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WO2021184318A1 - 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
WO2021184318A1
WO2021184318A1 PCT/CN2020/080278 CN2020080278W WO2021184318A1 WO 2021184318 A1 WO2021184318 A1 WO 2021184318A1 CN 2020080278 W CN2020080278 W CN 2020080278W WO 2021184318 A1 WO2021184318 A1 WO 2021184318A1
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Prior art keywords
battery
charging
stage
current
voltage
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PCT/CN2020/080278
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English (en)
French (fr)
Inventor
刘奥
龚美丽
高潮
方占召
Original Assignee
宁德新能源科技有限公司
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Priority to EP20925080.2A priority Critical patent/EP4123742A4/en
Priority to PCT/CN2020/080278 priority patent/WO2021184318A1/zh
Priority to CN202080002557.2A priority patent/CN112106248B/zh
Priority to US17/019,660 priority patent/US11843272B2/en
Publication of WO2021184318A1 publication Critical patent/WO2021184318A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/44—Methods for charging or discharging
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
    • C09J7/29—Laminated material
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/46—Accumulators structurally combined with charging apparatus
    • 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
    • H01M10/48—Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte
    • 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
    • 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
    • H01M50/46—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
    • 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
    • H02J7/0069—Charging or discharging for charge maintenance, battery initiation or rejuvenation
    • 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
    • H02J7/0071—Regulation of charging or discharging current or voltage with a programmable schedule
    • 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
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2203/00—Applications of adhesives in processes or use of adhesives in the form of films or foils
    • C09J2203/326—Applications of adhesives in processes or use of adhesives in the form of films or foils for bonding electronic components such as wafers, chips or semiconductors
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2409/00—Presence of diene rubber
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2425/00—Presence of styrenic polymer
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2427/00—Presence of halogenated polymer
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2433/00—Presence of (meth)acrylic polymer
    • 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
    • H01M2220/00—Batteries for particular applications
    • H01M2220/30—Batteries in portable systems, e.g. mobile phone, laptop
    • 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
    • H02J7/0042—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries characterised by the mechanical construction
    • 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 unsatisfactory cycle capacity retention rate of lithium-ion batteries under high temperature conditions is a common problem.
  • optimizing the electrolyte formulation is the main method, but the optimization of the electrolyte formulation will cause the deterioration of other battery performance (such as low-temperature discharge, high-rate charging) to a certain extent. Therefore, how to improve the cycle life of the battery under high temperature conditions has become a very important issue under the premise that the other electrical properties of the battery are not deteriorated.
  • An embodiment of the present application provides a method for improving the cycle performance of a battery, which is applied to a battery.
  • the battery includes a positive electrode sheet, a negative electrode sheet, and a separator provided between the positive electrode sheet and the negative electrode sheet.
  • the binding force between the isolation film and the positive electrode sheet or the negative electrode sheet is greater than or equal to 3N/m, and the method includes: in the first stage, charging the battery with the first stage current to the 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 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 substage.
  • the charging current of the stage 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 substage.
  • 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.
  • the isolation membrane includes a porous substrate, a heat-resistant coating disposed on the surface of the porous substrate, and a polymer adhesive layer disposed on the outermost side of the isolation membrane, the polymer The adhesive layer is formed on the surface of the heat-resistant coating or the surface of the porous substrate without the heat-resistant coating, the polymer adhesive layer includes polymer particles, and the polymer particles are The number of stacked layers in the polymer adhesive layer is less than or equal to 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%.
  • An embodiment of the present application provides an electronic device, including a battery and a battery management module.
  • the battery includes a positive electrode sheet, a negative electrode sheet, and a separator provided between the positive electrode sheet and the negative electrode sheet.
  • the binding force between the positive electrode sheet or the negative electrode sheet is greater than or equal to 3 N/m, and the battery management module is used to implement the method for improving the cycle performance of the battery as described above.
  • the embodiment of the present application combines a high-adhesion isolation film in the battery and a combination of increasing the charging limit voltage of the battery (that is, increasing the voltage from the first stage to the second stage voltage). It can shorten the time that the cathode of the battery is kept at a high potential, reduce the occurrence of side reactions, and improve the cycle performance of the battery.
  • the pressure of the pores in the battery pole pieces is increased, which can suppress the bloating of the battery cell after the charging limit voltage rises, thereby reducing the interface reaction rate between the cathode and the electrolyte, and further reducing the side reaction. Occurs, which can significantly improve the high temperature cycle performance of the battery during the cycle.
  • 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. 2.
  • FIG. 4 is a schematic diagram of the current and voltage changes with time during the charging process of the battery according to the first embodiment of the present application.
  • FIG. 5 is a schematic diagram of the current and voltage changes with time during the charging process of the battery according to the second embodiment of the present application.
  • Fig. 6 is a schematic diagram of the power and voltage changes with time in the first stage and the current and voltage changes with time in the second stage according to an embodiment of the present application.
  • FIG. 7 is a schematic diagram of the current and voltage changes with time during the charging process of the battery according to the third embodiment of the present application.
  • FIG. 8 is a schematic diagram of the current and voltage changes with time during the charging process of the battery 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. 2.
  • FIG. 10 is a third specific embodiment of the method for improving the cycle performance of the battery shown in FIG. 2.
  • FIG. 11 is a fourth specific embodiment of the method for improving the cycle performance of the battery shown in FIG. 2.
  • 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 is a rechargeable battery.
  • the battery 10 includes at least one battery cell, and the battery 10 can be repeatedly charged in a rechargeable manner.
  • the battery 10 is mainly composed of a positive pole piece, a negative pole piece, a separator, an electrolyte, and a packaging bag.
  • 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.
  • 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 the method for improving battery cycle performance according to an embodiment of the present application.
  • the method for improving the cycle performance of a battery is applied to a battery and 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 a positive electrode sheet, a negative electrode sheet, and a separator film disposed between the positive electrode sheet and the negative electrode sheet, and the separator film includes a porous substrate and a heat-resistant coating provided on the surface of the porous substrate.
  • the polymer adhesive layer includes polymer particles, and the number of stacked layers of the polymer particles in the polymer adhesive layer is less than or equal to four.
  • the polymer particles are polyvinylidene chloride, polyvinylidene fluoride-hexafluoropropylene copolymer, styrene-butadiene copolymer, polyacrylonitrile, butadiene-acrylonitrile polymer, At least one of polyacrylic acid, polyacrylate, and acrylate-styrene copolymer, or a copolymer of at least two of the above polymer monomers, the particle size of the polymer particles is 0.2 ⁇ m-2 ⁇ m. In another embodiment, the particle size of the polymer particles is 0.3 ⁇ m-1 ⁇ m.
  • the material of the porous substrate is polyethylene, polypropylene, polyethylene terephthalate (PET), cellulose or polyimide.
  • the isolation film is a high adhesion isolation film.
  • the high-adhesion separator in this application is a separator with a binding force between the positive electrode sheet or the negative electrode sheet greater than or equal to 3 N/m.
  • the binding force between the high-adhesion separator film and the positive electrode sheet or the negative electrode sheet is greater than or equal to 4.3 N/m.
  • the binding force between the high-adhesion separator and the positive electrode sheet or the negative electrode sheet can be adjusted by adjusting the type, particle size, content, etc. of the polymer particles.
  • the coverage area ratio of the polymer adhesive layer to the porous substrate or the heat-resistant coating is 15%-85%. In another embodiment, the coverage area ratio is 30%-70%.
  • the pressure of the pores in the pole piece is increased by controlling the adhesive force of the high-adhesive isolation film, and the problem of cell bloating can be suppressed.
  • the high-adhesion separator effectively reduces the distance between the pole piece and the separator, which can reduce the interface reaction rate between the cathode and the electrolyte, and improve the cycle performance of the battery.
  • FIG. 3 is a 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 a positive electrode sheet, a negative electrode sheet, and a separator film arranged between the positive electrode sheet and the negative electrode sheet, and the binding force between the separator film and the positive electrode sheet or the negative electrode sheet is greater than Or equal to 3N/m.
  • the binding force between the isolation film and the positive electrode sheet or the negative electrode sheet is greater than or equal to 4.3 N/m.
  • the isolation membrane includes a porous substrate, a heat-resistant coating disposed on the surface of the porous substrate, and a polymer adhesive layer disposed on the outermost side of the isolation membrane.
  • the layer is formed on the surface of the heat-resistant coating or the surface of the porous substrate without the heat-resistant coating, the polymer adhesive layer includes polymer particles, and the polymer particles are in the The number of stacked layers in the polymer adhesive layer is less than or equal to four.
  • the polymer particles are polyvinylidene chloride, polyvinylidene fluoride-hexafluoropropylene copolymer, styrene-butadiene copolymer, polyacrylonitrile, butadiene-acrylonitrile polymer, At least one of polyacrylic acid, polyacrylate, and acrylate-styrene copolymer, or a copolymer of at least two of the above polymer monomers, the particle size of the polymer particles is 0.2 ⁇ m-2 ⁇ m. In another embodiment, the particle size of the polymer particles is 0.3 ⁇ m-1 ⁇ m.
  • the material of the porous substrate is polyethylene, polypropylene, polyethylene terephthalate (PET), cellulose or polyimide.
  • the coverage area ratio of the polymer adhesive layer to the porous substrate or the heat-resistant coating is 15%-85%. In another embodiment, the coverage area ratio is 30%-70%.
  • the charging current in the (i+1)th charging sub-phase is less than or equal to the charging current in the i-th charging sub-phase.
  • the (i+1)th voltage is greater than or equal to the (i)th voltage.
  • the (i+1)th power is less than or equal to the (i)th 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 stored in the battery in advance.
  • 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-stages of the two stages charges the battery alternately with a constant charging current and a constant charging 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 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.
  • 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, the battery is charged to the voltage Ucl with a 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 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 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 j-th 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 Tj 1 time, and the j-th post-charge sub-phase is charged or discharged.
  • the electronic phase is charged with the j-th post-charger current for a duration of Tj2.
  • the charge or discharge current of the front charger is Tj 1 time.
  • 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 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 the 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 t(
  • the method for improving the cycle performance of the battery adopts a high-adhesion separator in the battery, and by increasing the charging limit voltage of the battery (that is, increasing the voltage from the first stage to the second stage voltage).
  • the way of combining It can shorten the time that the cathode of the battery is kept at a high potential, reduce the occurrence of side reactions, and improve the cycle performance of the battery.
  • the pressure of the pores in the battery pole pieces is increased, and the swelling of the cell after the voltage rises is suppressed, thereby reducing the interface reaction rate between the cathode and the electrolyte, further reducing the occurrence of side reactions, and can significantly improve the battery High temperature cycle performance during the cycle.
  • the battery system used in the comparative examples and examples described below uses lithium cobalt oxide as the cathode, graphite as the anode, plus isolation membrane, electrolyte and packaging shell, through mixing, coating, assembly, formation and aging And other processes are made.
  • the cathode is composed of 96.7% LiCoO 2 (as the cathode active material) plus 1.7% polyvinylidene fluoride (PVDF, as the binder) plus 1.6% conductive carbon black (SUPER-P, as the conductive agent), and the anode is composed of 98 % Artificial graphite (as anode active material) plus 1.0% styrene butadiene rubber (SBR, as binder) plus 1.0% sodium carboxymethyl cellulose (CMC, as thickener).
  • VDF polyvinylidene fluoride
  • SUPER-P conductive carbon black
  • the anode is composed of 98 % Artificial graphite (as anode active material) plus 1.0% styrene butadiene rubber (SBR, as binder) plus 1.0% sodium carboxymethyl cellulose (CMC, as thickener).
  • the comparative example and the embodiment adopt different new charging methods to charge the battery, and combine separators with different adhesion forces to improve the cycle performance of the battery.
  • the capacity retention rate and cell gas production after 500 cycles of charging and discharging of the battery were tested at an ambient temperature of 55°C.
  • the specific schemes and results are summarized in Table 1.
  • Comparative Examples 1 and 2 use low-adhesion separators
  • Comparative Examples 3 and Examples 1-26 use high-adhesion isolation films.
  • 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.
  • Table 1 The capacity retention rate and cell gas production of each comparative example and Examples 1-26 after cyclic charging and discharging
  • the existing charging methods in Comparative Example 1 and Comparative Example 3 are the constant current and constant voltage charging methods in the prior art.
  • the specific charging process of the existing charging method is as follows:
  • the ambient temperature is 55°C:
  • Step 1 Charge the battery to 4.4V with 0.7C constant current
  • Step 2 Charge the battery to 0.05C with a constant voltage of 4.4V;
  • 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.
  • Comparative Example 2 and Examples 1-22 adopt the new charging method 1 in this application, and the specific process is as follows:
  • the ambient temperature is 55°C;
  • Step 1 Charge the battery to 4.4V with 0.7C constant current
  • Step 2 Charge the battery to 4.45V with a constant current of 0.5C;
  • Step 3 Charge the battery to 4.54V with 0.4C constant current
  • 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.
  • Embodiment 23 adopts the new charging method 2 in this application, and the specific process is as follows:
  • the ambient temperature is 55°C;
  • Step 1 Charge the battery to 4.4V with 0.7C constant current
  • Step 2 Charge the battery to 0.4C with a constant voltage of 4.35V;
  • Step 3 Charge the battery to 0.13C with a constant voltage of 4.45V;
  • 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.
  • Embodiment 24 adopts the new charging method 3 in this application, and the specific process is as follows:
  • the ambient temperature is 55°C;
  • Step 1 Charge the battery to 4.4V with 0.7C (2.1A) constant current
  • Step 2 Charge the battery to 4.45V 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.
  • Embodiment 25 adopts the new charging method 4 in this application, and the specific process is as follows:
  • the ambient temperature is 55°C;
  • Step 1 Charge the battery to 4.4V with 0.7C constant current
  • Step 2 Charge the battery to 0.5C with a constant voltage of 4.4V;
  • Step 3 Charge the battery to 4.45V at a constant current of 0.5C;
  • Step 4 Charge the battery to 0.3C with a constant voltage of 4.45V;
  • Step 5 Let the battery stand for 5 minutes
  • Step 6 Discharge the battery to 3.0V at a constant current of 0.5C;
  • Step 7 Let the battery stand for 5 minutes
  • Step 8 Circulate 500 times from step 1 to step 7 above.
  • Embodiment 26 adopts the new charging method 5 in this application, and the specific charging process is as follows:
  • the ambient temperature is 55°C;
  • Step 1 Charge the battery to 4.4V with 0.7C constant current
  • Step 2 Leave the battery for 2.9 seconds
  • Step 3 Charge the battery with a constant current of 0.7C for 7.1 seconds, and judge whether the battery voltage is greater than or equal to 4.45V. When the battery voltage is greater than or equal to 4.45V, skip to step five;
  • 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 4.54V. When the battery voltage is greater than or equal to 4.54V, 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 calculation method of the capacity retention rate after 500 cycles of charge-discharge cycles at 55°C in Table 1 is: at an ambient temperature of 55°C, the batteries of the comparative example and the examples use the corresponding charging process cycles For 500 cycles, the discharge capacity of the battery after 500 cycles is divided by the discharge capacity of the first cycle to obtain the capacity retention rate.
  • the calculation method of cell gas production at an ambient temperature of 55°C, put the cell in the drainage meter before the test, record the weight of the water growth and calculate the volume value V1, then take out the cell, and use the phase at 55°C. After the corresponding charging process has been charged and discharged for 500 cycles, the volume value V2 is measured by the drainage method again. The value of V2-V1 is the gas production after the battery is charged and discharged for 500 cycles.
  • Table 1 The gas production of each comparative example and embodiment The results are shown in Table 1.
  • the adhesion between the positive and negative electrodes of the battery and the separator is enhanced, and the problem of cell bloating caused by the accelerated decomposition of solvents or additives in the electrolysis after the voltage is raised; and high viscosity
  • the isolation film effectively reduces the layer spacing between the positive and negative electrodes and the isolation film, reduces the interface reaction rate between the cathode and the electrolyte, reduces the occurrence of local side reactions at the interface, and the high temperature cycle performance of the battery can be significantly improved.
  • this application combines the use of a high-adhesion isolation film in the battery, and by increasing the charge limit voltage of the battery (for example, Example 1 increases the charge limit voltage of Comparative Examples 1 and 3 from 4.4V to 4.54V, etc.). In this way, the time that the cathode of the battery is maintained at a high potential can be shortened, and the occurrence of side reactions can be reduced, thereby improving the cycle performance of the battery.
  • the pressure of the pores in the battery pole pieces is increased, and the flatulence of the battery cell after the charging limit voltage rises is suppressed, thereby reducing the interface reaction rate between the cathode and the electrolyte, and further reducing the occurrence of side reactions. , Can significantly improve the high temperature cycle performance of the battery during the cycle.
  • 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 a positive electrode sheet, a negative electrode sheet, and a separator film arranged between the positive electrode sheet and the negative electrode sheet, and the binding force between the separator film and the positive electrode sheet or the negative electrode sheet is greater than Or equal to 3N/m.
  • 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.
  • the third 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.

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Abstract

提供一种改善电池（10）循环性能的方法，应用于一电池（10）中，所述电池（10）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，所述方法包括：在第一阶段，以第一阶段电流对电池（10）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（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。提供一种电子装置（1）。根据提供的方法能够显著改善电池（10）在高温环境下的循环性能。

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
近年随着消费类锂离子电池的普及应用，对所述锂离子电池进行不断迭代开发，使得锂离子电池的能量密度也逐渐提高。尤其是钴酸锂体系的锂离子电池，其阴极上限电压不断提高，造成阴极结构破坏加剧以及增加了副反应。
锂离子电池在高温情况下循环容量保持率不理想(即高温循环失效)是普遍存在的问题。隔离膜目前在解决高温循环失效的问题时，多以优化电解液配方为主要手段，但电解液的配方优化会带来电池其他性能(如低温放电、大倍率充电)的一定程度恶化。因此如何在保证电池的其他电性能无恶化的前提下，提升电池在高温情况下的循环寿命成为非常重要的问题。
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，可以显著改善电池的高温循环性能。
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，所述电池包括正极片、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。
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。
根据本申请的一些实施方式，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，所述聚合物粘接层形成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小于或等于四层。
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％。
本申请一实施方式提供一种电子装置，包括电池和电池管理模块，所述电池包括正极片、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，所述电池管理模块用于执行如上所述的改善电池循环性能的方法。
本申请的实施方式通过在电池中采用高粘接隔离膜，以及通过提高电池的充电限制电压(即从第一阶段电压提高到第二阶段电压)等相结合的方式。可以缩短电池的阴极在高电位下保持的时间，减少副反应的发生，从而改善电池的循环性能。此外，通过结合高粘接隔离膜，增强了电池的极片中孔隙的压强，能够抑制充电限制电压抬升后电芯的胀气，从而降低阴极与电解液间的界面反应速率，进一步降低副反应的发生，可显著改善电池循环过程中高温循环性能。
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2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在充电过程中的电流和电压随时间变化的示意图。
图5是根据本申请实施方式二的电池在充电过程中的电流和电压随时间变化的示意图。
图6是根据本申请一实施方式的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的示意图。
图7是根据本申请实施方式三的电池在充电过程中的电流和电压随时间变化的示意图。
图8是根据本申请实施方式四的电池在充电过程中的电流和电压随时间变化的示意图。
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。
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。
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。
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。
锂离子电池在高温情况下循环容量保持率不理想(即高温循环失效)是普遍存在的问题。经研究发现高温循环失效的原因有两个：一是电池在整个充电过程中高温高电压下持续时间较长，易造成副反应；二是电池在高温循环中会恶化电池体系的产气，在正负极与隔离膜粘接较弱的情况下，产气会造成正负极层间距的变大，从而加剧了阴极与电解液间的界面反应速率导致副反应增多。
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为可充电电池。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。在本实施方式中，所述电池10主要由正极极片、负极极片、隔离膜、电解液、包装袋组成。
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的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，所述聚合物粘接层形成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小于或等于四层。
在一些实施例中，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。在另一实施例中，所述聚合物颗粒的粒径为0.3μm-1μm。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。
在一些实施例中，所述隔离膜为高粘接隔离膜。本申请中的所述高粘接隔离膜为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的隔离膜。优选地，所述高粘接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4.3N/m。通过调节上述聚合物颗粒的种类、粒径、含量等可以调节所述高粘接隔离膜与所述正极片或所述负极片之间的粘结力。
在一些实施例中，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％。在另一实施例中，所述覆盖面积比为30％-70％。
在本实施方式中，通过控制高粘接隔离膜的粘结力，增强极片中孔隙的压强，能够抑制电芯胀气的问题。并且高粘接隔离膜有效地减 少了极片和隔离膜的层间距，可降低阴极与电解液间的界面反应速率，提升电池的循环性能。
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。优选地，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4.3N/m。
在一些实施例中，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，所述聚合物粘接层形成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小于或等于四层。
在一些实施例中，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。在另一实施例中，所述聚合物颗粒的粒径为0.3μm-1μm。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)、纤维素或聚酰亚胺等。
在一些实施例中，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％。在另一实施例中，所述覆盖面积比为30％-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。在一实施例中，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。在另一实施例中，所述第i+1电压大于或等于所述第i电压。在另一实施例中，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阳极析锂电位。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。
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-1)'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的充电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Tj 1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Tj 1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。
综上所述，本申请提供的改善电池循环性能的方法通过在电池中采用高粘接隔离膜，以及通过提高电池的充电限制电压(即从第一阶段电压提高到第二阶段电压)等相结合的方式。可以缩短电池的阴极在高电位下保持的时间，减少副反应的发生，从而改善电池的循环性 能。并且结合高粘接隔离膜增强了电池的极片中孔隙的压强，抑制电压抬升后电芯的胀气，从而降低阴极与电解液间的界面反应速率，进一步降低副反应的发生，可显著改善电池在循环过程中高温循环性能。
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，对本发明进一步详细说明。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。
下文所描述的对比例和实施例中采用的电池体系以钴酸锂作为阴极，石墨作为阳极，再加上隔离膜、电解液及包装壳，通过混料、涂布、装配、化成和陈化等工艺制成。其中，阴极由96.7％LiCoO 2(作为阴极活性物质)加1.7％聚偏氟乙烯(PVDF，作为粘结剂)加1.6％导电炭黑(SUPER-P，作为导电剂)混合组成，阳极由98％人造石墨(作为阳极活性物质)加1.0％丁苯橡胶(SBR，作为粘结剂)加1.0％羧甲基纤维素钠(CMC，作为增稠剂)混合组成。
对比例与实施例采用不同的新的充电方法对电池进行充电，并且结合不同粘接力的隔离膜来改善电池循环性能。并在环境温度为55℃时测试电池循环充放电500圈后的容量保持率及电芯产气量，具体方案及结果总结如表1，其中对比例1和2采用低粘接隔离膜，对比例3和实施例1-26采用高粘接隔离膜。在本实施方式中，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。
表1 各对比例和实施例1-26中循环充放电后的容量保持率和电芯产气量
Figure PCTCN2020080278-appb-000001
Figure PCTCN2020080278-appb-000002
其中，对比例1及对比例3中的现有充电方式为现有技术中的恒流恒压充电方法。所述现有充电方式的具体充电流程如下：
环境温度为55℃：
步骤一：以0.7C恒流对电池充电至4.4V；
步骤二：以4.4V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。
对比例2和实施例1-22采用本申请中的新充电方式1，具体流程如下：
环境温度为55℃；
步骤一：以0.7C恒流对电池充电至4.4V；
步骤二：以0.5C恒流对电池充电至4.45V；
步骤三：以0.4C恒流对电池充电至4.54V；
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23采用本申请中的新充电方式2，具体流程如下：
环境温度为55℃；
步骤一：以0.7C恒流对电池充电至4.4V；
步骤二：以4.35V恒压对电池充电至0.4C；
步骤三：以4.45V恒压对电池充电至0.13C；
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24采用本申请中的新充电方式3，具体流程如下：
环境温度为55℃；
步骤一：以0.7C(2.1A)恒流对电池充电至4.4V；
步骤二：以恒功率7W对电池充电至4.45V；
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25采用本申请中的新充电方式4，具体流程如下：
环境温度为55℃；
步骤一：以0.7C恒流对电池充电至4.4V；
步骤二：以4.4V恒压对电池充电至0.5C；
步骤三：以0.5C恒流对电池充电至4.45V；
步骤四：以4.45V恒压对电池充电至0.3C；
步骤五：将电池静置5分钟；
步骤六：以0.5C恒流对电池放电至3.0V；
步骤七：将电池静置5分钟；
步骤八：循环上述步骤一至步骤七500圈。
实施例26采用本申请中的新充电方式5，具体充电流程如下：
环境温度为55℃；
步骤一：以0.7C恒流对电池充电至4.4V；
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4.45V，当电池的电压大于或等于4.45V，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4.54V，当电池的电压大于或等于4.54V，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。
另外，需要说明的是，表1中55℃下500圈充放电循环后的容量保持率的计算方法为：在环境温度55℃时，对比例和实施例的电池均使用相对应的充电流程循环500圈，再将电池循环500圈后的放电容量除以其循环第1圈的放电容量以得到该容量保持率。
电芯产气量的计算方法：在环境温度55℃下，在测试前将电芯放 到排水仪中，记录水增长的重量并计算体积值V1，然后将电芯取出，在55℃下采用相对应的充电流程循环充放电500圈后，再次用排水法测得体积值V2，V2-V1的值即为该电芯循环充放电500圈后的产气量，各对比例和实施例的产气结果如表1所示。
由表1可知，从对比例2与对比例1可以看出：只采用新的充电方法可以改善电池循环后容量保持率，但提升幅度不大(大约5％)。这主要是由于新的充电方法虽然可以显著缩短满充时间，减少电池体系总副反应的产生时间。但由于电池在高温循环后期电解液中的添加剂逐渐消耗，电芯产气恶化，从而使得电池循环后的容量衰减速率增加。
从对比例3与对比例1可以看出：使用的高粘接隔离膜对电池循环后容量保持率的改善效果不太明显(大约6％)。这是由于虽然高粘接隔离膜能够增强极片中孔隙的压强，但采用常规的充电方法，电池的阴极在高电压下时间较长，已经对阴极材料造成一定程度的破坏，电池的副反应会加剧产生，而在循环后期由于极化较大，进而导致容量保持率较低。
从实施例1-26与对比例2、3可以看出，通过在电池中使用高粘接隔离膜及新的充电方法组合，在降低电池的电芯产气的同时可以显著提升电池循环后的容量保持率(最大可提升大约35％)，这主要是由于新的充电方法可以显著缩短电池在高电压下的时间，减少阴极破坏，降低电池体系总体反应产生。并且通过在电池体系中使用高粘接隔离膜，增强了电池的正负极与隔离膜的粘接，抑制抬升电压后电解中的溶剂或添加剂加速分解带来的电芯胀气问题；并且高粘接隔离膜有效减少了正负极和隔离膜的层间距，可降低阴极与电解液间的界面反应速率，减少界面局部副反应的产生，电池的高温循环性能可得到显著提升。
由此，本申请通过在电池中采用高粘接隔离膜，以及通过提高电池的充电限制电压(如实施例1将对比例1、3的充电限制电压4.4V提高到4.54V等)等相结合的方式，可以缩短电池的阴极在高电位下保持的时间，减少副反应的发生，从而改善电池的循环性能。并且通 过与高粘接隔离膜结合，增强了电池的极片中孔隙的压强，抑制充电限制电压抬升后电芯的胀气，从而降低阴极与电解液间的界面反应速率，进一步降低副反应的发生，可显著改善电池循环过程中高温循环性能。
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。
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。
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 (14)

  1. 一种改善电池循环性能的方法，应用于一电池中，所述电池包括正极片、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。
  2. 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。
  3. 如权利要求2所述的方法，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。
  4. 如权利要求2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。
  5. 如权利要求4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。
  6. 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。
  7. 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。
  8. 如权利要求1所述的方法，其特征在于，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，所述聚合物粘接层形成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小于或等于四层。
  9. 如权利要求8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。
  10. 如权利要求8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％。
  11. 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，所述电池管理模块用于执行如权利要求1-7任一项所述的方 法。
  12. 如权利要求11所述的电子装置，其特征在于，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，所述聚合物粘接层形成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小于或等于四层。
  13. 如权利要求12所述的电子装置，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。
  14. 如权利要求12所述的电子装置，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％。
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