WO2023273760A1 - 锂电池及其制备方法、充电方法和动力车辆 - Google Patents

锂电池及其制备方法、充电方法和动力车辆 Download PDF

Info

Publication number
WO2023273760A1
WO2023273760A1 PCT/CN2022/095952 CN2022095952W WO2023273760A1 WO 2023273760 A1 WO2023273760 A1 WO 2023273760A1 CN 2022095952 W CN2022095952 W CN 2022095952W WO 2023273760 A1 WO2023273760 A1 WO 2023273760A1
Authority
WO
WIPO (PCT)
Prior art keywords
lithium
battery
negative electrode
charging
lithium battery
Prior art date
Application number
PCT/CN2022/095952
Other languages
English (en)
French (fr)
Inventor
潘仪
马永军
郭姿珠
王良俊
孙华军
Original Assignee
比亚迪股份有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 比亚迪股份有限公司 filed Critical 比亚迪股份有限公司
Priority to EP22831582.6A priority Critical patent/EP4345943A1/en
Priority to CA3223903A priority patent/CA3223903A1/en
Priority to KR1020237045101A priority patent/KR20240014077A/ko
Publication of WO2023273760A1 publication Critical patent/WO2023273760A1/zh
Priority to US18/398,471 priority patent/US20240145760A1/en

Links

Images

Classifications

    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • 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
    • 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
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L50/00—Electric propulsion with power supplied within the vehicle
    • B60L50/50—Electric propulsion with power supplied within the vehicle using propulsion power supplied by batteries or fuel cells
    • B60L50/60—Electric propulsion with power supplied within the vehicle using propulsion power supplied by batteries or fuel cells using power supplied by batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0569—Liquid materials characterised by the solvents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • H01M10/446—Initial charging 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0416—Methods of deposition of the material involving impregnation with a solution, dispersion, paste or dry powder
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/043—Processes of manufacture in general involving compressing or compaction
    • H01M4/0435—Rolling or calendering
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0438—Processes of manufacture in general by electrochemical processing
    • H01M4/044—Activating, forming or electrochemical attack of the supporting material
    • H01M4/0445—Forming after manufacture of the electrode, e.g. first charge, cycling
    • H01M4/0447—Forming after manufacture of the electrode, e.g. first charge, cycling of complete cells or cells stacks
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • 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
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • 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
    • 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
    • H01M4/381—Alkaline or alkaline earth metals elements
    • H01M4/382—Lithium
    • 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
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/40—Alloys based on alkali metals
    • 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
    • H01M4/40—Alloys based on alkali metals
    • H01M4/405—Alloys based on lithium
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • 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
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/249—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders specially adapted for aircraft or vehicles, e.g. cars or trains
    • 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
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present application relates to the technical field of lithium batteries, in particular to a lithium battery, a preparation method thereof, a charging method and a power vehicle.
  • Lithium batteries have been widely used in mobile phones, laptops and other portable electronic products and new energy vehicles.
  • commercial lithium batteries generally use graphite as the negative electrode active material, and in order to ensure the efficient deintercalation of lithium ions in the positive and negative electrodes during the battery cycle, the effective capacity of the graphite negative electrode is generally greater than that of the positive electrode (that is, the N/P ratio of the battery Generally greater than 1), to prevent the precipitation of lithium dendrites on the negative electrode and affect the cycle performance, but this makes the volume and weight of the negative active material in the battery relatively high, which limits the improvement of the energy density of lithium-ion batteries, and it is difficult to exceed 350mAh/g , can no longer meet people's growing demand for battery life and standby.
  • Lithium metal has a high theoretical specific capacity (3861mAh/g) and the most negative electrochemical potential (-3.04V, compared to the standard hydrogen electrode), and is considered to be the best choice for the next generation of high energy density battery anode materials.
  • some institutions use lithium metal whose volume ratio is much lower than that of traditional negative electrodes, or even use lithium free negative electrodes (Lithium free), such as CN201911075192.1.
  • lithium batteries with high energy density can be obtained in this way, the cycle performance of the obtained batteries is relatively low. Poor, hindering the commercialization process of high energy density metal lithium batteries.
  • the present application provides a lithium battery, a preparation method thereof, a charging method and a power vehicle, so as to solve the current problem of poor cycle performance of metal lithium batteries.
  • the present application provides a lithium battery, including a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte between the positive electrode sheet and the negative electrode sheet, wherein the negative electrode material layer of the negative electrode sheet Containing a lithium-silicon composite negative electrode active material, the surface of the negative electrode material layer has a protective layer or the surface of the lithium-silicon composite negative electrode active material has a protective layer, and the protective layer includes a polymer matrix and a lithium salt; in the lithium battery In a fully charged state, the lithium-silicon composite negative electrode active material contains lithium element and lithium-silicon alloy Li 4.4 Si, and the molar ratio of the lithium element in the lithium-silicon composite negative electrode active material is 15%-95% %.
  • the lithium battery provided by the first aspect of the present application contains the above-mentioned lithium-silicon composite negative electrode active material, so that the lithium battery has high energy density, long cycle life and high safety performance.
  • the present application also provides a method for preparing a lithium battery, comprising the following steps:
  • the lithium thin film and the silicon-based material layer are subjected to hot-pressing treatment, so that all the lithium elements of the lithium thin film are transferred into the silicon-based material layer and react with the silicon-based material in situ forming a negative electrode material layer containing a lithium-silicon composite negative electrode active material to obtain a negative electrode sheet;
  • a protective layer is formed on the surface of the silicon-based material layer; or after the negative electrode material layer is formed, a protective layer is formed on the surface of the negative electrode material layer.
  • a protective layer; the protective layer includes a polymer matrix and a lithium salt;
  • the negative electrode sheet is assembled into a lithium battery; wherein, in the fully charged state of the lithium battery, the lithium-silicon composite negative electrode active material contains lithium element and lithium-silicon alloy Li 4.4 Si, and the lithium element is in the The molar proportion of the lithium-silicon composite negative electrode active material is 15%-95%.
  • the preparation method described in the second aspect of the present application has a simple process, is easy to control, and is suitable for large-scale industrial preparation.
  • the present application also provides a charging method for the foregoing lithium battery, comprising the following steps:
  • the charging cut-off voltage V s for controlling the charging of the lithium battery satisfies the following formula:
  • V s cV b +a ⁇ c ⁇ K+b ⁇ c ⁇ (dQ/dV)/(3.6 ⁇ CA), wherein, when the lithium battery exhibits long cycle life characteristics, the V s , the negative electrode of the lithium battery does not precipitate simple lithium, and V s ⁇ V h ;
  • V h is the charging upper limit voltage that the lithium battery can withstand
  • CA is the nominal capacity when the lithium battery is discharged at 0.33C
  • V b is that the negative electrode of the lithium battery does not precipitate lithium element under the real-time charging capacity
  • K is the real-time DC internal resistance of the lithium battery in the charging process and the internal resistance growth rate of the DC internal resistance of the factory
  • dQ/dV is the real-time differential value of the charging power and charging voltage of the lithium battery
  • c is the calibration factor of the real-time cell temperature of the lithium battery during charging
  • a is the calibration factor of K
  • b is the calibration factor of (dQ/dV)/CA.
  • the charging method provided in the third aspect of the present application can ensure that the cruising range of the lithium battery is as long as possible under a long service life.
  • the present application also provides a power vehicle, the battery system of which includes at least one first battery unit, and the first battery unit includes a plurality of lithium batteries as described in the first aspect of the present application and a first charging control device .
  • the powered vehicle with the first battery unit can regulate the charging cut-off voltage for charging each lithium battery of the first battery unit according to the actual mileage requirement.
  • FIG. 1 is a schematic structural diagram of a lithium battery provided in an embodiment of the present application.
  • FIG. 2 is a discharge curve of a lithium battery provided in an embodiment of the present application.
  • Fig. 3 is a schematic structural diagram of a powered vehicle provided by an embodiment of the present application.
  • Fig. 4 is another schematic structural diagram of a powered vehicle provided by an embodiment of the present application.
  • a lithium battery 100 includes a negative electrode sheet 10 , a positive electrode sheet 20 , a separator 30 and an electrolyte (not shown) between the positive electrode sheet 20 and the negative electrode sheet 10 .
  • the negative electrode sheet 10 includes a negative electrode current collector 11 and a negative electrode material layer 12 disposed on the negative electrode current collector 11.
  • the negative electrode material layer 12 contains a lithium-silicon composite negative electrode active material, and optional conductive agents and binders.
  • the positive electrode sheet 20 includes a positive electrode current collector 21 and a positive electrode material layer 22 disposed on the positive electrode current collector 21.
  • the positive electrode material layer 22 contains positive electrode active materials, and optional conductive agents and binders.
  • the surface of the negative electrode material layer 12 also has a protective layer 13 (see FIG. 1 ), or the surface of the lithium-silicon composite negative electrode active material has a protective layer, and the protective layer includes a polymer matrix and a lithium salt.
  • the protective layer can guide the flow of lithium ions, control the uniform deposition of lithium ions on the surface of the negative electrode sheet, effectively inhibit the growth of lithium dendrites on the surface of the negative electrode sheet 10 and avoid the internal short circuit of the battery caused by it piercing the separator, and can reduce the side reaction between the negative electrode and the electrolyte occur, relieve the volume expansion of the negative electrode during the cycle, and improve the cycle performance and safety performance.
  • the protective layer can better suppress the cycle attenuation and internal short circuit of the battery caused by the negative electrode lithium precipitation. Wherein, the protective layer is almost insoluble in the battery electrolyte.
  • the polymer matrix may include one of polyethylene oxide (polyethylene oxide, PEO), polysiloxane, polyvinylidene fluoride, polymethyl methacrylate, polyacrylonitrile and its derivatives and copolymers, etc. or more, but not limited to.
  • the lithium salt has ion conductivity and may include lithium nitrate (LiNO 3 ), lithium sulfide (Li 2 S), lithium chloride (LiCl), lithium bromide (LiBr), lithium iodide (LiI), lithium fluoride (LiF ), lithium phosphate (Li 3 PO 4 ), and the like.
  • the aforementioned protective layer may also contain inorganic fillers to increase lithium ion transmission channels, improve mechanical properties, and the like.
  • the inorganic filler may be at least one of oxides (such as silicon dioxide, aluminum oxide, titanium dioxide, etc.), hydroxides (such as aluminum hydroxide, magnesium hydroxide) and salts.
  • the lithium-silicon composite negative electrode active material contains lithium element and silicon element.
  • the lithium-silicon composite negative electrode active material contains lithium element and lithium-silicon alloy Li 4.4 Si, and the molar ratio of the lithium element in the lithium-silicon composite negative electrode active material is 15%. -95%.
  • “fully charged” means that the positive electrode of the battery is charged to 100% SOC (State of Charge). At this time, the capacity of the positive electrode of the battery is fully utilized, the energy density of the battery is high, and “lithium analysis” is generated at the negative electrode, and this part of “lithium analysis” is active lithium, which can exert capacity at the negative end. Since the negative electrode of the battery of the present application is fully charged, in addition to allowing the active lithium ions released from the positive electrode to be stored in the negative electrode in the form of an alloy material, it also accepts direct deposition in the negative electrode in the form of lithium as a single substance.
  • the completed preparation of the present application In the negative electrode material layer, the lithium-silicon alloy material Li x Si (0 ⁇ x ⁇ 4.4) is used in a small amount, which can significantly increase the energy density of the battery.
  • the lithium-silicon alloy material Li x Si (0 ⁇ x ⁇ 4.4) is used in a small amount, which can significantly increase the energy density of the battery.
  • it in conjunction with the setting of the above-mentioned protective layer, it can suppress the side reaction of the negative electrode of the battery in the state of high energy density, "lithium precipitation" and the electrolyte, and reduce the risk of the precipitated lithium dendrite piercing the separator. Therefore, the lithium battery of the embodiment of the present application not only has high energy density, but also has good cycle performance and safety performance.
  • the lithium-silicon composite negative electrode active material when the lithium battery 100 is not fully charged, such as when the SOC value of the positive electrode of the battery is lower than the first threshold, the lithium-silicon composite negative electrode active material does not contain lithium element.
  • the lithium-silicon alloy in the lithium-silicon composite negative electrode active material can be represented by the general chemical formula Li x Si, 0 ⁇ x ⁇ 4.4.
  • the "first threshold” is the positive charging SOC critical value when the negative terminal of the battery just happens to have metal lithium precipitated when the battery is charged, that is, the lithium-silicon alloy of the negative electrode of the battery is completely filled with lithium ions (that is, the lithium-silicon alloy is specifically Li 4.4 Si, At this time, it can also be called the SOC value when the negative electrode of the battery is charged to 100% SOC) but the lithium ions on the positive electrode side are not completely released.
  • the battery when the SOC charged at the positive electrode of the battery is lower than the first threshold, the battery does not decompose lithium, and the energy density of the lithium battery is not fully utilized, and the negative terminal only exerts the capacity of the lithium-silicon alloy Li x Si, and the volume expansion of the negative terminal It is also relatively weak, and the side reaction with the electrolyte is weak. In this way, the lithium battery can perform more charge and discharge cycles at a lower energy density (still much higher than the energy density of the current battery using graphite as the negative electrode), that is, it has a longer cycle life.
  • the lithium battery provided by this application can take into account the characteristics of "long cycle life” and the above-mentioned “high energy density”, and these two characteristics can be freely selected in combination with the battery management system of the lithium battery to meet the full life cycle requirements of power vehicles .
  • the active material of the lithium-silicon composite negative electrode has an adjustable ratio of lithium metal, and its molar proportion is in the range of 15%-95%.
  • the above-mentioned first threshold can be adjusted accordingly.
  • the first threshold is also in the range of 15%-95%. See the lithium battery discharge curve shown in Figure 2.
  • the lithium battery using lithium-silicon composite negative electrode active material has a discharge inflection point when the discharge capacity is 58mAh.
  • the "discharge inflection point" refers to the minimum value of dV/dQ in the battery discharge curve.
  • the energy density of the battery is high (that is, the product of the battery voltage and the battery power), which jointly exert the capacity of the lithium-silicon alloy Li 4.4 Si and the lithium element; after this inflection point, the SOC of the battery is low, and the negative electrode side Only by utilizing the capacity of the lithium-silicon alloy Li x Si, the energy density of the battery becomes lower, but the cycle life of the battery is longer.
  • the molar ratio of the lithium-silicon alloy Li 4.4 Si in the lithium-silicon composite negative electrode active material is 5%-85%.
  • the sum of the molar ratios of the lithium-silicon alloy Li 4.4 Si and the lithium element in the lithium-silicon composite negative electrode active material is 100%.
  • the lithium-silicon composite negative electrode active material is composed of lithium element and lithium-silicon alloy Li 4.4 Si.
  • the lithium-silicon composite negative electrode active material only contains lithium element and silicon element (that is, it can be formed by in-situ pressing of silicon element and metal lithium).
  • the battery N/P ratio of traditional lithium batteries is generally greater than 1 to prevent the precipitation of lithium dendrites and poor cycle performance when the N/P ratio is less than 1, and the battery N/P ratio When it is greater than 1, the volume ratio of the negative electrode active material in the entire battery is relatively large, generally more than 37%. At the same time, its volume ratio in the battery can reach 37%-44%.
  • the N/P of this lithium battery is less than 1, and its negative electrode active material in lithium battery like this
  • the volume ratio (less than 37%, for example, it can be below 20%) and the mass ratio can be small, which can significantly improve the energy density of the battery and increase its endurance; and based on the existence of the aforementioned protective layer, it can be used in the negative electrode "
  • the side reaction between the lithium element and the electrolyte and its disordered growth can be suppressed to pierce the separator, so that the cycle ability of the battery can also be better.
  • the N/P ratio of the lithium battery 100 in this application is less than 1, which specifically means that the ratio of the capacity of the lithium-silicon composite negative electrode active material to the capacity of the positive electrode active material is less than 1.
  • the capacity of the lithium-silicon composite negative electrode active material corresponding to the N/P ratio refers to the time when the negative electrode just intercalates lithium to form a lithium-silicon alloy Li 4.4 Si and does not precipitate elemental lithium (at this time, the lithium ions of the positive electrode have not been completely extracted)
  • the negative electrode capacity of that is, the negative electrode capacity corresponding to the above-mentioned first threshold.
  • the volume ratio of the lithium-silicon composite negative electrode active material to the positive electrode active material is 0.1375-0.825.
  • the ratio of the thickness of the positive electrode sheet 20 to the thickness of the negative electrode sheet 10 is 8:1-4:3. This can better ensure that the N/P ratio of the lithium battery is less than 1, which is conducive to improving the energy density of the battery.
  • the electrolyte solution of the lithium battery 100 generally contains a solvent and a second lithium salt.
  • the solvent in the electrolyte solution of the lithium battery 100 is a non-carbonate solvent.
  • the solvent in the electrolyte includes an ether solvent, specifically at least one of an unhalogenated ether solvent and a fluorinated ether solvent.
  • the side reaction between the carbonate solvent and the lithium metal negative electrode is fast, and it is easy to generate sharp lithium dendrites on the negative electrode of the battery to pierce the battery diaphragm and cause the battery to spontaneously ignite.
  • Ether solvents have good compatibility with lithium metal, and the side reactions between them and lithium metal are much lower than those between carbonate solvents and lithium metal, which can effectively suppress the consumption of active lithium in the cycle process, and at the same time Improve the uniformity and density of lithium ion deposition, avoiding the formation of sharp lithium dendrites and piercing the battery separator to cause safety risks.
  • the non-halogenated ether solvent can be selected from ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, triethyl Glycol dimethyl ether, tetraethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol monomethyl ether, diglyme, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether One or more of methyl ether, tetraglyme, etc., but not limited thereto.
  • the fluoroether solvent can be selected from 1,1,2,2-tetrafluoroethyl ethyl ether, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropane base ether, hexafluoroisopropyl ethyl ether, tetrafluoroethyl-tetrafluoropropyl ether, 2,2,2-trifluoroethyl ether, 1,1,2,2-tetrafluoroethyl-2,2, 2-trifluoroethyl ether, difluoromethyl-2,2,3,3-tetrafluoropropyl ether, 2,2,3,3,3-pentafluoropropyl methyl ether, 1,1,2, 3,3,3-Hexafluoropropyl ethyl ether, 1,1,2,3,3,3-pentafluoropropyl difluoromethyl ether, 1,1,2,2-tetrafluoropropan
  • the second lithium salt in the electrolyte can be selected from lithium bisfluorosulfonyl imide (LiN(SO 2 F) 2 ), lithium bis(trifluoromethylsulfonyl)imide (Li(CF 3 SO 2 ) 2 N), lithium bis(perfluoroethylsulfonyl)imide (Li(C 2 F 5 SO 2 ) 2 N), lithium dioxalate borate (LiB(C 2 O 4 ) 2 , LiBOB), trifluoromethane Lithium sulfonate (LiCF 3 SO 3 ), lithium perfluorobutyl sulfonate (LiC 4 F 9 SO 3 ), tris(trifluoromethylsulfonyl)methyllithium LiC(CF 3 SO 2 ) 3 , etc.
  • LiN(SO 2 F) 2 lithium bis(trifluoromethylsulfonyl)imide
  • Li(CF 3 SO 2 ) 2 N lithium bis(perflu
  • the lithium-silicon composite negative electrode active material is formed by in-situ pressing of a silicon-based material and lithium metal.
  • silicon-based materials may include, but are not limited to, simple silicon, silicon oxide, silicon-based non-lithium alloys (such as silicon-germanium alloys, silicon-magnesium alloys, silicon-copper alloys, silicon-iron alloys, etc.) or other silicon compounds.
  • the negative electrode material layer 12 containing the lithium-silicon composite negative electrode active material is formed by a lithium thin film (such as a lithium foil or a lithium thin film attached to a release film) and an initial negative electrode material layer containing a silicon-based material. Made by hot pressing. At this time, the lithium element of the lithium thin film can be completely transferred to the initial negative electrode material layer, and react with the silicon-based material in situ to form the lithium-silicon composite negative electrode active material.
  • the lithium-silicon composite negative electrode active material is formed by in-situ pressing of a mixture of lithium metal powder and silicon-based material (which can be wet slurry or dry powder).
  • the above-mentioned negative electrode material layer 12 can be formed by in-situ reaction on the negative electrode current collector to form lithium-containing silicon by coating the mixed slurry of silicon-based material and lithium powder on the negative electrode current collector, after drying and pressing.
  • the negative electrode material layer of the composite negative electrode active material; or, the lithium-silicon composite negative electrode active material formed by in-situ pressing of the mixture of metal lithium powder and silicon-based material is coated, dried, and pressed to form a negative electrode sheet.
  • the negative electrode material layer 12 when it is necessary to form the negative electrode material layer 12 with a protective layer on the surface, the lithium film attached to the release film and the silicon-based material layer with a protective layer on the surface (this silicon-based material layer is the aforementioned initial negative electrode)
  • the material layer which contains silicon-based material and optional binder, conductive agent) is subjected to in-situ hot pressing.
  • the negative electrode material layer with a protective layer on its surface may also be formed by forming a protective layer on its surface after forming the negative electrode material layer of a lithium-silicon composite negative electrode active material.
  • the negative electrode current collector 11 and the positive electrode current collector 21 are independently selected from simple metal foils or alloy foils.
  • the negative electrode current collector 11 may be specifically copper foil
  • the positive electrode current collector 21 may be specifically aluminum foil.
  • the positive electrode active material can be lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium cobalt phosphate, lithium cobalt oxide, lithium manganate, lithium nickel manganate, lithium nickel cobalt manganate (NCM), nickel cobalt At least one of lithium aluminate (NCA) and the like.
  • the binder and conductive agent in the negative electrode sheet 10 and the positive electrode sheet 20 can be conventional materials.
  • the conductive agent can be one or more of conductive carbon black (such as acetylene black, Ketjen black), carbon nanotube, carbon fiber, graphite and furnace black.
  • the binder can independently use styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), polyacrylonitrile (PAN), polyimide ( One or more of PI), polyacrylic acid (PAA), polyolefin (such as polyethylene, polypropylene, etc.), sodium carboxymethylcellulose (CMC) and sodium alginate, etc.
  • SBR styrene-butadiene rubber
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PVA polyvinyl alcohol
  • PAN polyacrylonitrile
  • PAA polyacrylic acid
  • PAA polyolefin
  • CMC sodium carboxymethylcellulose
  • the lithium battery provided in the embodiment of the present application contains the above-mentioned lithium-silicon composite negative electrode active material and protective layer, so the proportion of lithium-silicon composite negative electrode active material in the lithium battery can be relatively low, which is beneficial to improve the energy density of the battery, and the battery is Under the low SOC state, the negative electrode does not decompose lithium, showing a better cycle life; under the high SOC state, the energy density of the battery is very high, and the side effect of decomposing lithium is alleviated due to the setting of the protective layer. Batteries can take into account high energy density, long cycle life, high safety and so on.
  • the embodiment of the present application provides a preparation method of the above-mentioned lithium battery, comprising the following steps:
  • the lithium thin film and the silicon-based material layer are subjected to hot-pressing treatment, so that all the lithium elements of the lithium thin film are transferred into the silicon-based material layer and react with the silicon-based material in situ forming a negative electrode material layer containing a lithium-silicon composite negative electrode active material to obtain a negative electrode sheet;
  • a protective layer is formed on the surface of the silicon-based material layer; or after the negative electrode material layer is formed, a protective layer is formed on the surface of the negative electrode material layer.
  • a protective layer; the protective layer includes a polymer matrix and a lithium salt;
  • the negative electrode sheet is assembled into a lithium battery; wherein, in the fully charged state of the lithium battery, the lithium-silicon composite negative electrode active material contains lithium element and lithium-silicon alloy Li 4.4 Si, and the lithium element is in the The molar proportion of the lithium-silicon composite negative electrode active material is 15%-95%.
  • the silicon-based material may include but not limited to simple silicon, silicon oxide, silicon-based non-lithium alloys (such as silicon-germanium alloys, silicon-magnesium alloys, silicon-copper alloys, ferrosilicon alloys, etc.) or other silicon compounds (such as fluorine-containing silicon oxide, lithium hexafluorosilicate, silicon carbide, silicon boride), etc.
  • silicon-based non-lithium alloys such as silicon-germanium alloys, silicon-magnesium alloys, silicon-copper alloys, ferrosilicon alloys, etc.
  • other silicon compounds such as fluorine-containing silicon oxide, lithium hexafluorosilicate, silicon carbide, silicon boride
  • the lithium-silicon composite negative electrode active material also contains these elements correspondingly.
  • the lithium-silicon composite negative electrode active material when the silicon-based material is silicon, when the SOC of the battery is lower than the first threshold, the lithium-silicon composite negative electrode active material only contains lithium-silicon alloy Li x Si; when the lithium battery is fully charged, the The lithium-silicon composite negative electrode active material is only composed of lithium element and Li 4.4 Si.
  • the silicon-based material when the silicon-based material is silicon oxide, when the SOC of the battery is lower than the first threshold, the lithium-silicon composite negative electrode active material contains lithium-silicon alloy Li x Si and Li 2 O, Li 2 SiO 3 , etc. ; When the lithium battery is fully charged, the lithium-silicon composite negative electrode active material contains Li 4.4 Si, lithium simple substance and Li 2 O, Li 2 SiO 3 and the like.
  • the protective layer and the silicon-based material layer present a porous structure, and the lithium element of the lithium thin film can be Enter into the silicon-based material layer, and react with the silicon-based material in situ to form the lithium-silicon composite negative electrode active material, and finally form a negative electrode material layer with a protective layer, the negative electrode material layer contains the lithium-silicon composite negative electrode active material.
  • the lithium thin film that is hot-pressed with the silicon-based material layer can be directly a lithium foil, or a lithium thin film attached to a release film, and is preferably a lithium thin film attached to a release film to avoid lithium
  • the direct contact between the film and the pressing equipment brings loss of lithium element.
  • the protective layer can be formed on the negative electrode material layer by liquid phase coating, vapor phase deposition or electrodeposition.
  • assembling the negative electrode sheet into a lithium battery specifically includes: stacking the positive electrode sheet, the separator and the negative electrode sheet in sequence to make a bare cell; placing the bare cell in the battery case, And injecting electrolyte solution, after sealing the battery casing, a lithium battery is obtained.
  • the preparation method of the lithium battery provided in the embodiment of the present application has a simple process and is easy to control, and is suitable for large-scale industrial production of the above-mentioned lithium battery with both high energy density and long cycle life.
  • the embodiment of the present application provides a charging method for the above-mentioned lithium battery, comprising the following steps:
  • the charging cut-off voltage V s for controlling the charging of the lithium battery satisfies the following formula:
  • V s cV b +a ⁇ c ⁇ K+b ⁇ c ⁇ (dQ/dV)/(3.6 ⁇ CA), wherein, when the lithium battery exhibits long cycle life characteristics, the V s , the negative electrode of the lithium battery just does not precipitate simple lithium, and V s ⁇ V h ;
  • V h is the charging upper limit voltage that the lithium battery can withstand
  • CA is the nominal capacity when the lithium battery is discharged at 0.33C
  • V b is that the negative electrode of the lithium battery does not precipitate lithium element under the real-time charging capacity
  • K is the real-time DC internal resistance of the lithium battery in the charging process and the internal resistance growth rate of the DC internal resistance of the factory
  • dQ/dV is the real-time differential value of the charging power and charging voltage of the lithium battery
  • c is the calibration factor of the real-time cell temperature of the lithium battery during charging
  • a is the calibration factor of K
  • b is the calibration factor of (dQ/dV)/CA.
  • V s is also the battery voltage when the negative electrode of the lithium battery is charged to the point where lithium is just precipitated (that is, the positive electrode of the battery is charged to the above-mentioned first threshold).
  • the above V h is also the battery voltage when the lithium battery is fully charged (that is, the positive electrode is charged to 100% SOC), that is, the cut-off voltage corresponding to the maximum capacity that the positive electrode can exert, or called the rated voltage.
  • the capacity C s of the lithium battery at the voltage V s is smaller than the capacity C h of the lithium battery at the voltage V h .
  • the lithium battery when the lithium battery is required to exhibit long cycle life characteristics, under the charging cut-off voltage of V s , the negative electrode of the lithium battery does not precipitate lithium simple substance. At this time, the lithium battery is not fully charged, only charged To a lower SOC, the volume expansion suffered by the negative terminal is relatively weak, and the side reaction with the electrolyte is relatively weak. Therefore, the lithium battery can perform more charge and discharge cycles, that is, it has a longer cycle life.
  • the charging cut-off voltage of the lithium battery is V h
  • the negative electrode generally has a lithium-silicon alloy and a certain amount of lithium element at the voltage of V h .
  • the active lithium element is continuously consumed.
  • the negative electrode of the battery V s is adjusted up according to the above formula when charging until there is just lithium elemental precipitation, which can narrow the gap between V s and V h , and can ensure that the battery uses V s as the charging cut-off voltage without compromising the long cycle life of the battery.
  • the energy density of the battery which in turn enables the powered vehicle using the lithium battery to exhibit a longer cruising range.
  • the charging cut-off voltage of the lithium battery is V h when it is charged for the i-th time
  • the charging cut-off voltage of the lithium battery when it is charged for the i+1 time The voltage V s should be increased according to the above formula; in addition, if the lithium battery has never been charged with the charge cut-off voltage V h , the above V s remains unchanged when the lithium battery is required to exhibit long cycle life characteristics.
  • V b , dQ/dV, K, a, b, c can be obtained through the charging control equipment of the lithium battery, such as the battery management system (Battery Management System, BMS), and the BMS can monitor the status information of the battery, such as monitoring the battery Charging current, real-time charging voltage, temperature, internal resistance, etc.
  • BMS Battery Management System
  • dQ/dV represents the amount of electricity charged at a unit voltage, which can be calculated based on the current charging capacity point data (charging current and charging voltage) and the previous charging capacity point data in the same charging process learned by the battery BMS.
  • V b is the reference voltage of the lithium battery under the real-time charging capacity of the negative electrode that does not precipitate lithium .
  • the real-time battery voltage (ie, the voltage reference value) at any charging capacity is V b .
  • the V b at each charge capacity can be pre-stored in the BMS.
  • Parameters a, b, c are empirical values, dimensionless.
  • the value range of a is 0.02-1.2
  • the value range of b is -0.008--0.15
  • the value range of c is 0.8-1.5.
  • the parameters a, b, and c can be used to obtain the corresponding calibration factors corresponding to the current state information of the battery according to the established correspondence between the battery state information and the corresponding calibration factors. It should be noted that in the above formula, a, b, c, and K are all obtained for the same time point/time period in the same charging process of the lithium battery.
  • lithium batteries generally have a rated operating temperature range, such as between 10°C-40°C. If the temperature of the lithium battery is higher, such as above the threshold temperature (such as 42°C), such as 45°C, the value of c should be 0.92, so that the adjusted charging cut-off voltage V s is better, which can limit the phenomenon of lithium precipitation occurrence, and can fully utilize the capacity before lithium analysis.
  • the BMS may pre-store the correspondence between the real-time cell temperature of the battery during charging and the temperature calibration factor c, and based on the correspondence, the temperature calibration factor of the lithium battery cell at the current charging temperature may be known. Table 1A below shows the correspondence table between the cell temperature and the temperature calibration factor.
  • the above internal resistance growth rate K is the growth ratio between the collected real-time DC internal resistance of the lithium battery and its factory DC internal resistance (also referred to as "DC internal resistance in the initial state").
  • R b the real-time internal resistance collected at a certain charging time point is recorded as R c , then the growth rate K of the internal resistance is (R c -R b )/R b .
  • the correspondence between the internal resistance growth rate K and the internal resistance calibration factor b may be pre-stored in the mobile terminal.
  • the following table 1B shows the corresponding relationship between the internal resistance growth rate and the internal resistance calibration factor.
  • the charging method of the lithium battery includes: when the charging voltage of the lithium battery reaches V s , if the lithium battery is required to exhibit high energy density characteristics, then continue charging the lithium battery to the V h ; If the lithium battery is not required to exhibit high energy density characteristics (that is, to maintain long cycle life characteristics), then stop charging the lithium battery.
  • whether the lithium battery needs to exhibit high energy density characteristics can be remotely turned on by the user during the charging process, and the mode selection setting can also be performed before charging. The following will explain in detail when the powered vehicle is introduced.
  • the embodiment of the present application also provides a powered vehicle 300, the battery system of the powered vehicle includes at least one first battery unit, and the first battery unit includes a plurality of lithium battery.
  • the battery system of the powered vehicle can communicate with the vehicle drive unit 301 .
  • the powered vehicle 300 may be a pure electric vehicle, or a hybrid electric vehicle.
  • the vehicle drive unit 301 may be an electric motor.
  • the battery system of the powered vehicle 300 only includes the first battery unit 1 .
  • the first battery unit 1 may be a "no module” battery pack, or a “module” battery pack.
  • the first battery unit 1 is a "modular” battery pack, a plurality of lithium batteries 100 can be connected in series, parallel or a combination thereof to form a modular battery pack.
  • the first battery unit 1 includes a plurality of lithium batteries 100 and a first charging control device 110 .
  • the first charging control device 110 is used to supervise the status information of each lithium battery, such as voltage, current, internal resistance, temperature, etc., and control the charging status of each lithium battery 100 .
  • the first charging control device 110 may specifically be the BMS (Battery Management System, battery management system) of the first battery unit 1, or may be used as a separate module to be electrically connected to the BMS of the second battery unit (in this case, both Can be connected via CAN bus).
  • BMS Battery Management System, battery management system
  • the lithium battery can be controlled to be fully charged or charged at a lower SOC when charging the lithium battery according to the actual cruising range requirements of the powered vehicle, which can meet the requirements when necessary.
  • the demand for long battery life can also meet the long cycle life under the requirement of ensuring short battery life.
  • the first charging control device 110 is used to control the charging cut-off voltage of the lithium battery to be V s when the powered vehicle is to run in the first mode; the first charging control device is also used When the powered vehicle will run in the second mode, control the charging cut-off voltage when charging the lithium battery to be V h , and V s ⁇ V h , under the V s , the negative electrode of the lithium battery is not Precipitating simple lithium, the lithium battery has a long cycle life characteristic, V h is the charging upper limit voltage that the lithium battery can withstand; wherein, in the first mode, the first battery unit is used as the power The range provided by the vehicle is less than the range provided by the first battery unit for the powered vehicle in the second mode.
  • the first mode may be called a short battery life mode
  • the second mode may be called a long battery life mode.
  • the above-mentioned first mode is a mode in which powered vehicles are used more frequently, such as daily short- and medium-distance commuting to and from get off work; the second mode has a lower operating frequency and usually needs to be activated during long-distance driving during holidays.
  • the first battery unit 1 is controlled during the charging process of the powered vehicle, and the above-mentioned lithium battery is not charged to the charging upper limit voltage but charged to a lower SOC, which can ensure that the negative electrode of the battery does not precipitate lithium. Simple substance, thereby benefiting the lithium battery of the first battery unit to exert its characteristics of long cycle life.
  • the above-mentioned lithium battery When the power vehicle needs to run in the long-endurance mode, the above-mentioned lithium battery is fully charged to ensure that the first battery unit exhibits high energy density characteristics. In this way, although the cycle life of the lithium battery in the "long battery life mode" is not as long as its cycle life in the "short battery life mode", due to the low frequency of use of the "long battery life mode", the setting of the above-mentioned protective layer makes the lithium battery 100 in the "short battery life mode". In the state of high energy density, the side reaction with the electrolyte is suppressed, and the risk of lithium precipitation piercing the diaphragm is reduced, so that the first battery unit of the power vehicle can have more low-SOC cycles and more times of full charge. cycle and unleash long range for the vehicle when it needs it.
  • the cruising range of the powered vehicle in the first mode can be 400-800km, and the cruising range of the powered vehicle in the second mode can be 800-1200km.
  • the above-mentioned first mode may also be referred to as “everyday mode", which is the mode most commonly used by powered vehicles.
  • the second mode which may also be referred to as “holiday mode,” is the occasional mode used by the powered vehicle.
  • the default charging cut-off voltage for charging the lithium battery 100 is V s .
  • the first charging control device 110 receives an instruction for the power vehicle 300 to activate the second operating mode, control the process of charging the lithium battery The charging cut-off voltage is V h .
  • the "instruction for enabling the second operating mode of the powered vehicle” can be set for mode selection before charging, or can be turned on remotely during charging.
  • the instruction can be issued by the user of the powered vehicle pressing the mode button on the vehicle operation panel, or realized by the user remotely operating an intelligent terminal capable of communicating with the vehicle (for example, when the charging voltage of the lithium battery is close to V s , through the vehicle's
  • the intelligent network connection system pushes information such as "whether to turn on the long battery life mode" for the user).
  • the V s should be satisfy the following formula:
  • V s cV b +a ⁇ c ⁇ K+b ⁇ c ⁇ (dQ/dV)/(3.6 ⁇ CA),
  • CA is the nominal capacity of the lithium battery when it is discharged at 0.33C
  • Vb is the reference voltage of the negative electrode of the lithium battery under the real-time charging capacity without precipitation of lithium element
  • K is the lithium battery at the i+1th
  • dQ/dV is the real-time differential value of the charging power and charging voltage of the lithium battery in the i+1th charging process
  • c is The calibration factor of the real-time cell temperature during the i+1 charging process of the lithium battery
  • a is the calibration factor of K
  • b is the calibration factor of (dQ/dV)/CA.
  • the main purpose of adjusting V s is to narrow the gap between V s and V h , so as to ensure that the cruising range of the lithium battery is as long as possible under the long service life.
  • the battery system of the power vehicle 300 further includes at least one second battery unit 2, wherein the second battery unit 2 includes a plurality of second single cells 200, and the second single cells
  • the negative active material of 200 includes graphite and/or silicon-based materials.
  • the silicon-based material includes one or more of elemental silicon, silicon oxide, silicon-based alloy and silicon-carbon composite material.
  • the second single battery 200 is a conventional lithium battery that does not use metallic lithium (lithium element and/or lithium-silicon alloy) as the negative electrode active material, and its energy density is lower than that of the lithium battery 100 provided in the first aspect of the present application.
  • the second battery unit 2 may be a "moduleless" battery pack, or a “modular” battery pack, which may not only include a plurality of second single cells 200, but also A second charging control device 210 for monitoring the charging of the second single battery 200 is included.
  • the second charging control device 210 may specifically be the BMS of the second battery unit 2, or may be an independent module electrically connected to the BMS of the second battery unit.
  • the second charge control device 210 can also be integrated with the above-mentioned first charge control device 110 in the same controller.
  • the powered vehicle 300 operates in the first mode, and only the second battery unit 2 supplies power for the powered vehicle 300; the powered vehicle 300 operates in the second mode, powered by the first battery unit 1 and the second battery Units 2 jointly supply power to the powered vehicle 300, or only the first battery unit 1 supplies power to the powered vehicle 300; wherein, the cruising range of the powered vehicle in the first mode is smaller than the cruising range in the second mode .
  • the first charging control device 110 is used to control the charging of the first battery unit 1 when it is known that the powered vehicle will run in the second mode before or during charging the lithium battery 100 of the first battery unit 1.
  • the charge cut-off voltage when the lithium battery 100 is charged is the aforementioned V h . That is, when charging the lithium battery 100, it can be fully charged.
  • the first charging control device 110 is used to know that the powered vehicle will operate in the second mode before or during charging the lithium battery 100 of the first battery unit 1, and in this second mode the first battery
  • the charging cut-off voltage when charging the lithium battery 100 of the first battery unit 1 can also be controlled to be the above-mentioned V s .
  • the cruising range of the vehicle in the second mode is less than the cruising range provided by the second battery unit 2 and the first battery unit 1 charged to V h .
  • the power vehicle 300 does not need a particularly long cruising range (such as using the vehicle for commuting)
  • only the second battery unit 2 with low energy density can be used to provide power for the vehicle, so that the number of times the vehicle can withstand charging and discharging is relatively small. more, longer service life; when the vehicle occasionally needs a long mileage (such as using the vehicle for long-distance travel on holidays), the first battery unit 1 and the second battery unit 2 can be used to provide power for the vehicle together or only by The first battery unit 1 provides power for the vehicle, so that the vehicle can obtain more sufficient power, and can selectively achieve the purpose of long battery life without sacrificing the overall cycle life.
  • the power vehicle can selectively use different battery units of the battery system according to different cruising ranges, so that the battery units with low frequency of use and high energy density in the power vehicle can exhibit a longer cycle life, so that the overall battery
  • the system takes into account both long service life and long battery life.
  • the positive electrode active material ternary NCM 622 of 960g, the binding agent PVDF of 30g, the acetylene black conductive agent of 5g, the carbon fiber conductive agent of 5g are joined in the solvent NMP (nitrogen methyl pyrrolidone) of 2000g, then stir in the vacuum mixer , forming a stable and uniform cathode slurry;
  • NMP nitrogen methyl pyrrolidone
  • Slit coating equipment is used to uniformly and intermittently coat the above positive electrode slurry on both sides of the aluminum foil (the size of the aluminum foil is: width 160mm, thickness 16 ⁇ m); A positive electrode material layer with a thickness of 135 ⁇ m was formed on the aluminum foil to obtain a positive electrode sheet. Afterwards, the positive electrode sheet is cut into a rectangular electrode sheet with a size of 48mm*56mm, and the tab is spot-welded at its position in the width direction.
  • a First add 1000g of silica powder to 2000g of water, then add 50g of polyacrylic acid (PAA) binder and 20g of acetylene black conductive agent, and stir vigorously until a uniform and stable negative electrode slurry is formed.
  • PAA polyacrylic acid
  • the coating equipment evenly and intermittently coats the negative electrode slurry on both sides of the copper foil (the size of the copper foil is: width 160mm, thickness 8 ⁇ m); A silicon oxide negative electrode material layer with a thickness of 60 ⁇ m was formed on the foil to obtain a negative electrode sheet SA1.
  • the above-mentioned SA2 negative electrode sheet is attached to the lithium film (thickness of the lithium film is 15 ⁇ m) on the PET release film, so that the protection The layer is in contact with the lithium thin film, and under the action of a hot press, all the lithium elements on the lithium thin film are transferred to the negative electrode sheet SA2 to obtain the negative electrode sheet SA3, wherein the negative electrode material layer of the negative electrode sheet SA3 is 78 ⁇ m, and the lithium silicon negative electrode Active materials include lithium silicon alloy and Li2O . Cut the negative electrode sheet SA3 into a rectangular electrode sheet with a size of 49mm*57mm, and spot-weld the tabs at the positions in the width direction to obtain the negative electrode for assembling the battery.
  • the lithium-silicon composite negative electrode active material contains lithium element and lithium-silicon alloy Li 4.4 Si, and in the lithium-silicon composite negative electrode active material, the molar ratio of lithium element is 23%, and the molar ratio of lithium-silicon alloy Li 4.4 Si is 71%.
  • the lithium battery of Example 1 of the present application was subjected to a charge-discharge cycle test by the following method.
  • the lithium battery of Example 1 was subjected to a charge-discharge cycle test on a LAND CT 2001C secondary battery performance testing device at a temperature of 25 ⁇ 1°C.
  • the steps of the first conventional low SOC cycle are as follows: put aside for 10 minutes; first charge with a constant current of 0.2C to a charge cut-off voltage of 3.95V, then charge with a constant voltage to 0.05C; leave for 10 minutes; then discharge with a constant current until the voltage is 3.0 V, that is, one regular low SOC cycle. Repeat this step for 30 regular low SOC cycles.
  • the steps of the high-energy cycle are as follows: leave it on hold for 10 minutes; first charge it at a constant current of 0.2C to a voltage of 4.25V, then charge it at a constant voltage to 0.05C; leave it for 10 minutes; then discharge it at a constant current to 3.0V, which is a high-energy cycle.
  • a high-energy cycle is performed every 30 regular cycles.
  • V s cV b +a ⁇ c ⁇ K+b ⁇ c ⁇ (dQ/dV)/(3.6 ⁇ CA) to verify the charging cut-off voltage of the next conventional low-SOC cycle.
  • the cycle is terminated, and the number of cycles n is the cycle life of the lithium battery. Record the capacity retention rate under the number of cycles n, and use the ratio of the energy density of the battery under the number of cycles n to the first energy density as the energy retention rate of the lithium battery.
  • a lithium battery which differs from Example 1 in that: in step (3), 800g of silicon powder is used to replace silicon oxide powder, and the thickness of the lithium film coated on the PET release film is 12 ⁇ m.
  • the molar ratio of the lithium element is 24%
  • the molar ratio of the lithium-silicon alloy Li 4.4 Si is 76%
  • Example 2 The lithium battery in Example 2 was charged according to the charging and discharging system provided in Example 1.
  • a lithium battery the difference from Example 1 is that in step (3), 800g of silicon powder is used to replace silicon oxide powder, and the thickness of the lithium film coated on the PET release film is 10 ⁇ m.
  • the molar ratio of the lithium element is 18%, and the molar ratio of the lithium-silicon alloy Li 4.4 Si is 82%.
  • the lithium battery of Example 3 was charged according to the charging and discharging system provided in Example 1.
  • a lithium battery the structure of which is the same as that of Example 3, the difference being that the first conventional low SOC cycle in Example 3 is changed from "0.2C constant current charging to a charge cut-off voltage of 3.95V" to a charge cut-off voltage of 4.0 V.
  • a kind of lithium battery its difference with embodiment 1 is: in step (3), the negative electrode sheet SA1 that makes is directly used as the negative electrode sheet DS1 of assembling comparative example 1 lithium battery, and the negative electrode of embodiment 1 does not have lithium metal; Step In (2), the electrolyte solvent is an ester solvent, specifically a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) with a volume ratio of 4:6.
  • the electrolyte solvent is an ester solvent, specifically a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) with a volume ratio of 4:6.
  • the charging and discharging cycle test method of the lithium battery prepared in Comparative Example 1 is as follows: take 5 lithium batteries each, and charge and discharge the battery at 0.2C on the LAND CT2001C secondary battery performance testing device under the condition of 25 ⁇ 1°C test. The steps are as follows: put it on hold for 10 minutes, first charge it with a constant current of 0.2C until the charging cut-off voltage is 4.2V, then charge it with a constant voltage of 4.2V to a cut-off of 0.05C; put it aside for 10 minutes, and then discharge it at a constant current to 3.0V, which is one charge and discharge cycle.
  • a kind of preparation of lithium battery its difference with embodiment 1 is: in step (3), do not form protective layer on negative electrode sheet SA1, but carry out negative electrode sheet SA1 and the lithium thin film that is covered on PET release film Thermal compression bonding, the obtained negative electrode sheet DS2 was assembled to obtain the lithium battery of Comparative Example 2.
  • the battery was tested for energy density (testing battery volume and discharge energy) and cycle life.
  • the test results are shown in Table 2.
  • the lithium battery provided by the embodiment of the present application has the characteristics of high energy density and long cycle life at the same time.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Composite Materials (AREA)
  • Transportation (AREA)
  • Power Engineering (AREA)
  • Sustainable Energy (AREA)
  • Mechanical Engineering (AREA)
  • Sustainable Development (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Inorganic Chemistry (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Secondary Cells (AREA)

Abstract

本申请提供了锂电池及其制备方法、充电方法和动力车辆，锂电池包括正极片、负极片及位于正极片与负极片之间的隔膜和电解液，其中，负极片的负极材料层中含有锂硅复合负极活性材料，负极材料层的表面具有保护层或者锂硅复合负极活性材料的表面具有保护层，其中，保护层包括聚合物基体和锂盐；在锂电池完全充满电的状态下，锂硅复合负极活性材料含有锂单质和锂硅合金Li 4.4Si，且锂单质在锂硅复合负极活性材料中的摩尔占比为15％-95％。

Description

锂电池及其制备方法、充电方法和动力车辆
优先权信息
本申请请求于2021年06月29日向中国国家知识产权局提交的、专利申请号为202110730852.6、申请名称为“锂电池及其制备方法、充电方法和动力车辆”的中国专利申请的优先权，并且其全部内容通过引用结合在本公开中。
技术领域
本申请涉及锂电池技术领域，具体涉及一种锂电池及其制备方法、充电方法和动力车辆。
背景技术
锂电池已经在手机、笔记本电脑等便携式电子产品及新能源汽车等领域得到广泛应用。目前，商用的锂电池一般采用石墨作为负极活性材料，且为保证电池循环过程中锂离子在正负极中高效的脱嵌，石墨负极的有效容量一般大于正极(即，电池的N/P比一般大于1)，以防止在负极析出锂枝晶而影响循环性能，但这使得电池中负极活性材料的体积及重量占比较高，限制了锂离子电池能量密度的提高，很难超越350mAh/g，已不能满足人们日益增长的续航和待机需求。
而锂金属具有较高的理论比容量(3861mAh/g)和最负的电化学电势(-3.04V，相对于标准氢电极)，被认为是下一代高能量密度电池负极材料的最佳选择。目前，有些机构采用体积占比远低于传统负极的锂金属，甚至采用无锂负极(Lithium free)，如CN201911075192.1，尽管这样可以获得高能量密度的锂电池，但所得电池的循环性能较差，阻碍了高能量密度金属锂电池的商业化进程。
发明内容
有鉴于此，本申请提供一种锂电池及其制备方法、充电方法和动力车辆，以解决目前金属锂电池的循环性能较差的问题。
具体地，第一方面，本申请提供了一种锂电池，包括正极片、负极片及位于所述正极片与负极片之间的隔膜和电解液，其中，所述负极片的负极材料层中含有锂硅复合负极活性材料，所述负极材料层的表面具有保护层或者所述锂硅复合负极活性材料的表面具有保 护层，所述保护层包括聚合物基体和锂盐；在所述锂电池完全充满电的状态下，所述锂硅复合负极活性材料含有锂单质和锂硅合金Li 4.4Si，且所述锂单质在所述锂硅复合负极活性材料中的摩尔占比为15％-95％。
本申请第一方面提供的锂电池由于包含了上述锂硅复合负极活性材料，使得所述锂电池的能量密度高、循环寿命长、安全性能高。
第二方面，本申请还提供了一种锂电池的制备方法，包括以下步骤：
将含硅基材料、导电剂和粘结剂的混合浆料涂布在负极集流体上，经干燥、辊压后，在所述负极集流体上形成硅基材料层；
在手套箱中，将锂薄膜与所述硅基材料层进行热压处理，以使所述锂薄膜的锂元素全部转移到所述硅基材料层中，并与所述硅基材料原位反应形成含锂硅复合负极活性材料的负极材料层，得到负极片；
其中，在所述硅基材料层与锂薄膜进行热压处理之前，在所述硅基材料层的表面形成保护层；或者在形成所述负极材料层之后，在所述负极材料层的表面形成保护层；所述保护层包括聚合物基体和锂盐；
将所述负极片装配成锂电池；其中，在所述锂电池完全充满电的状态下，所述锂硅复合负极活性材料含有锂单质和锂硅合金Li 4.4Si，且所述锂单质在所述锂硅复合负极活性材料中的摩尔占比为15％-95％。
本申请第二方面所述的制备方法，工艺简单，易控制，适用于大规模的工业化制备。
第三方面，本申请还提供了一种前述锂电池的充电方法，包括以下步骤：
在需要所述锂电池发挥出长循环寿命特性的情况下，控制对所述锂电池进行充电的充电截止电压V s满足以下公式：
V s＝cV b+a×c×K+b×c×(dQ/dV)/(3.6×CA)，其中，在所述锂电池发挥出长循环寿命特性的情况下，在所述V s下，所述锂电池的负极不析出锂单质，且V s＜V h；
其中，V h为所述锂电池能耐受的充电上限电压，CA为所述锂电池以0.33C放电时的标称容量，V b为所述锂电池在实时充电容量下负极不析出锂单质的基准电压，K为所述锂电池在充电过程中的实时直流内阻与其出厂直流内阻的内阻增长率，dQ/dV为所述锂电池的充电电量与充电电压的实时微分值，c为所述锂电池在充电过程中的实时电芯温度的校准因子，a为所述K的校准因子，b为(dQ/dV)/CA的校准因子。
本申请第三方面提供的该充电方法，可以保证该锂电池在长寿命下的续航里程尽量长。
第四方面，本申请还提供了一种动力车辆，其电池系统包括至少一个第一电池单元，该 第一电池单元包括多个如本申请第一方面所述的锂电池和第一充电控制设备。
带有该第一电池单元的动力车辆，可根据实际续航里程需要来调控对第一电池单元的各锂电池进行充电的充电截止电压。
附图说明
图1为本申请实施例提供的锂电池的一种结构示意图。
图2为本申请实施例提供的锂电池的放电曲线。
图3为本申请实施例提供的动力车辆的一种结构示意图。
图4为本申请实施例提供的动力车辆的另一种结构示意图。
具体实施方式
以下所述是本申请的示例性实施方式，应当指出，对于本技术领域的普通技术人员来说，在不脱离本申请原理的前提下，还可以做出若干改进和润饰，这些改进和润饰也视为本申请的保护范围。
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行详细说明。
本申请实施例提供了一种锂电池，该锂电池的负极片中包括锂硅复合负极活性材料。本申请一些实施方式中，请参阅图1，锂电池100包括负极片10、正极片20以及位于正极片20和负极片10之间的隔膜30和电解液(未示出)。一般地，负极片10包括负极集流体11和设置在负极集流体11上的负极材料层12，负极材料层12含有锂硅复合负极活性材料，以及可选的导电剂和粘结剂等。类似地，正极片20包括正极集流体21和设置在正极集流体21上的正极材料层22，正极材料层22含有正极活性材料，以及可选的导电剂和粘结剂等。
其中，负极材料层12的表面还带有保护层13(参见图1)，或者所述锂硅复合负极活性材料的表面带有保护层，所述保护层包括聚合物基体和锂盐。保护层可引导锂离子流，控制锂离子在负极片表面均匀沉积，有效抑制负极片10表面的锂枝晶生长及避免其刺穿隔膜引发电池内部短路，且可减少负极与电解液的副反应发生，缓解负极在循环过程中的体积膨胀，提升循环性能和安全性能。
保护层可较好抑制负极析锂造成的循环衰减和电池内部短路问题。其中，所述保护层几乎不溶于电池电解液。具体地，聚合物基体可以包括聚氧化乙烯(polyethylene oxide，PEO)、聚硅氧烷、聚偏氟乙烯、聚甲基丙烯酸甲酯、聚丙烯腈及其衍生物和共聚物等中的一种或多种，但不限于此。所述锂盐具有离子电导能力，可以包括硝酸锂(LiNO 3)、硫化锂(Li 2S)、 氯化锂(LiCl)、溴化锂(LiBr)、碘化锂(LiI)、氟化锂(LiF)、磷酸锂(Li 3PO 4)等中的一种或多种。在一些实施方式中，前述保护层中还可以含有无机填料，以增加锂离子传输通道、提高力学性能等。该无机填料可以是氧化物(如二氧化硅、氧化铝、二氧化钛等)、氢氧化物(如氢氧化铝、氢氧化镁)和盐中的至少一种。
本申请中，所述锂硅复合负极活性材料中含有锂元素和硅元素。在锂电池100完全充满电的状态下，锂硅复合负极活性材料含有锂单质和锂硅合金Li 4.4Si，且所述锂单质在所述锂硅复合负极活性材料中的摩尔占比为15％-95％。
其中，“完全充满电”是指电池正极充电至100％SOC(State of Charge)。此时，电池的正极容量得到充分发挥，电池能量密度很高，并在负极产生了“析锂”，且这部分“析锂”为活性锂，可在负极端发挥容量。由于本申请电池的负极在电池满充时，除了允许正极脱出的活性锂离子以合金型材料的形式储存在负极外，还接受以锂单质形式直接沉积在负极中，因此，本申请制备完成的负极材料层中，锂硅合金材料Li xSi的(0<x≤4.4)的用量较少，进而可显著提升电池的能量密度。此外，配合上述保护层的设置，可抑制电池负极在高能量密度状态下“析锂”与电解液副反应、降低析出锂枝晶刺穿隔膜等风险。因此，本申请实施例的锂电池在具有高能量密度的同时，还具有良好的循环性能、安全性能等。
本申请实施方中，在锂电池100未完全充满电时，如电池正极充电的SOC值低于第一阈值时，所述锂硅复合负极活性材料不含有锂单质。此时，该锂硅复合负极活性材料中的锂硅合金可用化学通式Li xSi表示，0<x≤4.4。其中“第一阈值”是电池充电时负极端刚好有金属锂析出时的正极充电SOC临界值，也即是电池负极的锂硅合金完全嵌满锂离子(即锂硅合金具体为Li 4.4Si，此时也可称电池负极充电至100％SOC)而正极侧的锂离子未全部脱出时的SOC值。
其中，当电池正极充电的SOC低于第一阈值时，电池未析锂，锂电池的能量密度未充分发挥，负极端仅发挥了锂硅合金Li xSi的容量，负极端所承受的体积膨胀也相对较弱、与电解液的副反应较弱。这样，锂电池可在较低的能量密度(仍远高于目前采用石墨作负极的电池的能量密度)下进行较多次数的充放电循环，即具有较长的循环寿命。因此，本申请提供的锂电池能兼顾“长循环寿命”和上述“高能量密度”的特性，且这两种特性可以结合锂电池的电池管理系统进行自由选择，以满足动力车辆全寿命循环需求。
本申请中，在锂电池正极100％SOC充电状态下，锂硅复合负极活性材料具有比例可调的锂金属单质，其摩尔占比在15％-95％的范围内。相应地，根据该锂金属单质的摩尔占比，可相应调控上述第一阈值。可选地，第一阈值也在15％-95％的范围内。参见图2所示的锂 电池放电曲线。图2中，采用锂硅复合负极活性材料的锂电池在放电容量为58mAh时出现放电拐点，该“放电拐点”是指电池放电曲线中dV/dQ的最小值。在此拐点之前，电池的能量密度较高(即，电池电压与电池电量的乘积)，共同发挥锂硅合金Li 4.4Si与锂单质的容量；在此拐点之后，电池的SOC较低，负极侧仅发挥锂硅合金Li xSi的容量，电池的能量密度变低，但电池的循环寿命较长。
可选地，在锂电池100完全充满电的状态下，所述锂硅合金Li 4.4Si在所述锂硅复合负极活性材料中的摩尔占比为5％-85％。在一些实施方式中，在锂电池完全充满电的状态下，锂硅合金Li 4.4Si和锂单质在所述锂硅复合负极活性材料中的摩尔占比之和为100％。换句话说，在锂电池完全充满电的状态下，所述锂硅复合负极活性材料由锂单质和锂硅合金Li 4.4Si组成。此时，所述锂硅复合负极活性材料中仅含有锂元素和硅元素(也即其可由硅单质与金属锂原位压制而成)。
一般地，传统的锂电池(采用石墨或硅作负极)的电池N/P比一般大于1，以防止N/P比小于1时析出锂枝晶、恶劣循环性能等，且电池N/P比大于1时，负极活性材料在整个电池中的体积占比较大，一般在37％以上，例如负极采用石墨时，石墨在整个电池中的体积占比为44％-48％，负极活性材料为硅时，其在电池中的体积占比可达37％-44％。而本申请的锂电池中由于采用了前述满充时含锂单质和Li 4.4Si的锂硅复合负极活性材料，该锂电池的N/P小于1，这样该负极活性材料其在锂电池中的体积占比(低于37％，例如可在20％以下)和质量占比可较小，从而可显著提升电池的能量密度，增加其续航能力；且基于前述保护层的存在，可在负极“析锂”时，抑制锂单质与电解液的副反应及其无序生长刺穿隔膜，进而可使电池的循环能力也较优。
需要说明的是，本申请中锂电池100的N/P比小于1，具体是指，前述锂硅复合负极活性材料的容量与正极活性材料的容量之比小于1。其中，N/P比对应的锂硅复合负极活性材料的容量是指负极刚好嵌锂至形成锂硅合金Li 4.4Si的形式且不析出单质锂时(此时正极的锂离子还未完全脱出)的负极容量，也即是上述第一阈值下对应的负极容量。
可选地，锂电池100中，前述锂硅复合负极活性材料与正极活性材料的体积比为0.1375-0.825。正极片20的厚度与负极片10的厚度的比值为8:1-4:3。这样可更好地保证锂电池的N/P比小于1，利于提升电池的能量密度。
锂电池100的电解液中一般含有溶剂和第二锂盐。本申请实施方式中，锂电池100的电解液中的溶剂为非碳酸酯类溶剂。具体地，所述电解液中的溶剂包括醚类溶剂，具体可包括未卤代醚类溶剂和氟代醚类溶剂中的至少一种。其中，碳酸酯类溶剂与金属锂负极之 间的副反应速度快、易在电池负极生成尖尖的锂枝晶而刺穿电池隔膜、引起电池自燃。而醚类溶剂与金属锂的兼容性好，其与锂金属之间的副反应远低于碳酸酯类溶剂与锂金属之间的副反应，可以有效地抑制循环过程的活性锂的消耗，同时提高锂离子沉积的均匀性和致密性，避免形成尖锐的锂枝晶而刺穿电池隔膜引起安全风险。
可选地，未卤代醚类溶剂可以选自乙二醇二甲醚、乙二醇二乙醚、乙二醇二丙醚、乙二醇二丁醚、二乙二醇二甲醚、三乙二醇二甲醚、四乙二醇二甲醚、二丙二醇二甲醚、三丙二醇单甲醚、二甘醇二甲醚、二甘醇二乙醚、二甘醇二丁醚、三甘醇二甲醚、四甘醇二甲醚等中的一种或多种，但不限于此。可选地，氟代醚类溶剂可以选自1,1,2,2-四氟乙基乙醚、1,1,2,2-四氟乙基-2,2,3,3-四氟丙基醚、六氟异丙基乙醚、四氟乙基-四氟丙基醚、2,2,2-三氟乙基醚、1,1,2,2-四氟乙基-2,2,2-三氟乙基醚、二氟甲基-2,2,3,3-四氟丙基醚、2,2,3,3,3-五氟丙基甲醚、1,1,2,3,3,3-六氟丙基乙醚、1,1,2,3,3,3-五氟丙基二氟甲醚、1,1,2,2-四氟乙基-2,2,3,3-四氟丙基醚、1H,1H,5H-八氟戊基-1,1,2,2-四氟乙基醚和双(2,2,2-三氟乙基)醚等中的一种或多种，但不限于此。
其中，电解液中的第二锂盐可以选自双氟磺酰亚胺锂(LiN(SO 2F) 2)、二(三氟甲基磺酰)亚胺锂(Li(CF 3SO 2) 2N)、二(全氟乙基磺酰)亚胺锂(Li(C 2F 5SO 2) 2N)、二草酸硼酸锂(LiB(C 2O 4) 2，LiBOB)、三氟甲基磺酸锂(LiCF 3SO 3)、全氟丁基磺酸锂(LiC 4F 9SO 3)、三(三氟甲基磺酰)甲基锂LiC(CF 3SO 2) 3等中的一种或多种，但不限于此。
可选地，所述锂硅复合负极活性材料通过硅基材料与金属锂原位压制而成。其中，硅基材料可以包括不限于是硅单质、硅氧化物、硅基非锂合金(如硅锗合金、硅镁合金、硅铜合金、硅铁合金等)或其他硅化合物等。
在一些实施方式中，含所述锂硅复合负极活性材料的负极材料层12是通过锂薄膜(如锂箔或附在离型膜上的锂薄膜)与含硅基材料的初始负极材料层原位热压而成。此时，锂薄膜的锂元素可全部转印到初始负极材料层中，并与硅基材料原位反应形成所述锂硅复合负极活性材料。在另一些实施方式中，所述锂硅复合负极活性材料通过金属锂粉与硅基材料的混合物(可以是湿浆料或干粉料)原位压制而成。此时，上述负极材料层12可以通过将硅基材料与锂粉的混合浆料涂布在负极集流体上，经干燥、压制处理后，在所述负极集流体上原位反应形成含锂硅复合负极活性材料的负极材料层；或者，将金属锂粉与硅基材料的混合物原位压制形成的锂硅复合负极活性材料经涂覆、干燥、压片后再制成负极片。
其中，当需要形成表面具有保护层的负极材料层12时，可以通过将附在离型膜上的锂薄膜与到表面带保护层的硅基材料层(该硅基材料层即为前述初始负极材料层，其含有硅 基材料及可选的粘结剂、导电剂)进行原位热压。在本申请其他实施方式中，表面具有保护层的负极材料层还可以通过在形成含锂硅复合负极活性材料的负极材料层后，再在其表面形成保护层。
本申请中，上述负极集流体11、正极集流体21独立地选自金属单质箔材或合金箔材。示例性的，负极集流体11可以具体为铜箔、正极集流体21可以具体为铝箔。正极活性材料可以是磷酸铁锂、磷酸锰锂、磷酸锰铁锂、磷酸钒锂、磷酸钴锂、钴酸锂、锰酸锂、镍锰酸锂、镍钴锰酸锂(NCM)、镍钴铝酸锂(NCA)等中的至少一种。负极片10与正极片20中的粘结剂和导电剂采用现有常规材料即可。例如，导电剂可采用导电炭黑(如乙炔黑、科琴黑)、碳纳米管、碳纤维、石墨和炉黑中的一种或多种。而粘结剂可独立地采用丁苯橡胶(SBR)、聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、聚乙烯醇(PVA)、聚丙烯腈(PAN)、聚酰亚胺(PI)、聚丙烯酸(PAA)、聚烯烃(如聚乙烯、聚丙烯等)、羧甲基纤维素钠(CMC)和海藻酸钠等中的一种或多种。
本申请实施例提供的锂电池，由于包含了上述锂硅复合负极活性材料及保护层，该锂电池中锂硅复合负极活性材料的占比可较低，利于提升电池的能量密度，且电池在低SOC状态下负极不析锂，表现出较优的循环寿命；高SOC状态下电池的能量密度很高，且析锂的副作用因保护层的设置而得到缓解，因此，本申请实施例的锂电池可以兼顾高能量密度、长循环寿命、高安全性等。
第二方面，本申请实施例提供了上述锂电池的一种制备方法，包括以下步骤：
将含硅基材料、导电剂和粘结剂的混合浆料涂布在负极集流体上，经干燥、辊压后，在所述负极集流体上形成硅基材料层；
在手套箱中，将锂薄膜与所述硅基材料层进行热压处理，以使所述锂薄膜的锂元素全部转移到所述硅基材料层中，并与所述硅基材料原位反应形成含锂硅复合负极活性材料的负极材料层，得到负极片；
其中，在所述硅基材料层与锂薄膜进行热压处理之前，在所述硅基材料层的表面形成保护层；或者在形成所述负极材料层之后，在所述负极材料层的表面形成保护层；所述保护层包括聚合物基体和锂盐；
将所述负极片装配成锂电池；其中，在所述锂电池完全充满电的状态下，所述锂硅复合负极活性材料含有锂单质和锂硅合金Li 4.4Si，且所述锂单质在所述锂硅复合负极活性材料中的摩尔占比为15％-95％。
其中，所述硅基材料可以包括不限于是硅单质、硅氧化物、硅基非锂合金(如硅锗合 金、硅镁合金、硅铜合金、硅铁合金等)或其他硅化合物(如含氟氧化硅、六氟硅酸锂、碳化硅、硼化硅)等。当所用硅基材料中含有除硅以外的其他元素(如氧、氟时)，该锂硅复合负极活性材料也相应地含有这些元素。示例性的，当硅基材料为硅单质时，在电池的SOC低于第一阈值时，所述锂硅复合负极活性材料仅含有锂硅合金Li xSi；在锂电池完全充满电时，所述锂硅复合负极活性材料仅由锂单质和Li 4.4Si组成。示例性的，当硅基材料为硅氧化物时，在电池的SOC低于第一阈值时，所述锂硅复合负极活性材料含有锂硅合金Li xSi和Li 2O、Li 2SiO 3等；在锂电池完全充满电时，所述锂硅复合负极活性材料含有Li 4.4Si、锂单质和Li 2O、Li 2SiO 3等。
本申请实施方式中，在将表面带保护层的硅基材料层与锂薄膜进行原位热压时，在热压下，保护层及硅基材料层呈现出多孔结构，锂薄膜的锂元素可进入到硅基材料层中，并与硅基材料原位反应形成所述锂硅复合负极活性材料，最终形成带保护层的负极材料层，该负极材料层中含有锂硅复合负极活性材料。
其中，与所述硅基材料层进行热压处理的锂薄膜可以直接是锂箔，或者是附在离型膜上的锂薄膜，且优选是附在离型膜上的锂薄膜，以避免锂薄膜与压制设备直接接触带来锂元素的损失。
其中，所述保护层可以通过液相涂覆、气相沉积法或电沉积法等形成在所述负极材料层上。
其中，“将所述负极片装配成锂电池”具体包括：将正极极片、隔膜和所述负极片依次层叠放置，制成裸电芯；将所述裸电芯置于电池壳体中，并注入电解液，将所述电池壳体密封后，得到锂电池。
本申请实施例提供的锂电池的制备方法，工艺简单，易控制，适用于大规模的工业化制备上述可兼顾高能量密度和长循环寿命的锂电池。
第三方面，本申请实施例提供了上述锂电池的一种充电方法，包括以下步骤：
在需要所述锂电池发挥出长循环寿命特性的情况下，控制对所述锂电池进行充电的充电截止电压V s满足以下公式：
V s＝cV b+a×c×K+b×c×(dQ/dV)/(3.6×CA)，其中，在所述锂电池发挥出长循环寿命特性的情况下，在所述V s下，所述锂电池的负极刚好不析出锂单质，且V s＜V h；
其中，V h为所述锂电池能耐受的充电上限电压，CA为所述锂电池以0.33C放电时的标称容量，V b为所述锂电池在实时充电容量下负极不析出锂单质的基准电压，K为所述锂电池在充电过程中的实时直流内阻与其出厂直流内阻的内阻增长率，dQ/dV为所述锂电池的充电电 量与充电电压的实时微分值，c为所述锂电池在充电过程中的实时电芯温度的校准因子，a为所述K的校准因子，b为(dQ/dV)/CA的校准因子。
需要说明的是，上述V s也是所述锂电池的负极充至刚好有锂单质析出时(即，电池正极充至上述第一阈值)的电池电压。上述V h也是所述锂电池完全充满电(即，正极充电至100％SOC)下的电池电压，即，正极可发挥的最大容量对应的截止电压，或称为额定电压。显然地，所述锂电池在电压为V s下的容量C s小于所述锂电池在电压为V h下的容量C h。
其中，在需要所述锂电池发挥出长循环寿命特性时，在充电截止电压为V s下，所述锂电池的负极不析出锂单质，此时，锂电池并未完全充满电，仅被充电至较低SOC，负极端所承受的体积膨胀也相对较弱、与电解液的副反应较弱。因此，该锂电池可进行较多次数的充放电循环，即具有较长的循环寿命。而当需要锂电池发挥出高能量密度特性时，所述锂电池的充电截止电压为V h，在该V h电压下负极一般存在锂硅合金及一定量的锂单质。
因此，随着以充电截止电压V h对锂电池进行充电次数(即，满充)的增加，活性锂单质不断消耗，当再以充电截止电压V s对锂电池进行充电时，将该电池负极充电至刚好有锂单质析出时的V s根据上述公式调高，这样可缩小V s与V h的差距，可保证在不损害电池长循环寿命的情况下，提高电池以V s作充电截止电压的电池的能量密度，进而可使使用该锂电池的动力车辆展现出较长的续航里程。举例来说，当锂电池进行第i次充电时的充电截止电压为V h，则接下来在需要锂电池发挥出长循环寿命特性时，对锂电池进行第i+1次充电时的充电截止电压V s应根据上述公式调高；另外，若该锂电池从未以充电截止电压V h进行充电时，则在需要锂电池发挥出长循环寿命特性时，上述V s保持不变。
对于装配好的电池来说，其CA、V h是一定值。上述参数V b、dQ/dV、K、a、b、c可通过锂电池的充电控制设备，如电池管理系统(Battery Management System，BMS)获知，BMS可监控电池的状态信息，如监测电池的充电电流、实时充电电压、温度、内阻等。这些信息可具体通过BMS的采集模块采集获得，并可以存储在BMS的控制器中。其中，dQ/dV代表单位电压下充入的电量，可根据由电池BMS获知的同一充电过程中，当前充电容量点数据(充电电流和充电电压)与上一个充电容量点数据计算得到。
V b为锂电池在实时充电容量下负极不析出锂单质的基准电压，V b可根据锂硅复合负极活性材料在不析出锂单质的情况下的容量进行标定获得，更进一步地，可根据对正极最高的设计容量搭配过量10％的硅基负极的电池(即，N/P＝1.1的前述锂电池)进行充电，获得其充电容量与充电过程中实时电池电压的曲线，根据该曲线可获得在任一充电容量下的实时电池电压(即，电压基准值)，即为V b。各充电容量下的V b可以预先存在BMS中。
参数a、b、c为经验值，无量纲。可选地，a的取值范围是0.02-1.2，b的取值范围是-0.008～-0.15，c的取值范围是0.8-1.5。参数a、b、c可以根据建立的电池状态信息与相应校准因子之间的对应关系，获知电池在当前状态信息下对应的相应校准因子。需要注意的是，上述公式中，a、b、c、K均是针对锂电池在同一充电过程中的同一时间点/时间段获得。
举例来说，锂电池一般具有额度的工作温度范围，例如介于10℃-40℃之间。如果锂电池的温度较高，如在阈值温度(如42℃)以上，如45℃，则c的取值应变0.92，以使调整后的充电截止电压V s更优，既能限制析锂现象的发生，又能充分发挥析锂之前的容量。示例性的，BMS中可以预先存储有电池在充电过程中的实时电芯温度与温度校准因子c的对应关系，基于该对应关系可以获知该锂电池电芯在当前充电温度下的温度校准因子。下表1A示出了电芯温度与温度校准因子的对应关系表。
表1A
电芯温度(℃) 电芯温度校准因子c
-10 1.3
0 1.28
10 1.15
20 1.13
25 1.1
30 1
40 0.95
45 0.92
上述内阻增长率K为采集到的锂电池的实时直流内阻与其出厂直流内阻(也可称为“初始状态下的直流内阻”)的增长比率，比如锂电池的出厂直流内阻记作R b，在某一充电时间点采集到的实时内阻记作R c，则内阻增长率K为(R c-R b)/R b。类似地，内阻增长率K和内阻校准因子b之间的对应关系可以预先存储在移动终端。示例性的，下表1B示出了内阻增长率与内阻校准因子的对应关系表。
表1B
内阻增长率K 内阻校准因子a
≤0％ 1.15
5％ 1
10％ 0.9
20％ 0.8
30％ 0.7
50％ 0.5
80％ 0.2
120％ 0.1
＞120％ 0.05
类似地，单位容量下的电量微分((dQ/dV)/CA)与其校准因子b之间的对应关系可以预先存储在BMS中。示例性的，下表1C示出了(dQ/dV)/CA与其校准因子b的对应关系表。
表1C
Figure PCTCN2022095952-appb-000001
其中，所述锂电池的充电方法包括：当所述锂电池的充电电压达到V s时，若需要所述锂电池发挥出高能量密度特性，则对所述锂电池继续充电至所述V h；若不需要将所述锂电池发挥出高能量密度特性(即，保持长循环寿命特性)，则停止对所述锂电池充电。
其中，是否需要所述锂电池发挥出高能量密度特性，可由充电过程中用户远程开启，也可以在充电前进行模式选择设置。下文会在介绍动力车辆时详细说明。
第四方面，本申请实施例还提供了一种动力车辆300，所述动力车辆的电池系统包括至少一个第一电池单元，所述第一电池单元包括多个如本申请第一方面所述的锂电池。动力车辆的电池系统可以与车辆驱动部301实现通信。示例性的，该动力车辆300可以是为纯 电动汽车，也可以是混合动力电动汽车。车辆驱动部301可以是电动机。
在一些实施方式中，参见图3，动力车辆300的电池系统仅包含第一电池单元1。其中，第一电池单元1可以是“无模组”电池包，或者是“有模组”电池包。当第一电池单元1为“有模组”电池包时，多个锂电池100可通过串联、并联或其组合形成模块化的电池组。如图3所示，第一电池单元1包括多个锂电池100及第一充电控制设备110。第一充电控制设备110用于监管各锂电池的状态信息，如电压、电流、内阻、温度等，并控制各锂电池100的充电情况。第一充电控制设备110可以具体是第一电池单元1的BMS(Battery Management System，电池管理系统)，也可以作为单独的一个模块，与第二电池单元的BMS进行电连接(此时，二者可通过CAN总线连接)。
当动力车辆300的电池系统仅包含第一电池单元1时，可根据动力车辆的实际续航里程需求，在对该锂电池充电时控制其满充或充在较低SOC，既可满足必要时的长续航需求，又可满足保证短续航需求下的长循环寿命。
具体地，所述第一充电控制设备110用于在动力车辆将以第一模式运行时，控制对所述锂电池进行充电时的充电截止电压为V s；所述第一充电控制设备还用于在动力车辆将以第二模式运行时，控制对所述锂电池进行充电时的充电截止电压为V h，且V s＜V h，在所述V s下，所述锂电池的负极不析出锂单质，所述锂电池具有长循环寿命特性，V h为所述锂电池能耐受的充电上限电压；其中，在所述第一模式下，由所述第一电池单元为所述动力车辆提供的续航里程小于在所述第二模式下由所述第一电池单元为所述动力车辆提供的续航里程。这里，可将所述第一模式称为短续航模式，将所述第二模式称为长续航模式。
上述第一模式是动力车辆使用频率较高的模式，例如日常的中短途上下班；第二模式的运行频率较低，通常在假期驾车长途旅行时需要启用。在动力车辆需要在短续航模式运行时，第一电池单元1控制在动力车辆的充电过程中，对上述锂电池不充电至充电上限电压而是充电至较低SOC，可保证电池负极不析出锂单质，从而利于该第一电池单元的锂电池发挥其长循环寿命的特点。而在动力车辆需要在长续航模式运行时，对上述锂电池充满电，以保证该第一电池单元发挥出高能量密度特性。这样，尽管锂电池在“长续航模式”的循环寿命没有其在“短续航模式”的循环寿命长，但由于“长续航模式”的使用频率较低、上述保护层的设置使锂电池100在高能量密度状态下与电解液的副反应被抑制、析锂刺穿隔膜等风险得到降低，使得该动力车辆的第一电池单元整体可具有较多次数的低SOC循环及较多次数的满充循环，并在车辆需要时为车辆释放出长续航里程。
示例性的，动力车辆第一模式下的续航里程可以是400-800km，动力车辆在第二模式的 续航里程可以是800-1200km。此外，上述第一模式也可称为“日常模式”，是动力车辆最常采用的模式。第二模式也可称为“假日模式”，是动力车辆偶尔采用的模式。
其中，在对锂电池进行充电的过程中，若第一充电控制设备110未接收到动力车辆300启用第二运行模式的指令，则默认对锂电池100进行充电的充电截止电压为V s。在对锂电池100进行充电的过程中或在对锂电池100进行充电之前，若第一充电控制设备110接收到动力车辆300启用第二运行模式的指令，则控制对所述锂电池进行充电的充电截止电压为V h。
其中，“动力车辆启用第二运行模式的指令”可以在充电之前进行模式选择设置，或者在充电过程中远程开启。具体地，该指令可由动力车辆的用户按压车辆操作盘的模式按钮发出，或者由用户远程操作能与车辆通信的智能终端等实现(例如，当锂电池的充电电压接近V s时，通过汽车的智能网联系统为用户推送“是否开启长续航模式”等信息)。
本申请一些方式中，若锂电池进行第i次充电时的充电截止电压为V h，则对锂电池进行第i+1次充电时的充电截止电压调整为V s时，所述V s应满足以下公式：
V s＝cV b+a×c×K+b×c×(dQ/dV)/(3.6×CA)，
其中，CA为所述锂电池以0.33C放电时的标称容量，V b为所述锂电池在实时充电容量下负极不析出锂单质的基准电压，K为所述锂电池在第i+1次充电过程中的实时直流内阻与其出厂直流内阻的内阻增长率，dQ/dV为所述锂电池在第i+1次充电过程中的充电电量与充电电压的实时微分值，c为所述锂电池在第i+1次充电过程中的实时电芯温度的校准因子，a为所述K的校准因子，b为(dQ/dV)/CA的校准因子。
如本申请前文所述，此种情况下，调整V s主要是为了缩小V s与V h的差距，保证锂电池在长寿命下的续航里程尽量长。
在另一些实施方式中，参见图4，动力车辆300的电池系统还包括至少一个第二电池单元2，其中，第二电池单元2中包括多个第二单体电池200，第二单体电池200的负极活性材料包括石墨和/或硅基材料。其中，所述硅基材料包括单质硅、硅氧化物、硅基合金和硅碳复合材料中的一种或多种。第二单体电池200为常规的锂电池，不以金属锂(锂单质和/或锂硅合金)作负极活性材料，其能量密度低于本申请第一方面提供的锂电池100的能量密度。
与上述第一电池单元1类似，第二电池单元2可以是“无模组”电池包，或者是“有模组”电池包，其除可包括多个第二单体电池200外，还可包括用于监控第二单体电池200充电的第二充电控制设备210。类似地，第二充电控制设备210可以具体是第二电池单元2的 BMS，也可以是与第二电池单元的BMS进行电连接的独立模块。当然，第二充电控制设备210还可与上述第一充电控制设备110集成在同一控制器中。
本申请一些实施方式中，动力车辆300在第一模式下运行，仅由第二电池单元2为动力车辆300供电；动力车辆300在第二模式下运行，由第一电池单元1和第二电池单元2共同为动力车辆300供电，或者仅由第一电池单元1为动力车辆300供电；其中，所述动力车辆在所述第一模式下的续航里程小于在所述第二模式下的续航里程。
可选地，第一充电控制设备110用于在对第一电池单元1的锂电池100进行充电之前或充电过程中，获知动力车辆将以第二模式运行时，控制对第一电池单元1的锂电池100进行充电时的充电截止电压为上述V h。即，对锂电池100进行充电时可充满电。当然，第一充电控制设备110用于在对第一电池单元1的锂电池100进行充电之前或充电过程中，获知动力车辆将以第二模式运行，且在该第二模式下由第一电池单元1和第二电池单元2共同为动力车辆300供电时，也可以控制对第一电池单元1的锂电池100进行充电时的充电截止电压为上述V s。只是，此种情况下，车辆在第二模式下的续航里程小于由第二电池单元2及充电至V h的第一电池单元1所能提供的续航里程。
在动力车辆300不需要特别长的续航里程(如平时上下班使用该车辆)时，可以只使用低能量密度的第二电池单元2为该车辆提供动力，使该车辆可耐充放电的次数较多，使用寿命更长；当该车辆偶尔需要长的续航里程时(如节假日长途旅行使用该车辆)时，可使用第一电池单元1和第二电池单元2共同为该车辆提供动力或者仅由第一电池单元1为该车辆提供动力，可以使该车辆获得的动力更充足，且能在不牺牲整体循环寿命的前提下，选择性地达到长续航的目的。因此，所述动力车辆可以根据不同续航里程来选择性使用电池系统的不同的电池单元，以使动力车辆中使用频率低的高能量密度的电池单元展现出较长的循环寿命，使得整体的电池系统兼顾长使用寿命和长续航能力。
下面分多个实施例对本申请实施例进行进一步的说明。
实施例1
(1)正极片的制作
将960g的正极活性材料三元NCM 622、30g的粘接剂PVDF、5g的乙炔黑导电剂、5g的碳纤维导电剂加入到2000g的溶剂NMP(氮甲基吡咯烷酮)中，然后在真空搅拌机中搅拌，形成稳定均一的正极浆料；
采用狭缝涂布设备将上述正极浆料均匀地间歇涂布在铝箔(铝箔尺寸为：宽度160mm， 厚度16μm)的两面上；然后在温度393K下烘干，经过辊压机压片后，在铝箔上形成厚度为135μm的正极材料层，得到正极片。之后将正极片剪裁成尺寸为48mm*56mm的长方形极片，并在其在宽度方向位置点焊极耳。
(2)电解液的配制
在充满氩气的手套箱中(H 2O含量≤5ppm，O 2含量≤5ppm)，取乙二醇二甲醚(DME)、1,1,2,2-四氟乙基-2,2,3,3-四氟丙基醚(TTE)、二氟乙酸乙酯(DFEA)，按照体积比DME：TTE：DFEA＝30:50:20进行混合，然后向该混合溶液中加入60wt％的双氟磺酰亚胺锂LiN(SO 2F) 2，得到电解液。
(3)负极片的制作
a、将先将1000g的氧化亚硅粉加入到2000g水中，然后加入50g的聚丙烯酸(PAA)粘结剂及20g的乙炔黑导电剂，强力搅拌至形成均一稳定的负极浆料，采用狭缝涂布设备将该负极浆料均匀地间歇涂布在铜箔(铜箔尺寸为：宽度160mm，厚度8μm)的两面上；然后在温度393K下烘干，经过辊压机压片后，在铜箔上形成厚度为60μm的氧化亚硅负极材料层，得到负极片SA1。
b、先将200g、分子量为60万的PEO加入到2000g乙腈中，然后加入16g纳米氧化铝粉末和10g的无水硝酸锂粉末，强力搅拌至均一稳定的保护层浆料，将该保护层浆料均匀地间歇涂布在负极片SA1上，得到负极片SA2。
c、在手套箱中(H 2O含量≤5ppm，O 2含量≤5ppm)，将上述SA2负极片与覆在PET离型膜上的锂薄膜(锂薄膜厚度为15μm)相贴合，使保护层与锂薄膜接触，在热压机作用下，锂薄膜上的锂元素全部转移到负极片SA2上，得到负极片SA3，其中，该负极片SA3的负极材料层为78μm，其中的锂硅负极活性材料包括锂硅合金和Li 2O。将负极片SA3剪裁尺寸为49mm*57mm的长方形极片，在宽度方向位置点焊极耳，即得到用来组装电池的负电极。
(4)组装电池
将步骤(1)获得的正极片与步骤(3)获得的负极片与隔膜一起交替层叠，获得裸电芯，其中正、负极片之间被隔膜隔开。将该裸电芯置于铝塑膜外包装体中，注入步骤(2)配制得到的电解液，然后抽真空密封后，经60℃下搁置48h、60℃下加压化成、二次封装、排气、分容后，得到本实施例1的锂电池。
其中，实施例1的锂电池在完全充满电的状态下，锂硅复合负极活性材料含有锂单质和锂硅合金Li 4.4Si，且该锂硅复合负极活性材料中，锂单质的摩尔占比为23％，锂硅合金 Li 4.4Si的摩尔占比为71％。
本申请实施例1的锂电池通过以下方法进行充放电循环测试。
将本实施例1的锂电池在LAND CT 2001C二次电池性能检测装置上，25±1℃条件下进行充放电循环测试。其中，第一次常规低SOC循环的步骤如下：搁置10min；先以0.2C恒流充电至充电截止电压为3.95V，再恒压充电至0.05C；搁置10min；然后恒流放电至电压为3.0V，即为1次常规低SOC循环。重复该步骤，进行常规低SOC循环30次。高能量循环的步骤如下：搁置10min；先以0.2C恒流充电至电压4.25V，再恒压充电至0.05C；搁置10min；然后恒流放电至3.0V，即为1次高能量循环。其中，每间隔30次常规循环，进行一次高能量循环。每进行一次高能量循环后采用公式V s＝cV b+a×c×K+b×c×(dQ/dV)/(3.6×CA)校验下一次的常规低SOC循环的充电截止电压。
当循环过程中的电池放电容量低于首次放电容量的80％时，终止循环，该循环次数n即为该锂电池的循环寿命。记录该循环次数n下的容量保持率，并将在该循环次数n下的电池能量密度与首次能量密度的比值作为该锂电池的能量保持率。
实施例2
一种锂电池，其与实施例1的区别在于：步骤(3)中，采用800g的硅粉替换氧化亚硅粉，且覆在PET离型膜上的锂薄膜的厚度为12μm。
其中，实施例2的锂电池在完全充满电的状态下，锂硅复合负极活性材料中，锂单质的摩尔占比为24％，锂硅合金Li 4.4Si的摩尔占比为76％。
按照实施例1提供的充放电制度对实施例2的锂电池进行充电。
实施例3
一种锂电池，其与实施例1的区别在于：步骤(3)中，采用800g的硅粉替换氧化亚硅粉，且覆在PET离型膜上的锂薄膜的厚度为10μm。
其中，实施例3的锂电池在完全充满电的状态下，锂硅复合负极活性材料中，锂单质的摩尔占比为18％，锂硅合金Li 4.4Si的摩尔占比为82％。
按照实施例1提供的充放电制度对实施例3的锂电池进行充电。
实施例4
一种锂电池，其结构与实施例3相同，区别在于：将实施例3中第一次常规低SOC循 环的“0.2C恒流充电至充电截止电压为3.95V”改为充电截止电压为4.0V。
为突出本申请实施例的有益效果，特提供以下对比例：
对比例1
一种锂电池，其与实施例1的区别在于：步骤(3)中，直接将制得的负极片SA1作为组装对比例1锂电池的负极片DS1，实施例1的负极没有锂金属；步骤(2)中，电解液溶剂为酯类溶剂，具体是积比为4：6的碳酸乙烯酯(EC)和碳酸二乙酯(DEC)的混合。
对比例1制备得到的锂电池的充放电循环测试方法如下：各取5支锂电池，在LAND CT2001C二次电池性能检测装置上，25±1℃条件下，将电池以0.2C进行充放电循环测试。步骤如下：搁置10min，先以0.2C恒流充电至充电截止电压为4.2V，再以4.2V恒压充电至0.05C截止；搁置10min，然后恒流放电至3.0V，即为1次充放电循环。
重复以上充放电步骤，当循环过程中电池的放电容量低于首次放电容量的80％时，终止循环，该循环次数n即为该锂电池的循环寿命。记录该循环次数n下的容量保持率，并将在该循环次数n下的电池能量密度与首次能量密度的比值作为该锂电池的能量保持率。
对比例2
一种锂电池的制备，其与实施例1的区别在于：步骤(3)中，未在负极片SA1上形成保护层，而是将负极片SA1与覆在PET离型膜上的锂薄膜进行热压合，将得到的负极片DS2进行组装得到对比例2的锂电池。
为对本申请实施例技术方案带来的有益效果进行有力支持，对电池进行了能量密度(测试电池体积及放电能量)及循环寿命测试。测试结果如表2所示。
表2各组样品的能量密度及循环寿命测试数据表
Figure PCTCN2022095952-appb-000002
从表2可以获知，本申请实施例提供的锂电池同时具备高能量密度及长循环寿命的特质。
以上所述实施例仅表达了本申请的几种示例性实施方式，其描述较为具体和详细，但并不能因此而理解为对本申请专利范围的限制。应当指出的是，对于本领域的普通技术人员来说，在不脱离本申请构思的前提下，还可以做出若干变形和改进，这些都属于本申请的保护范围。因此，本申请专利的保护范围应以所附权利要求为准。

Claims (17)

  1. 一种锂电池，包括正极片、负极片及位于所述正极片与负极片之间的隔膜和电解液，所述负极片的负极材料层中含有锂硅复合负极活性材料，所述负极材料层的表面具有保护层或者所述锂硅复合负极活性材料的表面具有保护层，其中，所述保护层包括聚合物基体和锂盐；且
    在所述锂电池完全充满电的状态下，所述锂硅复合负极活性材料含有锂单质和锂硅合金Li 4.4Si，且所述锂单质在所述锂硅复合负极活性材料中的摩尔占比为15％-95％。
  2. 如权利要求1所述的锂电池，在所述锂电池完全充满电的状态下，所述锂硅合金Li 4.4Si在所述锂硅复合负极活性材料中的摩尔占比为5％-85％。
  3. 如权利要求1或2所述的锂电池，所述聚合物基体包括聚氧化乙烯、聚硅氧烷、聚偏氟乙烯、聚甲基丙烯酸甲酯、聚丙烯腈及其衍生物和共聚物中的一种或多种；所述锂盐包括硝酸锂、硫化锂、氯化锂、溴化锂、碘化锂、氟化锂、磷酸锂中的一种或多种。
  4. 如权利要求1-3任一项所述的锂电池，所述锂电池的N/P比小于1。
  5. 如权利要求1-4任一项所述的锂电池，所述电解液中的溶剂包括醚类溶剂，其中，所述醚类溶剂包括未卤代醚类溶剂和氟代醚类溶剂中的至少一种。
  6. 如权利要求1-5任一项所述的锂电池，在所述锂电池的正极充电的SOC低于第一阈值时，所述锂硅复合负极活性材料不含有锂单质；其中，所述第一阈值为15％-95％。
  7. 一种锂电池的制备方法，包括以下步骤：
    将含硅基材料、导电剂和粘结剂的混合浆料涂布在负极集流体上，经干燥、辊压后，在所述负极集流体上形成硅基材料层；
    在手套箱中，将锂薄膜与所述硅基材料层进行热压处理，以使所述锂薄膜的锂元素全部转移到所述硅基材料层中，并与所述硅基材料原位反应形成含锂硅复合负极活性材料的负极材料层，得到负极片；
    其中，在所述硅基材料层与锂薄膜进行热压处理之前，在所述硅基材料层的表面形成保护层；或者在形成所述负极材料层之后，在所述负极材料层的表面形成保护层；所述保护层包括聚合物基体和锂盐；
    将所述负极片装配成锂电池；其中，在所述锂电池完全充满电的状态下，所述锂硅复合负极活性材料含有锂单质和锂硅合金Li 4.4Si，且所述锂单质在所述锂硅复合负极活性材料中的摩尔占比为15％-95％。
  8. 如权利要求7所述的制备方法，所述硅基材料包括硅单质、硅氧化物、硅基非锂合 金及其他含硅化合物中的至少一种。
  9. 一种如权利要求1-6任一项所述的锂电池的充电方法，包括以下步骤：
    在需要所述锂电池发挥出长循环寿命特性的情况下，控制对所述锂电池进行充电的充电截止电压V s满足以下公式：
    V s＝cV b+a×c×K+b×c×(dQ/dV)/(3.6×CA)，其中，在所述锂电池发挥出长循环寿命特性的情况下，在所述V s下，所述锂电池的负极不析出锂单质，且V s＜V h；
    其中，V h为所述锂电池能耐受的充电上限电压，CA为所述锂电池以0.33C放电时的标称容量，V b为所述锂电池在实时充电容量下负极不析出锂单质的基准电压，K为所述锂电池在充电过程中的实时直流内阻与其出厂直流内阻的内阻增长率，dQ/dV为所述锂电池的充电电量与充电电压的实时微分值，c为所述锂电池在充电过程中的实时电芯温度的校准因子，a为所述K的校准因子，b为(dQ/dV)/CA的校准因子。
  10. 如权利要求9所述的锂电池的充电方法，当所述锂电池的充电电压达到所述V s时，若需要所述锂电池发挥出高能量密度特性，则对所述锂电池继续充电至所述V h；若不需要将所述锂电池发挥出高能量密度特性，则停止对所述锂电池充电；其中，在所述锂电池发挥出高能量密度特性的情况下，所述锂硅复合负极活性材料含有锂单质，所述锂电池的充电截止电压大于所述V s。
  11. 一种动力车辆，所述动力车辆的电池系统包括至少一个第一电池单元，所述第一电池单元包括多个如权利要求1-6任一项所述的锂电池和第一充电控制设备。
  12. 如权利要求11所述的动力车辆，所述第一充电控制设备用于在对所述第一电池单元的锂电池进行充电之前或在充电过程中，且获知所述动力车辆将以第一模式运行时，控制对所述锂电池进行充电时的充电截止电压为V s；
    所述第一充电控制设备还用于在对所述第一电池单元的锂电池进行充电之前或在充电过程中，且获知所述动力车辆将以第二模式运行时，控制对所述锂电池进行充电时的充电截止电压为V h，其中，V h为所述锂电池能耐受的充电上限电压，且V s＜V h，在所述V s下，所述锂电池的负极刚好不析出锂单质；
    其中，所述动力车辆在所述第一模式下的续航里程小于在所述第二模式下的续航里程。
  13. 如权利要求12所述的动力车辆，所述V s满足以下公式：
    V s＝cV b+a×c×K+b×c×(dQ/dV)/(3.6×CA)，
    其中，CA为所述锂电池以0.33C放电时的标称容量，V b为所述锂电池在实时充电容量下负极不析出锂单质的基准电压，K为所述锂电池在充电过程中的实时直流内阻与其出厂直流 内阻的内阻增长率，dQ/dV为所述锂电池的充电电量与充电电压的实时微分值，c为所述锂电池在充电过程中的实时电芯温度的校准因子，a为所述K的校准因子，b为(dQ/dV)/CA的校准因子。
  14. 如权利要求11所述的动力车辆，所述动力车辆的电池系统还包括至少一个第二电池单元，所述第二电池单元包括多个第二单体电池，所述第二单体电池的负极活性材料包括石墨和/或硅基材料。
  15. 如权利要求14所述的动力车辆，所述动力车辆在第一模式下运行，仅由所述第二电池单元为所述动力车辆供电；所述动力车辆在第二模式下运行，由所述第一电池单元和所述第二电池单元共同为所述动力车辆供电，或者仅由所述第一电池单元为所述动力车辆供电；
    其中，所述动力车辆在所述第一模式下的续航里程小于在所述第二模式下的续航里程。
  16. 如权利要求15所述的动力车辆，在对所述第一电池单元进行充电之前或充电过程中，所述第一充电控制设备获知所述动力车辆将以第二模式运行，且仅由所述第一电池单元为所述动力车辆供电时，控制对所述第一电池单元的各锂电池进行充电时的充电截止电压为V h，其中，V h为所述锂电池能耐受的充电上限电压。
  17. 如权利要求15所述的动力车辆，在对所述第一电池单元进行充电之前或充电过程中，所述第一充电控制设备获知所述动力车辆将以第二模式运行，且由所述第一电池单元和所述第二电池单元共同为所述动力车辆供电时，控制对所述第一电池单元的各锂电池进行充电时的充电截止电压为V s或V h；
    其中，V h为所述锂电池能耐受的充电上限电压；在所述V s下，所述锂电池的负极不析出锂单质，V s＜V h；且所述V s满足以下公式：
    V s＝cV b+a×c×K+b×c×(dQ/dV)/(3.6×CA)，
    其中，CA为所述锂电池以0.33C放电时的标称容量，V b为所述锂电池在实时充电容量下负极不析出锂单质的基准电压，K为所述锂电池在充电过程中的实时直流内阻与其出厂直流内阻的内阻增长率，dQ/dV为所述锂电池的充电电量与充电电压的实时微分值，c为所述锂电池在充电过程中的实时电芯温度的校准因子，a为所述K的校准因子，b为(dQ/dV)/CA的校准因子。
PCT/CN2022/095952 2021-06-29 2022-05-30 锂电池及其制备方法、充电方法和动力车辆 WO2023273760A1 (zh)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP22831582.6A EP4345943A1 (en) 2021-06-29 2022-05-30 Lithium battery and preparation method therefor, charging method, and power vehicle
CA3223903A CA3223903A1 (en) 2021-06-29 2022-05-30 Lithium battery and preparation method therefor, charging method, and power vehicle
KR1020237045101A KR20240014077A (ko) 2021-06-29 2022-05-30 리튬 배터리 및 그의 제조 방법, 충전 방법, 및 동력 차량
US18/398,471 US20240145760A1 (en) 2021-06-29 2023-12-28 Lithium battery and preparation method therefor, charging method, and power vehicle

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202110730852.6 2021-06-29
CN202110730852.6A CN115548275A (zh) 2021-06-29 2021-06-29 锂电池及其制备方法、充电方法和动力车辆

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US18/398,471 Continuation US20240145760A1 (en) 2021-06-29 2023-12-28 Lithium battery and preparation method therefor, charging method, and power vehicle

Publications (1)

Publication Number Publication Date
WO2023273760A1 true WO2023273760A1 (zh) 2023-01-05

Family

ID=84692515

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2022/095952 WO2023273760A1 (zh) 2021-06-29 2022-05-30 锂电池及其制备方法、充电方法和动力车辆

Country Status (6)

Country Link
US (1) US20240145760A1 (zh)
EP (1) EP4345943A1 (zh)
KR (1) KR20240014077A (zh)
CN (1) CN115548275A (zh)
CA (1) CA3223903A1 (zh)
WO (1) WO2023273760A1 (zh)

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007080619A (ja) * 2005-09-13 2007-03-29 Sony Corp 電池
JP2009199761A (ja) * 2008-02-19 2009-09-03 Nissan Motor Co Ltd リチウムイオン電池
US20170170473A1 (en) * 2014-02-03 2017-06-15 Ramot At Tel-Aviv University Ltd. Anode compositions and alkali metal batteries comprising same
CN109411694A (zh) * 2018-10-22 2019-03-01 天齐锂业（江苏）有限公司 一种金属锂复合负极及其制备方法与应用
US20190115617A1 (en) * 2017-10-13 2019-04-18 Nanotek Instruments, Inc. Surface-Stabilized Anode Active Material Particulates for Lithium Batteries and Production Method
JP2020095931A (ja) * 2018-12-11 2020-06-18 Tdk株式会社 リチウム二次電池
CN111952545A (zh) * 2019-05-16 2020-11-17 同济大学 预锂化后的锂离子二次电池负极材料及其机械预锂化方法
CN112397686A (zh) * 2020-11-13 2021-02-23 微宏动力系统（湖州）有限公司 负极、锂离子二次电池及其制备方法

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007080619A (ja) * 2005-09-13 2007-03-29 Sony Corp 電池
JP2009199761A (ja) * 2008-02-19 2009-09-03 Nissan Motor Co Ltd リチウムイオン電池
US20170170473A1 (en) * 2014-02-03 2017-06-15 Ramot At Tel-Aviv University Ltd. Anode compositions and alkali metal batteries comprising same
US20190115617A1 (en) * 2017-10-13 2019-04-18 Nanotek Instruments, Inc. Surface-Stabilized Anode Active Material Particulates for Lithium Batteries and Production Method
CN109411694A (zh) * 2018-10-22 2019-03-01 天齐锂业（江苏）有限公司 一种金属锂复合负极及其制备方法与应用
JP2020095931A (ja) * 2018-12-11 2020-06-18 Tdk株式会社 リチウム二次電池
CN111952545A (zh) * 2019-05-16 2020-11-17 同济大学 预锂化后的锂离子二次电池负极材料及其机械预锂化方法
CN112397686A (zh) * 2020-11-13 2021-02-23 微宏动力系统（湖州）有限公司 负极、锂离子二次电池及其制备方法

Also Published As

Publication number Publication date
CA3223903A1 (en) 2023-01-05
KR20240014077A (ko) 2024-01-31
US20240145760A1 (en) 2024-05-02
CN115548275A (zh) 2022-12-30
EP4345943A1 (en) 2024-04-03

Similar Documents

Publication Publication Date Title
JP5228576B2 (ja) リチウムイオン二次電池及び電気自動車用電源
CN112151764A (zh) 一种电极极片及其制备方法和应用
WO2013185629A1 (zh) 一种高能量密度充放电锂电池
CN111463403A (zh) 复合人工固态电解质界面膜修饰的负极材料及其电池应用
WO2021109811A1 (zh) 二次电池及含有它的电池模块、电池包和装置
CA3198026A1 (en) Lithium-ion battery
KR20160125895A (ko) 비수전해질 이차 전지용 부극 활물질 및 그의 제조 방법, 및 그 부극 활물질을 사용한 비수전해질 이차 전지 및 비수전해질 이차 전지용 부극재의 제조 방법
US20220352550A1 (en) Solid-state battery, battery module, battery pack, and apparatus associated therewith
CN112736277A (zh) 固态电解质-锂负极复合体及其制备方法和全固态锂二次电池
CN115148960A (zh) 负极极片及包含该负极极片的电化学装置、电子装置
WO2023070988A1 (zh) 电化学装置和包含其的电子装置
KR20160036577A (ko) 리튬 2 차 전지 및 리튬 2 차 전지용 전해액
CN116169249A (zh) 一种负极片、二次电池以及用电设备
CN109494348B (zh) 负极极片及二次电池
CN101783401A (zh) 一种负极和包括该负极的锂离子二次电池
WO2024016940A1 (zh) 正极片、二次电池、电池模组、电池包和用电装置
CN111864205B (zh) 硫化物固态电池正极极片及硫化物固态电池
CN115472896B (zh) 二次电池及用电装置
CN111463481A (zh) 一种复合准固态电解质、制备方法及全电池
WO2023184133A1 (zh) 负极极片、用于电化学装置中的负极极片、电化学装置及电子设备
WO2022241712A1 (zh) 锂离子二次电池、电池模块、电池包以及用电装置
WO2023273760A1 (zh) 锂电池及其制备方法、充电方法和动力车辆
WO2021258275A1 (zh) 二次电池和包含该二次电池的装置
US20220285744A1 (en) Battery system, and method of using the same and battery pack including the same
WO2023098311A1 (zh) 一种电化学装置和电子装置

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 22831582

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 3223903

Country of ref document: CA

ENP Entry into the national phase

Ref document number: 2023580400

Country of ref document: JP

Kind code of ref document: A

Ref document number: 20237045101

Country of ref document: KR

Kind code of ref document: A

WWE Wipo information: entry into national phase

Ref document number: 1020237045101

Country of ref document: KR

WWE Wipo information: entry into national phase

Ref document number: 2022831582

Country of ref document: EP

NENP Non-entry into the national phase

Ref country code: DE

ENP Entry into the national phase

Ref document number: 2022831582

Country of ref document: EP

Effective date: 20231228