aryl group having 6 to 30 atoms or an aryloxy group having 6 to 30 carbon atoms;
  • R 2 is selected from a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, and a carbon number of 1 to 20 The alkenyl group or the aryl group having 6 to 30 carbon atoms.
  • chain carboxylic acid ester compound it can be selected from methyl formate, methyl acetate, ethyl formate, ethyl acetate, propyl acetate, ethyl propionate, methyl propionate, n-propyl propionate Ester, isopropyl propionate, methyl propionate, n-propyl propionate, isopropyl propionate, n-butyl propionate, isobutyl propionate, n-pentyl propionate, isoamyl propionate, n-propyl propionate Ethyl butyrate, n-propyl n-butyrate, propyl isobutyrate, n-pentyl n-butyrate, n-pentyl isobutyrate, n-butyl n-butyrate, isobutyl isobutyrate, n-valerate
  • the chain carboxylic acid ester compound is one selected from the group consisting of methyl formate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and ethyl butyrate Or multiple.
  • the battery may also include lithium salt and additives.
  • the lithium salt may be one or more of inorganic lithium salt and organic lithium salt.
  • the lithium salt may be lithium hexafluorophosphate (LiPF 6 ), lithium difluorophosphate (LiPO 2 F 2 ), lithium tetrafluoroborate (LiBF 4 ), lithium hexafluoroarsenate, lithium perchlorate, difluorosulfonyl Lithium imide (LiFSI), lithium bistrifluoromethanesulfonimide (LiTFSI), lithium bisoxalate borate LiB (C 2 O 4 ) 2 (abbreviated as LiBOB), lithium difluorooxalate borate LiBF 2 (C 2 O 4 ) (Abbreviated as LiDFOB) one or more of them.
  • LiPF 6 lithium hexafluorophosphate
  • LiPO 2 F 2 lithium difluorophosphate
  • LiBF 4 lithium tetrafluorobo
  • the lithium salt is lithium hexafluorophosphate (LiPF 6 ).
  • the additives are additives known in the art to improve battery performance, such as SEI (solid electrolyte interface) film forming additives, flame retardant additives, anti-overcharge additives, conductive additives, and the like.
  • the battery further includes a positive electrode sheet, a negative electrode sheet, and a separator film disposed between the positive electrode sheet and the negative electrode sheet.
  • the separator film includes a porous substrate and The heat-resistant coating on the surface and the polymer adhesive layer provided on the outermost side of the isolation film, and the polymer adhesive layer is provided on the surface of the heat-resistant coating or on the surface of the heat-resistant coating.
  • the polymer adhesive layer includes polymer particles, and the number of stacked layers of the polymer particles in the polymer adhesive layer does not exceed four. Preferably, the number of stacked layers is less than or equal to 2 layers.
  • the coverage area ratio of the polymer adhesive layer to the porous substrate or the heat-resistant coating is 15%-85%.
  • the battery usually uses polyolefin material as the separator.
  • the thickness of the adhesive layer of the isolation film is relatively large and the adhesive force is low, which cannot meet the requirements of lithium ion batteries for electrical performance and energy density. Therefore, a high-adhesion isolation film is used in this application, and the high-adhesion isolation film includes a porous substrate, a heat-resistant coating coated on at least one side of the porous substrate, and a polymer adhesive layer on the outermost layer.
  • the polymer adhesive layer is coated on the surface of the heat-resistant coating or the surface of the porous substrate that is not coated with the heat-resistant coating.
  • the coverage area ratio of the polymer adhesive layer to the porous substrate or the heat-resistant coating is 15%-85%, preferably 30%-70%.
  • the polymer adhesive layer includes polymer particles, and the polymer particles are polyvinylidene chloride, polyvinylidene fluoride-hexafluoropropylene copolymer, styrene-butadiene copolymer, At least one of polyacrylonitrile, butadiene-acrylonitrile polymer, polyacrylic acid, polyacrylate, and acrylate-styrene copolymer, or a copolymer of at least two of the above polymer monomers.
  • the polymer particles are homogeneous polymer microspheres or core-shell structured microspheres.
  • the particle size of the polymer particles is 0.2 ⁇ m-2 ⁇ m, preferably 0.3 ⁇ m-1 ⁇ m.
  • the swelling degree of the polymer particles relative to the electrolyte is 20%-100%.
  • the outer shell of the core-shell structured microspheres has a high adhesion force (the adhesion force with the positive and negative electrodes is not less than 3N/m ) Polymer, that is, the binding force between the separator and the positive electrode sheet or the negative electrode sheet is greater than or equal to 3N/m; the core of the core-shell structure microsphere is an affinity electrolyte (electrolyte Swelling degree>100%) polymer.
  • the polymer adhesive layer further includes an auxiliary adhesive and a dispersant for coating and bonding with the porous substrate or the heat-resistant coating.
  • the material of the porous substrate is polyethylene, polypropylene, polyethylene terephthalate (PET), cellulose or polyimide.
  • the electrolyte containing high content of carboxylate has high conductivity, which can improve the battery dynamics, so that it can meet the demand of high-rate charging; and the above-mentioned high-viscosity
  • the conductive isolation membrane can reduce the distance between the pole piece and the isolation membrane in the lithium-ion battery, and the electrolyte at the interface is squeezed out to a certain extent, which can inhibit the growth rate of by-products at high temperatures and improve the high-temperature cycle capacity retention Rate.
  • FIG. 3 is a first specific embodiment of the method for improving the cycle performance of the battery shown in FIG. 2.
  • Step S31 In the first stage, the battery is charged to the first stage voltage with the first stage current.
  • the current in the first stage is a constant current, that is, a constant charging current is used when charging is started in the prior art.
  • the current in the first stage may also be a current of varying magnitude.
  • the battery is charged with a constant voltage, and the charging current corresponding to the constant voltage (that is, the first The size of the phase current) will vary, as long as the battery can be charged to the first phase voltage through the first phase current.
  • the first stage voltage is equal to the charging limit voltage of the battery (which can be understood as a well-known charging limit voltage).
  • Step S32 In the second stage, the battery is charged to the second stage voltage with the second stage current, the second stage voltage is greater than the first stage voltage, and the second stage current is smaller than the first stage voltage Current; the second stage adopts the first charging method or the second charging method to charge the battery to the second stage voltage.
  • the battery includes an electrolyte containing an organic solvent
  • the organic solvent includes a chain carboxylic acid ester compound
  • the weight percentage of the chain carboxylic acid ester compound to the organic solvent is 10% to 70%.
  • One of current, i+1th voltage, and i+1th power charges the battery; wherein, the charging current in the i+1th charging sub-phase is less than or equal to the i-th charging
  • the charging current in the electronic phase, or the (i+1)th voltage is greater than or equal to the i-th voltage, or the (i+1)th power is less than or equal to the i-th power.
  • the (i+1)th voltage is greater than or equal to the ith voltage, and the (i+1)th power is less than or equal to the ith power.
  • the average value of the charging current of the j+1th charging substage is less than or equal to the charging current of the jth charging substage, and when the third charging method adopts the second charging method, The average value of the charging current in the jth charging substage is smaller than the charging current in the first charging mode or the second charging mode.
  • the first stage voltage is equal to the charging limit voltage of the battery.
  • Lithium evolution potential can be obtained by testing in the following way.
  • the battery in this embodiment another three-electrode battery with the same specifications is produced.
  • the three-electrode battery has one more electrode, that is, it contains three electrodes, which are anodes. , Cathode and reference electrode.
  • the material of the reference electrode is lithium, and the three-electrode battery is used for testing to obtain the lithium evolution potential of the anode of the battery of this embodiment.
  • the specific test method for the lithium evolution potential of the anode is as follows: make a plurality of three-electrode batteries, and charge and discharge the three-electrode battery with charging currents of different magnifications (for example, 1C, 2C, 3C), and cycle multiple times ( For example, 10 times), and detect the potential difference between the anode and the reference electrode during the charge and discharge process. Then, the three-electrode battery was fully charged and disassembled, and the anodes of the three-electrode batteries charged with different rates were observed whether lithium evolution occurred (that is, whether lithium metal was deposited on the surface of the anode).
  • magnifications for example, 1C, 2C, 3C
  • cycle multiple times For example, 10 times
  • the minimum potential difference between the anode and the reference electrode during the charge and discharge process at the rate is used as the anode lithium evolution potential.
  • the charging current of lithium batteries is generally referred to by the rate C, which is the value corresponding to the capacity of the lithium battery.
  • Lithium battery capacity is generally expressed in Ah and mAh. For example, when the battery capacity is 1200mAh, the corresponding 1C is 1200mA, and 0.2C is equal to 240mA.
  • the anode does not undergo lithium evolution when using 1C and 2C charging and discharging, and the anode occurs when using 3C charging and discharging.
  • the minimum value of the potential difference between the anode and the reference electrode at the 2C rate is the anode lithium evolution potential.
  • the lithium evolution potential of the cathode can also be tested in a similar manner, which will not be repeated here.
  • the anode potential and the cathode potential of the battery can be further understood through the above anode lithium evolution potential test process as follows: the anode potential is the potential difference between the anode and the reference electrode, that is, the anode versus lithium potential, and the cathode potential is the cathode and the reference electrode. The potential difference than the electrode, that is, the potential of the cathode to lithium.
  • the second stage voltage is less than the oxidative decomposition voltage of the electrolyte in the battery.
  • the oxidative decomposition voltage of the electrolyte in the battery can be understood as follows: when the potential of the battery exceeds a certain potential threshold, the solvent molecules, additive molecules, and even impurity molecules in the electrolyte will irreversibly reduce at the interface between the electrode and the electrolyte. Or oxidative decomposition reaction, this phenomenon is called electrolyte decomposition.
  • the potential threshold is the reduction decomposition voltage and the oxidation decomposition voltage of the electrolyte in the battery.
  • the second stage voltage is also less than or equal to the first stage voltage plus 500 millivolts.
  • the cut-off condition for charging the battery may be A cut-off voltage, a cut-off current, or a cut-off capacity. More specifically, in the K-th charging sub-phase or the D-th charging sub-phase, when the charging current of the battery is equal to the cut-off current, the reached charging voltage (that is, the voltage difference between the positive electrode and the negative electrode) is equal to that of the battery. When the cut-off voltage or the electric capacity of the battery is equal to the cut-off capacity, the battery is stopped charging, that is, the charging is cut off.
  • the cut-off current, the cut-off voltage, and the cut-off capacity can be obtained by using the aforementioned three-electrode battery test method and observing that the cathode of the three-electrode battery does not undergo excessive delithiation.
  • the electric capacity of the battery is equivalent to that of the conventional charging method in the prior art, and to ensure that the cathode of the battery does not undergo excessive delithiation.
  • the first stage current, the first stage voltage, the i-th current of the i-th charging substage of the first stage, the One of the i-th voltage, and the i-th power, one of the i-th current, the i-th voltage, and the i-th power in the i-th charging substage of the second stage The second stage voltage and the value of the cut-off condition may be pre-stored in the battery or the processor 11, and the processor 11 reads the pre-stored value to correctly control The charging system 10 performs charging.
  • the first charging method is used to charge the battery in the first stage, and the first charging method includes K charging sub-stages in sequence, and the K charging sub-stages are respectively defined as the i-th charger.
  • i 1, 2,..., K
  • the battery In the first stage, from time 0 to t1, the battery is charged to voltage U1 with a constant current I1; from time t1 to t2, charged to voltage U2 with a constant current I2; from time t(i-2) to During t(i-1), charge with constant current I(i-1) to voltage U(i-1); between time ti-1 and ti, charge with constant current Ii to voltage Ui; at time t(K -1) Between tK, charge with constant current Icl to voltage Ucl. Between time t2 and t(i-2), and between time ti and t(K-1), similar charging is performed, but it is omitted in the figure and not shown.
  • the battery is charged with a constant current I1' to the voltage U1'; from time t2' to t3', the battery is charged with a constant voltage U1', the corresponding charging current for this period of time Decrease from I1' to current I2'; from time t3' to t4', charge the battery with a constant current I2' to voltage U2'; from time t4' to t5', charge the battery with a constant voltage U2'; Between time t(i-1)' and ti', charge the battery with a constant current Ii' to the voltage Ui'; between time ti' and t(i+1)', charge the battery with a constant voltage Ui', this period The charging current corresponding to time drops from I1' to the current I(i+1)'; between time t(K-2)' and t(K-1)', the charging current is charged to the voltage Um with a constant current Im; at
  • the tK and t1' are the same time.
  • the battery is charged with a constant charging current, and I1 ⁇ I2 ⁇ ... ⁇ Icl, U1 ⁇ U2 ⁇ ... ⁇ Ucl;
  • Each of the K charging sub-phases of the two stages charges the battery alternately with a constant charging current and a constant voltage, Icl ⁇ I1' ⁇ I2' ⁇ ... ⁇ Im', Ucl ⁇ U1' ⁇ U2' ⁇ ... ⁇ Um.
  • the battery In the first stage, between time 0 and t1, the battery is charged with a constant voltage U1 until the current is I1; between time t1 and t2, the battery is charged with a constant voltage U2 until the current is I2; at time t(i-1 Between) and ti, charge with a constant voltage Ui until the current is Ii; between time t(K-1) and tK, charge with a constant voltage Ucl until the current is Icl. Similar charging is performed between time t2 and t(i-1) and between time ti and t(K-1), but is omitted in the figure and not shown.
  • the battery is charged with a constant current I1' to the voltage U1'; from time t2' to t3', the battery is charged with a constant voltage U1', the corresponding charging current for this period of time Decrease from I1' to current I2'; from time t3' to t4', charge the battery with a constant current I2' to voltage U2'; from time t4' to t5', charge the battery with a constant voltage U2'; Between time t(i-1)' and ti', charge the battery with a constant current Ii' to the voltage Ui'; between time ti' and t(i+1)', charge the battery with a constant voltage Ui', this period The charging current corresponding to time drops from Ii' to the current I(i+1)'; between time t(K-2)' and t(K-1)', the charging current is charged to the voltage Um with a constant current Im; at
  • the tK and t1' are the same time.
  • the battery In each of the K charging sub-phases of the first stage, the battery is charged with a constant charging voltage, and U1 ⁇ U2 ⁇ ... ⁇ Ucl, I1 ⁇ I2 ⁇ ... ⁇ Icl.
  • the battery In each of the K charging sub-stages of the second stage, the battery is charged alternately with a constant charging current and a constant charging voltage, and Ucl ⁇ U1' ⁇ U2' ⁇ ... ⁇ Um, Icl ⁇ I1' ⁇ I2' ⁇ ... ⁇ Im'.
  • the battery In the first stage, between time 0 and t1, the battery is charged with constant power P1 until the voltage is U1; between time t1 and t2, the battery is charged with constant power P2 to voltage U2; at time t(i-2) To t(i-1), charge to voltage U(i-1) with constant power P(i-1); from time t(i-1) to ti, charge to voltage Ui with constant power Pi; Between time t(K-1) and tK, charge to voltage Ucl with constant power Pcl. Between time t2 and t(i-2), and between time ti and t(K-1), similar charging is performed, but it is omitted and not shown in the figure.
  • the battery is charged with a constant current I1' to the voltage U1'; from time t2' to t3', the battery is charged with a constant voltage U1', the corresponding charging current for this period of time Decrease from I1' to current I2'; from time t3' to t4', charge the battery with a constant current I2' to voltage U2'; from time t4' to t5', charge the battery with a constant voltage U2'; Between time t(i-1)' and ti', charge the battery with a constant current Ii' to the voltage Ui'; between time ti' and t(i+1)', charge the battery with a constant voltage Ui', this period The charging current corresponding to time drops from I1' to the current I(i+1)'; between time t(K-2)' and t(K-1)', the charging current is charged to the voltage Um with a constant current Im; at
  • the battery in each of the K charging sub-stages of the first stage, the battery is charged with a constant power, and P1 ⁇ P2 ⁇ ... ⁇ Pcl, U1 ⁇ U2 ⁇ ... ⁇ Ucl.
  • the battery is charged alternately with a constant charging current and a constant charging voltage, and Ucl ⁇ U1' ⁇ U2' ⁇ ... ⁇ Um, Icl ⁇ I1' ⁇ I2' ⁇ ... ⁇ Im'.
  • the battery In the first stage, from time 0 to t1, the battery is charged with a constant current I1 to the voltage U1; from time t1 to t2, the battery is charged with a constant voltage U1, the corresponding charging current during this period of time decreases from I1 To the current I2; from time t2 to t3, charge the battery with a constant current I2 to the voltage U2; from time t3 to t4, charge the battery with a constant voltage U2, the corresponding charging current for this period of time drops from I2 to the current I3; From time t(i-2) to t(i-1), charge the battery with a constant current Ii to the voltage Ui; from time t(i-1) to ti, charge the battery with a constant voltage Ui; at time t(K From -2) to t(K-1), charge the battery with a constant current Icl to the voltage Ucl; from time t(K-1) to tK, charge the battery with a constant voltage Ucl, the
  • the battery is charged with a constant current I1' to the voltage U1'; from time t2' to t3', the battery is charged with a constant voltage U1', the corresponding charging current for this period of time Decrease from I1' to current I2'; from time t3' to t4', charge the battery with a constant current I2' to voltage U2'; from time t4' to t5', charge the battery with a constant voltage U2'; Between time t(i-1)' and ti', charge the battery with a constant current Ii' to the voltage Ui'; between time ti' and t(i+1)', charge the battery with a constant voltage Ui', this period The charging current corresponding to time drops from I1' to the current I(i+1)'; between time t(K-2)' and t(K-1)', the charging current is charged to the voltage Um with a constant current Im; at
  • a constant charging current and a constant charging voltage alternately charge the battery
  • I1 ⁇ I2 ⁇ ... ⁇ Icl, U1 ⁇ U2 ⁇ ... ⁇ Ucl In each of the K charging sub-phases of the second stage, the battery is also charged alternately with a constant charging current and a constant charging voltage, and I1' ⁇ I2' ⁇ ... ⁇ Im', U1' ⁇ U2' ⁇ ... ⁇ Um, and Icl ⁇ I1', Ucl ⁇ U1'.
  • the battery In one of the j-th pre-charge sub-phase and the j-th post-charge sub-phase, the battery is not charged or is charged or discharged with a j-th pre-charger current for Tj 1 time. In the other of the j-th pre-charging sub-stage and the j-th post-charging sub-stage, the battery is charged with a j-th post-charge sub-current for a duration of Tj2.
  • the absolute value of the j-th front charger current is smaller than the absolute value of the j-th rear charger current.
  • the battery is charged by pulse charging or pulse charging and discharging, and the average value of the charging current of the j+1 charging substage is less than or It is equal to the charging current of the jth charging sub-stage, for example, (the first front charger current ⁇ T11+the first rear charger current ⁇ T12)/(T11+T12) is greater than or equal to (the second front charger current ⁇ T21+ The second rear charger current ⁇ T22)/(T21+T22), (the second front charger current ⁇ T21+the second rear charger current ⁇ T22)/(T21+T22) is greater than or equal to (the third front charger current ⁇ T31+third post-charger current ⁇ T32)/(T31+T32) and so on.
  • the sum of the duration of each Tj1 and the duration of Tj2 is the charging period or the charging and discharging period of the pulse charging or the pulse charging and discharging in the jth charging sub-phase.
  • the j-th pre-charger current is used to charge or discharge for Tj1 time
  • the j-th post-charger In the stage charging is performed with the j-th post-charger current for a duration of Tj2.
  • the charge or discharge current of the front charger is Tj1.
  • the charging sub-phase before the jth charge is not charged or is left to stand that is, the charging current is 0 at this time
  • the charging sub-phase after the jth charge After the jth sub-current is charged or discharged for Tj2 duration.
  • time t1 and t1000 that is, in each charging sub-stage from the first charging sub-stage to the 1000th charging sub-stage of the first stage, the current I2 is first applied to The battery is charged, and then the battery is charged with a current I3. Between time tx and t1000, similar charging is performed, but it is omitted and not shown in the figure.
  • the battery in the D charging sub-phases of the first phase, the battery is charged in three different pulse charging or pulse charging and discharging methods.
  • the charging period or the charging and discharging period of different pulse charging or pulse charging and discharging may also be different.
  • the battery In the second stage, from time t1' to t2', the battery is charged with a constant current I1' to the voltage U1'; from time t2' to t3', the battery is charged with a constant voltage U1', the corresponding charging current for this period of time Decrease from I1' to current I2'; from time t3' to t4', charge the battery with a constant current I2' to voltage U2'; from time t4' to t5', charge the battery with a constant voltage U2'; Between time ti' and t(i+1)', charge with constant current Ii' to voltage Ui'; between time t(i+1)' and t(i+2)', use constant voltage Ui' to When charging the battery, the charging current corresponding to this period of time drops from I1' to the current I(i+1)'; during the time t(D-2)' to t(D-1)', the constant current Im is charged to the voltage Um; between time
  • FIG. 9 is a second specific embodiment of the method for improving battery cycle performance shown in FIG. 2.
  • the second specific embodiment is similar to the first specific embodiment, and the second specific embodiment also includes step S91 and step S92.
  • step S91 which is specifically as follows:
  • Step S91 In the first stage, the battery is charged to the first stage voltage with the first stage current.
  • a third charging method is used to charge the battery to the first stage voltage, and the third charging method is the first charging method or the second charging method.
  • the first charging method and the second charging method are the same as the first charging method and the second charging method in the first specific embodiment, and will not be repeated here.
  • the number of charging sub-stages K between the two may be the same, that is, the charging sub-stages included in the first charging method adopted in the first stage
  • the number may be the same as the number of charging sub-stages included in the first charging method adopted in the second stage; or when the third charging method adopts the second charging method, the charging between the two
  • the number D of electronic stages may be the same, that is, the number of charging sub-stages included in the second charging method adopted in the first stage and the charging sub-stages included in the second charging method adopted in the second stage The number can be the same.
  • the number of charging sub-stages K between the two may be different, that is, the charging sub-stages included in the first charging method adopted in the first stage
  • the number may be different from the number of charging sub-stages included in the first charging method used in the second stage; or when the third charging method uses the second charging method, the charge between the two
  • the number D of electronic stages may be different, that is, the number of charging sub-stages included in the second charging method adopted in the first stage and the number of charging sub-stages included in the second charging method adopted in the second stage The number can be different.
  • FIG. 10 is a third specific embodiment of the method for improving the cycle performance of the battery shown in FIG. 2.
  • the third specific embodiment is similar to the first specific embodiment, and the third specific embodiment also includes step S101 and step S102.
  • the difference lies in step S101 and step S102, which are specifically as follows:
  • Step S101 In the first stage, the battery is charged to the first stage voltage with the first stage current.
  • a third charging method is used to charge the battery to the first stage voltage, and the third charging method is the first charging method or the second charging method.
  • the first charging method and the second charging method are the same as the first charging method and the second charging method in the first specific embodiment, and will not be repeated here.
  • Step S102 In the second stage, the battery is charged to the second stage voltage with the second stage current, the second stage voltage is greater than the first stage voltage, and the second stage current is smaller than the first stage voltage Current; the second stage adopts the first charging method or the second charging method to charge the battery to the second stage voltage;
  • the battery includes an electrolyte containing an organic solvent
  • the organic solvent includes a chain carboxylic acid ester compound
  • the weight percentage of the chain carboxylic acid ester compound to the organic solvent is 10% to 70%.
  • the second stage current is a constant current, that is, an existing charging current that uses constant current charging when charging is started.
  • the current in the second stage may also be a current of varying magnitude.
  • the battery is charged with a constant voltage, and the charging current corresponding to the constant voltage (that is, the second The size of the phase current) will vary, as long as the battery can be charged to the second phase voltage through the second phase current.
  • FIG. 11 is a fourth specific embodiment of the method for improving battery cycle performance shown in FIG. 2.
  • the fourth specific embodiment is similar to the first specific embodiment, and the fourth specific embodiment also includes step S111 and step S112. The difference is that the fourth specific embodiment further includes step S113, which is specifically as follows:
  • Step S113 In the third stage, charge the battery at a constant voltage with the second stage voltage.
  • the battery in the third stage, is charged at a constant voltage with the second stage voltage until the battery is fully charged.
  • the second specific embodiment can be improved with reference to the fourth embodiment, and step S113 is added: in the third stage, the battery is charged at a constant voltage with the second stage voltage.
  • step S113 is added: In the third stage, charge the battery at a constant voltage with the second stage voltage
  • this application provides a new combination solution for optimizing the battery cell system.
  • the use of high-content carboxylate solvent electrolyte combined with high-adhesion isolation membrane applications can inhibit the side reactions of carboxylic acid ester and the interface of positive and negative electrodes, effectively improve the cycle performance of the battery at high temperature, and improve the storage condition of the battery at high temperature; on the other hand, through the carboxylic acid ester
  • the low viscosity and high conductivity characteristics of the solvent electrolyte can improve the poor wettability of the high-adhesive separator electrolyte and the low electrolyte transmission speed, improve the kinetics of the cell system, and improve the cycle performance of the battery at low temperatures.
  • the method for improving the cycle performance of the battery is actually to charge the optimized battery cell system through a new charging method.
  • the new charging method is to charge the adjusted battery to the first stage voltage by at least one of constant current, constant voltage or constant power in the first stage; and use constant current in the second stage , At least one of constant voltage or constant power to charge the adjusted battery.
  • the charging method of pulse charging or pulse charging and discharging may also be adopted in the first stage and the second stage. Therefore, the time required for the battery to be fully charged can be significantly shortened, and by shortening the cathode high potential time, the time for the positive electrode to react with the electrolyte under high voltage can be reduced, and the cycle performance of the battery can be further improved.
  • the conventional charging method and the new charging method 1 of the present application and the change of the lithium potential of the respective cathodes are described.
  • the curve C1 is the conventional charging method
  • the curve C2 is the new charging method 1.
  • the time when the potential of the cathode to lithium is greater than 4.4V is 45 minutes
  • the time of the new charging method 1 when the potential of the cathode to lithium is greater than 4.4V is 31 minutes. Because the cathode of the battery is at a high potential for lithium, the time is significantly shortened. Therefore, the new charging method 1 can reduce the probability of side reactions at the cathode potential of the battery, and can increase the service life of the battery.
  • Table 1 shows the comparison of the time when the cathode-to-lithium potential is greater than 4.4V between the conventional charging method and multiple new charging methods.
  • the specific charging process of the conventional charging method is: charging the battery with a constant current of 0.7C until the battery voltage reaches 4.45V; and then charging the battery with a constant voltage of 4.45V until the battery current is 0.05C.
  • the specific charging process of the new charging method 1 of this application is: use a constant current of 0.7C to charge the battery until the battery voltage reaches 4.45V; use a constant current of 0.5C to charge the battery until the battery voltage reaches 4.5V; then use a constant 4.5V The voltage charges the battery until the battery current is 0.18C.
  • the cut-off voltage (4.5V) of the constant current charging process in the new charging method 1 is higher than the cut-off voltage (4.45V) of the constant current charging process in the conventional charging method.
  • the time for the cathode to lithium potential greater than 4.4V is 31 minutes, which is somewhat shorter than the conventional charging method.
  • the specific charging process of the new charging method 2 of this application is: use 1.2C constant current to charge the battery until the battery voltage reaches 4.25V; then use 0.7C constant current to charge the battery until the battery voltage reaches 4.45V; use 0.5C constant The current charges the battery until the battery voltage reaches 4.5V; then uses a constant voltage of 4.5V to charge the battery until the battery current is 0.19C.
  • the new charging method 2 includes three constant current charging processes, and the final cut-off voltage (4.5V) of the constant current charging process is higher than the cut-off voltage (4.45V) of the constant current charging process in the conventional charging method.
  • the time for the cathode to lithium potential greater than 4.4V is 27 minutes, which is significantly shorter than the conventional charging method. And compared to the new charging method 1, the time is also shortened to a certain extent.
  • the specific charging process of the new charging method 3 of this application is: use a 0.7C constant current to charge the battery until the battery voltage reaches 4.55V; then use a 4.4V constant voltage to charge the battery until the battery current is 0.4C; and then use 4.5V Charge the battery with a constant voltage until the battery current is 0.13C.
  • the cut-off voltage (4.55V) of the constant current charging process in the new charging method 3 is higher than the cut-off voltage (4.45V) of the constant current charging process in the conventional charging method.
  • the time for the new charging method 3 when the cathode to lithium potential is greater than 4.4V is 24 minutes, which is almost half the time of the conventional charging method, and also shorter than the new charging method 2 and the new charging method 1.
  • the specific charging process of the new charging method 4 of this application is: charge the battery with a constant current of 0.7C until the battery voltage reaches 4.45V; charge the battery with a constant power of 7W to 4.5V; charge the battery with a constant power of 5.5W Charge to 4.55V.
  • the cut-off voltage (4.55V) of the constant current charging process in the new charging method FFC4 is higher than the cut-off voltage (4.45V) of the constant current charging process in the conventional charging method.
  • the time for new charging method 4 when the cathode to lithium potential is greater than 4.4V is 23 minutes, which is almost half the time of the conventional charging method, which is shorter than the time of new charging method 3, new charging method 2 and new charging method 1.
  • the specific charging process of the new charging method 5 of this application is: charge the battery with a constant current of 0.7C until the battery voltage reaches 4.45V; leave the battery to stand for 2.9 seconds; charge the battery with a constant current of 0.7C for 7.1 seconds Clock, judge whether the battery voltage is greater than or equal to 4.5V, when the battery voltage is greater than or equal to 4.5V, skip to the next step; discharge the battery with a constant current of 0.05C for 1 second; charge the battery with a constant current of 0.41C 9 Seconds, it is judged whether the battery voltage is greater than or equal to 4.55V. When the battery voltage is greater than or equal to 4.55V, the charging is stopped.
  • the cut-off voltage (4.55V) of the constant current charging process in the new charging method 5 is higher than the cut-off voltage (4.45V) of the constant current charging process in the conventional charging method.
  • the time for new charging method 5 when the cathode to lithium potential is greater than 4.4V is 23 minutes, which is almost half the time of the conventional charging method, which is longer than the new charging method 3, new charging method 2 and new charging method 1 of this application. short.
  • FIG. 15 Please refer to FIG. 15 for a comparison diagram of the adhesion of different isolation films. It can be seen that the adhesion of the high-adhesion separator film to the anode is increased by about 11 N/m compared to the low-adhesion separator film, and the adhesion of the high-adhesion separator film to the cathode is increased by approximately 5 N/m compared with the low adhesion separator film.
  • the low-adhesion separator is a separator with a binding force between the positive electrode sheet or the negative electrode sheet of less than 3 N/m.
  • the adhesion force of the low adhesion isolation film is about 1 N/m.
  • This application combines a high-adhesive separator, a new charging method with a high-content carboxylate electrolyte system, and improves the interface between the separator and the positive and negative electrodes through the high-adhesive separator.
  • the new charging method shortens the battery's high voltage Lower charging time, inhibit side reaction production, and improve the high-temperature cycle performance of the high-content carboxylate electrolyte system full battery; improve the system kinetics through the carboxylate-containing solvent electrolyte, and strengthen the wettability of the electrolyte and the separator , Speed up the electrolyte transmission speed, meet the requirements of the electrolyte channel for circulation under low temperature conditions, and improve the low temperature circulation.
  • the high-adhesion isolation membrane and the carboxylate-containing solvent electrolyte complement each other, plus the advantages of the new charging method, improve the battery's high and low temperature cycle and high temperature storage performance.
  • the battery system used in the comparative example and the embodiment adopts a general lithium-ion battery manufacturing process, and the positive and negative active materials are respectively stirred with a binder, a solvent, etc. into a uniform slurry, and are respectively coated on the aluminum foil and the copper foil. After cold pressing, slitting and other processes, the required length and width of the pole piece is obtained, and the electrode assembly is wound together with the isolating film, and after encapsulation, liquid injection, and formation, the finished cell is made.
  • the battery cells of this system adopt different carboxylate content electrolytes, different adhesion membranes and different charging methods to perform low-temperature and high-temperature cycle performance testing and high-temperature storage. The specific schemes are shown in Table 2 and compared with 12°C. And the capacity retention rate of the battery after 500 cycles of charge and discharge at 45°C and the cell expansion rate after 8 hours of storage at an ambient temperature of 80°C.
  • Electrolyte Contains ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), and does not contain non-carboxylate;
  • Isolation film a low-adhesion isolating film ( ⁇ 1N/m) is used.
  • the base material of the low-adhesion isolating film is polyethylene
  • the polymer adhesive layer is polyvinylidene fluoride (PVDF)
  • the polymer particle size is 100nm, the coverage rate of the polymer adhesive layer is 23%;
  • Step 1 Use a constant current of 0.7C to charge the battery until the battery voltage reaches 4.45V;
  • Step 2 Use a constant voltage of 4.45V to charge the battery until the battery current reaches 0.05C;
  • Step 3 Let the battery stand for 5 minutes
  • Step 4 Use a constant current of 0.5C to discharge the battery until the battery voltage is 3.0V;
  • Step 5 Let the battery stand for 5 minutes
  • Step 6 Repeat the above steps 1 to 5 for 500 cycles.
  • Electrolyte The composition is the same as that of the comparative example;
  • Isolation film same as the comparative example
  • Charging method adopt the new charging method 1 in this application, and the specific process is as follows:
  • Step 1 Use a constant current of 0.7C to charge the battery until the battery voltage reaches 4.45V;
  • Step 2 Use a constant current of 0.5C to charge the battery until the battery voltage reaches 4.5V;
  • Step 3 Use a constant voltage of 4.5V to charge the battery until the battery current reaches 0.18C;
  • Step 4 Let the battery stand for 5 minutes
  • Step 5 Use a constant current of 0.5C to discharge the battery until the battery voltage is 3.0V;
  • Step 6 Let the battery stand for 5 minutes
  • Step 7 Repeat the above steps 1 to 6 for 500 cycles.
  • Electrolyte The composition is the same as that of the comparative example;
  • Isolation film a high-adhesion isolating film ( ⁇ 12N/m), the base material of the high-adhesion isolating film is polyethylene, the polymer adhesive layer is polyacrylic acid, the polymer particle size is 500nm, and the polymer is bonded Layer coverage rate is 40%;
  • Charging method adopt the conventional charging method, namely constant current-constant voltage charging method.
  • the specific process please refer to the comparative example, which will not be repeated here.
  • Electrolyte The composition is the same as that of the comparative example, except that 40% carboxylate is added;
  • Isolation film same as the comparative example
  • Charging method adopt the conventional charging method, namely constant current-constant voltage charging method.
  • the specific process please refer to the comparative example, which will not be repeated here.
  • Electrolyte The composition is the same as the comparative example, except that 6% carboxylate is added;
  • Isolation film the same as in Example 2;
  • Charging method adopt the new charging method 1 in this application.
  • Electrolyte The composition is the same as that of the comparative example, except that 10% carboxylate is added;
  • Isolation film the same as in Example 2;
  • Charging method adopt the new charging method 1 in this application.
  • Electrolyte The composition is the same as that of the comparative example, except that 20% of carboxylic acid ester is added;
  • Isolation film the same as in Example 2;
  • Charging method adopt the new charging method 1 in this application.
  • Electrolyte The composition is the same as that of the comparative example, except that 30% of carboxylic acid ester is added;
  • Isolation film the same as in Example 2;
  • Charging method adopt the new charging method 1 in this application.
  • Electrolyte The composition is the same as that of the comparative example, except that 40% carboxylate is added;
  • Isolation film the same as in Example 2;
  • Charging method adopt the new charging method 1 in this application.
  • Electrolyte The composition is the same as that of the comparative example, except that 50% carboxylic acid ester is added;
  • Isolation film the same as in Example 2;
  • Charging method adopt the new charging method 1 in this application.
  • Electrolyte The composition is the same as that of the comparative example, except that 60% of carboxylate is added;
  • Isolation film the same as in Example 2;
  • Charging method adopt the new charging method 1 in this application.
  • Electrolyte The composition is the same as that of the comparative example, except that 70% of carboxylate is added;
  • Isolation film the same as in Example 2;
  • Charging method adopt the new charging method 1 in this application.
  • Electrolyte The composition is the same as that of the comparative example, except that 74% of carboxylic acid ester is added;
  • Isolation film the same as in Example 2;
  • Charging method adopt the new charging method 1 in this application.
  • Electrolyte The composition is the same as that of the comparative example, except that 40% carboxylate is added;
  • Isolation film same as the comparative example
  • Charging method adopt the new charging method 1 in this application.
  • Electrolyte The composition is the same as that of the comparative example, except that 40% carboxylate is added;
  • Isolation film same as the comparative example
  • Charging method adopt the conventional charging method, namely constant current-constant voltage charging method.
  • the specific process please refer to the comparative example, which will not be repeated here.
  • Electrolyte The composition is the same as that of the comparative example, except that 40% carboxylate is added;
  • Isolation film a high-adhesion isolating film ( ⁇ 3.2N/m) is used.
  • the base material of the high-adhesion isolating film is polyethylene
  • the polymer adhesive layer is polyacrylic acid
  • the polymer particle size is 200nm
  • the polymer adhesive The coverage rate of the bonding layer is 15%;
  • Charging method adopt the new charging method 1 in this application.
  • Electrolyte The composition is the same as that of the comparative example, except that 40% carboxylate is added;
  • Isolation film a high-adhesion isolating film ( ⁇ 20N/m), the base material of the high-adhesion isolating film is polyethylene, the polymer adhesive layer is polyacrylic acid, the polymer particle size is 500nm, and the polymer is bonded Layer coverage rate is 85%;
  • Charging method adopt the new charging method 1 in this application.
  • Electrolyte The composition is the same as that of the comparative example, except that 40% carboxylate is added;
  • Isolation film the same as in Example 2;
  • Step 1 Use a constant current of 1.2C to charge the battery until the battery voltage reaches 4.25V,
  • Step 2 Use a constant current of 0.7C to charge the battery until the battery voltage reaches 4.45V;
  • Step 3 Use a constant current of 0.5C to charge the battery until the battery voltage reaches 4.5V;
  • Step 4 Use a constant voltage of 4.5V to charge the battery until the battery current reaches 0.19C;
  • Step 5 Let the battery stand for 5 minutes
  • Step 6 Use a constant current of 0.5C to discharge the battery until the battery voltage is 3.0V;
  • Step 7 Let the battery stand for 5 minutes
  • Step 8 Repeat the above steps 1 to 7 for 500 cycles.
  • Electrolyte The composition is the same as that of the comparative example, except that 40% carboxylate is added;
  • Isolation film the same as in Example 2;
  • Step 1 Use a constant current of 0.7C to charge the battery until the battery voltage reaches 4.45V;
  • Step 2 Use a constant voltage of 4.4V to charge the battery until the battery current reaches 0.4C;
  • Step 3 Use a constant voltage of 4.5V to charge the battery until the battery current reaches 0.13C;
  • Step 4 Let the battery stand for 5 minutes
  • Step 5 Use a constant current of 0.5C to discharge the battery until the battery voltage is 3.0V;
  • Step 6 Let the battery stand for 5 minutes
  • Step 7 Repeat the above steps 1 to 6 for 500 cycles.
  • Electrolyte The composition is the same as that of the comparative example, except that 40% carboxylate is added;
  • Isolation film the same as in Example 2;
  • Step 1 Use a constant current of 0.7C to charge the battery until the battery voltage reaches 4.45V;
  • Step 2 Charge the battery to 4.5V with a constant power of 7W;
  • Step 3 Charge the battery to 4.55V with a constant power of 5.5W;
  • Step 4 Let the battery stand for 5 minutes
  • Step 5 Discharge the battery to 3.0V at a constant current of 0.5C;
  • Step 6 Let the battery stand for 5 minutes
  • Step 7 Cycle the above steps 1 to 6 for 500 times.
  • Electrolyte The composition is the same as that of the comparative example, except that 40% carboxylate is added;
  • Isolation film the same as in Example 2;
  • Step 1 Use a constant current of 0.7C to charge the battery until the battery voltage reaches 4.45V;
  • Step 2 Leave the battery for 2.9 seconds
  • Step 3 Charge the battery at a constant current of 0.7C for 7.1 seconds, and judge whether the battery voltage is greater than or equal to 4.5V. When the battery voltage is greater than or equal to 4.5V, skip to step 5;
  • Step 4 Cycle Step 2 to Step 3 100000 times
  • Step 5 Discharge the battery for 1 second at a constant current of 0.05C;
  • Step 6 Charge the battery with a constant current of 0.41C for 9 seconds, and judge whether the battery voltage is greater than or equal to 4.55V. When the battery voltage is greater than or equal to 4.55V, skip to step 8;
  • Step 7 Let the battery stand for 5 minutes
  • Step 8 Discharge the battery to 3.0V at a constant current of 0.5C;
  • Step 9 Let the battery stand for 5 minutes
  • Step 10 Cycle the above steps 1 to 9 500 times.
  • the comparative example adopts a carboxylate-free solvent electrolyte, a conventional charging method, and a low-viscosity isolation film to prepare a battery cell, and performs high-temperature and low-temperature cycle tests and high-temperature storage tests.
  • Example 1 the new charging method 1 in this application is adopted, which can shorten the time that the positive electrode is under high pressure during the charging process during the cycle, the side reaction of the electrolyte and the positive electrode is reduced, the high temperature cycle is improved, and the low temperature cycle is the same as the comparative example. level.
  • the battery system in Example 2 incorporates a high-adhesive separator. Since the electrolyte does not contain carboxylic acid esters, the kinetics is poor, and the high-adhesive separator has poor wettability, and the low-temperature cycle performance is seriously deteriorated compared to the comparative example; in addition, The high-temperature storage performance is slightly improved due to the increased adhesion of the high-adhesive isolation film.
  • the battery system in Example 3 introduces a carboxylate-containing solvent electrolyte. Compared with the comparative example, the battery kinetics are improved, and the low-temperature cycle is improved, but the side reactions increase at high temperature, and the high-temperature cycle and high-temperature storage performance deteriorate.
  • the battery system in Example 8 simultaneously introduces a carboxylate-containing solvent electrolyte and a high-adhesive separator, and then uses the new charging method 1 in this application for charging and discharging tests.
  • the high-viscosity The isolation membrane is connected to improve the battery interface and reduce the side reactions of the battery containing carboxylate solvent electrolyte.
  • the carboxylate solvent electrolyte has high kinetics, improves the wettability of the high adhesion isolation membrane, and improves the electrolyte transmission capacity.
  • the new charging method 1 in this application can reduce the charging time of the battery under high voltage, and the high temperature and low temperature cycle and high temperature storage of the battery are improved.
  • the battery system in Examples 5-11 uses 10%-70% different content of carboxylate solvent electrolyte with high adhesion isolation film and the new charging method 1 in this application, both of which can improve the high temperature cycle and high temperature storage performance of the battery , And with the increase of carboxylate solvent content, the improvement of low temperature cycle performance is more obvious.
  • Example 4 The battery system in Comparative Examples 5-11 has an electrolyte carboxylate solvent content of less than 10%, insufficient kinetics, and deterioration of low-temperature cycle performance, which cannot meet the requirements.
  • the battery system in Example 12 and Comparative Examples 5-11 has an electrolyte carboxylate solvent content higher than 70%, high electrolyte activity, aggravated side reactions at high temperatures, and significantly deteriorated high-temperature cycling and high-temperature storage performance.
  • Example 13 Comparing Example 13 to Example 8, it can be seen that the high-adhesion isolation film can strengthen the battery interface, reduce side reactions, and significantly improve the high-temperature cycle and high-temperature storage performance.
  • Example 14 Comparing Example 14 to Example 8, it can be seen that the new charging method 1 in this application has a significant improvement in high temperature cycle performance compared with the conventional charging method.
  • Examples 15 and 16 are compared with Example 8 to further illustrate the effect of the adhesive force of the isolation film on high-temperature cycling and high-temperature storage.
  • Example 8 shows that the new charging method can improve the high temperature cycle.
  • Step 1 0.7C constant current to charge the battery to 4.45V;
  • Step 2 4.45V constant voltage to charge the battery to 0.05C;
  • Step 3 Let the battery stand for 5 minutes
  • Step 4 Discharge the battery to 3.0V at a constant current of 0.5C;
  • Step 5 Let the battery stand for 5 minutes
  • Step 6 Cycle the above steps 1 to 5 for 500 times.
  • the capacity retention rate of the battery after 500 cycles of charge and discharge at 12°C is the ratio of the discharge capacity of the battery after 500 cycles of charge and discharge to the discharge capacity of the battery after the first cycle of charge and discharge.
  • Step 1 0.7C constant current to charge the battery to 4.45V;
  • Step 2 4.45V constant voltage to charge the battery to 0.05C;
  • Step 3 Let the battery stand for 5 minutes
  • Step 4 Discharge the battery to 3.0V at a constant current of 0.5C;
  • Step 5 Let the battery stand for 5 minutes
  • Step 6 Cycle the above steps 1 to 5 for 500 times.
  • the capacity retention rate of the battery after 500 cycles of charge and discharge at 45°C is the ratio of the discharge capacity of the battery after 500 cycles of charge and discharge to the discharge capacity of the battery after the first cycle of charge and discharge.
  • Step 1 Test the cell thickness, voltage and impedance of the battery under the initial voltage
  • Step 2 Fully charge the battery, specifically, charge the battery to 4.45V at a constant current of 0.7C, and charge the battery to 0.02C at a constant voltage of 4.45V;
  • Step 3 Test the cell thickness, voltage, and impedance of the battery in a fully charged state
  • Step 4 Put the battery cell in a furnace at 80°C for 8 hours;
  • Step 5 Test the cell thickness, voltage and impedance of the battery after storage.
  • the calculation method of the cell expansion rate is: (cell thickness after high temperature storage-cell thickness under initial voltage)/cell thickness under initial voltage. That is, the difference between the thickness of the battery tested in step 5 minus the thickness of the battery tested in step 1 divided by the thickness of the battery tested in step 1.
  • this application adjusts the weight ratio of the lithium cobalt oxide primary particles and the lithium cobalt oxide secondary particles in the positive electrode active material of the battery, and in the first stage, uses at least one of constant current, constant voltage or constant power.
  • the adjusted battery is charged to the first stage voltage; and in the second stage, the adjusted battery is charged in at least one of a constant current, a constant voltage, or a constant power.
  • the charging method of pulse charging or pulse charging and discharging may also be used in the first stage and the second stage.
  • the battery cycle performance can be further improved, and the low-temperature discharge performance during the battery cycle can be significantly improved.

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Abstract

一种改善电池(10)循环性能的方法和一种电子装置(1)，所述方法应用于一电池(10)中，所述方法包括：(S21)在第一阶段，以第一阶段电流对所述电池(10)充电至第一阶段电压；(S22)在第二阶段，以第二阶段电流对所述电池(10)充电至第二阶段电压，所述第二阶段电压大于所述第一阶段电压，所述第二阶段电流小于所述第一阶段电流；其中，所述电池(10)包括含有有机溶剂的电解液，所述有机溶剂包括链状羧酸酯类化合物，所述链状羧酸酯类化合物与所述有机溶剂的重量百分比为10％-70％。根据上述方法可以改善电池(10)的高温循环及存储性能。

Description

改善电池循环性能的方法和电子装置 技术领域
本申请涉及电池技术领域，尤其涉及一种改善电池循环性能的方法和电子装置。
背景技术
随着近些年来消费类锂离子电池不断迭代开发，市场对电池的充电速度的要求越来越高。随着电解液的动力学性能的不断改善，含羧酸酯溶剂的电解液具有粘度低、动力学高的特点，可有效提高锂离子电池的充电速度，并有效改善低温条件下的循环性能。但是羧酸酯溶剂性质活泼，易在电池的正负极之间发生副反应，尤其在高温条件下，容易发生产气副反应，导致电芯膨胀变形，影响电池的高温循环及存储性能。
发明内容
有鉴于此，有必要提供一种改善电池循环性能的方法和电子装置，可以改善电池的高温循环及存储性能。
本申请一实施方式提供了一种改善电池循环性能的方法，应用于一电池中，所述方法包括：在第一阶段，以第一阶段电流对所述电池充电至第一阶段电压；在第二阶段，以第二阶段电流对所述电池充电至第二阶段电压，所述第二阶段电压大于所述第一阶段电压，所述第二阶段电流小于所述第一阶段电流；其中，所述电池包括含有有机溶剂的电解液，所述有机溶剂包括链状羧酸酯类化合物，所述链状羧酸酯类化合物与所述有机溶剂的重量百分比为10％-70％。
根据本申请的一些实施方式，所述链状羧酸酯类化合物选自式I所示的化合物中的至少一种：
Figure PCTCN2020082255-appb-000001
其中，R 1选自氢原子、卤原子、羟基、碳原子数为1～20的烷基、碳原子数为1～20的烷氧基、碳原子数为1～20的链烯基、碳原子数为6～30的芳基或碳原子数为6～30的芳氧基；R 2选自氢原子、卤原子、碳原子数为1～20的烷基、碳原子数为1～20的链烯基或碳原子数为6～30的芳基。
根据本申请的一些实施方式，所述链状羧酸酯化合物选自甲酸甲酯、乙酸甲酯、甲酸乙酯、乙酸乙酯、乙酸丙酯、丙酸乙酯、丙酸甲酯、丙酸正丙酯、丙酸异丙酯、丙酸甲酯、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、异丁酸异丁酯和正戊酸正戊酯中的至少一种。
根据本申请的一些实施方式，所述电解液还包括锂盐，所述锂盐选自六氟磷酸锂、二氟磷酸锂、四氟硼酸锂、六氟砷酸锂、高氯酸锂、双氟磺酰亚胺锂、双三氟甲烷磺酰亚胺锂、双草酸硼酸锂和二氟草酸硼酸锂中的至少一种。
根据本申请的一些实施方式，所述电池还包括正极片、负极片和设置在所述正极片与所述负极片之间的隔离膜，所述隔离膜包括多孔基材、设置于所述多孔基材表面的耐热涂层和设置于所述隔离膜最外侧的聚合物粘接层，所述聚合物粘接层设置于所述耐热涂层的表面或未具有所述耐热涂层的所述多孔基材的表面，所述聚合物粘接层中包括聚合物颗粒，所述聚合物颗粒在所述聚合物粘接层中的堆积层数不超过四层。
根据本申请的一些实施方式，所述聚合物颗粒为聚偏氯乙烯、聚偏氟乙烯-六氟丙烯共聚物、苯乙烯-丁二烯共聚物、聚丙烯腈、丁二烯-丙烯腈聚合物、聚丙烯酸、聚丙烯酸酯和丙烯酸酯-苯乙烯共合物中的至少一种，或以上聚合物单体中的至少两种的共聚物，所述聚合物颗粒的粒径为0.2μm-2μm。
根据本申请的一些实施方式，所述聚合物粘接层对所述多孔基材或所述耐热涂层的覆盖面积比为15％-85％。
根据本申请的一些实施方式，所述隔离膜与所述正极片或所述负极片之间的粘结力大于或等于3N/m。
根据本申请的一些实施方式，所述第二阶段采用第一充电方式或第二充电方式对电池充电至所述第二阶段电压；所述第一充电方式包括依序的K个子阶段，K为大于或等于2的整数，所述K个子阶段分别定义为第i子阶段，i＝1、2、…、K；在所述第i子阶段时，以第i电流、第i电压及第i功率的其中一者对所述电池进行充电；在第i+1子阶段时，以第i+1电流、第i+1电压及第i+1功率的其中一者对所述电池进行充电；其中，在所述第i+1子阶段时的充电电流小于或等于在所述第i子阶段时的充电电流，或者所述第i+1电压大于或等于所述第i电压，或者所述第i+1功率小于或等于所述第i功率；以及所述第二充电方式包括依序的D个充电子阶段，D为大于或等于2的整数，所述D个充电子阶段分别定义为第j充电子阶段，j＝1、2、…、D，且每一个所述第j充电子阶段包括第j前充电子阶段及第j后充电子阶段；在所述第j前充电子阶段及所述第j后充电子阶段的其中一者，对所述电池不充电或以第j前充电子电流进行充电或放电达Tj1时长；在所述第j前充电子阶段及所述第j后充电子阶段的其中另一者，对所述电池以第j后充电子电流进行充电达Tj2时长；其中，所述第j前充电子电流的绝对值小于所述第j后充电子电流的绝对值。
根据本申请的一些实施方式，第j充电子阶段的充电电流的平均值小于所述第一阶段的充电电流，第j+1充电子阶段的充电电流的平均值小于或等于所述第j充电子阶段的充电电流。
根据本申请的一些实施方式，所述第一阶段采用第三充电方式对电池充电至所述第一阶段电压，所述第三充电方式采用所述第一充电方式或所述第二充电方式。
根据本申请的一些实施方式，当所述第三充电方式采用所述第一充电方式时，两者之间的充电子阶段个数K相同；或者当所述第三充电方式采用所述第二充电方式时，两者之间的充电子阶段个数D相同。
根据本申请的一些实施方式，所述第一阶段电压等于所述电池的充电限制电压，所述第二阶段电压小于所述电池中电解液的氧化分解电压。
根据本申请的一些实施方式，所述第二阶段电压小于或等于所述第一阶段电压加上500毫伏特。
根据本申请的一些实施方式，所述方法还包括：在第三阶段，以所述第二阶段电压对所述电池进行恒压充电。
本申请一实施方式还提供了一种电子装置，包括电池和电池管理模块，所述电池包括含有有机溶剂的电解液，所述有机溶剂包括链状羧酸酯类化合物，所述链状羧酸酯类化合物与所述有机溶剂的重量百分比为10％-70％，所述电池管理模块用于执行如上所述的任一种方法。
本申请的实施方式通过采用含有高含量羧酸酯的电解液和特定的充电方法(提高电池的充电限制电压)相结合，可以提高电池的充电速度，显著缩短电池的满充时间，还可以缩短电池的正极处于高电压下的时间，减少正极在高电压下与电解液发生副反应的时间，从而能够改善电池的循环性能。此外，通过采用高粘接性的隔离膜，可以进一步改善电池的循环性能。
附图说明
图1是根据本申请一实施方式的电子装置的示意图。
图2是根据本申请一实施方式的改善电池循环性能的方法的流程图。
图3为图1所示的改善电池循环性能的方法的第一种具体实施例。
图4是根据本申请实施方式一的电池充电过程中电流和电压随时间变化示意图。
图5是根据本申请实施方式二的电池充电过程中电流和电压随时间变化示意图。
图6是根据本申请一实施方式第一阶段中功率和电压随时间变化，以及第二阶段中电流和电压随时间变化示意图。
图7是根据本申请实施方式三的电池充电过程中电流和电压随时间变化示意图。
图8是根据本申请实施方式四的电池充电过程中电流和电压随时间变化示意图。
图9为图1所示的改善电池循环性能的方法的第二种具体实施例。
图10为图1所示的改善电池循环性能的方法的第三种具体实施例。
图11为图1所示的改善电池循环性能的方法的第四种具体实施例。
图12为常规的充电方法与改善电池循环性能的方法中的新充电方式对电池充电时电池阴极对锂电位的变化情形。
图13为不同羧酸酯含量溶剂电解液的电导率对比图。
图14为全电池阻抗示意图。
图15为不同隔离膜粘接力对比示意图。
主要元件符号说明
电子装置        1
电池            10
控制单元        11
电池管理模块    12
具体实施方式
下面将结合本申请实施方式中的附图，对本申请实施方式中的技术方案进行清楚、完整地描述，显然，所描述的实施方式是本申请一部分实施方式，而不是全部的实施方式。
基于本申请中的实施方式，本领域普通技术人员在没有付出创造性劳动前提下所获得的所有其他实施方式，都是属于本申请保护的范围。
请参阅图1，图1为本申请一实施例的电子装置的示意图。所述电子装置1包括电池10、控制单元11和电池管理模块12。所述电池 10、控制单元11和电池管理模块12之间可以通过总线连接，也可以直接连接。所述电池10包括至少一个电芯，所述电池10可以采用可循环再充电的方式反复充电。例如，所述电池为锂离子电池。所述控制单元11可以控制所述电池管理模块12以执行所述改善电池循环性能的方法。所述控制单元11可以是一个微控制器(Microcontroller，MCU)、一个处理器(Processor)或一个特殊应用集成电路(Application-specific integrated circuit，ASIC)等，并能够控制所述电池管理模块12执行所述改善电池循环性能的方法。
需要说明的是，图1仅为举例说明电子装置1。在其他实施方式中，电子装置1也可以包括更多或者更少的元件，或者具有不同的元件配置。所述电子装置1可以为电动摩托、电动单车、电动汽车、手机、平板电脑、个数数字助理、个人电脑，或者任何其他适合的可充电式设备。
尽管未示出，所述电子装置1还可以包括无线保真(Wireless Fidelity，WiFi)单元、蓝牙单元、扬声器等其他组件，在此不再一一赘述。
请参阅图2，图2为根据本申请一实施方式所述改善电池循环性能的方法的流程图。所述改善电池循环性能的方法应用于一电池中，包括下列步骤：
步骤S21：在第一阶段，以第一阶段电流对所述电池充电至第一阶段电压。
步骤S22：在第二阶段，以第二阶段电流对所述电池充电至第二阶段电压，所述第二阶段电压大于所述第一阶段电压，所述第二阶段电流小于所述第一阶段电流；
其中，所述电池包括含有有机溶剂的电解液，所述有机溶剂包括链状羧酸酯类化合物，所述链状羧酸酯类化合物与所述有机溶剂的重量百分比为10％-70％。
在本实施例中，所述链状羧酸酯类化合物选自式I所示的化合物中的至少一种：
Figure PCTCN2020082255-appb-000002
其中，R 1选自氢原子、卤原子、羟基、碳原子数为1～20的烷基、碳原子数为1～20的烷氧基、碳原子数为1～20的链烯基、碳原子数为6～30的芳基或碳原子数为6～30的芳氧基；R 2选自氢原子、卤原子、碳原子数为1～20的烷基、碳原子数为1～20的链烯基或碳原子数为6～30的芳基。
作为所述链状羧酸酯类化合物的示例，可以选自甲酸甲酯、乙酸甲酯、甲酸乙酯、乙酸乙酯、乙酸丙酯、丙酸乙酯、丙酸甲酯、丙酸正丙酯、丙酸异丙酯、丙酸甲酯、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、正戊酸正戊酯中的一种。
特别的，所述链状羧酸酯类化合物为选自甲酸甲酯、乙酸乙酯、乙酸丙酯、丙酸甲酯、丙酸乙酯、丙酸丙酯以及丁酸乙酯中的一种或多种。
可以理解的是，所述电池还可以包括锂盐和添加剂。所述锂盐可以是无机锂盐和有机锂盐中的一种或几种。优选地，所述锂盐可以是六氟磷酸锂(LiPF 6)、二氟磷酸锂(LiPO 2F 2)、四氟硼酸锂(LiBF 4)、六氟砷酸锂、高氯酸锂、双氟磺酰亚胺锂(LiFSI)、双三氟甲烷磺酰亚胺锂(LiTFSI)、双草酸硼酸锂LiB(C 2O 4) 2(简写为LiBOB)、二氟草酸硼酸锂LiBF 2(C 2O 4)(简写为LiDFOB)中的一种或几种。进一步优选地，所述锂盐为六氟磷酸锂(LiPF 6)。所述添加剂为本领域技术公知的提高电池的性能的添加剂，如SEI(solid electrolyte interface)膜成膜添加剂、阻燃添加剂、防过充添加剂、导电添加剂等。
在本实施方式中，所述电池还包括正极片、负极片和设置在所述正极片与所述负极片之间的隔离膜，所述隔离膜包括多孔基材、设置于所述多孔基材表面的耐热涂层和设置于所述隔离膜最外侧的聚合物粘接层，所述聚合物粘接层设置于所述耐热涂层的表面或未具有所述 耐热涂层的所述多孔基材的表面，所述聚合物粘接层中包括聚合物颗粒，所述聚合物颗粒在所述聚合物粘接层中的堆积层数不超过四层。优选地，所述堆积层数小于或等于2层。
在本实施方式中，所述聚合物粘接层对所述多孔基材或所述耐热涂层的覆盖面积比为15％-85％。
现有技术中，所述电池通常采用聚烯烃材料作为隔离膜。此种隔离膜粘接层厚度较大且粘接力较低，无法满足锂离子电池对电性能及能量密度的要求。因此，本申请中采用高粘结隔离膜，所述高粘接隔离膜包括多孔基材、涂布在多孔基材至少一面的耐热涂层和位于最表层的聚合物粘接层。具体地，所述聚合物粘接层涂布在耐热涂层表面或未涂布耐热涂层的多孔基材表面。所述聚合物粘接层对多孔基材或耐热涂层的覆盖面积比为15％-85％，优选为30％-70％。
在本实施方式中，所述聚合物粘接层中包括聚合物颗粒，所述聚合物颗粒为聚偏氯乙烯、聚偏氟乙烯-六氟丙烯共聚物、苯乙烯-丁二烯共聚物、聚丙烯腈、丁二烯-丙烯腈聚合物、聚丙烯酸、聚丙烯酸酯和丙烯酸酯-苯乙烯共合物中的至少一种，或以上聚合物单体中的至少两种的共聚物。所述聚合物颗粒为均质聚合物微球，或是核壳结构微球。所述聚合物颗粒的粒径为0.2μm-2μm，优选为0.3μm-1μm。所述聚合物颗粒相对于电解液的溶胀度为20％～100％。
在一实施方式中，当所述聚合物颗粒为核壳结构微球时，所述核壳结构微球的外壳为粘接力高(与正负极片的粘接力不低于3N/m)的聚合物，即所述隔离膜与所述正极片或所述负极片之间的粘结力大于或等于3N/m；所述核壳结构微球的内核为亲和电解液(电解液溶胀度＞100％)的聚合物。
需要说明的是，所述聚合物粘接层中还包括与多孔基材或耐热涂层进行涂布粘接的辅助粘接剂和分散剂。所述多孔基材的材料为聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯(PET)、纤维素或聚酰亚胺。
通过采用如上所述的电解液构成的电池，含有高含量的羧酸酯电解液具有高的电导率，可以改善电池动力学，使其可满足大倍率充电需求；而采用如上所述具有高粘接性的隔离膜，可以减小锂离子电池 中极片和隔离膜的距离，同时界面处的电解液被一定程度挤出，从而能够抑制高温下的副产物增长速率，提升了高温循环容量保持率。
请参阅图3，图3为图2所示的改善电池循环性能的方法的第一种具体实施例。
步骤S31：在第一阶段，以第一阶段电流对所述电池充电至第一阶段电压。
在本实施例中，所述第一阶段电流为恒定电流，即为现有的在开始充电时采用恒定的充电电流。或者，所述第一阶段电流也可以为大小有变化的电流，例如在所述第一阶段，以恒定电压对所述电池充电，则所述恒定电压所对应的充电电流(即所述第一阶段电流)的大小会有变化，只要通过所述第一阶段电流可以将所述电池充电至所述第一阶段电压即可。所述第一阶段电压等于所述电池的充电限制电压(可以理解为公知的充电限制电压)。
步骤S32：在第二阶段，以第二阶段电流对所述电池充电至第二阶段电压，所述第二阶段电压大于所述第一阶段电压，所述第二阶段电流小于所述第一阶段电流；所述第二阶段采用第一充电方式或第二充电方式对电池充电至所述第二阶段电压。
其中，所述电池包括含有有机溶剂的电解液，所述有机溶剂包括链状羧酸酯类化合物，所述链状羧酸酯类化合物与所述有机溶剂的重量百分比为10％-70％。
其中，所述第一充电方式包括依序的K个充电子阶段，K为大于或等于2的整数，所述K个充电子阶段分别定义为第i充电子阶段，i＝1、2、…、K；在所述第i充电子阶段时，以第i电流、第i电压及第i功率的其中一者对所述电池进行充电；在第i+1充电子阶段时，以第i+1电流、第i+1电压及第i+1功率的其中一者对所述电池进行充电；其中，在所述第i+1充电子阶段时的充电电流小于或等于在所述第i充电子阶段时的充电电流，或者所述第i+1电压大于或等于所述第i电压，或者所述第i+1功率小于或等于所述第i功率。
在本实施方式中，所述第i+1电压大于或等于所述第i电压，所述第i+1功率小于或等于所述第i功率。
所述第二充电方式包括依序的D个充电子阶段，D为大于或等于2的整数，所述D个充电子阶段分别定义为第j充电子阶段，j＝1、2、…、D，且每一个所述第j充电子阶段包括第j前充电子阶段及第j后充电子阶段；在所述第j前充电子阶段及所述第j后充电子阶段的其中一者，对所述电池不充电或以第j前充电子电流进行充电或放电达Tj1时长；在所述第j前充电子阶段及所述第j后充电子阶段的其中另一者，对所述电池以第j后充电子电流进行充电达Tj2时长；其中，所述第j前充电子电流的绝对值小于所述第j后充电子电流的绝对值。
在本实施方式中，第j+1充电子阶段的充电电流的平均值小于或等于所述第j充电子阶段的充电电流，且当所述第三充电方式采用所述第二充电方式时，第j充电子阶段的充电电流的平均值小于所述第一充电方式或所述第二充电方式中的充电电流。
需要说明的是，所述第一阶段电压等于所述电池的充电限制电压。
由于在第二阶段的第1充电子阶段的充电电流小于所述第一阶段电流，且在所述第i+1充电子阶段的充电电流小于或等于在所述第i充电子阶段的充电电流，使得所述电池的阳极电位不低于一个析锂电位。析锂电位可以通过如下的途径测试而获得。针对本实施例中的所述电池，制作另一个规格相同的三电极电池，所述三电极电池相较于本实施例的所述电池多增加一个电极，也就是包含三个电极，分别是阳极、阴极及参比电极。所述参比电极的材料为锂，所述三电极电池用于测试，以获得本实施例的所述电池的阳极的析锂电位。
所述阳极的析锂电位的具体测试方法为：制作多个三电极电池，分别采用不同倍率(例如1C、2C、3C)的充电电流对所述三电极电池进行充放电，且循环多次(例如10次)，并检测充放电过程中阳极与参比电极的电位差。然后，对所述三电极电池进行满充拆解，分别观察采用不同倍率充电的三电极电池的阳极是否发生析锂现象(即观察阳极表面是否有金属锂析出)。确定未发生析锂现象的三电极电池所对应的最大倍率，则将所述倍率下充放电过程中阳极与参比电极的电位差的最小值作为阳极的析锂电位。另外要补充说明的是：锂电池的充电电流一般用倍率C作参照，C是对应锂电池容量的数值。锂电池容量一 般用Ah、mAh表示，例如电池容量是1200mAh时，对应的1C就是1200mA，0.2C就等于240mA。
再举例来说，分别以1C、2C和3C的充电电流对多个三电极电池进行充放电且循环10次。通过拆解三电极电池发现，采用1C与2C充放电时阳极未发生析锂现象，采用3C充放电时阳极发生析锂现象。那么，2C倍率下阳极与参比电极的电位差的最小值即为阳极的析锂电位。此外，阴极的析锂电位也可以采用类似的方式作测试，此处不再赘述。通过上述阳极的析锂电位的测试过程还可以对所述电池的阳极电位及阴极电位进一步理解如下：阳极电位为阳极与参比电极的电位差，即阳极对锂电位，阴极电位为阴极与参比电极的电位差，即阴极对锂电位。
所述第二阶段电压小于所述电池中电解液的氧化分解电压。电池中电解液的氧化分解电压可以作如下的理解：在电池的电位超过某个电位阈值时，电解液中溶剂分子、添加剂分子、甚至是杂质分子会在电极与电解液的界面发生不可逆的还原或氧化分解的反应，这种现象称为电解液分解。所述电位阈值即为电池中电解液的还原分解电压及氧化分解电压。在本实施例中，所述第二阶段电压还小于或等于所述第一阶段电压加上500毫伏特。
在所述第二阶段的所述第K充电子阶段或者第D充电子阶段时，对所述电池进行充电至所述第二阶段电压，此时，对所述电池进行充电的截止条件可以是一个截止电压、一个截止电流或一个截止容量。更具体地说，在所述第K充电子阶段或者第D充电子阶段时，当电池的充电电流等于所述截止电流、所达到的充电电压(即正极与负极之间的电压差)等于所述截止电压或者所述电池的电容量等于所述截止容量时，停止对所述电池进行充电，即充电截止。针对不同规格的所述电池，所述截止电流、所述截止电压、所述截止容量可以采用前述三电极电池的测试方式，观察所述三电极电池的阴极不发生过脱锂的现象而获得，以确保所述电池的电容量与现有技术的常规充电方式的电容量相当，并确保所述电池的阴极不发生过脱锂。
另外，要补充说明的是：在本实施例中，所述第一阶段电流、所述第一阶段电压、所述第一阶段的所述第i充电子阶段的所述第i电流、所述第i电压、与所述第i功率的其中一者、所述第二阶段的所述第i充电子阶段的所述第i电流、所述第i电压、与所述第i功率的其中一者、所述第二阶段电压及所述截止条件的数值可以是预先储存于所述电池中或所述处理器11中，所述处理器11读取所述预先储存的数值，以正确地控制所述充电系统10进行充电。
参阅图4所示，在第一阶段采用第一充电方式对电池充电，且所述第一充电方式包括依序的K个充电子阶段，所述K个充电子阶段分别定义为第i充电子阶段，i＝1、2、…、K；在所述第i充电子阶段时，以第i电流对所述电池进行充电。在第二阶段采用第一充电方式对电池充电，且所述第一充电方式包括依序的K个充电子阶段，所述K个充电子阶段分别定义为第i充电子阶段，i＝1、2、…、K；在所述第i充电子阶段时以第i电流对所述电池进行充电，在所述第i+1充电子阶段时以第i电压对所述电池进行充电，如此交替循环充电。
在第一阶段，在时间0至t1间，以恒定电流I1对所述电池充电至电压U1；在时间t1至t2间，以恒定电流I2充电至电压U2；在时间t(i-2)至t(i-1)间，以恒定电流I(i-1)充电至电压U(i-1)；在时间ti-1至ti间，以恒定电流Ii充电至电压Ui；在时间t(K-1)至tK间，以恒定电流Icl充电至电压Ucl。在时间t2至t(i-2)间，及在时间ti至t(K-1)间，执行类似的充电，但在图中省略而未画出。
在第二阶段，在时间t1'至t2'间，以恒定电流I1'充电至电压U1'；在时间t2'至t3'间，以恒定电压U1'对电池充电，此段时间对应的充电电流由I1'下降至电流I2'；在时间t3'至t4'间，以恒定电流I2'对电池进行充电至电压U2'；在时间t4'至t5'间，以恒定电压U2'对电池充电；在时间t(i-1)'至ti'间，以恒定电流Ii'充电至电压Ui'；在时间ti'至t(i+1)'间，以恒定电压Ui'对电池充电，此段时间对应的充电电流由I1'下降至电流I(i+1)'；在时间t(K-2)'至t(K-1)'间，以恒定电流Im充电至电压Um；在时间t(K-1)'至tK'间，以恒定电压Um对电池充电，此段时 间对应的充电电流由Im下降至电流Im'。在时间t5'至t(i-1)'间，在时间t(i+1)'至t(K-2)'间，执行类似的充电，但在图中省略而未画出。
需要说明的是，所述tK与t1'为同一时间。在第一阶段的K个充电子阶段中的每一个充电子阶段，都以一个恒定的充电电流对所述电池充电，且I1≧I2≧…≧Icl，U1≦U2≦…≦Ucl；在第二阶段的K个充电子阶段中的每一个充电子阶段，都以一个恒定的充电电流和恒定电压交替对所述电池充电，Icl≧I1'≧I2'≧…≧Im'，Ucl≦U1'≦U2'≦…≦Um。
参阅图5，在第一阶段采用第一充电方式对电池充电，且所述第一充电方式包括依序的K个充电子阶段，所述K个充电子阶段分别定义为第i充电子阶段，i＝1、2、…、K；在所述第i充电子阶段时，以第i电压对所述电池进行充电。在第二阶段采用第一充电方式对电池充电，且所述第一充电方式包括依序的K个充电子阶段，所述K个充电子阶段分别定义为第i充电子阶段，i＝1、2、…、K；在所述第i充电子阶段时以第i电流对所述电池进行充电，在所述第i+1充电子阶段时以第i电压对所述电池进行充电，如此交替循环充电。
在第一阶段，在时间0至t1间，以恒定电压U1对所述电池充电至电流为I1；在时间t1至t2间，以恒定电压U2充电至电流为I2；在时间t(i-1)至ti间，以恒定电压Ui充电至电流为Ii；在时间t(K-1)至tK间，以恒定电压Ucl充电至电流为Icl。在时间t2至t(i-1)间，及在时间ti至t(K-1)间执行类似的充电，但在图中省略而未画出。
在第二阶段，在时间t1'至t2'间，以恒定电流I1'充电至电压U1'；在时间t2'至t3'间，以恒定电压U1'对电池充电，此段时间对应的充电电流由I1'下降至电流I2'；在时间t3'至t4'间，以恒定电流I2'对电池进行充电至电压U2'；在时间t4'至t5'间，以恒定电压U2'对电池充电；在时间t(i-1)'至ti'间，以恒定电流Ii'充电至电压Ui'；在时间ti'至t(i+1)'间，以恒定电压Ui'对电池充电，此段时间对应的充电电流由Ii'下降至电流I(i+1)'；在时间t(K-2)'至t(K-1)'间，以恒定电流Im充电至电压Um；在时间t(K-1)'至tK'间，以恒定电压Um对电池充电，此段时 间对应的充电电流由Im下降至电流Im'。在时间t5'至t(i-1)'间，在时间t(i+1)'至t(K-2)'间，执行类似的充电，但在图中省略而未画出。
需要说明的是，所述tK与t1'为同一时间。在第一阶段的K个充电子阶段中的每一个充电子阶段，都以一个恒定的充电电压对所述电池充电，且U1≦U2≦…≦Ucl，I1≧I2≧…≧Icl。在第二阶段的K个充电子阶段中的每一个充电子阶段，都以一个恒定的充电电流和恒定的充电电压交替对所述电池充电，且Ucl≦U1'≦U2'≦…≦Um，Icl≧I1'≧I2'≧…≧Im'。
参阅图6所示，在第一阶段采用第一充电方式对电池充电，且所述第一充电方式包括依序的K个充电子阶段，所述K个充电子阶段分别定义为第i充电子阶段，i＝1、2、…、K；在所述第i充电子阶段时，以第i功率对所述电池进行充电。在第二阶段采用第一充电方式对电池充电，且所述第一充电方式包括依序的K个充电子阶段，所述K个充电子阶段分别定义为第i充电子阶段，i＝1、2、…、K；在所述第i充电子阶段时以第i电流对所述电池进行充电，在所述第i+1充电子阶段时以第i电压对所述电池进行充电，如此交替循环充电。
在第一阶段，在时间0至t1间，以恒定功率P1对所述电池充电至电压为U1；在时间t1至t2间，以恒定功率P2充电至电压U2；在时间t(i-2)至t(i-1)间，以恒定功率P(i-1)充电至电压U(i-1)；在时间t(i-1)至ti间，以恒定功率Pi充电至电压Ui；在时间t(K-1)至tK间，以恒定功率Pcl充电至电压Ucl。在时间t2至t(i-2)间，及在时间ti至t(K-1)间，执行类似的充电，但在图中省略而未画出。
在第二阶段，在时间t1'至t2'间，以恒定电流I1'充电至电压U1'；在时间t2'至t3'间，以恒定电压U1'对电池充电，此段时间对应的充电电流由I1'下降至电流I2'；在时间t3'至t4'间，以恒定电流I2'对电池进行充电至电压U2'；在时间t4'至t5'间，以恒定电压U2'对电池充电；在时间t(i-1)'至ti'间，以恒定电流Ii'充电至电压Ui'；在时间ti'至t(i+1)'间，以恒定电压Ui'对电池充电，此段时间对应的充电电流由I1'下降至电流I(i+1)'；在时间t(K-2)'至t(K-1)'间，以恒定电流Im充电至电压Um；在时间t(K-1)'至tK'间，以恒定电压Um对电池充电，此段时 间对应的充电电流由Im下降至电流Im'。在时间t5'至t(i-1)'间，在时间t(i+1)'至t(K-2)'间，执行类似的充电，但在图中省略而未画出。
需要说明的是，在第一阶段的K个充电子阶段中的每一个充电子阶段，都以一个恒定的功率对所述电池充电，且P1≧P2≧…≧Pcl，U1≦U2≦…≦Ucl。在第二阶段的K个充电子阶段中的每一个充电子阶段，都以一个恒定的充电电流和恒定的充电电压交替对所述电池充电，且Ucl≦U1'≦U2'≦…≦Um，Icl≧I1'≧I2'≧…≧Im'。
参阅图7所示，在第一阶段采用第一充电方式对电池充电，且所述第一充电方式包括依序的K个充电子阶段，所述K个充电子阶段分别定义为第i充电子阶段，i＝1、2、…、K；在所述第i充电子阶段时，以第i电流对所述电池进行充电；在所述第i+1充电子阶段时，以第i电压对所述电池进行充电，如此交替循环充电。在第二阶段采用第一充电方式对电池充电，且所述第一充电方式包括依序的K个充电子阶段，所述K个充电子阶段分别定义为第i充电子阶段，i＝1、2、…、K；在所述第i充电子阶段时以第i电流对所述电池进行充电，在所述第i+1充电子阶段时以第i电压对所述电池进行充电，如此交替循环充电。
在第一阶段，在时间0至t1间，以恒定电流I1对所述电池充电至电压U1；在时间t1至t2间，以恒定电压U1对电池充电，此段时间对应的充电电流由I1下降至电流I2；在时间t2至t3间，以恒定电流I2充电至电压U2；在时间t3至t4间，以恒定电压U2对电池充电，此段时间对应的充电电流由I2下降至电流I3；在时间t(i-2)至t(i-1)间，以恒定电流Ii充电至电压Ui；在时间t(i-1)至ti间，以恒定电压Ui对电池充电；在时间t(K-2)至t(K-1)间，以恒定电流Icl充电至电压Ucl；在时间t(K-1)至tK间，以恒定电压Ucl对电池充电，此段时间对应的充电电流由Icl下降至电流I1'。在时间t4至t(i-2)间，及在时间ti至t(K-2)间，执行类似的充电，但在图中省略而未画出。
在第二阶段，在时间t1'至t2'间，以恒定电流I1'充电至电压U1'；在时间t2'至t3'间，以恒定电压U1'对电池充电，此段时间对应的充电电流由I1'下降至电流I2'；在时间t3'至t4'间，以恒定电流I2'对电池 进行充电至电压U2'；在时间t4'至t5'间，以恒定电压U2'对电池充电；在时间t(i-1)'至ti'间，以恒定电流Ii'充电至电压Ui'；在时间ti'至t(i+1)'间，以恒定电压Ui'对电池充电，此段时间对应的充电电流由I1'下降至电流I(i+1)'；在时间t(K-2)'至t(K-1)'间，以恒定电流Im充电至电压Um；在时间t(K-1)'至tK'间，以恒定电压Um对电池充电，此段时间对应的充电电流由Im下降至电流Im'。在时间t5'至t(i-1)'间，及在时间t(i+1)'至t(K-2)'间，执行类似的充电，但在图中省略而未画出。
需要说明的是，在第一阶段的K个充电子阶段中的每一个充电子阶段，恒定的充电电流和恒定的充电电压交替对所述电池充电，且I1≧I2≧…≧Icl，U1≦U2≦…≦Ucl。在第二阶段的K个充电子阶段中的每一个充电子阶段，也都以一个恒定的充电电流和恒定的充电电压交替对所述电池充电，且I1'≧I2'≧…≧Im'，U1'≦U2'≦…≦Um，且Icl≧I1'，Ucl≦U1'。
当采用第二充电方式对电池充电时，所述第一阶段包含依序的D个充电子阶段，D为正整数，所述D个充电子阶段分别定义为第j充电子阶段，j＝1、2、…、D，每一个所述第j充电子阶段包括一个第j前充电子阶段及一个第j后充电子阶段。所述第二阶段同样地包含依序的D个充电子阶段，D为正整数，所述D个充电子阶段分别定义为第j充电子阶段，j＝1、2、…、D，每一个所述第j充电子阶段包括一个第j前充电子阶段及一个第j后充电子阶段。需要说明的是，第一阶段的充电子阶段个数D与第二阶段的D可以相同，也可以不同。
在所述第j前充电子阶段及所述第j后充电子阶段的其中一者，对所述电池不充电或以一个第j前充电子电流进行充电或放电达Tj 1时长。在所述第j前充电子阶段及所述第j后充电子阶段的其中另一者，对所述电池以一个第j后充电子电流进行充电达Tj2时长。所述第j前充电子电流的绝对值小于所述第j后充电子电流的绝对值。
也就是说，在每一所述第j充电子阶段，是以脉冲充电或脉冲充放电的方式对所述电池进行充电，且所述第j+1充电子阶段的充电电流的平均值小于或等于所述第j充电子阶段的充电电流，例如，(第1前充电子电流×T11+第1后充电子电流×T12)/(T11+T12)大于或等于 (第2前充电子电流×T21+第2后充电子电流×T22)/(T21+T22)、(第2前充电子电流×T21+第2后充电子电流×T22)/(T21+T22)大于或等于(第3前充电子电流×T31+第3后充电子电流×T32)/(T31+T32)等等。每一所述Tj1时长与Tj2时长的和，即为在所述第j充电子阶段的脉冲充电或脉冲充放电的充电周期或充放电周期。
另外，要特别补充说明的是：在本实施例中，在所述第j前充电子阶段以所述第j前充电子电流进行充电或放电达Tj1时长，且在所述第j后充电子阶段以所述第j后充电子电流进行充电达Tj2时长。而在其他实施例中，也可以是在所述第j充电前充电子阶段以所述第j后充电子电流进行充电达Tj2时长，且在所述第j充电后充电子阶段以所述第j前充电子电流进行充电或放电达Tj1时长。在其他实施例中，还可以是在所述第j充电前充电子阶段不充电或静置(即此时的充电电流为0)达Tj1时长，且在所述第j后充电子阶段以所述第j后子电流进行充电或放电达Tj2时长。
参阅图8所示，在时间t1至t1000间，也就是在所述第一阶段的所述第1充电子阶段至所述第1000充电子阶段的每一个充电子阶段中，先以电流I2对所述电池充电，再以电流I3对所述电池充电。在时间tx至t1000间，执行类似的充电，但在图中省略而未画出。
在时间t1000至t2000间，也就是在所述第一阶段的所述第1001充电子阶段至所述第2000充电子阶段的每一个子充电阶段中，先以电流I10011对所述电池充电，再对所述电池静置(即不充电也不放电)。在时间ty至t2000间，执行类似的充电，但在图中省略而未画出。在时间t2000至tD间，也就是在所述第一阶段的所述第2001充电子阶段至所述第D充电子阶段的每一个充电子阶段中，先以电流I20011对所述电池充电，再以电流I20012对所述电池放电，直到所述电池的电压等于电压Ucl(即截止电压)。在时间t2002至t(D-1)间，执行类似的充电，但在图中省略而未画出。
也就是说，在所述第一阶段的所述D个充电子阶段中，分成三种不同的脉冲充电或脉冲充放电的方式对所述电池充电。另外要补充说明的是：D个充电子阶段中的每一个的脉冲充电或脉冲充放电的充电 周期或充放电周期相同，即t1＝(t1001-t1000)＝(t2001-t2000)，而在其他实施例中，不同的脉冲充电或脉冲充放电的充电周期或充放电周期也可以不相同。
在第二阶段，在时间t1'至t2'间，以恒定电流I1'充电至电压U1'；在时间t2'至t3'间，以恒定电压U1'对电池充电，此段时间对应的充电电流由I1'下降至电流I2'；在时间t3'至t4'间，以恒定电流I2'对电池进行充电至电压U2'；在时间t4'至t5'间，以恒定电压U2'对电池充电；在时间ti'至t(i+1)'间，以恒定电流Ii'充电至电压Ui'；在时间t(i+1)'至t(i+2)'间，以恒定电压Ui'对电池充电，此段时间对应的充电电流由I1'下降至电流I(i+1)'；在时间t(D-2)'至t(D-1)'间，以恒定电流Im充电至电压Um；在时间t(D-1)'至tD'间，以恒定电压Um对电池充电，此段时间对应的充电电流由Im下降至电流Im'。在时间t5'至ti'间，及在时间t(i+2)'至t(D-2)'间，执行类似的充电，但在图中省略而未画出。
请参阅图9，图9为图2所示的改善电池循环性能的方法的第二种具体实施例。所述第二种具体实施例与所述第一种具体实施例相似，所述第二种具体实施例也包括步骤S91及步骤S92。不同之处在于步骤S91，具体如下：
步骤S91：在第一阶段，以第一阶段电流对所述电池充电至第一阶段电压。所述第一阶段采用第三充电方式对电池充电至所述第一阶段电压，所述第三充电方式采用所述第一充电方式或所述第二充电方式。
在本实施例中，所述第一充电方式及所述第二充电方式与所述第一种具体实施例中的第一充电方式及第二充电方式相同，在此不进行赘述。
当所述第三充电方式采用所述第一充电方式时，两者之间的充电子阶段个数K可相同，即所述第一阶段采用的所述第一充电方式所包括的充电子阶段个数与所述第二阶段采用的所述第一充电方式所包括的充电子阶段个数可相同；或者当所述第三充电方式采用所述第二充电方式时，两者之间的充电子阶段个数D可相同，即所述第一阶段采用的所述第二充电方式所包括的充电子阶段个数与所述第二阶段采用的 所述第二充电方式所包括的充电子阶段个数可相同。
当所述第三充电方式采用所述第一充电方式时，两者之间的充电子阶段个数K可不相同，即所述第一阶段采用的所述第一充电方式所包括的充电子阶段个数与所述第二阶段采用的所述第一充电方式所包括的充电子阶段个数可不相同；或者当所述第三充电方式采用所述第二充电方式时，两者之间的充电子阶段个数D可不相同，即所述第一阶段采用的所述第二充电方式所包括的充电子阶段个数与所述第二阶段采用的所述第二充电方式所包括的充电子阶段个数可不相同。
请参阅图10，图10为图2所示的改善电池循环性能的方法的第三种具体实施例。所述第三种具体实施例与所述第一种具体实施例相似，所述第三种具体实施例也包括步骤S101及步骤S102。不同之处在于步骤S101及步骤S102，具体如下：
步骤S101：在第一阶段，以第一阶段电流对所述电池充电至第一阶段电压。所述第一阶段采用第三充电方式对电池充电至所述第一阶段电压，所述第三充电方式采用所述第一充电方式或所述第二充电方式。
在本实施例中，所述第一充电方式及所述第二充电方式与所述第一种具体实施例中的第一充电方式及第二充电方式相同，在此不进行赘述。
步骤S102：在第二阶段，以第二阶段电流对所述电池充电至第二阶段电压，所述第二阶段电压大于所述第一阶段电压，所述第二阶段电流小于所述第一阶段电流；所述第二阶段采用第一充电方式或第二充电方式对电池充电至所述第二阶段电压；
其中，所述电池包括含有有机溶剂的电解液，所述有机溶剂包括链状羧酸酯类化合物，所述链状羧酸酯类化合物与所述有机溶剂的重量百分比为10％-70％。
在本实施例中，所述第二阶段电流为恒定电流，即为现有的在开始充电时采用恒流充电的充电电流。或者，所述第二阶段电流也可以为大小有变化的电流，例如在所述第二阶段，以恒定电压对所述电池充电，则所述恒定电压所对应的充电电流(即所述第二阶段电流)的大 小会有变化，只要通过所述第二阶段电流可以将所述电池充电至所述第二阶段电压即可。
请参阅图11，图11为图2所示的改善电池循环性能的方法的第四种具体实施例。所述第四种具体实施例与所述第一种具体实施例相似，所述第四种具体实施例也包括步骤S111及步骤S112。不同之处在于所述第四种具体实施例还包括步骤S113，具体如下：
步骤S113：在第三阶段，以所述第二阶段电压对所述电池进行恒压充电。
在本实施例中，在第三阶段，以所述第二阶段电压对所述电池进行恒压充电直至电池满充。
在其他实施例中，第二种具体实施例可参照第四实施例进行相应的改进，增加步骤S113：在第三阶段，以所述第二阶段电压对所述电池进行恒压充电。
在其他实施例中，若第三种具体实施例中的第二阶段的第二阶段电流为恒定电流，所述第三种具体实施例可参照第四实施例进行相应的改进，增加步骤S113：在第三阶段，以所述第二阶段电压对所述电池进行恒压充电
综上所述，本申请提供一种新的对电芯体系进行优化的组合方案。例如，使用高含量羧酸酯溶剂电解液与高粘接隔离膜结合应用。一方面通过高粘接隔离膜可以抑制羧酸酯与正负极界面的产气副反应，有效提升电池在高温下的循环性能，改善电池在高温下的存储状况；另一方面通过羧酸酯溶剂电解液的低粘度高电导特点，可以改善高粘接隔离膜电解液浸润性差，传输电解液速度低的问题，提升电芯体系动力学，改善电池在低温下的循环性能。
此外，本申请提供的改善电池循环性能的方法实际是将优化后的电芯体系通过一种新的充电方法来进行充电。其中，所述新的充电方法为在第一阶段以恒定电流、恒定电压或恒定功率的其中至少一种方式对调整后的电池充电至所述第一阶段电压；并在第二阶段以恒定电流、恒定电压或恒定功率的其中至少一种方式对调整后的电池充电。或者，在所述第一阶段和所述第二阶段也可以是脉冲充电或脉冲充放 电的充电方式。从而可以显著缩短电池满冲所需的时间，并且通过缩短阴极高电位时间，可以减少正极在高电压下与电解液发生副反应的时间，可进一步改善电池的循环性能。
参阅图12所示，说明常规充电方法与本申请的新充电方式1，各自的阴极对锂电位的变化情形。其中，曲线C1为常规的充电方法，曲线C2为新充电方式1。常规的充电方法中在阴极对锂电位大于4.4V的时间位为45分钟，新充电方式1在阴极对锂电位大于4.4V的时间为31分钟。由于电池的阴极对锂电位处于高电位的时间明显缩短。因此，新充电方式1能够降低所述电池的阴极电位发生副反应的机率，可以提高电池的使用寿命。
另外，如下表1所示为常规充电方法与多个新充电方式过程中阴极对锂电位大于4.4V以上的时间对比。
表1 不同充电方法对应的阴极对锂电位大于4.4V以上的时间对比表
Figure PCTCN2020082255-appb-000003
需要说明的是，所述常规充电方法的具体充电流程为：使用0.7C恒定电流对电池充电，直到电池电压达到4.45V；再使用4.45V恒定电压对电池充电，直到电池电流为0.05C。
本申请的新充电方式1的具体充电流程为：使用0.7C恒定电流对电池充电，直到电池电压达到4.45V；使用0.5C恒定电流对电池充电，直到电池电压达到4.5V；再使用4.5V恒定电压对电池充电，直到电池电流为0.18C。新充电方式1中恒流充电过程的截止电压(4.5V)高于常规充电方法中恒流充电过程的截止电压(4.45V)。新充电方式1在阴极对锂电位大于4.4V的时间为31分钟，较常规充电方法而言，时间有一定的缩短。
本申请的新充电方式2的具体充电流程为：使用1.2C恒定电流对电池充电，直到电池电压达到4.25V；再使用0.7C恒定电流对电池充 电，直到电池电压达到4.45V；使用0.5C恒定电流对电池充电，直到电池电压达到4.5V；再使用4.5V恒定电压对电池充电，直到电池电流为0.19C。新的充电方法2中包括三个恒流充电过程，且最后恒流充电过程的截止电压(4.5V)高于常规充电方法中恒流充电过程的截止电压(4.45V)。新充电方式2在阴极对锂电位大于4.4V的时间为27分钟，较常规充电方法而言，时间明显缩短。并且较新充电方式1而言，时间也有一定的缩短。
本申请的新充电方式3的具体充电流程为：使用0.7C恒定电流对电池充电，直到电池电压达到4.55V；再使用4.4V恒定电压对电池充电，直到电池电流为0.4C；再使用4.5V恒定电压对电池充电，直到电池电流为0.13C。新充电方式3中恒流充电过程的截止电压(4.55V)高于常规充电方法中恒流充电过程的截止电压(4.45V)。新充电方式3在阴极对锂电位大于4.4V的时间为24分钟，几乎只有常规充电方法的时间的一半，也比新充电方式2和新充电方式1的时间短。
本申请的新充电方式4的具体充电流程为：使用0.7C的恒定电流对电池进行充电，直到电池的电压达到4.45V；以恒功率7W对电池充电至4.5V；以恒功率5.5W对电池充电至4.55V。新的充电方法FFC4中恒流充电过程的截止电压(4.55V)高于常规充电方法中恒流充电过程的截止电压(4.45V)。新充电方式4在阴极对锂电位大于4.4V的时间为23分钟，几乎只有常规充电方法的时间的一半，比新充电方式3、新充电方式2和新充电方式1的时间都要短。
本申请的新充电方式5的具体充电流程为：使用0.7C的恒定电流对电池进行充电，直到电池的电压达到4.45V；将电池静置2.9秒钟；以0.7C恒流对电池充电7.1秒钟，判断电池的电压是否大于或等于4.5V，当电池的电压大于或等于4.5V，跳转至下一步；以0.05C恒流对电池放电1秒钟；以0.41C恒流对电池充电9秒钟，判断电池的电压是否大于或等于4.55V，当电池的电压大于或等于4.55V，则充电截止。新充电方式5中恒流充电过程的截止电压(4.55V)高于常规充电方法中恒流充电过程的截止电压(4.45V)。新充电方式5在阴极对锂电位大于4.4V的时间为23分钟，几乎只有常规充电方法的时间的一 半，比本申请的新充电方式3、新充电方式2和新充电方式1的时间都要短。
另外，从图13所示的不同羧酸酯含量(以EP为例)溶剂电解液的电导率对比图可明显看出，随着羧酸酯含量的提升，电解液的电导率也随之提高。
对应地，从图14所示的全电池阻抗示意图中可知，随着羧酸酯含量的提升，全电池的阻抗随之减小，从而可提高全电池的大倍率充电能力，满足市场快充需求，但高羧酸酯含量电解液因为其电导率高，动力学活泼，在高温下易与正负极材料发生副反应，导致电解液与锂离子被消耗，生成的副产物。
请参阅图15所示的不同隔离膜粘接力的对比示意图。可知高粘接隔离膜对阳极粘接力相对低粘接隔离膜粘接力提高大约11N/m，高粘接隔离膜对阴极粘接力相对低粘接隔离膜提高大约5N/m。从而可以有效的减小锂离子电池中极片和隔离膜的距离，同时界面处电解液被一定程度挤出，从而抑制高温下的副产物增长速率，提升了高温循环容量保持率及降低高温存储电芯膨胀率。需要说明的是，所述低粘接隔离膜为与所述正极片或所述负极片之间的粘结力小于3N/m的隔离膜。在本实施方式中，所述低粘接隔离膜的粘结力大约为1N/m。
本申请通过将高粘接隔离膜、新充电方式与高含量羧酸酯电解液体系相结合，通过高粘接隔离膜改善隔离膜与及正负极界面，新的充电方法缩短电池在高电压下的充电时间，抑制副反应生产，而达到改善高含量羧酸酯电解液体系全电池的高温循环性能；通过含羧酸酯溶剂电解液提高体系动力学，加强电解液与隔离膜的浸润性，加快电解液传输速度，满足低温条件下循环对电解液通道的要求，改善低温循环。高粘接隔离膜与含羧酸酯溶剂电解液互相弥补，再加上新的充电方法的优势，改善电池的高低温循环及高温存储性能。
为了使本申请的发明目的、技术方案和技术效果更加清晰，以下结合附图和实施例，对本申请进一步详细说明。应当理解的是，本说明书中给出的实施例只是为了解释本申请，并非为了限定本申请，本申请并不局限于说明书中给出的实施例。
对比例和实施例采用的电池体系采用通用锂离子电池制作工艺，将正负极活性物质分别与粘结剂、溶剂等搅拌成均匀的浆料，分别涂覆在铝箔和铜箔上。经过冷压分条等工序得到所需长宽的极片，与隔离膜一起卷绕成电极组件，经过封装、注液、化成，制成成品电芯。对该体系电芯分别采用不同羧酸酯含量电解液和不同粘接力的隔离膜及不同的充电方法相互搭配进行低温及高温循环性能测试和高温存储，具体方案见表2，并对比12℃及45℃下电池充放电循环500圈后的容量保持率和在80℃环境温度下存储8小时后的电芯膨胀率。
对比例
电解液：含有碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸二乙酯(DEC)，不含有无羧酸酯；
隔离膜：采用低粘接隔离膜(～1N/m)，所述低粘接隔离膜的基材为聚乙烯，聚合物粘接层为聚偏二氟乙烯(PVDF)，聚合物粒径为100nm，聚合物粘接层覆盖率为23％；
充电方法：采用常规充电方法，具体流程如下：
环境温度12℃/45℃；
步骤一：使用0.7C的恒定电流对电池进行充电，直到电池的电压达到4.45V；
步骤二：使用4.45V的恒定电压对电池进行充电，直到电池的电流达到0.05C；
步骤三：将电池静置5分钟；
步骤四：使用0.5C的恒定电流对电池放电，直到电池的电压为3.0V；
步骤五：将电池静置5分钟；
步骤六：重复上述步骤一至步骤五500个循环。
实施例1
电解液：成分与对比例相同；
隔离膜：与对比例相同；
充电方法：采用本申请中的新充电方式1，具体流程如下：
环境温度12℃/45℃：
步骤一：使用0.7C的恒定电流对电池进行充电，直到电池的电压达到4.45V；
步骤二：使用0.5C的恒定电流对电池进行充电，直到电池的电压达到4.5V；
步骤三：使用4.5V的恒定电压对电池进行充电，直到电池的电流达到0.18C；
步骤四：将电池静置5分钟；
步骤五：使用0.5C的恒定电流对电池放电，直到电池的电压为3.0V；
步骤六：将电池静置5分钟；
步骤七：重复上述步骤一至步骤六500个循环。
实施例2
电解液：成分与对比例相同；
隔离膜：采用高粘接隔离膜(～12N/m)，所述高粘接隔离膜的基材为聚乙烯，聚合物粘接层为聚丙烯酸，聚合物粒径为500nm，聚合物粘接层覆盖率为40％；
充电方法：采用常规充电方法，即恒流-恒压充电方法。具体流程参见对比例，在此不再赘述。
实施例3
电解液：成分与对比例相同，不同的是添加40％的羧酸酯；
隔离膜：与对比例相同；
充电方法：采用常规充电方法，即恒流-恒压充电方法。具体流程参见对比例，在此不再赘述。
实施例4
电解液：成分与对比例相同，不同的是添加6％的羧酸酯；
隔离膜：与实施例2相同；
充电方法：采用本申请中的新充电方式1，具体流程参见实施例1，在此不再赘述。
实施例5
电解液：成分与对比例相同，不同的是添加10％的羧酸酯；
隔离膜：与实施例2相同；
充电方法：采用本申请中的新充电方式1，具体流程参见实施例1，在此不再赘述。
实施例6
电解液：成分与对比例相同，不同的是添加20％的羧酸酯；
隔离膜：与实施例2相同；
充电方法：采用本申请中的新充电方式1，具体流程参见实施例1，在此不再赘述。
实施例7
电解液：成分与对比例相同，不同的是添加30％的羧酸酯；
隔离膜：与实施例2相同；
充电方法：采用本申请中的新充电方式1，具体流程参见实施例1，在此不再赘述。
实施例8
电解液：成分与对比例相同，不同的是添加40％的羧酸酯；
隔离膜：与实施例2相同；
充电方法：采用本申请中的新充电方式1，具体流程参见实施例1，在此不再赘述。
实施例9
电解液：成分与对比例相同，不同的是添加50％的羧酸酯；
隔离膜：与实施例2相同；
充电方法：采用本申请中的新充电方式1，具体流程参见实施例1，在此不再赘述。
实施例10
电解液：成分与对比例相同，不同的是添加60％的羧酸酯；
隔离膜：与实施例2相同；
充电方法：采用本申请中的新充电方式1，具体流程参见实施例1，在此不再赘述。
实施例11
电解液：成分与对比例相同，不同的是添加70％的羧酸酯；
隔离膜：与实施例2相同；
充电方法：采用本申请中的新充电方式1，具体流程参见实施例1，在此不再赘述。
实施例12
电解液：成分与对比例相同，不同的是添加74％的羧酸酯；
隔离膜：与实施例2相同；
充电方法：采用本申请中的新充电方式1，具体流程参见实施例1，在此不再赘述。
实施例13
电解液：成分与对比例相同，不同的是添加40％的羧酸酯；
隔离膜：与对比例相同；
充电方法：采用本申请中的新充电方式1，具体流程参见实施例1，在此不再赘述。
实施例14
电解液：成分与对比例相同，不同的是添加40％的羧酸酯；
隔离膜：与对比例相同；
充电方法：采用常规充电方法，即恒流-恒压充电方法。具体流程参见对比例，在此不再赘述。
实施例15
电解液：成分与对比例相同，不同的是添加40％的羧酸酯；
隔离膜：采用高粘接隔离膜(～3.2N/m)，所述高粘接隔离膜的基材为聚乙烯，聚合物粘接层为聚丙烯酸，聚合物粒径为200nm，聚合物粘接层覆盖率为15％；
充电方法：采用本申请中的新充电方式1，具体流程参见实施例1，在此不再赘述。
实施例16
电解液：成分与对比例相同，不同的是添加40％的羧酸酯；
隔离膜：采用高粘接隔离膜(～20N/m)，所述高粘接隔离膜的基材为聚乙烯，聚合物粘接层为聚丙烯酸，聚合物粒径为500nm，聚合物粘接层覆盖率为85％；
充电方法：采用本申请中的新充电方式1，具体流程参见实施例1，在此不再赘述。
实施例17
电解液：成分与对比例相同，不同的是添加40％的羧酸酯；
隔离膜：与实施例2相同；
充电方法：采用本申请中的新充电方式2，具体流程如下
环境温度12℃/45℃；
步骤一：使用1.2C的恒定电流对电池进行充电，直到电池的电压达到4.25V，
步骤二：使用0.7C的恒定电流对电池进行充电，直到电池的电压达到4.45V；
步骤三：使用0.5C的恒定电流对电池进行充电，直到电池的电压达到4.5V；
步骤四：使用4.5V的恒定电压对电池进行充电，直到电池的电流达到0.19C；
步骤五：将电池静置5分钟；
步骤六：使用0.5C的恒定电流对电池放电，直到电池的电压为3.0V；
步骤七：将电池静置5分钟；
步骤八：重复上述步骤一至步骤七500个循环。
实施例18
电解液：成分与对比例相同，不同的是添加40％的羧酸酯；
隔离膜：与实施例2相同；
充电方法：采用本申请中的新充电方式3，具体流程如下
环境温度12℃/45℃；
步骤一：使用0.7C的恒定电流对电池进行充电，直到电池的电压达到4.45V；
步骤二：使用4.4V的恒定电压对电池进行充电，直到电池的电流达到0.4C；
步骤三：使用4.5V的恒定电压对电池进行充电，直到电池的电流 达到0.13C；
步骤四：将电池静置5分钟；
步骤五：使用0.5C的恒定电流对电池放电，直到电池的电压为3.0V；
步骤六：将电池静置5分钟；
步骤七：重复上述步骤一至步骤六500个循环。
实施例19
电解液：成分与对比例相同，不同的是添加40％的羧酸酯；
隔离膜：与实施例2相同；
充电方法：采用本申请中的新充电方式4，具体流程如下
环境温度12℃/45℃；
步骤一：使用0.7C的恒定电流对电池进行充电，直到电池的电压达到4.45V；
步骤二：以恒功率7W对电池充电至4.5V；
步骤三：以恒功率5.5W对电池充电至4.55V；
步骤四：将电池静置5分钟；
步骤五：以0.5C恒流对电池放电至3.0V；
步骤六：将电池静置5分钟；
步骤七：循环上述步骤一至步骤六500圈。
实施例20
电解液：成分与对比例相同，不同的是添加40％的羧酸酯；
隔离膜：与实施例2相同；
充电方法：采用本申请中的新充电方式5，具体流程如下
环境温度12℃/45℃；
步骤一：使用0.7C的恒定电流对电池进行充电，直到电池的电压达到4.45V；
步骤二：将电池静置2.9秒钟；
步骤三：以0.7C恒流对电池充电7.1秒钟，判断电池的电压是否大于或等于4.5V，当电池的电压大于或等于4.5V，跳转至步骤五；
步骤四：循环步骤二至步骤三100000次；
步骤五：以0.05C恒流对电池放电1秒钟；
步骤六：以0.41C恒流对电池充电9秒钟，判断电池的电压是否大于或等于4.55V，当电池的电压大于或等于4.55V，跳转至步骤八；
步骤七：将电池静置5分钟；
步骤八：以0.5C恒流对电池放电至3.0V；
步骤九：将电池静置5分钟；
步骤十：循环上述步骤一至步骤九500圈。
表2 对比例和实施例1-20中电池的低温和高温循环性能测试及高温存储性能
Figure PCTCN2020082255-appb-000004
Figure PCTCN2020082255-appb-000005
对比例采用不含羧酸酯溶剂电解液、常规充电方法以及低粘隔离膜制备成电芯，并做高温及低温循环测试和高温存储测试。
实施例1中采用本申请中的新充电方式1，可以缩短循环过程中正极在充电过程中处在高压下的时间，电解液与正极副反应减少，高温循环得到改善，低温循环与对比例同一水平。
实施例2中的电池体系引入高粘接隔离膜，由于电解液不含羧酸酯，动力学较差，高粘接隔离膜浸润性较差，低温循环性能相比对比例严重恶化；此外，由于高粘接隔离膜的粘接力增强，高温存储性能轻微改善。
实施例3中的电池体系引入含羧酸酯溶剂电解液，与对比例相比，电池动力学提升，低温循环有所改善，但高温下副反应增加，高温循环及高温存储性能出现恶化。
实施例8中的电池体系同时引入含羧酸酯溶剂电解液和高粘接隔离膜，再采用本申请中的新充电方式1进行充放电测试，与对比例相比可以看出，通过高粘接隔离膜改善电池界面，减小含羧酸酯溶剂电解液电池的界面副反应，而含羧酸酯溶剂电解液动力学高，改善高粘接隔离膜的浸润性，提高电解液传输能力，再加上本申请中的新充电方式1可以减少电池在高电压下充电时间，电池的高温及低温循环及高温存储都得到改善。
实施例5-11中的电池体系采用10％-70％不同含量羧酸酯溶剂电解液搭配高粘接隔离膜和本申请中的新充电方式1，均可改善电池的高温循环及高温存储性能，并随着羧酸酯溶剂含量的增加，低温循环性能改善越明显。
实施例4对比实施例5-11中的电池体系的电解液羧酸酯溶剂含量低于10％，动力学不足，低温循环性能恶化，无法满足要求。
实施例12对比实施例5-11中的电池体系的电解液羧酸酯溶剂含量高于70％，电解液活性高，高温下副反应加剧，高温循环及高温存 储性能明显恶化。
实施例13对比实施例8可以得知，高粘接隔离膜可以强化电池界面，减少副反应，明显改善高温循环及高温存储性能。
实施例14对比实施例8可以得知，本申请中的新充电方式1对比常规充电方法对高温循环性能具有明显改善。
实施例15、16对比实施例8，进一步说明隔离膜粘接力大小对高温循环及高温存储的作用效果，粘接力越大，改善效果越明显。
实施例17、18、19、20对比实施例8，说明新的充电方法对高温循环都会有改善作用。
需要说明的是，表2中的12℃和45℃下500圈充放电循环后的容量保持率的计算方法分别为：
调节测试温度为12℃，具体充放电流程如下：
步骤一：0.7C恒流对电池充电至4.45V；
步骤二：4.45V恒压对电池充电至0.05C；
步骤三：将电池静置5分钟；
步骤四：以0.5C恒流对电池放电至3.0V；
步骤五：将电池静置5分钟；
步骤六：循环上述步骤一至步骤五500圈。
那么，12℃下500圈充放电循环后电池的容量保持率为：500圈充放电循环后电池的放电容量与第一圈充放电循环后电池的放电容量的比值。
调节测试温度为45℃，具体充放电流程如下：
步骤一：0.7C恒流对电池充电至4.45V；
步骤二：4.45V恒压对电池充电至0.05C；
步骤三：将电池静置5分钟；
步骤四：以0.5C恒流对电池放电至3.0V；
步骤五：将电池静置5分钟；
步骤六：循环上述步骤一至步骤五500圈。
那么，45℃下500圈充放电循环后电池的容量保持率为：500圈充放电循环后电池的放电容量与第一圈充放电循环后电池的放电容量 的比值。
电池在80℃的环境温度中存储8小时后，电芯膨胀率测试方法：
步骤一：测试初始电压下电池的电芯厚度、电压、阻抗；
步骤二：将电池满充，具体地，以0.7C恒流对电池充电至4.45V，以4.45V恒压对电池充电至0.02C；
步骤三：测试所述电池在满充状态下的电芯厚度、电压、阻抗；
步骤四：将所述电芯放置在80℃炉子中存储8小时；
步骤五：测试存储后电池的电芯厚度、电压、阻抗。
所述电芯膨胀率的计算方法为：(高温存储后电芯厚度-初始电压下电芯厚度)/初始电压下电芯厚度。即，步骤五中测试的电芯厚度减去步骤一中测试的电芯厚度的差值除以步骤一中测试的电芯厚度。
由此，本申请通过调整电池正极活性物质中的钴酸锂一次颗粒和钴酸锂二次颗粒的重量比，以及在第一阶段以恒定电流、恒定电压或恒定功率的其中至少一种方式对调整后的电池充电至所述第一阶段电压；并在第二阶段以恒定电流、恒定电压或恒定功率的其中至少一种方式对调整后的电池充电。或者，在所述第一阶段和所述第二阶段也可以是脉冲充电或脉冲充放电的充电方式。可进一步提升电池循环性能，并且能够显著改善电池循环过程中低温放电性能。
对于本领域技术人员而言，显然本申请不限于上述示范性实施例的细节，而且在不背离本申请的精神或基本特征的情况下，能够以其他的具体形式实现本申请。因此，无论从哪一点来看，均应将本申请上述的实施例看作是示范性的，而且是非限制性的，本申请的范围由所附权利要求而不是上述说明限定，因此旨在将落在权利要求的等同要件的含义和范围内的所有变化涵括在本申请内。

Claims (15)

  1. 一种改善电池循环性能的方法，应用于一电池中，其特征在于，所述方法包括：
    在第一阶段，以第一阶段电流对所述电池充电至第一阶段电压；
    在第二阶段，以第二阶段电流对所述电池充电至第二阶段电压，所述第二阶段电压大于所述第一阶段电压，所述第二阶段电流小于所述第一阶段电流；
    其中，所述电池包括含有有机溶剂的电解液，所述有机溶剂包括链状羧酸酯类化合物，所述链状羧酸酯类化合物与所述有机溶剂的重量百分比为10％-70％。
  2. 如权利要求1所述的方法，其特征在于，所述链状羧酸酯类化合物选自式I所示的化合物中的至少一种：
    Figure PCTCN2020082255-appb-100001
    其中，R 1选自氢原子、卤原子、羟基、碳原子数为1～20的烷基、碳原子数为1～20的烷氧基、碳原子数为1～20的链烯基、碳原子数为6～30的芳基或碳原子数为6～30的芳氧基；R 2选自氢原子、卤原子、碳原子数为1～20的烷基、碳原子数为1～20的链烯基或碳原子数为6～30的芳基。
  3. 如权利要求2所述的方法，其特征在于，所述链状羧酸酯类化合物物选自甲酸甲酯、乙酸甲酯、甲酸乙酯、乙酸乙酯、乙酸丙酯、丙酸乙酯、丙酸甲酯、丙酸正丙酯、丙酸异丙酯、丙酸甲酯、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、异丁酸异丁酯和正戊酸正戊酯中的至少一种。
  4. 如权利要求1所述的方法，其特征在于，所述电解液还包括锂 盐，所述锂盐选自六氟磷酸锂、二氟磷酸锂、四氟硼酸锂、六氟砷酸锂、高氯酸锂、双氟磺酰亚胺锂、双三氟甲烷磺酰亚胺锂、双草酸硼酸锂和二氟草酸硼酸锂中的至少一种。
  5. 如权利要求1所述的方法，其特征在于，所述电池还包括正极片、负极片和设置在所述正极片与所述负极片之间的隔离膜，所述隔离膜包括多孔基材、设置于所述多孔基材表面的耐热涂层和设置于所述隔离膜最外侧的聚合物粘接层，所述聚合物粘接层设置于所述耐热涂层的表面或未具有所述耐热涂层的所述多孔基材的表面，所述聚合物粘接层中包括聚合物颗粒，所述聚合物颗粒在所述聚合物粘接层中的堆积层数不超过四层。
  6. 如权利要求5所述的方法，其特征在于，所述聚合物颗粒为聚偏氯乙烯、聚偏氟乙烯-六氟丙烯共聚物、苯乙烯-丁二烯共聚物、聚丙烯腈、丁二烯-丙烯腈聚合物、聚丙烯酸、聚丙烯酸酯和丙烯酸酯-苯乙烯共合物中的至少一种，或以上聚合物单体中的至少两种的共聚物，所述聚合物颗粒的粒径为0.2μm-2μm。
  7. 如权利要求5所述的方法，其特征在于，所述聚合物粘接层对所述多孔基材或所述耐热涂层的覆盖面积比为15％-85％。
  8. 如权利要求5所述的方法，其特征在于，所述隔离膜与所述正极片或所述负极片之间的粘结力大于或等于3N/m。
  9. 如权利要求1所述的方法，其特征在于，所述第二阶段采用第一充电方式或第二充电方式对电池充电至所述第二阶段电压；
    所述第一充电方式包括依序的K个子阶段，K为大于或等于2的整数，所述K个子阶段分别定义为第i子阶段，i＝1、2、…、K；在所述第i子阶段时，以第i电流、第i电压及第i功率的其中一者对所述电池进行充电；在第i+1子阶段时，以第i+1电流、第i+1电压及第i+1功率的其中一者对所述电池进行充电；其中，在所述第i+1子阶段时的充电电流小于或等于在所述第i子阶段时的充电电流，或者所述第i+1电压大于或等于所述第i电压，或者所述第i+1功率小于或等于所述第i功率；以及
    所述第二充电方式包括依序的D个充电子阶段，D为大于或等于2的整数，所述D个充电子阶段分别定义为第j充电子阶段，j＝1、2、…、D，且每一个所述第j充电子阶段包括第j前充电子阶段及第j后充电子阶段；在所述第j前充电子阶段及所述第j后充电子阶段的其中一者，对所述电池不充电或以第j前充电子电流进行充电或放电达Tj1时长；在所述第j前充电子阶段及所述第j后充电子阶段的其中另一者，对所述电池以第j后充电子电流进行充电达Tj2时长；其中，所述第j前充电子电流的绝对值小于所述第j后充电子电流的绝对值。
  10. 如权利要求9所述的充电方法，其特征在于，第j充电子阶段的充电电流的平均值小于所述第一阶段的充电电流，第j+1充电子阶段的充电电流的平均值小于或等于所述第j子阶段的充电电流。
  11. 如权利要求9所述的方法，其特征在于，所述第一阶段采用第三充电方式对电池充电至所述第一阶段电压，所述第三充电方式采用所述第一充电方式或所述第二充电方式。
  12. 如权利要求11所述的方法，其特征在于，当所述第三充电方式采用所述第一充电方式时，两者之间的充电子阶段个数K相同；或者当所述第三充电方式采用所述第二充电方式时，两者之间的充电子阶段个数D相同。
  13. 如权利要求1所述的方法，其特征在于，所述第一阶段电压等于所述电池的充电限制电压，所述第二阶段电压小于所述电池中电解液的氧化分解电压。
  14. 如权利要求1所述的方法，其特征在于，所述第二阶段电压小于或等于所述第一阶段电压加上500毫伏特。
  15. 一种电子装置，包括电池和电池管理模块，其特征在于，所述电池包括含有有机溶剂的电解液，所述有机溶剂包括链状羧酸酯类化合物，所述链状羧酸酯类化合物与所述有机溶剂的重量百分比为10％-70％，所述电池管理模块用于执行如权利要求1至14中任一项所述的方法。
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117524328A (zh) * 2024-01-04 2024-02-06 北京金羽新材科技有限公司 一种基于预设成分的电解液模拟分析方法、装置、设备及介质
CN115820064B (zh) * 2022-01-27 2024-03-22 宁德时代新能源科技股份有限公司 涂料组合物、隔离膜、二次电池、电池模块、电池包和用电装置

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103078141A (zh) * 2013-01-25 2013-05-01 宁德新能源科技有限公司 锂离子二次电池及其电解液
US10153512B2 (en) * 2015-05-25 2018-12-11 Panasonic Intellectual Property Management Co., Ltd. Electrolyte solution and battery
CN110098646A (zh) * 2018-01-31 2019-08-06 宁德新能源科技有限公司 充电方法、充电装置、终端及可读存储介质
CN209418618U (zh) * 2018-12-28 2019-09-20 佛山市实达科技有限公司 一种锂离子电池隔膜

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104934636A (zh) * 2015-06-17 2015-09-23 宁德时代新能源科技有限公司 电解液以及包含该电解液的锂离子电池
JP6683202B2 (ja) * 2015-08-06 2020-04-15 株式会社村田製作所 二次電池の充電方法、充電制御装置及び二次電池
CN105576283A (zh) * 2016-02-03 2016-05-11 东莞市凯欣电池材料有限公司 一种兼顾高低温性能的高电压电解液及使用该电解液的锂离子电池
WO2018027652A1 (zh) * 2016-08-10 2018-02-15 东莞新能源科技有限公司 隔膜、制备方法及电化储能装置
CN109119685A (zh) * 2017-06-23 2019-01-01 宁德时代新能源科技股份有限公司 电解液及锂离子电池
CN108615955B (zh) * 2018-05-07 2020-08-28 深圳市壹绿通环保资源有限公司 一种磷酸铁锂电池的化成方法

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103078141A (zh) * 2013-01-25 2013-05-01 宁德新能源科技有限公司 锂离子二次电池及其电解液
US10153512B2 (en) * 2015-05-25 2018-12-11 Panasonic Intellectual Property Management Co., Ltd. Electrolyte solution and battery
CN110098646A (zh) * 2018-01-31 2019-08-06 宁德新能源科技有限公司 充电方法、充电装置、终端及可读存储介质
CN209418618U (zh) * 2018-12-28 2019-09-20 佛山市实达科技有限公司 一种锂离子电池隔膜

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP4131562A4 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115820064B (zh) * 2022-01-27 2024-03-22 宁德时代新能源科技股份有限公司 涂料组合物、隔离膜、二次电池、电池模块、电池包和用电装置
CN117524328A (zh) * 2024-01-04 2024-02-06 北京金羽新材科技有限公司 一种基于预设成分的电解液模拟分析方法、装置、设备及介质
CN117524328B (zh) * 2024-01-04 2024-04-02 北京金羽新材科技有限公司 一种基于预设成分的电解液模拟分析方法、装置、设备及介质

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