WO2023092390A1 - 电化学装置及其控制方法、电子装置和存储介质 - Google Patents

电化学装置及其控制方法、电子装置和存储介质 Download PDF

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WO2023092390A1
WO2023092390A1 PCT/CN2021/133152 CN2021133152W WO2023092390A1 WO 2023092390 A1 WO2023092390 A1 WO 2023092390A1 CN 2021133152 W CN2021133152 W CN 2021133152W WO 2023092390 A1 WO2023092390 A1 WO 2023092390A1
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electrochemical device
voltage
threshold
internal resistance
control method
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PCT/CN2021/133152
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English (en)
French (fr)
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邹邦坤
屈长明
杨帆
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宁德新能源科技有限公司
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Priority to PCT/CN2021/133152 priority Critical patent/WO2023092390A1/zh
Priority to CN202180022455.1A priority patent/CN115298870A/zh
Publication of WO2023092390A1 publication Critical patent/WO2023092390A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—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
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/44—Methods for charging or discharging
    • H01M10/448—End of discharge regulating measures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • 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
    • 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
    • H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
    • H02J7/0031—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits using battery or load disconnect circuits
    • 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
    • H02J7/0047—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with monitoring or indicating devices or circuits
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of electrochemical energy storage, in particular to an electrochemical device and a control method thereof, an electronic device and a storage medium.
  • Some embodiments of the present application provide a method for controlling an electrochemical device.
  • the initial discharge cut-off voltage of the electrochemical device is a first voltage
  • the initial charge cut-off voltage is a second voltage.
  • the control method includes step a) and step b): a) when the rate of change of internal resistance of the electrochemical device is less than the first threshold, charge and discharge with the first voltage and the second voltage; b) when the rate of change of internal resistance of the electrochemical device is greater than or equal to the first threshold, charge and discharge with the first voltage
  • the boost amount boosts the discharge cut-off voltage of the electrochemical device.
  • increasing the discharge cut-off voltage of the electrochemical device by a first increase amount includes: c) when the rate of change of internal resistance of the electrochemical device is greater than or equal to When it is equal to the first threshold and less than or equal to the second threshold, the discharge cut-off voltage of the electrochemical device is promoted by the first promotion amount, wherein the second threshold is greater than the first threshold; d) when the rate of change of the internal resistance of the electrochemical device is greater than the first When the second threshold is reached, operations related to the charge and discharge state of the electrochemical device are performed.
  • the high energy density characteristic of the electrochemical device can be fully utilized in the early stage when the internal resistance change rate is small.
  • the state of the rate of change of the internal resistance of the electrochemical device can be automatically monitored, and it is intelligently determined whether to increase the discharge cut-off voltage of the electrochemical device by the first boost amount or to perform an operation related to the charge and discharge state of the electrochemical device. operation, thereby improving the cycle life of the electrochemical device while maintaining the high energy density of the electrochemical device.
  • the electrochemical device includes a negative electrode tab, the negative electrode tab includes a negative active material layer, and the negative active material layer includes a silicon-based material.
  • the silicon-based material includes at least one of silicon, silicon-oxygen material, silicon-carbon material, or silicon-oxygen-carbon material.
  • the mass ratio of the Si element in the negative electrode active material layer to the mass of the negative electrode active material layer is 1% to 90%.
  • the mass ratio of the Si element in the negative electrode active material layer to the mass of the negative electrode active material layer is too small, the effect of improving the energy density of the electrochemical device is relatively limited; if the Si element in the negative electrode active material layer accounts for the negative active material If the mass ratio of the material layer is too large, the cycle expansion of the silicon-based material will be too large, which will affect the cycle performance of the electrochemical device.
  • the value range of the first voltage is 2.5V to 3.5V
  • the value range of the second voltage is 4.2V to 4.6V.
  • the first voltage is too high, it is not conducive to fully utilizing the energy density of the electrochemical device; when the first voltage is too low, it is easy to cause irreversible damage to the electrochemical device.
  • the second voltage is too high, it is easy to cause irreversible damage to the electrochemical device; when the second voltage is too low, it is not conducive to fully utilize the energy density of the electrochemical device.
  • the first threshold satisfies: 1% ⁇ first threshold ⁇ 10%.
  • the first threshold is set too small, the discharge cut-off voltage will be increased when the cycle state of the electrochemical device is good, which is not conducive to fully utilizing the energy density of the electrochemical device. If the first threshold is set too large, the effect of improving the cycle life of the electrochemical device will be relatively limited.
  • the second threshold satisfies 10% ⁇ second threshold ⁇ 20%. If the second threshold is set too small, operations related to the charging and discharging state of the electrochemical device will be performed when the cycle state of the electrochemical device is good. If the second threshold is set too large, the effect of increasing the cycle life of the electrochemical device and improving the safety performance of the electrochemical device will be relatively limited. In some embodiments, the value range of the first boost amount is 0.03V to 0.6V.
  • performing an operation related to the charging and discharging state of the electrochemical device includes at least one of steps e) to f) of: e) stopping the charging and discharging operation of the electrochemical device; f) sending a signal to stop the electrochemical device Prompt information for charging and discharging operations.
  • the cycle of the electrochemical device may be abnormal at this time, by stopping the charging and discharging operation of the electrochemical device and/or sending a prompt message to stop the charging and discharging operation of the electrochemical device , for example, reminding the user to replace the battery can avoid safety risks such as battery inflation.
  • Another embodiment of the present application provides a computer-readable storage medium, wherein a computer program is stored in the computer-readable storage medium, and when the computer program is executed by a processor, the above control method of the electrochemical device is implemented.
  • a charging device including a processor and a computer-readable storage medium
  • the computer-readable storage medium stores computer-executable instructions that can be executed by the processor, and when the processor executes the computer-executable instructions , realizing the above-mentioned control method of the electrochemical device.
  • an electrochemical device which includes a processor and a computer-readable storage medium
  • the initial discharge cut-off voltage of the electrochemical device is a first voltage
  • the initial charge cut-off voltage is a second voltage
  • the readable storage medium stores computer-executable instructions that can be executed by the processor. When the processor executes the computer-executable instructions, the control method is implemented.
  • the control method includes steps a) and steps b): a) when the internal resistance of the electrochemical device When the rate of change is less than the first threshold, charge and discharge with the first voltage and the second voltage; b) When the rate of change of the internal resistance of the electrochemical device is greater than or equal to the first threshold, increase the discharge cut-off of the electrochemical device by a first boost amount Voltage.
  • increasing the discharge cut-off voltage of the electrochemical device by a first increase amount includes: c) when the rate of change of internal resistance of the electrochemical device is greater than or equal to When it is equal to the first threshold and less than or equal to the second threshold, the discharge cut-off voltage of the electrochemical device is promoted by the first promotion amount, wherein the second threshold is greater than the first threshold; d) when the rate of change of the internal resistance of the electrochemical device is greater than the first When the second threshold is reached, operations related to the charge and discharge state of the electrochemical device are performed.
  • the electrochemical device includes a negative electrode tab, the negative electrode tab includes a negative active material layer, and the negative active material layer includes a silicon-based material.
  • the silicon-based material includes at least one of silicon, silicon-oxygen material, silicon-carbon material, or silicon-oxygen-carbon material.
  • the mass ratio of the Si element in the negative electrode active material layer to the mass of the negative electrode active material layer is 1% to 90%.
  • the value range of the first voltage is 2.5V to 3.5V
  • the value range of the second voltage is 4.2V to 4.6V.
  • the first threshold satisfies: 1% ⁇ first threshold ⁇ 10%
  • the second threshold satisfies 10% ⁇ second threshold ⁇ 20%.
  • the value range of the first boost amount is 0.03V to 0.6V.
  • performing an operation related to the charging and discharging state of the electrochemical device includes at least one of steps e) to f) of: e) stopping the charging and discharging operation of the electrochemical device; f) sending a signal to stop the electrochemical device Prompt information for charging and discharging operations.
  • An embodiment of the present application also provides an electronic device, including the above-mentioned electrochemical device.
  • the embodiments of the present application monitor the change of the internal resistance change rate of the electrochemical device and control the electrochemical device accordingly based on the internal resistance change rate, thereby improving the performance of the electrochemical device while maintaining the high energy density of the electrochemical device. cycle performance.
  • Fig. 1 shows a schematic diagram of a control method of an electrochemical device according to some embodiments of the present application.
  • Fig. 2 is a schematic structural diagram of a charging device according to some embodiments of the present application.
  • Fig. 3 is a schematic structural diagram of a system in some embodiments of the present application.
  • the initial discharge cut-off voltage of the electrochemical device is a first voltage
  • the initial charge cut-off voltage is a second voltage.
  • the initial discharge cut-off voltage of the electrochemical device refers to the voltage when the electrochemical device can no longer continue to discharge (that is, the discharge to the state of charge (SOC) is 0%), and the initial charge cut-off voltage of the electrochemical device refers to the electrochemical device. Charge to the voltage at which the SOC is 100%.
  • electrochemical devices include, but are not limited to, lithium-ion batteries.
  • the control method of the present application includes step a) and step b).
  • step a) when the internal resistance change rate of the electrochemical device is less than the first threshold, charge and discharge are performed at the first voltage and the second voltage, that is, charge and discharge are performed at the initial charge cut-off voltage and the initial discharge cut-off voltage.
  • the rate of change of the internal resistance of the electrochemical device refers to the rate of change of the current internal resistance of the electrochemical device relative to the internal resistance before 100 cycles, taking one charging and one discharging process as a cycle. For example, if the internal resistance of the electrochemical device in the unused state is tested by an internal resistance meter, it is n, and the internal resistance of the electrochemical device is tested every 100 cycles, and the internal resistance change rate is (m-n)/n.
  • the electrochemical device is taken out from the electronic device using the electrochemical device, the internal resistance of the electrochemical device is tested by an internal resistance meter, and then by making the electrochemical device discharge and charge cycle, every 100 cycles (discharge once and charge One whole cycle is regarded as one cycle)
  • the internal resistance of the electrochemical device is tested by an internal resistance meter. It should be understood that this is only exemplary, and other suitable internal resistance change rate testing methods may also be used.
  • the internal resistance of the electrochemical device tends to increase.
  • the change rate of the internal resistance of the electrochemical device within every 100 cycles is less than the first threshold, it indicates that the cycle of the electrochemical device is in a controllable range, and the charge and discharge cycles can be performed according to the initial setting conditions.
  • step b) when the change rate of the internal resistance of the electrochemical device is greater than or equal to a first threshold, the discharge cut-off voltage of the electrochemical device is increased by a first increase amount.
  • the rate of change of the internal resistance of the electrochemical device increases to the first threshold value.
  • the discharge cut-off voltage of the electrochemical device is increased by the first boost amount, that is, the full charge and shallow discharge mode is used to increase the discharge cut-off voltage of the electrochemical device.
  • the discharge cut-off voltage can reduce the charge and discharge depth of the negative electrode sheet, so that the negative electrode active material is in a full charge and shallow discharge mode, thereby improving the cycle life of the electrochemical device.
  • step c) when the rate of change of the internal resistance of the electrochemical device is greater than or equal to a first threshold, increasing the discharge cut-off voltage of the electrochemical device by a first boost amount includes steps c) and d).
  • step c) when the change rate of the internal resistance of the electrochemical device is greater than or equal to the first threshold and less than or equal to the second threshold, the discharge cut-off voltage of the electrochemical device is increased by a first increase amount, wherein the second threshold is greater than first threshold.
  • the rate of change of the internal resistance of the electrochemical device increases above the first threshold and below the second threshold.
  • the discharge cut-off voltage of the electrochemical device is increased by the first boost amount, that is, using In the full charge and shallow discharge mode, increasing the discharge cut-off voltage can reduce the charge and discharge depth of the negative electrode sheet, so that the negative electrode active material is in the full charge and shallow discharge mode, which in turn can improve the cycle life of the electrochemical device.
  • step d) when the rate of change of the internal resistance of the electrochemical device is greater than a second threshold, operations related to the state of charge and discharge of the electrochemical device are performed.
  • operations related to the charge and discharge state of the electrochemical device include any operation that affects the charge and discharge of the electrochemical device, including but not limited to stopping the charge and discharge operation of the electrochemical device and sending a message to stop the charge and discharge of the electrochemical device Operation prompt information.
  • the rate of change of the internal resistance of the electrochemical device increases above the second threshold.
  • the high energy density characteristic of the electrochemical device can be fully utilized in the early stage when the internal resistance change rate is small.
  • it can be determined whether to increase the discharge cut-off voltage of the electrochemical device or perform an operation related to the charge and discharge state of the electrochemical device by the first boost amount, and then While maintaining the high energy density of the electrochemical device, the cycle life of the electrochemical device is improved.
  • the value range of the first voltage is 2.5V to 3.5V
  • the value range of the second voltage is 4.2V to 4.6V.
  • the first voltage is too high, it is not conducive to fully utilizing the energy density of the electrochemical device; when the first voltage is too low, it is easy to cause irreversible damage to the electrochemical device.
  • the second voltage is too high, it is easy to cause irreversible damage to the electrochemical device; when the second voltage is too low, it is not conducive to fully utilize the energy density of the electrochemical device.
  • the first threshold satisfies: 1% ⁇ first threshold ⁇ 10%.
  • 1% ⁇ the first threshold ⁇ 10% it indicates that the internal change rate of the electrochemical device is small, the cycle of the electrochemical device is in a controllable range, and the charge-discharge cycle can be performed according to the initial setting conditions.
  • the first threshold is set too small, the discharge cut-off voltage will be increased when the cycle state of the electrochemical device is good, which is not conducive to fully utilizing the energy density of the electrochemical device. If the first threshold is set too large, the effect of improving the cycle life of the electrochemical device will be relatively limited.
  • the first threshold may be 1%, 3%, 5%, 7%, 10% or other suitable values.
  • the second threshold satisfies: 10% ⁇ second threshold ⁇ 20%.
  • the discharge cut-off voltage of the electrochemical device can be increased by the first increase amount, that is, the method of full charge and shallow discharge can be used to increase the discharge voltage of the electrochemical device. cycle life. If the second threshold is set too small, operations related to the charging and discharging state of the electrochemical device will be performed when the cycle state of the electrochemical device is good. If the second threshold is set too large, the effect of increasing the cycle life of the electrochemical device and improving the safety performance of the electrochemical device will be relatively limited. In some embodiments, the second threshold may be 11%, 13%, 15%, 17%, 20% or other suitable values.
  • the value range of the first boost amount is 0.03V to 0.6V. If the value of the first increase amount is too small, it may be necessary to frequently increase the discharge cut-off voltage, or the effect of increasing the cycle life of the electrochemical device is relatively limited. If the value of the first boost amount is too large, the discharge cut-off voltage of the electrochemical device will be too large, which is not conducive to fully utilizing the energy density of the electrochemical device. In some embodiments, the value of the first boost amount may be 0.03V, 0.1V, 0.2V, 0.3V, 0.4V, 0.5V, 0.6V or other suitable values.
  • the cut-off voltage of the discharge can be increased by the first increase amount multiple times until the cut-off voltage of the electrochemical device reaches 3.9V or the discharge cut-off voltage of the electrochemical device
  • the internal resistance change rate is greater than the second threshold.
  • performing an operation related to the charging and discharging state of the electrochemical device includes at least one of steps e) to f) of: e) stopping the charging and discharging operation of the electrochemical device; f) sending a signal to stop the electrochemical device Prompt information for charging and discharging operations.
  • the cycle of the electrochemical device may be abnormal at this time, by stopping the charging and discharging operation of the electrochemical device and/or sending a prompt message to stop the charging and discharging operation of the electrochemical device , for example, reminding the user to replace the battery can avoid safety risks such as battery inflation.
  • the electrochemical device includes a negative electrode tab, the negative electrode tab includes a negative active material layer, and the negative active material layer includes a silicon-based material.
  • the silicon-based material includes at least one of silicon, silicon-oxygen material, silicon-carbon material, or silicon-oxygen-carbon material.
  • the mass ratio of the Si element in the negative electrode active material layer to the mass of the negative electrode active material layer is 1% to 90%.
  • the mass ratio of the Si element in the negative electrode active material layer to the mass of the negative electrode active material layer is 5% to 20%.
  • the test method of the ratio of the quality of the Si element in the negative electrode active material layer to the mass of the negative electrode active material layer can be passed through an inductively coupled plasma optical emission spectrometer (ICP-OES): first, the negative electrode sheet is pretreated, The pre-treatment method is to take the negative electrode sheet in the battery cell and bake it in an oven at 400°C for 1 hour, then make the negative electrode material layer fall off from the current collector to obtain the negative electrode material, weigh 0.2g of the negative electrode material, and put it into 50mL In a plastic volumetric flask, the dissolution process is carried out by microwave digestion. The acid used for digestion is 10mL HNO 3 +5mL HF.
  • the coupled plasma emission spectrometer test method is well known to those skilled in the art and will not be described here. It should be noted that, the lithium-ion battery cells used in the test can be used as an example after formation, which is not limited here.
  • the electrochemical device may include an electrode assembly including a positive pole piece, a negative pole piece, and a separator disposed between the positive pole piece and the negative pole piece.
  • the negative electrode sheet further includes a negative electrode current collector.
  • the negative active material layer may be located on one side or both sides of the negative current collector.
  • a conductive agent and a binder may also be included in the negative electrode active material layer.
  • the conductive agent in the negative electrode active material layer may include at least one of conductive carbon black, Ketjen black, flake graphite, graphene, carbon nanotubes, or carbon fibers.
  • the binder in the negative active material layer may include carboxymethylcellulose (CMC), polyacrylic acid, polyvinylpyrrolidone, polyaniline, polyimide, polyamideimide, polysilicon At least one of oxane, styrene-butadiene rubber, epoxy resin, polyester resin, polyurethane resin or polyfluorene.
  • the mass ratio of the negative active material, the conductive agent and the binder in the negative active material layer may be (78 to 98.5):(0.1 to 10):(0.1 to 10). It should be understood that the above description is only an example, and any other suitable materials and mass ratios may be used.
  • the negative electrode current collector may use at least one of copper foil, nickel foil, or carbon-based current collector.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector, and the positive electrode active material layer may include a positive electrode active material.
  • the positive electrode active material includes lithium cobaltate, lithium iron phosphate, lithium manganese iron phosphate, sodium iron phosphate, lithium vanadium phosphate, sodium vanadium phosphate, lithium vanadyl phosphate, sodium vanadyl phosphate, lithium vanadate, manganese Lithium oxide, lithium nickelate, lithium nickel cobalt manganese oxide, lithium-rich manganese-based materials or lithium nickel cobalt aluminate.
  • the positive active material layer may further include a conductive agent.
  • the conductive agent in the positive electrode active material layer may include at least one of conductive carbon black, Ketjen black, flake graphite, graphene, carbon nanotubes, or carbon fibers.
  • the positive electrode active material layer can also include a binder, and the binder in the positive electrode active material layer can include carboxymethylcellulose (CMC), polyacrylic acid, polyvinylpyrrolidone, polyaniline, polyamide At least one of imine, polyamideimide, polysiloxane, styrene-butadiene rubber, epoxy resin, polyester resin, polyurethane resin or polyfluorene.
  • CMC carboxymethylcellulose
  • the mass ratio of the positive active material, the conductive agent and the binder in the positive active material layer may be (80 to 99):(0.1 to 10):(0.1 to 10).
  • the positive active material layer may have a thickness of 10 ⁇ m to 500 ⁇ m. It should be understood that the above description is only an example, and any other suitable material, thickness and mass ratio may be used for the positive electrode active material layer.
  • Al foil may be used as the positive current collector, and of course, other current collectors commonly used in the art may also be used.
  • the positive electrode collector may have a thickness of 1 ⁇ m to 50 ⁇ m.
  • the positive active material layer may be coated only on a partial area of the current collector of the positive electrode.
  • the isolation film includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyethylene terephthalate, polyimide, or aramid.
  • polyethylene includes at least one selected from high-density polyethylene, low-density polyethylene, or ultra-high molecular weight polyethylene.
  • the thickness of the isolation film is in the range of about 3 ⁇ m to 20 ⁇ m.
  • the surface of the isolation membrane may also include a porous layer, the porous layer is arranged on at least one surface of the isolation membrane, the porous layer includes inorganic particles and a binder, and the inorganic particles are selected from alumina (Al 2 O 3 ), Silicon oxide (SiO 2 ), magnesium oxide (MgO), titanium oxide (TiO 2 ), hafnium oxide (HfO 2 ), tin oxide (SnO 2 ), cerium oxide (CeO 2 ), nickel oxide (NiO), oxide Zinc (ZnO), calcium oxide (CaO), zirconia (ZrO 2 ), yttrium oxide (Y 2 O 3 ), silicon carbide (SiC), boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide or sulfuric acid at least one of barium.
  • alumina Al 2 O 3
  • Silicon oxide SiO 2
  • magnesium oxide MgO
  • titanium oxide TiO 2
  • hafnium oxide HfO 2
  • the pores of the isolation membrane have a diameter in the range of about 0.01 ⁇ m to 1 ⁇ m.
  • the binder of the porous layer is selected from polyvinylidene fluoride, copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, poly At least one of vinylpyrrolidone, polyvinyl ether, polymethylmethacrylate, polytetrafluoroethylene or polyhexafluoropropylene.
  • the porous layer on the surface of the separator can improve the heat resistance, oxidation resistance and electrolyte wettability of the separator, and enhance the adhesion between the separator and the pole piece.
  • the electrochemical device includes a lithium-ion battery, although the present application is not limited thereto.
  • the electrochemical device further includes an electrolyte, and the electrolyte includes at least one of fluoroether, fluoroethylene carbonate, or ether nitrile.
  • the electrolyte solution also includes a lithium salt, the lithium salt includes lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate, the concentration of the lithium salt is 1mol/L to 2mol/L, and the bis(fluorosulfonyl)imide The mass ratio of lithium imide and lithium hexafluorophosphate is 0.06-5.
  • the electrolyte solution may also include a non-aqueous solvent.
  • the non-aqueous solvent can be carbonate compound, carboxylate compound, ether compound, other organic solvent or their combination.
  • the carbonate compound can be a chain carbonate compound, a cyclic carbonate compound, a fluorocarbonate compound or a combination thereof.
  • chain carbonate compounds are diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methyl carbonate Ethyl Ester (MEC) and combinations thereof.
  • chain carbonate compounds are diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methyl carbonate Ethyl Ester (MEC) and combinations thereof.
  • Examples of the cyclic carbonate compound are ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylethylene carbonate (VEC), or combinations thereof.
  • fluorocarbonate compound examples include fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, Fluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-carbonic acid - Difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, trifluoromethylethylene carbonate, or a combination thereof.
  • FEC fluoroethylene carbonate
  • 1,2-difluoroethylene carbonate 1,1-difluoroethylene carbonate
  • 1,1,2-trifluoroethylene carbonate Fluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-carbonic acid - Difluoro-1-methylethylene carbonate, 1,1,2-trifluor
  • carboxylate compounds are methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, ⁇ -butyrolactone, decanolactone, Valerolactone, mevalonolactone, caprolactone, methyl formate, or combinations thereof.
  • ether compounds are dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxy ethyl ethane, 2-methyltetrahydrofuran, tetrahydrofuran or a combination thereof.
  • organic solvents examples include dimethylsulfoxide, 1,2-dioxolane, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, methyl Amides, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, and phosphate esters or combinations thereof.
  • the electrode assembly of the electrochemical device is a wound electrode assembly, a stacked electrode assembly or a folded electrode assembly.
  • the positive pole piece and/or the negative pole piece of the electrochemical device can be a multilayer structure formed by winding or stacking, or a single-layer structure in which a single-layer positive electrode, a separator, and a single-layer negative electrode are stacked. .
  • the positive electrode sheet, separator, and negative electrode sheet are wound or stacked in order to form an electrode assembly, and then packed into an aluminum-plastic film for packaging, and injected with electrolytic Liquid, formed, packaged, that is, made into a lithium-ion battery. Then, performance tests were performed on the prepared lithium-ion batteries.
  • Preparation of the positive electrode sheet mix the positive active material lithium cobaltate, conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) according to a weight ratio of 97:1.4:1.6, and add N-methylpyrrolidone (NMP) As a solvent, stir well.
  • the slurry solid content is 72wt%) is uniformly coated on the aluminum foil of the positive electrode current collector with a coating thickness of 80 ⁇ m, dried at 85°C, and then cold-pressed, cut into pieces, and slit, and vacuum-coated at 85°C Drying under the same conditions for 4 hours to obtain a positive electrode sheet.
  • negative electrode sheet artificial graphite, binder polyacrylic acid and sodium carboxymethyl cellulose (CMC) are dissolved in deionized water in the ratio of 97: 1.5: 1.5 by weight to form negative electrode slurry (solid content is 40wt %).
  • Copper foil with a thickness of 10 ⁇ m was used as the negative electrode current collector, and the negative electrode slurry was coated on the negative electrode current collector with a coating thickness of 50 ⁇ m, dried at 85 ° C, and then cold-pressed, cut into pieces, and cut at 120 °C under vacuum conditions for 12 hours to obtain a negative electrode sheet.
  • the isolation membrane is polyethylene (PE) with a thickness of 7 ⁇ m.
  • EC ethylene carbonate
  • PC propylene carbonate
  • DEC diethyl carbonate
  • Lithium-ion battery preparation stack the positive pole piece, the separator, and the negative pole piece in order, so that the separator is in the middle of the positive electrode and the negative pole to play the role of isolation, and wind up to obtain the electrode assembly.
  • the electrode assembly is placed in the outer packaging aluminum-plastic film, after dehydration at 80°C, the above electrolyte is injected and packaged, and the lithium-ion battery is obtained through chemical formation, degassing, trimming and other processes.
  • a single cycle condition does not change, wherein the first voltage is 3.0V, and the second voltage is 4.45V.
  • the content of the silicon-based material and the charging and discharging method are changed on the basis of the steps of the comparative example 1, and the specific changed parameters are as follows.
  • Battery charging cut-off voltage, battery discharge cut-off voltage test You can use a battery voltage internal resistance tester or a multimeter to test.
  • the equipment is a battery voltage internal resistance tester. First, the internal resistance of the electrochemical device is tested as n when it is not in use, and the internal resistance of the electrochemical device is tested every 100 cycles. The internal resistance is m, then the internal resistance The rate of change is (m-n)/n.
  • Battery cycle number test Through the cycle test instrument (select the Xinwei battery tester on the market), the constant current and constant voltage charge and discharge test is carried out on the battery cell according to the set charge and discharge cut-off voltage. For example, the charge cut-off voltage of a single battery is 4.45V, and the discharge cut-off voltage is 3.0V.
  • the cycle tester charges and charges to 4.45V with 3C constant current at 25°C, and then discharges at 1C to 3.0V as a cycle, and repeats continuously. Different cycle numbers were tested as single cells.
  • the cycle number corresponding to 80% (or less than 80% of the initial capacity) is recorded as the cycle number when the capacity decays to 80%.
  • testing of lithium-ion battery voltage, internal resistance, and cycle life is well known to those skilled in the art and will not be described here, and the testing method is not limited to the method described in this application, and other suitable testing methods can also be used.
  • Comparative Example 1 replace part of the artificial graphite with silicon-based material silicon oxide (SiOx, 0 ⁇ x ⁇ 2), and design the ratio of the mass of Si element to the mass of the negative electrode active material layer to be 1%, 5% respectively , 25%, 50%, and 90%, set the first voltage to 3.0V, and the second voltage to 4.45V. It can be seen from Table 1 that the energy density of the electrochemical device increases with the increase of Si content, but the cycle The lifetime decays significantly with the increase of Si content.
  • SiOx silicon-based material silicon oxide
  • part of the artificial graphite is replaced by silicon-based material SiC, and when the mass ratio of Si element to the mass of the negative electrode active material layer is designed to be 25%, the second voltage remains 4.45% by setting different first voltages.
  • V is constant, when the first voltage is set to 2.5V, 2.8V, 3.0V, 3.2V, 3.3V, 3.4V, 3.5V in the embodiment, it can be seen from Table 2 that the cycle life of the electrochemical device increases with As the first voltage rises, the cycle life is obviously improved.
  • part of the artificial graphite is replaced by the silicon-based material Si, and when the mass of the Si element is designed to account for 25% of the mass of the negative electrode active material layer, the first voltage is set to be 3.0V.
  • the cycle life of the electrochemical device decreased as the second voltage increased, as shown in Table 3.
  • Embodiment 1-5 are identical to Embodiment 1-5:
  • Table 5 shows the number of cycles when the discharge voltage of the electrochemical device starts to rise and the number of cycles when the discharge voltage decays to 80% when different first thresholds are set.
  • the number of cycles when the discharge voltage starts to rise is the corresponding cycle number when the discharge voltage is raised for the first time. That is, it corresponds to the number of cycles when the internal resistance change rate of the electrochemical device is not less than the first threshold for the first time.
  • part of the artificial graphite is replaced by silicon-based material SiC, and when the mass ratio of Si element to the mass of the negative electrode active material layer is designed to be 25%, the first voltage is 3.0V, and the second voltage is 4.5V. V, the first threshold satisfies: 1% ⁇ first threshold ⁇ 10%. When 1% ⁇ the first threshold ⁇ 10%, it indicates that the internal change rate of the electrochemical device is small, the cycle of the electrochemical device is in a controllable range, and the charge-discharge cycle can be performed according to the initial setting conditions.
  • the first threshold is set smaller (as in the embodiment, the setting value is 1%), it will make the discharge cut-off voltage increase when the electrochemical device cycles 100 times (the value of the first promotion amount in this embodiment is 0.2V) , which is not conducive to fully utilizing the energy density of the electrochemical device.
  • the first threshold is set larger (as in the embodiment, the setting value is 10%)
  • the discharge cut-off voltage will be raised only when the electrochemical device is cycled 600 times (usually, the capacity of the lithium-ion battery decays to 80% The number of cycles is required to reach 800-1000 times. If the discharge cut-off voltage is increased only after 600 cycles, the cycle performance improvement effect is relatively limited), so that the improvement of the cycle life of the electrochemical device is relatively limited, as shown in Table 4.
  • part of the artificial graphite is replaced by silicon-based material SiC, and when the mass ratio of Si element to the mass of the negative electrode active material layer is designed to be 25%, the first voltage is 3.0V, and the second voltage is 4.5V. V, the first threshold a is set to 5%, and the value of the first boost is 0.2V. It can be seen from Example 4 that the first threshold is reached after 300 cycles, thereby increasing the discharge cut-off voltage to 3.2V. In a further cycle, the second threshold is set, and the second threshold satisfies: 10% ⁇ second threshold ⁇ 20%.
  • embodiment 6 does not set the second threshold value, and when the rate of change of internal resistance is greater than the first threshold value of 5%, the discharge cut-off voltage is increased by 0.2V, and when the discharge cut-off voltage reaches 4.4V, the charging and discharging state related to the electrochemical device is performed. operate.
  • the discharge cut-off voltage reaches 4.2V, the raising of the discharge voltage is stopped.
  • the discharge cut-off voltage of the electrochemical device can be increased by the first increase amount, that is, the method of full charge and shallow discharge can be used to increase the discharge voltage of the electrochemical device. cycle life.
  • the second threshold is set too small, operations related to the charging and discharging state of the electrochemical device will be performed when the cycle state of the electrochemical device is good. If the second threshold is set too large, the effect of increasing the cycle life of the electrochemical device and improving the safety performance of the electrochemical device will be relatively limited. In an embodiment, the second threshold may be 11%, 13%, 15%, 17%, and 20%, and the results are shown in Table 5.
  • an embodiment of the present application also provides a charging device, which includes a processor and a computer-readable storage medium.
  • the computer-readable storage medium stores computer-executable instructions that can be executed by the processor.
  • the processor executes the computer-executable instructions, the steps of the control method described in any of the above-mentioned embodiments are implemented.
  • the processor and the computer-readable storage medium can be installed on the same carrier (for example, a circuit board), or can be distributed on different carriers. wireless) to access computer-executable instructions in a remote computer-readable storage medium.
  • the computer-readable storage medium and the processor may be disposed on one or more of the electrochemical device, the electronic device connected to the electrochemical device, and the charging device connected to the electrochemical device.
  • the computer-readable storage medium and the processor may be provided on the same device (eg, an electrochemical device, or an electronic device or a charging device). In some embodiments, the computer-readable storage medium and the processor may be respectively disposed on two different devices. For example, a computer readable storage medium may be provided on the electrochemical device, and a processor may be provided on the charging device.
  • the embodiment of the present application also provides an electrochemical device, which includes a processor and a computer-readable storage medium.
  • the initial discharge cut-off voltage of the electrochemical device is the first voltage
  • the initial charge cut-off voltage is the second voltage.
  • the computer-readable storage medium stores computer-executable instructions that can be executed by the processor. When the processor executes the computer-executable instructions, the steps of the control method described in any of the above-mentioned embodiments are implemented.
  • the processor is used to: when the rate of change of the internal resistance of the electrochemical device is less than a first threshold, control the electrochemical device to charge and discharge at the first voltage and the second voltage; when the rate of change of the internal resistance of the electrochemical device When greater than or equal to the first threshold and less than or equal to the second threshold, the discharge cut-off voltage of the electrochemical device is increased by the first boost amount, wherein the second threshold is greater than the first threshold; when the internal resistance change rate of the electrochemical device is greater than the first When the second threshold is reached, operations related to the charge and discharge state of the electrochemical device are performed.
  • the electrochemical device includes a negative electrode tab, the negative electrode tab includes a negative active material layer, and the negative active material layer includes a silicon-based material.
  • the silicon-based material includes at least one of silicon, silicon-oxygen material, silicon-carbon material, or silicon-oxygen-carbon material.
  • the mass ratio of the Si element in the negative electrode active material layer to the mass of the negative electrode active material layer is 1% to 90%.
  • the first voltage is 2.5V to 3.5V
  • the second voltage is 4.2V to 4.6V.
  • the first threshold satisfies: 1% ⁇ first threshold ⁇ 10%.
  • the second threshold satisfies 10% ⁇ second threshold ⁇ 20%.
  • the value range of the first boost amount is 0.03V to 0.6V.
  • performing an operation related to the charging and discharging state of the electrochemical device comprises at least one of steps d) to e) of: d) stopping the charging and discharging operation of the electrochemical device; e) sending a signal to stop the electrochemical device Prompt information for charging and discharging operations.
  • the high energy density characteristic of the electrochemical device can be fully utilized in the early stage when the internal resistance change rate is small.
  • it can be determined whether to increase the discharge cut-off voltage of the electrochemical device or perform an operation related to the charge and discharge state of the electrochemical device by the first boost amount, and then While maintaining the high energy density of the electrochemical device, the cycle life of the electrochemical device is improved.
  • the embodiment of the present application also provides a charging device. As shown in FIG. , an interface 505, a power interface 506, and a rectification circuit 507.
  • the detection circuit module 503 is used to detect the rate of change of the internal resistance of the lithium-ion battery, and sends the detection result to the processor 501;
  • the charging and discharging circuit 504 is used to receive instructions from the processor 501 to charge or charge the lithium-ion battery 605.
  • the interface 505 is used to electrically connect with the lithium ion battery 605; the power interface 506 is used to connect to an external power supply; the rectifier circuit 507 is used to rectify the input current; the machine-readable storage medium 502 stores the The machine-executable instructions, when the processor 501 executes the machine-executable instructions, implement the method steps described in any one of the above implementations.
  • the system 600 includes a second processor 601 and a second machine-readable storage medium 602.
  • the system 600 may also include a detection circuit module 603, a charge and discharge circuit 604 , a lithium ion battery 605 and a second interface 606 .
  • the detection circuit module 603 is used to detect the rate of change of the internal resistance of the lithium-ion battery 605, and sends the detection result to the second processor 601;
  • the ion battery 605 is charged or discharged;
  • the second interface 606 is used to connect with the interface of the external charger 700;
  • the external charger 700 is used to provide power;
  • the external charger 700 may include a first processor 701, a first machine-readable storage medium 702, a first interface 703, and a corresponding rectification circuit.
  • the external charger may be a commercially available charger, and the embodiment of the present application does not change its structure. Be specific.
  • the embodiment of the present application also provides a computer-readable storage medium.
  • a computer program is stored in the computer-readable storage medium.
  • the computer-readable storage medium may include a random access memory (Random Access Memory, RAM for short), and may also include a non-volatile memory (non-volatile memory), such as at least one magnetic disk memory.
  • the memory may also be at least one storage device located far away from the aforementioned processor.
  • the above-mentioned processor can be a general-purpose processor, including a central processing unit (Central Processing Unit, referred to as CPU), a network processor (Network Processor, referred to as NP), etc.; it can also be a digital signal processor (Digital Signal Processing, referred to as DSP) , Application Specific Integrated Circuit (ASIC for short), Field Programmable Gate Array (Field-Programmable Gate Array, FPGA for short) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. It should be understood that the above-mentioned processor may be included in an electrochemical device, a charging device, or an electronic device including an electrochemical device (for example, a mobile phone, etc.).
  • CPU Central Processing Unit
  • NP Network Processor
  • DSP Digital Signal Processing
  • ASIC Application Specific Integrated Circuit
  • FPGA Field-Programmable Gate Array
  • FPGA Field-Programmable Gate Array
  • the above-mentioned processor may be included in an electrochemical device, a charging
  • Embodiments of the present application also provide an electronic device including the above electrochemical device.
  • the electronic device in the embodiment of the present application is not particularly limited, and it may be used in any electronic device known in the prior art.
  • electronic devices may include, but are not limited to, notebook computers, pen-based computers, mobile computers, e-book players, cellular phones, portable fax machines, portable copiers, portable printers, headsets, VCRs, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles, bicycles, Drones, lighting equipment, toys, game consoles, clocks, electric tools, flashlights, cameras, large household storage batteries and lithium-ion capacitors, etc.
  • the electronic device may be a device with a built-in lithium-ion battery and data processing capability, such as a mobile phone and a tablet computer.

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Abstract

本申请提供了电化学装置及其控制方法、电子装置和存储介质。电化学装置的控制方法包括步骤a)和b)：a)当电化学装置的内阻变化率小于第一阈值时，以第一电压和第二电压进行充放电；b)当所述电化学装置的内阻变化率大于等于所述第一阈值时，以第一提升量提升电化学装置的放电截止电压。通过监测电化学装置的内阻变化率的变化，并且基于内阻变化率对电化学装置进行相应控制，从而在保持电化学装置的高能量密度的同时，改善电化学装置的循环性能。

Description

电化学装置及其控制方法、电子装置和存储介质 技术领域
本申请涉及电化学储能领域，尤其涉及电化学装置及其控制方法、电子装置和存储介质。
背景技术
随着电化学装置(例如，锂离子电池)的发展和进步，对其循环性能和能量密度提出了越来越高的要求。目前，在改善电化学装置的能量密度方面，在负极中采用硅基材料是当前的趋势。除了对材料的改进，也期望其他方面的改进以提升电化学装置的循环性能和能量密度。
发明内容
本申请的一些实施例提供了一种电化学装置的控制方法，电化学装置的初始放电截止电压为第一电压，初始充电截止电压为第二电压，控制方法包括步骤a)和步骤b)：a)当电化学装置的内阻变化率小于第一阈值时，以第一电压和第二电压进行充放电；b)当电化学装置的内阻变化率大于等于第一阈值时，以第一提升量提升电化学装置的放电截止电压。
在一些实施例中，当电化学装置的内阻变化率大于等于第一阈值时，以第一提升量提升电化学装置的放电截止电压包括：c)当电化学装置的内阻变化率大于或等于第一阈值并且小于或等于第二阈值时，以第一提升量提升电化学装置的放电截止电压，其中，第二阈值大于第一阈值；d)当电化学装置的内阻变化率大于第二阈值时，执行与电化学装置的充放电状态有关的操作。通过采用本申请的控制方法，在使用电化学装置时，在内阻变化率较小的前期阶段，能够充分利用电化学装置的高能量密度特性。此外，在循环过程中，能够自动监测电化学装置的内阻变化率状态，智能地确定是否要以第一提升量提升电化学装置的放电截止电压或执行与电化学装置的充放电状态有关的操作，进而在保持电化学装置的高能量密度的同时，提升电化学装置的循环寿命。
在一些实施例中，电化学装置包括负极极片，负极极片包括负极活性材料层，负极活性材料层包括硅基材料。通过采用硅基材料，可以提升电化学装置的能量密度。在一些实施例中，硅基材料包括硅、硅氧材料、硅碳材料或硅氧碳材料中的至少一种。在一些实施例中，负极活性材料层中的Si元素的质量占负极活性材料层的质量的比例为1％至90％。如果负极活性材料层中的Si元素的质量占负极活性材料层的质量的比例太小，则提升电化学装置的能量密度的作用相对有限；如果负极活性材料层中的Si元素的质量占负极活性材料层的质量的比例太大，则硅基材料的循环膨胀太大而影响电化学装置的循环性能。
在一些实施例中，第一电压的取值范围为2.5V至3.5V，第二电压的取值范围为4.2V至4.6V。当第一电压太高时，不利于充分利用电化学装置的能量密度；当第一电压太低时，容易造成电化学装置的不可逆损害。当第二电压太高时，容易造成电化学装置的不可逆损害；当第二电压太低时，不利于充分利用电化学装置的能量密度。在一些实施例中，第一阈值满足：1％≤第一阈值≤10％。如果第一阈值设置得太小，会使得在电化学装置的循环状态较好的时候就提升放电截止电压，进而不利于充分利用电化学装置的能量密度。如果第一阈值设置得太大，会使得提升电化学装置的循环寿命的作用相对受限。在一些实施例中，第二阈值满足10％＜第二阈值≤20％。如果第二阈值设置得太小，会使得在电化学装置的循环状态较好的时候就要执行与电化学装置的充放电状态有关的操作。如果第二阈值设置得太大，会使得提升电化学装置的循环寿命和改善电化学装置的安全性能的作用相对受限。在一些实施例中，第一提升量的取值范围为0.03V至0.6V。如果第一提升量的取值太小，则可能需要频繁进行提升放电截止电压的操作，或者提升电化学装置的循环寿命的作用相对受限。如果第一提升量的取值太大，则会使得电化学装置的放电截止电压太大而不利于充分利用电化学装置的能量密度。在一些实施例中，执行与电化学装置的充放电状态有关的操作包括步骤的e)至f)中的至少一个：e)停止电化学装置的充放电操作；f)发送停止电化学装置的充放电操作的提示信息。在电化学装置的内阻变化率大于第二阈值时，此时电化学装置的循环可能存在异常，通过停止电化学装置的充放电操作和/或 发送停止电化学装置的充放电操作的提示信息，例如，提醒用户更换电池，可以避免发生电池胀气等安全风险。
本申请的另一实施例提供了一种计算机可读存储介质，其中，计算机可读存储介质内存储有计算机程序，计算机程序被处理器执行时实现电化学装置的上述控制方法。
本申请的另一实施例提供了一种充电装置，包括处理器和计算机可读存储介质，计算机可读存储介质存储有能够被处理器执行的计算机可执行指令，处理器执行计算机可执行指令时，实现电化学装置的上述控制方法。
本申请的另一实施例提供了一种电化学装置，其中，包括处理器和计算机可读存储介质，电化学装置的初始放电截止电压为第一电压，初始充电截止电压为第二电压，计算机可读存储介质存储有能够被处理器执行的计算机可执行指令，处理器执行计算机可执行指令时，实现控制方法，控制方法包括步骤a)和步骤b)：a)当电化学装置的内阻变化率小于第一阈值时，以第一电压和第二电压进行充放电；b)当电化学装置的内阻变化率大于等于第一阈值时，以第一提升量提升电化学装置的放电截止电压。
在一些实施例中，当电化学装置的内阻变化率大于等于第一阈值时，以第一提升量提升电化学装置的放电截止电压包括：c)当电化学装置的内阻变化率大于或等于第一阈值并且小于或等于第二阈值时，以第一提升量提升电化学装置的放电截止电压，其中，第二阈值大于第一阈值；d)当电化学装置的内阻变化率大于第二阈值时，执行与电化学装置的充放电状态有关的操作。
在一些实施例中，电化学装置包括负极极片，负极极片包括负极活性材料层，负极活性材料层包括硅基材料。在一些实施例中，硅基材料包括硅、硅氧材料、硅碳材料或硅氧碳材料中的至少一种。在一些实施例中，负极活性材料层中的Si元素的质量占负极活性材料层的质量的比例为1％至90％。
在一些实施例中，第一电压的取值范围为2.5V至3.5V，第二电压的取值范围为4.2V至4.6V。在一些实施例中，第一阈值满足：1％≤第一阈值≤10％，第二阈值满足10％＜第二阈值≤20％。在一些实施例中，第一提升量的取值范围为0.03V至0.6V。在一些实施例中，执行与电化学装置的充放电状态有关的操作包括步骤的e)至f)中的至少一个：e)停止电化学装置的充放电操作；f)发送停止电化学装置的充放电操作的提示信息。
本申请的实施例还提供了一种电子装置，包括上述电化学装置。
本申请的实施例通过监测电化学装置的内阻变化率的变化，并且基于内阻变化率对电化学装置进行相应控制，从而在保持电化学装置的高能量密度的同时，改善电化学装置的循环性能。
附图说明
图1示出了本申请的一些实施例的电化学装置的控制方法的示意图。
图2为本申请的一些实施例的充电装置的结构示意图。
图3为本申请的一些实施例的系统的结构示意图。
具体实施方式
下面的实施例可以使本领域技术人员更全面地理解本申请，但不以任何方式限制本申请。
如图1所示，本申请的一些实施例提供了一种电化学装置的控制方法。在一些实施例中，电化学装置的初始放电截止电压为第一电压，初始充电截止电压为第二电压。电化学装置的初始放电截止电压指的是电化学装置不能再继续放电(即放电至荷电状态(SOC)为0％)时的电压，电化学装置的初始充电截止电压指的是电化学装置充电至SOC为100％时的电压。在一些实施例中，电化学装置包括但不限于锂离子电池。在一些实施例中，本申请的控制方法包括步骤a)和步骤b)。
在步骤a)中，当电化学装置的内阻变化率小于第一阈值时，以第一电压和第二电压进行充放电，即，以初始充电截止电压和初始放电截止电压进行充放电。在本申请中，电化学装置的内阻变化率是指以一次充电和一次放电过程作为一个循环，电化学装置的当前内阻相对于100次循环之前的内阻的变化率。例如，通过内阻仪测试电化学装置未使用状态下的内阻为n，每隔100次循环测试电化学装置的内阻为m，则内阻变化率为(m-n)/n。例如，从采用电化学装置的电子装置中取出电化学装置，通过内阻仪测试电化学装置的内阻，然后通过使电化学装置进行放电和充电循环，每隔100次循环(放电一次和充电一次整体视为一次循环)通过内阻仪测试电化学装置的内阻。应该理解，这仅是示例性的，也可以采用其他合适的内阻变化率测试方法。 随着电化学装置的不断循环，电化学装置的内阻有增大的趋势。当电化学装置的内阻在每100次循环内的变化率小于第一阈值时，表明电化学装置的循环处于可控范围，可以按照初始的设置条件进行充放电循环。
在步骤b)中，当电化学装置的内阻变化率大于等于第一阈值时，以第一提升量提升电化学装置的放电截止电压。随着电化学装置的循环的进行，电化学装置的内阻变化率提高到第一阈值，此时通过以第一提升量提升电化学装置的放电截止电压，即使用满充浅放模式，提升放电截止电压可以降低负极极片的充放电深度，使得负极活性材料处于满充浅放模式，进而可以提升电化学装置的循环寿命。
在一些实施例中，当电化学装置的内阻变化率大于等于第一阈值时，以第一提升量提升电化学装置的放电截止电压包括步骤c)和d)。在步骤c)中，当电化学装置的内阻变化率大于或等于第一阈值并且小于或等于第二阈值时，以第一提升量提升电化学装置的放电截止电压，其中，第二阈值大于第一阈值。随着电化学装置的循环的进行，电化学装置的内阻变化率提高到第一阈值以上并且在第二阈值以下，此时通过以第一提升量提升电化学装置的放电截止电压，即使用满充浅放模式，提升放电截止电压可以降低负极极片的充放电深度，使得负极活性材料处于满充浅放模式，进而可以提升电化学装置的循环寿命。
在步骤d)中，当电化学装置的内阻变化率大于第二阈值时，执行与电化学装置的充放电状态有关的操作。在一些实施例中，与电化学装置的充放电状态有关的操作包括影响电化学装置的充放电的任意操作，包括但不限于停止电化学装置的充放电操作以及发送停止电化学装置的充放电操作的提示信息。随着电化学装置的循环的进行，电化学装置的内阻变化率提高到第二阈值之上，此时判定电化学装置的循环存在异常，需要进行更大的干预，即执行与电化学装置的充放电状态有关的操作，以提升电化学装置的循环寿命并且减小安全事故发生的可能性。
通过采用本申请的控制方法，在使用电化学装置时，在内阻变化率较小的前期阶段，能够充分利用电化学装置的高能量密度特性。此外，在循环过程中，能够根据电化学装置的内阻变化率状态，确定是否要以第一提升量提升电化学装置的放电截止电压或执行与电化学装置的充放电状态有关的操 作，进而在保持电化学装置的高能量密度的同时，提升电化学装置的循环寿命。
在一些实施例中，第一电压的取值范围为2.5V至3.5V，第二电压的取值范围为4.2V至4.6V。当第一电压太高时，不利于充分利用电化学装置的能量密度；当第一电压太低时，容易造成电化学装置的不可逆损害。当第二电压太高时，容易造成电化学装置的不可逆损害；当第二电压太低时，不利于充分利用电化学装置的能量密度。
在一些实施例中，第一阈值满足：1％≤第一阈值≤10％。在1％≤第一阈值≤10％时，表明此时电化学装置的内部变化率较小，电化学装置的循环处于可控范围，可以按照初始的设置条件进行充放电循环。如果第一阈值设置得太小，会使得在电化学装置的循环状态较好的时候就提升放电截止电压，进而不利于充分利用电化学装置的能量密度。如果第一阈值设置得太大，会使得提升电化学装置的循环寿命的作用相对受限。在一些实施例中，第一阈值可以为1％、3％、5％、7％、10％或其他合适的值。
在一些实施例中，第二阈值满足：10％＜第二阈值≤20％。在电化学装置的内部变化率在第一阈值和第二阈值之间时，通过以第一提升量提升电化学装置的放电截止电压，即采用满充浅放的方式，可以提升电化学装置的循环寿命。如果第二阈值设置得太小，会使得在电化学装置的循环状态较好的时候就要执行与电化学装置的充放电状态有关的操作。如果第二阈值设置得太大，会使得提升电化学装置的循环寿命和改善电化学装置的安全性能的作用相对受限。在一些实施例中，第二阈值可以为11％、13％、15％、17％、20％或其他合适的值。
在一些实施例中，第一提升量的取值范围为0.03V至0.6V。如果第一提升量的取值太小，则可能需要频繁进行提升放电截止电压的操作，或者提升电化学装置的循环寿命的作用相对受限。如果第一提升量的取值太大，则会使得电化学装置的放电截止电压太大而不利于充分利用电化学装置的能量密度。在一些实施例中，第一提升量的值可以为0.03V、0.1V、0.2V、0.3V、0.4V、0.5V、0.6V或其他合适的值。在一些实施例中，当电化学装置的内阻变化率满足相应的条件时，可以多次以第一提升量提升放电截止电压，直到电化学装置的放电截止电压达到3.9V或者电化学装置的内阻变化率大于第二阈值。
在一些实施例中，执行与电化学装置的充放电状态有关的操作包括步骤的e)至f)中的至少一个：e)停止电化学装置的充放电操作；f)发送停止电化学装置的充放电操作的提示信息。在电化学装置的内阻变化率大于第二阈值时，此时电化学装置的循环可能存在异常，通过停止电化学装置的充放电操作和/或发送停止电化学装置的充放电操作的提示信息，例如，提醒用户更换电池，可以避免发生电池胀气等安全风险。
在一些实施例中，电化学装置包括负极极片，负极极片包括负极活性材料层，负极活性材料层包括硅基材料。通过采用硅基材料，可以提升电化学装置的能量密度。在一些实施例中，硅基材料包括硅、硅氧材料、硅碳材料或硅氧碳材料中的至少一种。在一些实施例中，负极活性材料层中的Si元素的质量占负极活性材料层的质量的比例为1％至90％。在一些实施例中，如果负极活性材料层中的Si元素的质量占负极活性材料层的质量的比例太小，则提升电化学装置的能量密度的作用相对有限；如果负极活性材料层中的Si元素的质量占负极活性材料层的质量的比例太大，则硅基材料的循环膨胀太大而影响电化学装置的循环性能。在一些实施例中，负极活性材料层中的Si元素的质量占负极活性材料层的质量的比例为5％至50％，此时既可以实现提升电化学装置的能量密度，又可以使得最小化硅基材料的循环膨胀的不利影响。更进一步地，负极活性材料层中的Si元素的质量占负极活性材料层的质量的比例为5％至20％。
本申请中，负极活性材料层中的Si元素的质量占负极活性材料层的质量的比例的测试方法可通过电感耦合等离子体发射光谱仪(ICP-OES)：首先，对负极极片进行前处理，前处理的方法是取电池单体中的负极极片放在400℃的烘箱中烘烤1h，然后使得负极材料层从集流体中脱落，得到负极材料，称取负极材料0.2g，放入50mL塑料容量瓶中，通过微波消解的方法进行溶解处理，消解所用的酸为10mL HNO 3+5mL HF，所得的溶液经过过滤后即可通过ICP测试，得到Si元素的浓度(mg/L)，电感耦合等离子体发射光谱仪测试方法属于本领域技术人员公知的技术，在此不展开描述。需要说明的是，测试中所采用的锂离子电池单体，作为示例，可使用化成之后的锂离子电池，在此不做限定。
在一些实施例中，电化学装置可以包括电极组件，电极组件包括正极极片、负极极片、设置在正极极片和负极极片之间的隔离膜。
在一些实施例中，负极极片还包括负极集流体。在一些实施例中，负极活性材料层可以位于负极集流体的一侧或两侧上。在一些实施例中，负极活性材料层中还可以包括导电剂和粘结剂。在一些实施例中，负极活性材料层中的导电剂可以包括导电炭黑、科琴黑、片层石墨、石墨烯、碳纳米管或碳纤维中的至少一种。在一些实施例中，负极活性材料层中的粘结剂可以包括羧甲基纤维素(CMC)、聚丙烯酸、聚乙烯基吡咯烷酮、聚苯胺、聚酰亚胺、聚酰胺酰亚胺、聚硅氧烷、丁苯橡胶、环氧树脂、聚酯树脂、聚氨酯树脂或聚芴中的至少一种。在一些实施例中，负极活性材料层中的负极活性材料、导电剂和粘结剂的质量比可以为(78至98.5)：(0.1至10)：(0.1至10)。应该理解，以上所述仅是示例，可以采用任何其他合适的材料和质量比。在一些实施例中，负极集流体可以采用铜箔、镍箔或碳基集流体中的至少一种。
在一些实施例中，正极极片包括正极集流体和设置在正极集流体上的正极活性材料层，正极活性材料层可以包括正极活性材料。在一些实施例中，正极活性材料包括钴酸锂、磷酸铁锂、磷酸锰铁锂、磷酸铁钠、磷酸钒锂、磷酸钒钠、磷酸钒氧锂、磷酸钒氧钠、钒酸锂、锰酸锂、镍酸锂、镍钴锰酸锂、富锂锰基材料或镍钴铝酸锂中的至少一种。在一些实施例中，正极活性材料层还可以包括导电剂。在一些实施例中，正极活性材料层中的导电剂可以包括导电炭黑、科琴黑、片层石墨、石墨烯、碳纳米管或碳纤维中的至少一种。在一些实施例中，正极活性材料层还可以包括粘结剂，正极活性材料层中的粘结剂可以包括羧甲基纤维素(CMC)、聚丙烯酸、聚乙烯基吡咯烷酮、聚苯胺、聚酰亚胺、聚酰胺酰亚胺、聚硅氧烷、丁苯橡胶、环氧树脂、聚酯树脂、聚氨酯树脂或聚芴中的至少一种。在一些实施例中，正极活性材料层中的正极活性材料、导电剂和粘结剂的质量比可以为(80至99)：(0.1至10)：(0.1至10)。在一些实施例中，正极活性材料层的厚度可以为10μm至500μm。应该理解，以上所述仅是示例，正极活性材料层可以采用任何其他合适的材料、厚度和质量比。
在一些实施例中，正极集流体可以采用Al箔，当然，也可以采用本领域常用的其他集流体。在一些实施例中，正极集流体的厚度可以为1μm至50μm。在一些实施例中，正极活性材料层可以仅涂覆在正极的集流体的部分区域上。
在一些实施例中，隔离膜包括聚乙烯、聚丙烯、聚偏氟乙烯、聚对苯二甲酸乙二醇酯、聚酰亚胺或芳纶中的至少一种。例如，聚乙烯包括选自高密度聚乙烯、低密度聚乙烯或超高分子量聚乙烯中的至少一种。尤其是聚乙烯和聚丙烯，它们对防止短路具有良好的作用，并可以通过关断效应改善电池的稳定性。在一些实施例中，隔离膜的厚度在约3μm至20μm的范围内。
在一些实施例中，隔离膜表面还可以包括多孔层，多孔层设置在隔离膜的至少一个表面上，多孔层包括无机颗粒和粘结剂，无机颗粒选自氧化铝(Al 2O 3)、氧化硅(SiO 2)、氧化镁(MgO)、氧化钛(TiO 2)、二氧化铪(HfO 2)、氧化锡(SnO 2)、二氧化铈(CeO 2)、氧化镍(NiO)、氧化锌(ZnO)、氧化钙(CaO)、氧化锆(ZrO 2)、氧化钇(Y 2O 3)、碳化硅(SiC)、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙或硫酸钡中的至少一种。在一些实施例中，隔离膜的孔具有在约0.01μm至1μm的范围的直径。多孔层的粘结剂选自聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、羧甲基纤维素钠、聚乙烯呲咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯或聚六氟丙烯中的至少一种。隔离膜表面的多孔层可以提升隔离膜的耐热性能、抗氧化性能和电解质浸润性能，增强隔离膜与极片之间的粘结性。
在一些实施例中，电化学装置包括锂离子电池，但是本申请不限于此。在一些实施例中，电化学装置还包括电解液，电解液包括氟醚、氟代碳酸乙烯酯或醚腈中至少一种。在一些实施例中，电解液还包括锂盐，锂盐包括双(氟磺酰基)酰亚胺锂和六氟磷酸锂，锂盐的浓度为1mol/L至2mol/L，且双(氟磺酰基)酰亚胺锂和六氟磷酸锂的质量比为0.06至5。在一些实施例中，电解液还可以包括非水溶剂。非水溶剂可为碳酸酯化合物、羧酸酯化合物、醚化合物、其它有机溶剂或它们的组合。
碳酸酯化合物可为链状碳酸酯化合物、环状碳酸酯化合物、氟代碳酸 酯化合物或其组合。
链状碳酸酯化合物的实例为碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸甲乙酯(MEC)及其组合。所述环状碳酸酯化合物的实例为碳酸亚乙酯(EC)、碳酸亚丙酯(PC)、碳酸亚丁酯(BC)、碳酸乙烯基亚乙酯(VEC)或者其组合。所述氟代碳酸酯化合物的实例为碳酸氟代亚乙酯(FEC)、碳酸1,2-二氟亚乙酯、碳酸1,1-二氟亚乙酯、碳酸1,1,2-三氟亚乙酯、碳酸1,1,2,2-四氟亚乙酯、碳酸1-氟-2-甲基亚乙酯、碳酸1-氟-1-甲基亚乙酯、碳酸1,2-二氟-1-甲基亚乙酯、碳酸1,1,2-三氟-2-甲基亚乙酯、碳酸三氟甲基亚乙酯或者其组合。
羧酸酯化合物的实例为乙酸甲酯、乙酸乙酯、乙酸正丙酯、乙酸叔丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、γ-丁内酯、癸内酯、戊内酯、甲瓦龙酸内酯、己内酯、甲酸甲酯或者其组合。
醚化合物的实例为二丁醚、四甘醇二甲醚、二甘醇二甲醚、1,2-二甲氧基乙烷、1,2-二乙氧基乙烷、乙氧基甲氧基乙烷、2-甲基四氢呋喃、四氢呋喃或者其组合。
其它有机溶剂的实例为二甲亚砜、1,2-二氧戊环、环丁砜、甲基环丁砜、1,3-二甲基-2-咪唑烷酮、N-甲基-2-吡咯烷酮、甲酰胺、二甲基甲酰胺、乙腈、磷酸三甲酯、磷酸三乙酯、磷酸三辛酯、和磷酸酯或者其组合。
在本申请的一些实施例中，电化学装置的电极组件为卷绕式电极组件、堆叠式电极组件或折叠式电极组件。在一些实施例中，电化学装置的正极极片和/或负极极片可以是卷绕或堆叠式形成的多层结构，也可以是单层正极、隔离膜、单层负极叠加的单层结构。
在本申请的一些实施例中，以锂离子电池为例，将正极极片、隔离膜、负极极片按顺序卷绕或堆叠成电极组件，之后装入例如铝塑膜中进行封装，注入电解液，化成、封装，即制成锂离子电池。然后，对制备的锂离子电池进行性能测试。
本领域的技术人员将理解，以上描述的电化学装置(例如，锂离子电池)的制备方法仅是实施例。在不背离本申请公开的内容的基础上，可以采用本领域常用的其他方法。
下面列举了一些具体实施例和对比例以更好地对本申请进行说明，其中，采用锂离子电池作为示例。
对比例1
正极极片的制备：将正极活性材料钴酸锂、导电炭黑(Super P)、聚偏二氟乙烯(PVDF)按照重量比97：1.4：1.6进行混合，加入N-甲基吡咯烷酮(NMP)作为溶剂，搅拌均匀。将浆料(固含量为72wt％)均匀涂覆在正极集流体铝箔上，涂覆厚度为80μm，在85℃下烘干，然后经过冷压、裁片、分切后，在85℃的真空条件下干燥4小时，得到正极极片。
负极极片的制备：将人造石墨、粘结剂聚丙烯酸和羧甲基纤维素钠(CMC)按重量:97：1.5：1.5的比例溶于去离子水中，形成负极浆料(固含量为40wt％)。采用10μm厚度铜箔作为负极集流体，将负极浆料涂覆于负极的集流体上，涂覆厚度为50μm，在85℃下烘干，然后经过冷压、裁片、分切后，在120℃的真空条件下干燥12小时，得到负极极片。
隔离膜的制备：隔离膜为7μm厚的聚乙烯(PE)。
电解液的制备：在干燥的氩气气氛手套箱中，将碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸二乙酯(DEC)按照质量比为EC：PC：DEC＝1：1：1进行混合，溶解并充分搅拌后加入锂盐LiPF 6，混合均匀后获得电解液，其中LiPF 6的浓度为1mol/L。
锂离子电池的制备：将正极极片、隔离膜、负极极片按顺序依次叠好，使隔离膜处于正极和负极中间，起到隔离的作用，并卷绕得到电极组件。将电极组件置于外包装铝塑膜中，在80℃下脱去水分后，注入上述电解液并封装，经过化成，脱气，切边等工艺流程得到锂离子电池。
采用单一循环条件不变化，其中，第一电压为3.0V，第二电压为4.45V。
其他实施例和对比例是在对比例1的步骤的基础上对硅基材料的含量和充放电方法进行变更，具体变更的参数如下所述。
下面描述本申请的各个参数的测试方法。
1.电池充电截止电压、电池放电截止电压测试：可使用电池电压内阻测试仪或者万用表测试。
2.内阻变化率测试：设备为电池电压内阻测试仪，首先测试电化学装置未使用状态下的内阻为n，每隔100次循环测试电化学装置的内阻为m，则内阻变化率为(m-n)/n。
3.电池循环数测试：通过循环测试仪器(选用市面上的新威电池测试仪)对电池单体按照设置的充放电截止电压进行恒流恒压充放电测试。例如一单体电池的充电截止电压为4.45V，放电截止电压为3.0V，循环测试仪在25℃下以3C恒流充电充电到4.45V，再以1C放电到3.0V作为一次循环，不断反复测试作为单体电池的不同循环数。容量衰减至80％时的循环数测试：对化成后的电池单体进行在25℃下以3C恒流充电，再以1C放电，此时的容量记为初始容量，电池容量首次衰减至初始容量80％(或小于初始容量80％)时对应的循环数记为容量衰减至80％时的循环数。
4.能量密度测试：在25℃下，将制备得到的锂离子电池以3C倍率满充、以1C倍率满放，记录此时的放电容量；在25℃下，使用电子天平对该锂离子电池进行称重；锂离子电池放电容量与锂离子电池重量的比值即为锂离子电池的能量密度。
应该理解，锂离子电池电压、内阻、循环寿命的测试属于本领域技术人员公知的技术，在此不展开描述，并且测试方法不限于本申请描述的方法，还可以采用其他合适的测试方法。
对比例1-6：
根据对比例1的步骤，将部分人造石墨替换为硅基材料氧化亚硅(SiOx，0＜x＜2)，设计Si元素的质量占负极活性材料层的质量的比例分别为1％、5％、25％、50％、90％时，设置第一电压为3.0V，第二电压为4.45V，可以从表1中看出该电化学装置的能量密度随着Si含量增加有增加，但是循环寿命随着Si含量增加有明显衰减。
表1：
Figure PCTCN2021133152-appb-000001
Figure PCTCN2021133152-appb-000002
对比例7-13：
根据对比例1的步骤，将部分人造石墨替换为硅基材料SiC，设计Si元素的质量占负极活性材料层的质量的比例分别为25％时，通过设置不同第一电压，第二电压保持4.45V不变，实施例中对第一电压设置为2.5V、2.8V、3.0V、3.2V、3.3V、3.4V、3.5V时，通过表2可以看出该电化学装置的循环寿命随着第一电压的抬升，循环寿命明显改善。
表2：
Figure PCTCN2021133152-appb-000003
对比例14-17：
根据对比例1的步骤，将部分人造石墨替换为硅基材料Si，设计Si元素的质量占负极活性材料层的质量的比例分别为25％时，通过设置第一电压为3.0V不变，设置不同第二电压4.2V、4.3V、4.45V、4.6V时，该电化学装置的循环寿命随着第二电压的抬升而下降，如表3所示。
表3：
Figure PCTCN2021133152-appb-000004
实施例1-5：
表5示出了设置不同的第一阈值，电化学装置对应的放电电压开始抬升时的循环数和衰减至80％的循环数。放电电压开始抬升时的循环数为首次抬升放电电压时对应的循环数。即对应电化学装置的内阻变化率首次不小于第一阈值时的循环数。
根据对比例1的步骤，将部分人造石墨替换为硅基材料SiC，设计Si元素的质量占负极活性材料层的质量的比例分别为25％时，第一电压为3.0V，第二电压为4.5V，第一阈值满足：1％≤第一阈值≤10％。在1％≤第一阈值≤10％时，表明此时电化学装置的内部变化率较小，电化学装置的循环处于可控范围，可以按照初始的设置条件进行充放电循环。如果第一阈值设置得较小(如实施例中设置值为1％)，会使得在电化学装置的循环100次时就提升放电截止电压(本实施例第一提升量的值为0.2V)，进而不利于充分利用电化学装置的能量密度。如果第一阈值设置得较大(如实施例中设置值为10％)，会使得在电化学装置的循环600次时才提升放电截止电压(通常地，锂离子电池的容量衰减至80％的循环数要求达到800-1000次。循环600次时才开始提升放电截止电压的话，循环性能改善效果相对受限)，从而电化学装置的循环寿命提升相对受限，如表4所示。
表4：
Figure PCTCN2021133152-appb-000005
Figure PCTCN2021133152-appb-000006
实施例6-11：
根据对比例1的步骤，将部分人造石墨替换为硅基材料SiC，设计Si元素的质量占负极活性材料层的质量的比例分别为25％时，第一电压为3.0V，第二电压为4.5V，设置第一阈值a为5％，第一提升量的值为0.2V，通过实施例4可知，在300次循环后达到第一阈值，从而提升放电截止电压到3.2V。进一步循环中，进行第二阈值的设置，第二阈值满足：10％＜第二阈值≤20％。其中，实施例6未设置第二阈值，在内阻变化率大于第一阈值5％时，放电截止电压提升0.2V，直到放电截止电压达到4.4V时执行与电化学装置的充放电状态有关的操作。在实施例7-11中，当放电截止电压达到4.2V时，停止抬升放电电压。在电化学装置的内部变化率在第一阈值和第二阈值之间时，通过以第一提升量提升电化学装置的放电截止电压，即采用满充浅放的方式，可以提升电化学装置的循环寿命。如果第二阈值设置得太小，会使得在电化学装置的循环状态较好的时候就要执行与电化学装置的充放电状态有关的操作。如果第二阈值设置得太大，会使得提升电化学装置的循环寿命和改善电化学装置的安全性能的作用相对受限。在实施例中，第二阈值可以为11％、13％、15％、17％、20％，结果如表5所示。
表5：
Figure PCTCN2021133152-appb-000007
Figure PCTCN2021133152-appb-000008
另外，本申请实施例还提供了一种充电装置，该充电装置包括处理器和计算机可读存储介质。计算机可读存储介质存储有能够被处理器执行的计算机可执行指令，处理器执行计算机可执行指令时，实现上述任一实施方案所述的控制方法步骤。在一些实施例中，处理器和计算机可读存储介质既可以安装在同一载体(例如，电路板)上，也可以分布在不同的载体上，例如，处理器可以通过各种通信方式(有线或无线)访问远程的计算机可读存储介质中的计算机可执行指令。计算机可读存储介质和处理器可以设置在电化学装置、与电化学装置连接的电子装置、与电化学装置连接的充电装置中的其中一个或者多个上。在一些实施例中，计算机可读存储介质和处理器可以设置在同一个装置(例如，电化学装置、或电子装置或充电装置)上。在一些实施例中，计算机可读存储介质和处理器可以分别设置在两个不同的装置上。例如，计算机可读存储介质可以设置在电化学装置上，处理器可以设置在充电装置上。
本申请实施例还提供了一种电化学装置，该电化学装置包括处理器和计算机可读存储介质。电化学装置的初始放电截止电压为第一电压，初始充电截止电压为第二电压。计算机可读存储介质存储有能够被处理器执行的计算机可执行指令，处理器执行计算机可执行指令时，实现上述任一实施方案所述的控制方法步骤。
在一些实施例中，处理器用于：当电化学装置的内阻变化率小于第一阈值时，控制电化学装置以第一电压和第二电压进行充放电；当电化学装置的内阻变化率大于或等于第一阈值并且小于或等于第二阈值时，以第一提升量提升电化学装置的放电截止电压，其中，第二阈值大于第一阈值；当电化学装置的内阻变化率大于第二阈值时，执行与电化学装置的充放电状态有关的操作。
在一些实施例中，电化学装置包括负极极片，负极极片包括负极活性材料层，负极活性材料层包括硅基材料。在一些实施例中，硅基材料包括硅、 硅氧材料、硅碳材料或硅氧碳材料中的至少一种。在一些实施例中，负极活性材料层中的Si元素的质量占负极活性材料层的质量的比例为1％至90％。
在一些实施例中，第一电压为2.5V至3.5V，第二电压为4.2V至4.6V。在一些实施例中，第一阈值满足：1％≤第一阈值≤10％。在一些实施例中，第二阈值满足10％＜第二阈值≤20％。在一些实施例中，第一提升量的取值范围为0.03V至0.6V。在一些实施例中，执行与电化学装置的充放电状态有关的操作包括步骤的d)至e)中的至少一个：d)停止电化学装置的充放电操作；e)发送停止电化学装置的充放电操作的提示信息。
通过采用本申请的电化学装置，在内阻变化率较小的前期阶段，能够充分利用电化学装置的高能量密度特性。此外，在循环过程中，能够根据电化学装置的内阻变化率状态，确定是否要以第一提升量提升电化学装置的放电截止电压或执行与电化学装置的充放电状态有关的操作，进而在保持电化学装置的高能量密度的同时，提升电化学装置的循环寿命。
本申请实施例还提供了一种充电装置，如图2所示，该充电装置500包括处理器501和机器可读存储介质502，该充电装置500还可以包括检测电路模块503、充放电电路504、接口505、电源接口506、整流电路507。其中，检测电路模块503用于检测锂离子电池的内阻变化率，并将检测结果发送至处理器501；充放电电路504用于接收处理器501发出的指令，对锂离子电池605进行充电或放电操作；接口505用于与锂离子电池605电连接；电源接口506用于与外部电源连接；整流电路507用于对输入电流进行整流；机器可读存储介质502存储有能够被处理器执行的机器可执行指令，处理器501执行机器可执行指令时，实现上述任一实施方案所述的方法步骤。
本申请实施例还提供了一种系统，如图3所示，该系统600包括第二处理器601和第二机器可读存储介质602，该系统600还可以包括检测电路模块603、充放电电路604、锂离子电池605以及第二接口606。其中，检测电路模块603用于检测锂离子电池605的内阻变化率，并将检测结果发送至第二处理器601；充放电电路604用于接收第二处理器601发出的指令，从而对锂离子电池605进行充电或放电操作；第二接口606用于与外部充电器700的接口连接；外部充电器700用于提供电力；第二机器可读存储介质602存 储有能够被处理器执行的机器可执行指令，第二处理器601执行机器可执行指令时，实现上述任一实施方案所述的方法步骤。外部充电器700可以包括第一处理器701、第一机器可读存储介质702、第一接口703及相应的整流电路，该外部充电器可以是市售充电器，本申请实施例对其结构不做具体限定。本申请实施例还提供了一种计算机可读存储介质，计算机可读存储介质内存储有计算机程序，计算机程序被处理器执行时，实现上述任一实施方案所述的控制方法步骤。计算机可读存储介质可以包括随机存取存储器(Random Access Memory，简称RAM)，也可以包括非易失性存储器(non-volatile memory)，例如至少一个磁盘存储器。可选的，存储器还可以是至少一个位于远离前述处理器的存储装置。上述的处理器可以是通用处理器，包括中央处理器(Central Processing Unit，简称CPU)、网络处理器(Network Processor，简称NP)等；还可以是数字信号处理器(Digital Signal Processing，简称DSP)、专用集成电路(Application Specific Integrated Circuit，简称ASIC)、现场可编程门阵列(Field-Programmable Gate Array，简称FPGA)或者其他可编程逻辑器件、分立门或者晶体管逻辑器件、分立硬件组件。应该理解，上述的处理器可以包括在电化学装置内、充电装置内或含有电化学装置的电子装置(例如，移动电话等)内。
本申请的实施例还提供了包括上述电化学装置的电子装置。本申请实施例的电子装置没有特别限定，其可以是用于现有技术中已知的任何电子装置。在一些实施例中，电子装置可以包括，但不限于，笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、无人机、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池和锂离子电容器等。示例性地，该电子装置可以是移动电话、平板电脑等内置锂离子电池、具有数据处理能力的装置。
对于充电装置/电化学装置/计算机可读存储介质/电子装置实施例而言，由于其基本相似于方法实施例，所以描述的比较简单，相关之处参见方法实施例的部分说明即可。
以上描述仅为本申请的较佳实施例以及对所运用技术原理的说明。本领域技术人员应当理解，本申请中所涉及的公开范围，并不限于上述技术特征的特定组合而成的技术方案，同时也应涵盖由上述技术特征或其等同特征进行任意组合而形成的其它技术方案。例如上述特征与本申请中公开的具有类似功能的技术特征进行互相替换而形成的技术方案。

Claims (20)

  1. 一种电化学装置的控制方法，所述电化学装置的初始放电截止电压为第一电压，初始充电截止电压为第二电压，所述控制方法包括步骤a)和b)：
    a)当所述电化学装置的内阻变化率小于第一阈值时，以所述第一电压和所述第二电压进行充放电；
    b)当所述电化学装置的内阻变化率大于等于所述第一阈值时，以第一提升量提升所述电化学装置的放电截止电压。
  2. 根据权利要求1所述的电化学装置的控制方法，其中，当所述电化学装置的内阻变化率大于等于所述第一阈值时，以所述第一提升量提升所述电化学装置的放电截止电压包括：
    c)当所述电化学装置的内阻变化率大于或等于所述第一阈值并且小于或等于第二阈值时，以所述第一提升量提升所述电化学装置的放电截止电压，其中，所述第二阈值大于所述第一阈值；
    d)当所述电化学装置的内阻变化率大于所述第二阈值和/或当所述电化学装置的放电截止电压被提升至第一电压阈值时，执行与所述电化学装置的充放电状态有关的操作。
  3. 根据权利要求1所述的电化学装置的控制方法，其中，所述电化学装置包括负极极片，所述负极极片包括负极活性材料层，所述负极活性材料层包括硅基材料。
  4. 根据权利要求3所述的电化学装置的控制方法，其中，所述负极活性材料层中的Si元素的质量占所述负极活性材料层的质量的比例为1％至90％。
  5. 根据权利要求1所述的电化学装置的控制方法，其中，所述第一电压的取值范围为2.5V至3.5V，所述第二电压的取值范围为4.2V至4.6V。
  6. 根据权利要求1所述的电化学装置的控制方法，其中，所述第一阈值满足：1％≤第一阈值≤10％。
  7. 根据权利要求2所述的电化学装置的控制方法，其中，所述第二阈值满足10％＜第二阈值≤20％。
  8. 根据权利要求1所述的电化学装置的控制方法，其中，所述第一提升量的取值范围为0.03V至0.6V。
  9. 根据权利要求2所述的电化学装置的控制方法，其中，所述执行与所述电化学装置的充放电状态有关的操作包括步骤的e)至f)中的至少一个：
    e)停止所述电化学装置的充放电操作；
    f)发送停止所述电化学装置的充放电操作的提示信息。
  10. 一种计算机可读存储介质，其中，所述计算机可读存储介质内存储有计算机程序，所述计算机程序被处理器执行时实现权利要求1至9中任一项所述的控制方法。
  11. 一种充电装置，包括处理器和计算机可读存储介质，所述计算机可读存储介质存储有能够被所述处理器执行的计算机可执行指令，所述处理器执行所述计算机可执行指令时，实现权利要求1至9中任一项所述的控制方法。
  12. 一种电化学装置，其中，包括处理器和计算机可读存储介质，所述电化学装置的初始放电截止电压为第一电压，初始充电截止电压为第二电压，所述计算机可读存储介质存储有能够被所述处理器执行的计算机可执行指令，所述处理器执行所述计算机可执行指令时，实现控制方法，所述控制方法包括步骤a)和b)：
    a)当所述电化学装置的内阻变化率小于第一阈值时，以所述第一电压和所述第二电压进行充放电；
    b)当所述电化学装置的内阻变化率大于等于所述第一阈值时，以第一提升量提升所述电化学装置的放电截止电压。
  13. 根据权利要求12所述的电化学装置，其中，当所述电化学装置的内阻变化率大于等于所述第一阈值时，以所述第一提升量提升所述电化学装置的放电截止电压包括：
    c)当所述电化学装置的内阻变化率大于或等于所述第一阈值并且小于或等于第二阈值时，以所述第一提升量提升所述电化学装置的放电截止电压，其中，所述第二阈值大于所述第一阈值；
    d)当所述电化学装置的内阻变化率大于所述第二阈值和/或当所述电化学装置的放电截止电压被提升至第一电压阈值时，执行与所述电化学装置的充放电状态有关的操作。
  14. 根据权利要求12所述的电化学装置，其中，所述电化学装置包括负极极片，所述负极极片包括负极活性材料层，所述负极活性材料层包括硅基材料。
  15. 根据权利要求14所述的电化学装置，其中，所述负极活性材料层中的Si元素的质量占所述负极活性材料层的质量的比例为1％至90％。
  16. 根据权利要求12所述的电化学装置，其中，所述第一电压的取值范围为2.5V至3.5V，所述第二电压的取值范围为4.2V至4.6V。
  17. 根据权利要求13所述的电化学装置，其中，所述第一阈值满足：1％≤第一阈值≤10％，所述第二阈值满足10％＜第二阈值≤20％。
  18. 根据权利要求12所述的电化学装置，其中，所述第一提升量的取值范围为0.03V至0.6V。
  19. 根据权利要求13所述的电化学装置，其中，所述执行与所述电化学装置的充放电状态有关的操作包括步骤的e)至f)中的至少一个：
    e)停止所述电化学装置的充放电操作；
    f)发送停止所述电化学装置的充放电操作的提示信息。
  20. 一种电子装置，包括根据权利要求12至19中任一项所述的电化学装置。
PCT/CN2021/133152 2021-11-25 2021-11-25 电化学装置及其控制方法、电子装置和存储介质 WO2023092390A1 (zh)

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